This document provides an overview of artificial human vision (AHV) technology and research. It discusses the main causes of blindness worldwide and the mobility challenges faced by blind individuals. Four locations for electrical stimulation to restore vision are reviewed: subretinal, epiretinal, optic nerve, and visual cortex. Cortical stimulation research dating back to the 1920s is summarized, including both surface electrode and intracortinal electrode studies. Key AHV system requirements like cameras, image processing, transmitters/receivers, and stimulators/electrodes are also outlined. The document reviews some of the major research projects exploring cortical stimulation to restore vision, including work by Dobelle, Brindley & Lewin, the US National
Neuroradiology is the subspecialty of radiology focused on imaging the central and peripheral nervous systems. The document discusses several key imaging modalities used in neuroradiology including CT, MRI, ultrasound, angiography, and myelography. It provides details on the techniques, advantages, and limitations of each modality. CT and MRI are currently the main modalities used for evaluating neurological pathology, though each has specific scenarios where it is particularly useful over the other. Recent technological advances have improved imaging capabilities and increased accessibility of various modalities.
The document provides an overview of approaches to artificial vision and visual neuroprosthetics. It discusses the history of artificial vision from early electrical stimulation experiments to modern retinal implants. Current approaches to prosthetic rehabilitation include epiretinal, subretinal, transchoroidal, and optic nerve implants as well as cortical implants. Each approach has advantages and drawbacks related to safety, acuity restoration potential, and applicable patient populations. Key challenges to developing effective neuroprosthetics include electrode miniaturization, signal processing algorithms, and targeting specific cell types. The field remains nascent but promising strategies involving optogenetics and cell therapy are emerging.
Image Processing Technique for Brain Abnormality DetectionCSCJournals
Medical imaging is expensive and very much sophisticated because of proprietary software and expert personalities. This paper introduces an inexpensive, user friendly general-purpose image processing tool and visualization program specifically designed in MATLAB to detect much of the brain disorders as early as possible. The application provides clinical and quantitative analysis of medical images. Minute structural difference of brain gradually results in major disorders such as schizophrenia, Epilepsy, inherited speech and language disorder, Alzheimer's dementia etc. Here the main focusing is given to diagnose the disease related to the brain and its psychic nature (Alzheimer’s disease).
Artificial Implants and the Field of Visual Prosthesis Research PaperBrittney Pfeifer
This document summarizes artificial implants and the field of visual prosthesis. It discusses how retinal diseases like age-related macular degeneration and retinitis pigmentosa cause blindness but leave the visual pathway intact, opening possibilities for visual prostheses. The history of the field is outlined from early electrical stimulation experiments in the brain and retina to establishing cortical, optic nerve, and retinal prostheses. Examples of current epiretinal prostheses like Argus II and subretinal prostheses like Alpha-IMS are provided, along with their advantages and disadvantages.
The document discusses the development of an artificial eye called the Argus II, which aims to restore functional vision. It consists of a camera that attaches to glasses and captures images, a processing unit that converts images to electrical signals, and an implant with electrodes that stimulates the retina to produce phosphenes resembling dots of light. Several patients have been able to perform basic visual tasks like detecting objects and reading large text after receiving the implant. While promising, the technology is still limited and very expensive, but ongoing research seeks to improve artificial vision systems.
Bionic eye is a device that can provide sight-detection of light.
Researches working for the Boston Retinal Implant Project have been developing Bionic eye implant that could restore the eye sight of people who suffer from age related blindness.
It is based on a small chip that is surgically implanted behind the retina, at the back of the eye ball.
Ultra thin wires strengthens the damaged optic nerve.
The user should wear special eye glasses battery powered camera and a transmitter.
This document provides an overview of bionic eyes, including how they work and their development. It discusses how Dr. Mark Humayun's research in the late 1990s demonstrated that electrical stimulation of the optic nerve could allow blind individuals to see light. This led to efforts to create a retinal prosthesis that could translate images into electrical pulses. The Argus II is described as the first approved bionic eye, consisting of an externally worn camera and processor that transmit data and power to an implanted retinal chip. The document outlines the components of the Argus II and how it provides a basic form of artificial vision. It notes ongoing research aims to improve resolution and develop third generation devices. Limitations include the invasive surgery required and current high
Artificial Implants and the Field of Visual ProsthesisBrittney Pfeifer
This document outlines a presentation on visual prostheses and a study testing the Alpha-IMS subretinal prosthesis. The presentation covers retinal anatomy, diseases like AMD and RP, and different types of prostheses. The study tested the Alpha-IMS device in 9 patients, finding it restored some visual function like light perception and motion detection. Patients reported recognizing faces, objects, and letters. While results were promising, long-term testing is still needed to evaluate stability and recognition abilities over time. Visual prostheses show potential to treat retinal diseases but continued research and development is required.
Neuroradiology is the subspecialty of radiology focused on imaging the central and peripheral nervous systems. The document discusses several key imaging modalities used in neuroradiology including CT, MRI, ultrasound, angiography, and myelography. It provides details on the techniques, advantages, and limitations of each modality. CT and MRI are currently the main modalities used for evaluating neurological pathology, though each has specific scenarios where it is particularly useful over the other. Recent technological advances have improved imaging capabilities and increased accessibility of various modalities.
The document provides an overview of approaches to artificial vision and visual neuroprosthetics. It discusses the history of artificial vision from early electrical stimulation experiments to modern retinal implants. Current approaches to prosthetic rehabilitation include epiretinal, subretinal, transchoroidal, and optic nerve implants as well as cortical implants. Each approach has advantages and drawbacks related to safety, acuity restoration potential, and applicable patient populations. Key challenges to developing effective neuroprosthetics include electrode miniaturization, signal processing algorithms, and targeting specific cell types. The field remains nascent but promising strategies involving optogenetics and cell therapy are emerging.
Image Processing Technique for Brain Abnormality DetectionCSCJournals
Medical imaging is expensive and very much sophisticated because of proprietary software and expert personalities. This paper introduces an inexpensive, user friendly general-purpose image processing tool and visualization program specifically designed in MATLAB to detect much of the brain disorders as early as possible. The application provides clinical and quantitative analysis of medical images. Minute structural difference of brain gradually results in major disorders such as schizophrenia, Epilepsy, inherited speech and language disorder, Alzheimer's dementia etc. Here the main focusing is given to diagnose the disease related to the brain and its psychic nature (Alzheimer’s disease).
Artificial Implants and the Field of Visual Prosthesis Research PaperBrittney Pfeifer
This document summarizes artificial implants and the field of visual prosthesis. It discusses how retinal diseases like age-related macular degeneration and retinitis pigmentosa cause blindness but leave the visual pathway intact, opening possibilities for visual prostheses. The history of the field is outlined from early electrical stimulation experiments in the brain and retina to establishing cortical, optic nerve, and retinal prostheses. Examples of current epiretinal prostheses like Argus II and subretinal prostheses like Alpha-IMS are provided, along with their advantages and disadvantages.
The document discusses the development of an artificial eye called the Argus II, which aims to restore functional vision. It consists of a camera that attaches to glasses and captures images, a processing unit that converts images to electrical signals, and an implant with electrodes that stimulates the retina to produce phosphenes resembling dots of light. Several patients have been able to perform basic visual tasks like detecting objects and reading large text after receiving the implant. While promising, the technology is still limited and very expensive, but ongoing research seeks to improve artificial vision systems.
Bionic eye is a device that can provide sight-detection of light.
Researches working for the Boston Retinal Implant Project have been developing Bionic eye implant that could restore the eye sight of people who suffer from age related blindness.
It is based on a small chip that is surgically implanted behind the retina, at the back of the eye ball.
Ultra thin wires strengthens the damaged optic nerve.
The user should wear special eye glasses battery powered camera and a transmitter.
This document provides an overview of bionic eyes, including how they work and their development. It discusses how Dr. Mark Humayun's research in the late 1990s demonstrated that electrical stimulation of the optic nerve could allow blind individuals to see light. This led to efforts to create a retinal prosthesis that could translate images into electrical pulses. The Argus II is described as the first approved bionic eye, consisting of an externally worn camera and processor that transmit data and power to an implanted retinal chip. The document outlines the components of the Argus II and how it provides a basic form of artificial vision. It notes ongoing research aims to improve resolution and develop third generation devices. Limitations include the invasive surgery required and current high
Artificial Implants and the Field of Visual ProsthesisBrittney Pfeifer
This document outlines a presentation on visual prostheses and a study testing the Alpha-IMS subretinal prosthesis. The presentation covers retinal anatomy, diseases like AMD and RP, and different types of prostheses. The study tested the Alpha-IMS device in 9 patients, finding it restored some visual function like light perception and motion detection. Patients reported recognizing faces, objects, and letters. While results were promising, long-term testing is still needed to evaluate stability and recognition abilities over time. Visual prostheses show potential to treat retinal diseases but continued research and development is required.
The document discusses bionic eyes, which are electronic devices that can replace dysfunctional parts of the eye and restore vision. It describes two approaches for a bionic eye - an artificial silicon retina (ASR) which is a microchip implanted under the retina, and a multi-unit artificial retina chipset (MARC) which uses an external camera, transmitter and implanted chip and electrodes. Both aim to stimulate remaining healthy retinal cells and transmit signals to the brain to provide a limited form of artificial vision. However, challenges remain in developing a bionic eye with sufficient resolution and long-term durability.
The Argus II is a retinal prosthesis system that provides a sense of sight to people who are blind from conditions like macular degeneration. It consists of a camera and video processing unit that captures images and converts them to electrical pulses, a transmitter that sends the pulses to an implanted retinal stimulator with electrodes, which substitutes for damaged photoreceptors. The implant stimulates the retina to allow the brain to interpret patterns of light and dark and form basic visual perceptions. Early testing shows recipients can detect shapes and motion, and the technology may eventually provide clearer vision like facial recognition.
The document discusses electronic eye technology for the blind. It describes how electronic eyes work by replacing damaged photoreceptors or simulating remaining retinal cells. Techniques discussed include the MIT-Harvard device, Artificial Silicon Retina (ASR), Multi-unit Artificial Retina Chipset System (MARC), and Argus II. MARC is highlighted as using a 6x6mm chip with diagnostic capabilities to stimulate the retina with less stress. While electronic eyes have advantages like size and function, challenges remain in powering them and interfacing with the brain.
1. Scientists are developing a bionic eye called an artificial retina that could restore vision. It works by using a small implanted chip with light-sensitive cells that transmit signals to the optic nerve and brain.
2. The chip detects incoming light and transmits electrical signals to stimulate remaining retinal cells. Early versions used silicon but now scientists are testing ceramic cells that are safer for the human body.
3. The surgery to implant the chip involves making small incisions to insert the chip and use fluid to lift the retina and seal it over the chip. The goal is to replace damaged photoreceptor cells and restore basic vision.
This document discusses an artificial vision system that could restore sight for those with retinal diseases. It describes the major components of the system: an artificial silicon retina implanted in the eye that converts light to electrical signals; a miniature video camera that captures images; a video processing unit that simplifies the images; and an infrared LCD screen on goggles that converts signals to light pulses for the retina. The system provides basic vision allowing users to identify objects, but has limitations in cost, resolution, and applicability to infants. Overall, it represents an important breakthrough for treating retinal degeneration and other vision-impairing diseases.
visual prosthesis replicates the natural vision of the eye and are one of the newer innovations in the field of ophthalmology. Helps in degenerative disease like Age related macular degeneration , retinitis pigmentosa etc.
The document discusses various methods for providing artificial vision to blind individuals, including digital artificial vision using a miniature camera, microchip, and electrode array implanted in the occipital lobe of the brain. The camera feeds images to a microcomputer for edge detection processing before electrical signals are sent to each electrode to simulate vision. The electrodes are implanted by piercing a platinum foil ground plate inserted into the skull. This allows blind individuals to perceive visual stimuli through artificial stimulation of the visual cortex.
An artificial eye is a prosthetic that replaces a missing natural eye. It fits over an orbital implant under the eyelids. The document discusses how eyes work and the visual system, and describes the manufacturing process for artificial eyes. It also outlines different types of eye removal surgeries and possible medical conditions that could necessitate an artificial eye. The conclusion discusses how this research aims to help those who are visually impaired or blind, and could aid other human-machine interface projects.
The document describes the development of an "Electronic Eye" technology to help restore vision. Researchers are creating an artificial retina made of silicon microchips that can be implanted in the eye. The chips contain photodiodes that convert light into electrical signals to bypass retinal cells damaged by conditions like macular degeneration. Early results show people able to see spots of light or basic shapes. The technology relies on a small camera, processor, and implants in the visual cortex to allow some sight. This could help the millions of people worldwide suffering from blindness.
Argus II is an electronic retinal implant
It is manufactured by the American company Second Sight Medical Products
The technology and development of Argus II was pioneered by Mark Humayun
Argus II retinal prosthesis aimed at partially restoring vision to people blinded by retinal degenerative diseases such as retinitis pigmentosa (RP).
Argus II retinal prosthesis system received CE (Conformité Européenne) marking in March 2011 and the Food and Drug Administration (FDA) approval in February 2013
Wheelchair controlled by human brainwave using brain-computer interface syste...journalBEEI
1. Researchers developed an integrated wheelchair controlled by human brainwaves using a brain-computer interface system. An electroencephalography device called Mindwave Mobile Plus was used to obtain attention values, eye blink detection, and eyebrow movement to control the wheelchair's movement and modes.
2. Statistical analysis found that the threshold attention values for controlling the wheelchair differed according to users' gender and age. For example, the threshold was higher for male adults than female children.
3. Testing showed the system could reliably detect users' attention levels, eye blinks, and eyebrow movements to move the wheelchair forward, backward, left, and right or stop through brainwave signals alone. This provided a new assistive technology option
The document discusses artificial eyes and how they work. It describes that artificial eyes consist of a camera, video processing unit, radio transmitter, radio receiver, and retinal implant. The camera captures images and sends them to the video processing unit which simplifies the images into light spots. The processed images are then sent to the retinal implant via the radio transmitter and receiver. The retinal implant stimulates the retina and optic nerve to send signals to the brain, allowing individuals with eye diseases to regain vision. The technology provides basic object and shape recognition but has limitations such as the need for surgery and the high cost. It represents an important development for restoring sight.
This document summarizes research on bionic eye technologies and their applications. It discusses two main types of retinal prosthesis devices - epiretinal (Argus II) and subretinal (Alpha IMS). Both have been tested in clinical trials involving patients with retinitis pigmentosa and age-related macular degeneration. Results show some success in restoring basic visual functions like detecting light, objects, and movement. However, challenges remain around providing sufficient power and interfacing with the brain. Overall, these technologies demonstrate the potential for restoring vision to those with retinal diseases, though continued advances are still needed.
This document summarizes an artificial retina system (ARS) that aims to restore vision to blind individuals. It discusses the history of ARS development led by Dr. Mark Humayun beginning in 2002. The first ARS model, Argus I, contained 16 electrodes and allowed patients to distinguish light and dark and locate objects. Later models like Argus II contained more electrodes and were smaller and less invasive. The ARS works by implanting a chip containing electrodes that stimulate the retina. Technological challenges remain around biocompatibility, resolution, and cost, but advances are being made to improve the design. The overall goal is for ARS to help millions of blind individuals see well enough to navigate, read, and recognize faces
The document discusses the development of artificial vision technology known as the Argus II retinal prosthesis system. It describes the components of the system, which includes a small implanted electronic device, an external video camera and processing unit. The camera captures images and sends signals to the implant, which stimulates neurons in the retina to allow individuals to perceive patterns of light and basic shapes. While providing an ability to perform some visual tasks, the technology remains limited and very expensive. Future developments aim to reduce costs and further miniaturize the devices using advanced technologies.
- The study evaluated the feasibility of using iPad technology to allow remote stroke assessments via telemedicine while patients were in a moving ambulance.
- Interrater reliability between remote and in-person National Institutes of Health Stroke Scale (NIHSS) assessments on 30 simulated stroke patients in ambulances was strong, except for assessments of language and motor function of the right leg which had poorer agreement.
- Technological issues like audiovisual problems impacted some assessments remotely, but the overall high success rate indicates telestroke in ambulances is feasible and could help reduce time to treatment for acute stroke patients.
Intracerebral Hemorrhage (ICH): Understanding the CT imaging featuresPetteriTeikariPhD
Overview of CT basics and deep learning literature mostly focused on the analysis of ICH.
Intracerebral hemorrhage (ICH), also known as cerebral bleed, is a type of intracranial bleed that occurs within the brain tissue or ventricles. Intracerebral bleeds are the second most common cause of stroke, accounting for 10% of hospital admissions for stroke.
For spontaneous ICH seen on CT scan, the death rate (mortality) is 34–50% by 30 days after the insult,and half of the deaths occur in the first 2 days. Even though the majority of deaths occurs in the first days after ICH, survivors have a long term excess mortality of 27% compared to the general population.
Deep learning and computational steps roughly can be categorized to 1) Preprocessing, 2) Image Restoration (denoising, deblurring, inpainting, reconstruction), 3) Diffeomorphic registration for spatial normalization, 4) Hand-crafted radiomics and texture analysis, 5) Hemorrhage segmentation, among other relevant head CT issues
Alternative download link: https://www.dropbox.com/s/8l2h93cl2pmle4g/CT_hemorrhage.pdf?dl=0
Elekta's Versa HD linear accelerators provide Odense University Hospital the speed needed to routinely perform stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) for multiple patients per week. Versa HD's high dose rate mode and fast-moving leaves reduce treatment times by 60%, allowing lung SBRT to be delivered in about 3 minutes and brain SRS in 20 minutes. This efficiency has led OUH to treat over 250 patients with SBRT/SRS annually since acquiring Versa HD in 2013.
The document discusses the development of an artificial retina using thin film transistor technology. It describes how retinal conditions like retinitis pigmentosa and age-related macular degeneration cause vision loss and how an artificial retina could help. The artificial retina would be implanted either on top of the retina (epiretinal) or underneath (subretinal) and use thin film transistors to detect light and stimulate remaining retinal cells via electrical pulses. Both approaches have advantages and disadvantages relating to attachment, heat dissipation, power requirements and image processing. Complications from long-term implantation are also addressed. The technology shows promise for restoring basic vision but has limitations and further development is still needed.
in this presentation we have worked in the theme of bio MEMS in the midical staffs specially in bionic eye
this technologie help blind peopls to get there vision back
thanks to Pr.brandly in 1960 how invented the first device which colled bionic eye
Using off-the-shelf ultrasound imagers, and transition to portable system-on-chip ultrasound imagers such as Butterfly IQ.
Embedded devices such as Butterfly IQ can be further improved by integrating deep learning / artificial intelligence at device level, and naturally at the post-processing and analysis levels
Alternative download link:
https://www.dropbox.com/s/rlwv7m29mh6y2w6/pupillometry_throughTheEyelids.pdf?dl=0
The document discusses bionic eyes, which are electronic devices that can replace dysfunctional parts of the eye and restore vision. It describes two approaches for a bionic eye - an artificial silicon retina (ASR) which is a microchip implanted under the retina, and a multi-unit artificial retina chipset (MARC) which uses an external camera, transmitter and implanted chip and electrodes. Both aim to stimulate remaining healthy retinal cells and transmit signals to the brain to provide a limited form of artificial vision. However, challenges remain in developing a bionic eye with sufficient resolution and long-term durability.
The Argus II is a retinal prosthesis system that provides a sense of sight to people who are blind from conditions like macular degeneration. It consists of a camera and video processing unit that captures images and converts them to electrical pulses, a transmitter that sends the pulses to an implanted retinal stimulator with electrodes, which substitutes for damaged photoreceptors. The implant stimulates the retina to allow the brain to interpret patterns of light and dark and form basic visual perceptions. Early testing shows recipients can detect shapes and motion, and the technology may eventually provide clearer vision like facial recognition.
The document discusses electronic eye technology for the blind. It describes how electronic eyes work by replacing damaged photoreceptors or simulating remaining retinal cells. Techniques discussed include the MIT-Harvard device, Artificial Silicon Retina (ASR), Multi-unit Artificial Retina Chipset System (MARC), and Argus II. MARC is highlighted as using a 6x6mm chip with diagnostic capabilities to stimulate the retina with less stress. While electronic eyes have advantages like size and function, challenges remain in powering them and interfacing with the brain.
1. Scientists are developing a bionic eye called an artificial retina that could restore vision. It works by using a small implanted chip with light-sensitive cells that transmit signals to the optic nerve and brain.
2. The chip detects incoming light and transmits electrical signals to stimulate remaining retinal cells. Early versions used silicon but now scientists are testing ceramic cells that are safer for the human body.
3. The surgery to implant the chip involves making small incisions to insert the chip and use fluid to lift the retina and seal it over the chip. The goal is to replace damaged photoreceptor cells and restore basic vision.
This document discusses an artificial vision system that could restore sight for those with retinal diseases. It describes the major components of the system: an artificial silicon retina implanted in the eye that converts light to electrical signals; a miniature video camera that captures images; a video processing unit that simplifies the images; and an infrared LCD screen on goggles that converts signals to light pulses for the retina. The system provides basic vision allowing users to identify objects, but has limitations in cost, resolution, and applicability to infants. Overall, it represents an important breakthrough for treating retinal degeneration and other vision-impairing diseases.
visual prosthesis replicates the natural vision of the eye and are one of the newer innovations in the field of ophthalmology. Helps in degenerative disease like Age related macular degeneration , retinitis pigmentosa etc.
The document discusses various methods for providing artificial vision to blind individuals, including digital artificial vision using a miniature camera, microchip, and electrode array implanted in the occipital lobe of the brain. The camera feeds images to a microcomputer for edge detection processing before electrical signals are sent to each electrode to simulate vision. The electrodes are implanted by piercing a platinum foil ground plate inserted into the skull. This allows blind individuals to perceive visual stimuli through artificial stimulation of the visual cortex.
An artificial eye is a prosthetic that replaces a missing natural eye. It fits over an orbital implant under the eyelids. The document discusses how eyes work and the visual system, and describes the manufacturing process for artificial eyes. It also outlines different types of eye removal surgeries and possible medical conditions that could necessitate an artificial eye. The conclusion discusses how this research aims to help those who are visually impaired or blind, and could aid other human-machine interface projects.
The document describes the development of an "Electronic Eye" technology to help restore vision. Researchers are creating an artificial retina made of silicon microchips that can be implanted in the eye. The chips contain photodiodes that convert light into electrical signals to bypass retinal cells damaged by conditions like macular degeneration. Early results show people able to see spots of light or basic shapes. The technology relies on a small camera, processor, and implants in the visual cortex to allow some sight. This could help the millions of people worldwide suffering from blindness.
Argus II is an electronic retinal implant
It is manufactured by the American company Second Sight Medical Products
The technology and development of Argus II was pioneered by Mark Humayun
Argus II retinal prosthesis aimed at partially restoring vision to people blinded by retinal degenerative diseases such as retinitis pigmentosa (RP).
Argus II retinal prosthesis system received CE (Conformité Européenne) marking in March 2011 and the Food and Drug Administration (FDA) approval in February 2013
Wheelchair controlled by human brainwave using brain-computer interface syste...journalBEEI
1. Researchers developed an integrated wheelchair controlled by human brainwaves using a brain-computer interface system. An electroencephalography device called Mindwave Mobile Plus was used to obtain attention values, eye blink detection, and eyebrow movement to control the wheelchair's movement and modes.
2. Statistical analysis found that the threshold attention values for controlling the wheelchair differed according to users' gender and age. For example, the threshold was higher for male adults than female children.
3. Testing showed the system could reliably detect users' attention levels, eye blinks, and eyebrow movements to move the wheelchair forward, backward, left, and right or stop through brainwave signals alone. This provided a new assistive technology option
The document discusses artificial eyes and how they work. It describes that artificial eyes consist of a camera, video processing unit, radio transmitter, radio receiver, and retinal implant. The camera captures images and sends them to the video processing unit which simplifies the images into light spots. The processed images are then sent to the retinal implant via the radio transmitter and receiver. The retinal implant stimulates the retina and optic nerve to send signals to the brain, allowing individuals with eye diseases to regain vision. The technology provides basic object and shape recognition but has limitations such as the need for surgery and the high cost. It represents an important development for restoring sight.
This document summarizes research on bionic eye technologies and their applications. It discusses two main types of retinal prosthesis devices - epiretinal (Argus II) and subretinal (Alpha IMS). Both have been tested in clinical trials involving patients with retinitis pigmentosa and age-related macular degeneration. Results show some success in restoring basic visual functions like detecting light, objects, and movement. However, challenges remain around providing sufficient power and interfacing with the brain. Overall, these technologies demonstrate the potential for restoring vision to those with retinal diseases, though continued advances are still needed.
This document summarizes an artificial retina system (ARS) that aims to restore vision to blind individuals. It discusses the history of ARS development led by Dr. Mark Humayun beginning in 2002. The first ARS model, Argus I, contained 16 electrodes and allowed patients to distinguish light and dark and locate objects. Later models like Argus II contained more electrodes and were smaller and less invasive. The ARS works by implanting a chip containing electrodes that stimulate the retina. Technological challenges remain around biocompatibility, resolution, and cost, but advances are being made to improve the design. The overall goal is for ARS to help millions of blind individuals see well enough to navigate, read, and recognize faces
The document discusses the development of artificial vision technology known as the Argus II retinal prosthesis system. It describes the components of the system, which includes a small implanted electronic device, an external video camera and processing unit. The camera captures images and sends signals to the implant, which stimulates neurons in the retina to allow individuals to perceive patterns of light and basic shapes. While providing an ability to perform some visual tasks, the technology remains limited and very expensive. Future developments aim to reduce costs and further miniaturize the devices using advanced technologies.
- The study evaluated the feasibility of using iPad technology to allow remote stroke assessments via telemedicine while patients were in a moving ambulance.
- Interrater reliability between remote and in-person National Institutes of Health Stroke Scale (NIHSS) assessments on 30 simulated stroke patients in ambulances was strong, except for assessments of language and motor function of the right leg which had poorer agreement.
- Technological issues like audiovisual problems impacted some assessments remotely, but the overall high success rate indicates telestroke in ambulances is feasible and could help reduce time to treatment for acute stroke patients.
Intracerebral Hemorrhage (ICH): Understanding the CT imaging featuresPetteriTeikariPhD
Overview of CT basics and deep learning literature mostly focused on the analysis of ICH.
Intracerebral hemorrhage (ICH), also known as cerebral bleed, is a type of intracranial bleed that occurs within the brain tissue or ventricles. Intracerebral bleeds are the second most common cause of stroke, accounting for 10% of hospital admissions for stroke.
For spontaneous ICH seen on CT scan, the death rate (mortality) is 34–50% by 30 days after the insult,and half of the deaths occur in the first 2 days. Even though the majority of deaths occurs in the first days after ICH, survivors have a long term excess mortality of 27% compared to the general population.
Deep learning and computational steps roughly can be categorized to 1) Preprocessing, 2) Image Restoration (denoising, deblurring, inpainting, reconstruction), 3) Diffeomorphic registration for spatial normalization, 4) Hand-crafted radiomics and texture analysis, 5) Hemorrhage segmentation, among other relevant head CT issues
Alternative download link: https://www.dropbox.com/s/8l2h93cl2pmle4g/CT_hemorrhage.pdf?dl=0
Elekta's Versa HD linear accelerators provide Odense University Hospital the speed needed to routinely perform stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) for multiple patients per week. Versa HD's high dose rate mode and fast-moving leaves reduce treatment times by 60%, allowing lung SBRT to be delivered in about 3 minutes and brain SRS in 20 minutes. This efficiency has led OUH to treat over 250 patients with SBRT/SRS annually since acquiring Versa HD in 2013.
The document discusses the development of an artificial retina using thin film transistor technology. It describes how retinal conditions like retinitis pigmentosa and age-related macular degeneration cause vision loss and how an artificial retina could help. The artificial retina would be implanted either on top of the retina (epiretinal) or underneath (subretinal) and use thin film transistors to detect light and stimulate remaining retinal cells via electrical pulses. Both approaches have advantages and disadvantages relating to attachment, heat dissipation, power requirements and image processing. Complications from long-term implantation are also addressed. The technology shows promise for restoring basic vision but has limitations and further development is still needed.
in this presentation we have worked in the theme of bio MEMS in the midical staffs specially in bionic eye
this technologie help blind peopls to get there vision back
thanks to Pr.brandly in 1960 how invented the first device which colled bionic eye
Using off-the-shelf ultrasound imagers, and transition to portable system-on-chip ultrasound imagers such as Butterfly IQ.
Embedded devices such as Butterfly IQ can be further improved by integrating deep learning / artificial intelligence at device level, and naturally at the post-processing and analysis levels
Alternative download link:
https://www.dropbox.com/s/rlwv7m29mh6y2w6/pupillometry_throughTheEyelids.pdf?dl=0
This document describes a smart home system designed to aid paralyzed individuals living alone. EEG signals are collected from 25 paralyzed subjects to study brain activity related to hunger, thirst, sleepiness, excitement and stress. The EEG data is preprocessed and classified using kNN classifiers to identify the individual's needs. An Internet of Things platform uses the classified EEG data to make logical decisions and control automated modules to meet the person's basic needs. These include modules for feeding, sleep, temperature control and more. Experimental results showed an overall 89.73% accuracy for automating units to fulfill a paralyzed person's basic needs. The system aims to help paralyzed individuals live more independently at home.
This document discusses a study that aims to classify glaucomatous images based on wavelet features with high accuracy. It analyzes energy distributions from several wavelet filters to extract texture features from retinal images. These features are ranked and selected before being introduced to classifiers like support vector machine, sequential minimal optimization, random forest, and naive Bayes. The proposed system is expected to achieve over 95% accuracy in glaucoma classification, outperforming existing techniques.
This document summarizes research on bionic eye technologies, including the Argus II and Alpha IMS retinal prosthesis devices. It provides background on common eye diseases like retinitis pigmentosa and age-related macular degeneration. Clinical trials show that the Argus II and Alpha IMS devices helped some patients detect light, objects, and even read to varying degrees. However, challenges remain in providing long-term power and interfacing with the brain. Overall, bionic eyes demonstrate the potential to restore vision but further developments are needed to improve functionality.
This document summarizes research on bionic eye technologies, including the Argus II and Alpha IMS retinal prosthesis devices. It provides background on common eye diseases like retinitis pigmentosa and age-related macular degeneration. Clinical trials show that both devices allowed some patients to detect light, movement, and basic shapes. However, limitations remain in fully restoring vision. Ongoing research aims to improve resolution and processing power while addressing engineering challenges of biocompatibility and interfacing with the brain.
Present-day advancements in embedded systems have uncovered a wide area of innovation in inexpensive supportive systems for the visually impaired. Right from the uncomplicated white cane up to the most exceptional electronic walking stick, many designs have been proposed aiming at assisting and protecting visually challenged persons. This paper aims at contributing to these assistive aids by designing a bamboo stick sensor-based unit with ultrasonic and water detection sensors which is robust, cheap, and easily operated for the deprived blind person. Thus, improving the usefulness of the current white stick to consolidate both above-knee and below-knee deterrent identifications. The developed bamboo stick simply operates using ultrasound sensors for sensing the impediments before contact and a water detection sensor for water detection on the pathway. It offers vibration and different sound feedbacks to the operator per the spot of the obstacle. The results obtained by trial from a volunteer who walked an obstructed path blindfolded were excellent. The results ensure quick detection, safety and enhance the speed of mobility of the user. The simulations performed were accurate and relevant to the ultimate goal of the paper. The electronic bamboo walking stick developed can be used to guide the visually impaired in an indoor or outdoor environment.
ALTERNATE EYES FOR BLIND advanced wearable for visually impaired peopleIRJET Journal
This document describes a proposed wearable device called the "Third Eye for Blind" that aims to help visually impaired people navigate indoor environments independently. The device uses an ultrasonic sensor and microcontroller to detect nearby obstacles and alert the user via vibration and sound from a buzzer. As the distance to an obstacle decreases, the intensity of the vibration and sound increases. The goal is to provide a low-cost, compact, and easy-to-use solution to help the visually impaired avoid collisions while navigating indoor spaces unassisted. The document outlines the motivation, proposed system design and components, working principles, results of testing, and conclusions that such a wearable device could significantly benefit visually impaired individuals and communities.
RASPBERRY PI BASED SMART WALKING STICK FOR VISUALLY IMPAIRED PERSONIRJET Journal
This document summarizes a proposed smart walking stick system for visually impaired people. The system uses a Raspberry Pi, camera module, GPS module, ultrasonic sensors, and other hardware. It aims to provide artificial vision, object identification, navigation assistance, and emergency alert functions. When an obstacle is detected by the ultrasonic sensors, the camera takes a picture which is analyzed using algorithms like Tesseract OCR and speech synthesis to audibly inform the user. The GPS module tracks the user's location to send alerts in emergencies. The overall goal is to provide a low-cost assistive device that gives visually impaired users more independence and safety.
This document summarizes research on developing artificial vision systems to restore sight for the blind. It describes two key technologies: the artificial silicon retina and artificial retina component chip. The artificial silicon retina is a microchip implanted in the eye that contains photodiodes that convert light into electrical signals to stimulate the retina. The artificial retina component chip is similar and provides a 10x10 or 250x250 pixel visual field. The document explains how these devices work and the surgical process for implantation. It also outlines an artificial vision system using a camera, signal processor and brain implants to transmit images and provide a limited form of artificial sight.
Small overview of the startups involved in healthcare artificial intelligence, the OCT market, investments, patent and IP issues and FDA regulation.
Alternative download link: https://dl.dropboxusercontent.com/u/6757026/slideShare/retinalAI_landscape.pdf
The document discusses the bio electronic eye, which replaces some or all functionality of the eye using electronics. It provides a history of the development of the bionic eye, describes how the human eye works compared to the bionic version, and details the key components and working principle of the MARC retinal prosthesis system. Some advantages are that it can be implanted with minimal surgery and has low power needs, though limitations include the difficulty of repairs and high costs. The conclusion is that while full vision may not be restored, bionic eyes can help the blind see shapes and objects.
DIABETIC RETINOPATHY DETECTION USING MACHINE LEARNING TECHNIQUEIRJET Journal
1) The document discusses a method for detecting diabetic retinal disease using integrated shallow convolutional neural networks, which can improve classification accuracy by 3% on small datasets compared to other CNN techniques.
2) It aims to classify retinal images to detect diabetic retinopathy through shallow CNNs, focusing on cases with limited labelled training data, as deep CNNs typically require large datasets for high accuracy.
3) Experimental results show the proposed approach reduces time cost to around 30% of the smallest dataset tested, which is 10% of the original dataset, while maintaining classification accuracy compared to other integrated CNN learning algorithms.
SVM based CSR disease detection for OCT and Fundus ImagingIRJET Journal
This document discusses using support vector machines (SVM) to detect central serous retinopathy (CSR) disease from optical coherence tomography (OCT) and fundus images. CSR is a retinal disease caused by fluid accumulation beneath the retina that can impair vision. The document reviews literature on CSR detection using machine learning and deep learning techniques. It then describes using SVM on OCT and fundus image datasets to classify and identify CSR disease, with the findings and accuracy compared after implementation.
Brain Computer Interfacing using Electroencephalography and Convolutional Neu...ijtsrd
This document discusses brain-computer interfaces (BCIs) that use electroencephalography (EEG) and convolutional neural networks. It begins by defining a BCI as a system that interprets brain activity to control devices without using muscles. It then discusses how EEG can be used to detect electrical brain activity and discusses sensorimotor rhythms, slow cortical potentials, and evoked potentials measured by EEG that can be used in BCIs. Convolutional neural networks are discussed as a method to classify EEG data. Benefits of BCIs include assisting those unable to move and reducing accidents, but risks include signal interference and privacy concerns. The document concludes that while BCIs have advanced, further development is still needed to fully realize their healthcare potential
The document discusses the optical time-domain reflectometer (OTDR), which is a device that measures distances to reflection surfaces in optical fibers. It does this by measuring the time it takes for a light pulse to reflect from the surface. Reflection surfaces can include fiber ends, breaks, splices, and connectors. The OTDR works by generating light pulses and measuring the scattered and reflected light returning from the pulses. It displays the reflected light on an oscilloscope, and by knowing the time delay and speed of light in the fiber, it can determine the distance to discontinuities in the fiber that cause reflections. The index of refraction must be known for accurate distance measurements.
Diabetic Retinopathy Detection Design and Implementation on Retinal ImagesIRJET Journal
The document describes a proposed method for detecting diabetic retinopathy through retinal image analysis. It involves developing an automated system to segment retinal blood vessels from images using a graph theoretical model. This model represents the vasculature as a vessel fragment graph. Features of the segmented vessels like central retinal artery equivalent and central retinal vein equivalent would then be analyzed to predict and diagnose cardiovascular diseases. The proposed method aims to automate diabetic retinopathy detection for efficient screening and analysis of large retinal image datasets.
Design and implementation of smart guided glass for visually impaired peopleIJECEIAES
The objective of this paper is to develop an innovative microprocessor-based sensible glass for those who are square measure visually impaired. Among all existing devices in the market, one can help blind people by giving a buzzer sound when detecting an object. There are no devices that can provide object, hole, and barrier information associated with distance, family member, and safety information in a single device. Our proposed guiding glass provides all that necessary information to the blind person’s ears as audio instructions. The proposed system relies on Raspberry pi three model B, Pi camera, and NEO-6M global positioning system (GPS) module. We use TensorFlow and faster region-based convolutional neural network (R-CNN) approach for detection of objects and recognition of family members of the blind man. This system provides voice information through headphones to the ears of the blind person, and facile the blind individual to gain independence and freedom within the indoor and outdoor atmosphere.
For the full video of this presentation, please visit: https://www.edge-ai-vision.com/2024/06/building-and-scaling-ai-applications-with-the-nx-ai-manager-a-presentation-from-network-optix/
Robin van Emden, Senior Director of Data Science at Network Optix, presents the “Building and Scaling AI Applications with the Nx AI Manager,” tutorial at the May 2024 Embedded Vision Summit.
In this presentation, van Emden covers the basics of scaling edge AI solutions using the Nx tool kit. He emphasizes the process of developing AI models and deploying them globally. He also showcases the conversion of AI models and the creation of effective edge AI pipelines, with a focus on pre-processing, model conversion, selecting the appropriate inference engine for the target hardware and post-processing.
van Emden shows how Nx can simplify the developer’s life and facilitate a rapid transition from concept to production-ready applications.He provides valuable insights into developing scalable and efficient edge AI solutions, with a strong focus on practical implementation.
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
GraphRAG for Life Science to increase LLM accuracyTomaz Bratanic
GraphRAG for life science domain, where you retriever information from biomedical knowledge graphs using LLMs to increase the accuracy and performance of generated answers
Goodbye Windows 11: Make Way for Nitrux Linux 3.5.0!SOFTTECHHUB
As the digital landscape continually evolves, operating systems play a critical role in shaping user experiences and productivity. The launch of Nitrux Linux 3.5.0 marks a significant milestone, offering a robust alternative to traditional systems such as Windows 11. This article delves into the essence of Nitrux Linux 3.5.0, exploring its unique features, advantages, and how it stands as a compelling choice for both casual users and tech enthusiasts.
Full-RAG: A modern architecture for hyper-personalizationZilliz
Mike Del Balso, CEO & Co-Founder at Tecton, presents "Full RAG," a novel approach to AI recommendation systems, aiming to push beyond the limitations of traditional models through a deep integration of contextual insights and real-time data, leveraging the Retrieval-Augmented Generation architecture. This talk will outline Full RAG's potential to significantly enhance personalization, address engineering challenges such as data management and model training, and introduce data enrichment with reranking as a key solution. Attendees will gain crucial insights into the importance of hyperpersonalization in AI, the capabilities of Full RAG for advanced personalization, and strategies for managing complex data integrations for deploying cutting-edge AI solutions.
Programming Foundation Models with DSPy - Meetup SlidesZilliz
Prompting language models is hard, while programming language models is easy. In this talk, I will discuss the state-of-the-art framework DSPy for programming foundation models with its powerful optimizers and runtime constraint system.
GraphSummit Singapore | The Art of the Possible with Graph - Q2 2024Neo4j
Neha Bajwa, Vice President of Product Marketing, Neo4j
Join us as we explore breakthrough innovations enabled by interconnected data and AI. Discover firsthand how organizations use relationships in data to uncover contextual insights and solve our most pressing challenges – from optimizing supply chains, detecting fraud, and improving customer experiences to accelerating drug discoveries.
UiPath Test Automation using UiPath Test Suite series, part 5DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 5. In this session, we will cover CI/CD with devops.
Topics covered:
CI/CD with in UiPath
End-to-end overview of CI/CD pipeline with Azure devops
Speaker:
Lyndsey Byblow, Test Suite Sales Engineer @ UiPath, Inc.
“An Outlook of the Ongoing and Future Relationship between Blockchain Technologies and Process-aware Information Systems.” Invited talk at the joint workshop on Blockchain for Information Systems (BC4IS) and Blockchain for Trusted Data Sharing (B4TDS), co-located with with the 36th International Conference on Advanced Information Systems Engineering (CAiSE), 3 June 2024, Limassol, Cyprus.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
How to Get CNIC Information System with Paksim Ga.pptxdanishmna97
Pakdata Cf is a groundbreaking system designed to streamline and facilitate access to CNIC information. This innovative platform leverages advanced technology to provide users with efficient and secure access to their CNIC details.
HCL Notes and Domino License Cost Reduction in the World of DLAUpanagenda
Webinar Recording: https://www.panagenda.com/webinars/hcl-notes-and-domino-license-cost-reduction-in-the-world-of-dlau/
The introduction of DLAU and the CCB & CCX licensing model caused quite a stir in the HCL community. As a Notes and Domino customer, you may have faced challenges with unexpected user counts and license costs. You probably have questions on how this new licensing approach works and how to benefit from it. Most importantly, you likely have budget constraints and want to save money where possible. Don’t worry, we can help with all of this!
We’ll show you how to fix common misconfigurations that cause higher-than-expected user counts, and how to identify accounts which you can deactivate to save money. There are also frequent patterns that can cause unnecessary cost, like using a person document instead of a mail-in for shared mailboxes. We’ll provide examples and solutions for those as well. And naturally we’ll explain the new licensing model.
Join HCL Ambassador Marc Thomas in this webinar with a special guest appearance from Franz Walder. It will give you the tools and know-how to stay on top of what is going on with Domino licensing. You will be able lower your cost through an optimized configuration and keep it low going forward.
These topics will be covered
- Reducing license cost by finding and fixing misconfigurations and superfluous accounts
- How do CCB and CCX licenses really work?
- Understanding the DLAU tool and how to best utilize it
- Tips for common problem areas, like team mailboxes, functional/test users, etc
- Practical examples and best practices to implement right away
Let's Integrate MuleSoft RPA, COMPOSER, APM with AWS IDP along with Slackshyamraj55
Discover the seamless integration of RPA (Robotic Process Automation), COMPOSER, and APM with AWS IDP enhanced with Slack notifications. Explore how these technologies converge to streamline workflows, optimize performance, and ensure secure access, all while leveraging the power of AWS IDP and real-time communication via Slack notifications.
In his public lecture, Christian Timmerer provides insights into the fascinating history of video streaming, starting from its humble beginnings before YouTube to the groundbreaking technologies that now dominate platforms like Netflix and ORF ON. Timmerer also presents provocative contributions of his own that have significantly influenced the industry. He concludes by looking at future challenges and invites the audience to join in a discussion.
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
2. Dowling
2 Expert Rev. Med. Devices 2(1), (2005)
Most existing mobility aids for the blind provide information
in either tactile or auditory form. The two most widely used
devices are the long cane and the guide dog, however, these
devices have limitations; the long cane is only effective over a
short range and a guide dog requires expensive training and
maintenance. A number of electronic travel aids (ETAs) have
also been developed, generally using ultrasound or lasers.
These devices have usually failed commercially due to their
expense, lack of benefit in improved mobility and cosmetic
unattractiveness [9]. The objective assessment of technical aids
for the blind (e.g., using Percentage of Preferred Walking
Speed [10]) could provide useful information during device
development and for consumers.
AHV technology & requirements
The development of an artificial human vision (AHV) system is
a multidisciplinary field, involving inputs from neuroscience,
engineering, computer science and ophthalmology, in addition
to orientation and mobility specialists.
With the exception of subretinal prostheses, most AHV sys-
tems have similar system requirements. The main components,
which will need to function in real time, are:
• A Camera – required to capture and digitize image informa-
tion from the environment. Charged Coupled Device
(CCD)-based digital cameras are inexpensive, small and can
be easily interfaced to other system components. An adaptive
mechanism (such as an automatic gain in current video cam-
eras) will also be required to allow the device to function at
different levels of illumination [11]. CCD camera sensors have
a linear response to light intensity. A logarithmic camera has
a similar response to the human visual system and can reduce
saturation in high contrast visual scenes. The use of a loga-
rithmic camera in an AHV is being investigated in at least
one current research project [12].
• Image processing – there will be more data retrieved from the
camera than can be used in an AHV device. The image data
will usually be preprocessed to reduce noise. After this, an
information reduction (such as edge detection or segmenta-
tion) or a scene understanding approach, attempting to
extract information, can be used. Cortical prosthesis research
by the Dobelle Institute (Portugal) has found that edge detec-
tion and image reversal enhance the ability of subjects to rec-
ognize important scene components (such as doorways) [13].
An alternate, and alternative, approach to traditional image
processing is the use of neuromorphic vision systems,
designed to mimic the design of the human visual system [14].
• Transmitter/receiver – a link is required from the cam-
era/image processing components to the stimulator and elec-
trode array, which are usually located inside the body. Percuta-
neous connections have been used for most research due to
their simplicity and reliability [15], however, the risk of chronic
infection is higher with this type of connection. The Dobelle
Institute system uses a percutateous connecting pedestal for
connection to the image processing unit (a notebook PC). A
transcutaneous connection, as used in cochlear implants, uses
radiofrequency telemetry to send data and power to the
embedded stimulator, reducing the risk of infection. Most
AHV research projects plan to eventually use transcutaneous
connections. Reverse telemetry can also be used to provide
details of stimulation voltage waveforms, impedance measure-
ments and reconstruction of stimulation voltage waveforms
[16]. A good description of a high efficiency transcutaneous
data link for implanted electronic devices is provided by
Troyke and Schwan [17].
• Stimulator/electrodes – an electrode is a thin wire, which
allows a small amount of precisely controlled electrical cur-
rent to pass through it. Electrodes can be used for either
stimulation or recording the electrical activity of the brain.
The purpose of the stimulator is to send current through
multiple electrodes. There are two main types of electrodes
discussed in the AHV literature; surface electrodes, which lie
flat against the stimulation/recording target and penetrating
electrodes, which are inserted inside the stimulation/record-
ing target. The biocompatability, long-term effectiveness
and safe threshold levels for implanted electrodes need to be
carefully considered.
Cortical stimulation
In the functioning human vision system, two types of photore-
ceptors in the retina (rods and cones) are activated by light,
which has been focused by the lens and cornea in the eye. Elec-
trical signals from these photoreceptors are then processed
through a layer of bipolar and ganglion cells within the retina,
before passing to the optic nerve [18]. The amount of informa-
tion entering the eye is reduced considerably - there are over 120
million photoreceptors and only about 1 million ganglion cells
[19]. Most of the signals from the optic nerve pass through the
lateral geniculate body to the visual cortex, although, approxi-
mately 20–30% of fibers connect to the superior colliculus,
which appears to be responsible for eye movements [20].
Cortical-based AHV systems use either surface or intracorti-
cal stimulation, using penetrating electrodes. Cortical stimula-
tion is the only treatment available for blindness caused by
glaucoma, optic atrophy or diseases of the central visual path-
ways, such as brain injuries or stroke. The main negative feature
of a cortical implant is the lack of preliminary processing by the
brain, particularly in the retina where much of the information
reduction takes place.
Most research regarding AHV has focused on sending a cap-
tured image to the brain as a bitmap representation. The bitmap
approach to cortical devices has been questioned [21]. Research
performed by Hubel and Weisel in macaque monkeys has found
that, in addition to spatial location of a stimulus in the visual
field, neurons in the visual cortex are selective for spatial, tempo-
ral, chromatic and binocular cues [22]. A greater knowledge of
cortical physiology may be required before a cortical prosthesis
provides useful vision. Evidence
has also been found to suggest that there may be specialized
cortical areas for the analysis of biologically important images
(such as faces) [23].
3. Artificial human vision
www.future-drugs.com 3
Cortical surface stimulation
The early developments in cortical prostheses involved surface
electrode arrays. The first person to expose the human occipital
pole to electrical stimulation was the German researcher For-
ester in 1929, who noticed that stimulation caused the subject
to see a spot of light in a position that depended on the site of
stimulation [1].
Brindley & Lewin
Brindley and Lewin published the results of a groundbreak-
ing study on cortical stimulation in 1968. In their study, a
52-year-old legally blind subject was implanted with an array
of 80 platinum electrodes, a design which had previously
been tested in baboons. These electrodes were stimulated by
pulsed radio signals from an oscillator. Stimulation of these
electrodes produced discernible phosphenes [24]. Brindley
and Lewin suggested that there was probably no flicker
fusion frequency for this implant. They also found that phos-
phenes moved with eye movements and that phosphene per-
ception usually (but not always) stopped when stimulation
ceased. Stimulation of one electrode was found to produce
multiple phosphenes and when multiple electrodes in close
vicinity were activated, a larger, straight light phosphene was
produced. Unfortunately, the monophasic stimulus pulses
used long-term in these earlier studies were also likely to
cause irreversible damage at the electrode-tissue interface [25].
Dobelle & Mladejovsky
Brindley and Lewin’s research inspired pioneering work
involving 37 human subjects by Dobelle and Mladejovsky in
1974, where electrical stimulation was applied to patients
hospitalized for cranial surgery [26]. Supporting Brindley and
Lewin’s work, they found eye movements caused phosphenes
to move and multiple phosphenes could be produced from a
single electrode. However, Dobelle and Mladejovsky found
that constant stimulation caused phosphenes to fade, sug-
gesting that phosphenes need to be refreshed. In a later paper,
it was reported that subjects were able to read electrode-
induced Braille characters more efficiently than using their
tactile sense [27].
In 2000, Dobelle published a paper describing a subject who
had been using a cortical visual prosthesis system for over
20 years [13]. The system used a 64-channel electrode array,
which had been implanted on the mesial surface of the subject’s
right occipital lobe in 1978. When stimulated, each electrode
produced one to four closely spaced phosphenes. The stimula-
tion parameters and phosphene locations had been stable for
the past 20 years, however, the electrode thresholds required a
15-min recalibration every morning. This system utilized a
black and white camera connected to a notebook computer.
Cables from the notebook were connected to a percutaneous
connecting pedestal, which interfaced to the microcontroller,
stimulus generator and electrode array. Dobelle reported that
frame rates of around 4 fps have been found to be optimal. The
subject has a visual acuity of approximately 20/200.
Bionic eye research project
Although research in the early 1990s moved towards intrac-
ortical stimulation, a recently commenced project at the
University of New South Wales ([NSW], Australia) is investi-
gating the use of technology adapted from cochlear implants
(which generally use surface electrodes). An in vivo model
has been reported, in which the transcallosal evoked
response to cortical stimulation on the opposite hemisphere.
Future psychophysical experiments in a human subject are
planned [28,29].
Intracortical stimulation
National Institute of Health
The Neuroprosthesis Program at the US National Institute of
Health (NIH) was the first to publish research concerning the
use of intracortical stimulation to produce phosphenes. In this
study by Bak and colleagues, three normally sighted patients,
undergoing occipital craniotomies for other conditions, were
tested for an hour each [30]. Surface stimulation produced the
same phosphenes described by Dobelle and Brindley. Following
this, a dual microelectrode was inserted to level 4B in the pri-
mary visual cortex and stimulation applied. Unlike surface elec-
trodes, the intracortical electrode phosphenes did not flicker.
An important finding from this research was the discovery that
intracortical stimulation required 10–100 times less electrical
current to produce phosphenes than surface electrodes. In addi-
tion, intracortical electrodes located as closely as 500 µm could
evoke distinct phosphenes.
A more detailed experiment by the NIH team was described
in 1996 by Schmidt and colleagues [31]. 38 microelectrodes
were inserted into the right visual cortex of a 42-year-old
woman for 4 months. The patient, who had been blind for
22 years, was consistently able to perceive phosphenes at stable
positions in visual space. Phosphenes were produced with 34 of
the microelectrodes, at thresholds usually at 25 µA. It was
found that these phosphenes did not flicker and changing the
stimulus amplitude, frequency and pulse duration could change
phosphene brightness. A perception of depth from the stimula-
tion was also reported and as the stimulation level was
increased, the phosphenes generally changed color (white, yel-
lowish and grayish). Supporting earlier research, phosphenes
moved with eye movements. Schmidt and colleagues suggested
that electrodes could be placed five times closer than surface
stimulation. An important result of this study concerned after-
discharge; one phosphene was observed for up to 25 min after
cessation of stimulation, which suggests that even small electri-
cal currents from repeated, patterned stimulation may be epi-
leptogenic. At least six of the electrode leads broke during the
study, due to accidental movement of the patient during sleep,
which limited testing on pattern recognition. The percutaneous
leads and electrodes were removed after 4 months.
The NIH Neuroprosthesis Program was discontinued by
2001 [32]. However, there is continuing collaboration with the
intracortical visual prosthesis team at the Illinois Institute of
Technology (IL, USA).
4. Dowling
4 Expert Rev. Med. Devices 2(1), (2005)
University of Utah
The University of Utah (UT, USA) currently has an active
intracortical research group led by Richard Normann. This
team has focused mainly on electrode array design for stimula-
tion and recording, behavioral experiments and psychophysical
experiments.
The University of Utah has developed an array of 100 pene-
trating cortical electrodes, each 1.5 mm in length and separated
by 400 µ. This length has been selected to reach level 4Cb of
the visual cortex, where neurons have the smallest and simplest
receptive fields and where lower thresholds can be used for gen-
erating phosphenes [33]. Manual insertion of the array was
found to cause cortical deformation, therefore, a pneumatic
insertion device has also been developed and tested [34]. The
biocompatibility of this array has been extensively evaluated
and arrays have been inserted for up to 14 months in cats [35].
The Utah electrode array (UEA) has been investigated as a
recording structure for potential brain-computer interfaces [36]
and recently for investigating representations of simple visual
stimuli in the cat visual cortex [37]. A modification of the UEA
is available which has graded electrodes, allowing stimulation
and recording to be conducted in both horizontal and vertical
directions [38].
Cortical implant for the blind
The Cortical Implant for the Blind (CORTIVIS) project, com-
menced in 2001, is lead by Edwardo Fernandez of the Univer-
sity of Miguel Hernandez (Spain), and involves researchers
from Spain, Germany, Austria, France and Portugal.
The group has investigated the use of the UEA in animal
experiments (cats, rabbits and rats) over a period of 12 h to
6 months. The electrodes were found to be well-tolerated by
the cortex, despite some inflammatory responses in the vicinity
of the electrode tracks [39].
In order to develop a methodology to identify feasibility of a
cortical prosthesis for a patient and the preferred location for
the prosthesis, Fernandez and colleagues have used transcranial
magnetic stimulation (TMS) to evoke phosphenes in 13 legally
blind and 19 normally sighted patients [40]. The advantage of
TMS is that it is painless and noninvasive. In total, 28-posi-
tions arranged in a 2 × 2 cm grid over the occipital area were
stimulated and phosphenes were perceived by 94% of the nor-
mally sighted participants. However, only 54% of the legally
blind patients perceived phosphenes (even after adjusting the
stimulation parameters). Evoked phosphenes were topographi-
cally organized and the mapping results could generally be
reproduced between participants.
The CORTIVIS project is also developing a retina-like proc-
essor, designed to simulate the functioning of the human retina
to produce optimal electrode stimulation at the cortical level
[41]. The output of this system is a series of spike patterns,
which could be used to stimulate neurons in the visual cortex.
In a study of brain plasticity by the CORTIVIS group, fMRI
was used to study the differences in reading Braille in normally
sighted and congenitally blind people [42]. Unlike normally
sighted participants, activation of the occipital cortex was
recorded in blind participants. The authors note that where
cross modal plasticity has been activated in this way, the
processing of tactile information is associated with significantly
improved tactile reading skill.
Intracortical visual prosthesis
The intracortical visual prosthesis (Illinois Institute of Technol-
ogy) project is led by Philip R Troyk, Director of the Laboratory
of Neuroprosthetic Research, and involves collaboration with
other institutions and former staff from the NIH Neuroprosthe-
sis Program. Their approach is to use small implanted arrays
(consisting of eight electrodes) in groups of intracortical elec-
trodes which tile the visual cortex. In a recent paper, Troyke and
colleagues describe an interesting animal experiment, using a
male macaque, designed to investigate visual prosthesis function-
ing with this tiled design [21]. Prior to implantation, the animal
was presented with a flash of light, and then trained to continue
staring at the flash location (so only the memory of the flash
remains); 192 tiled electrodes were then implanted into area V1
of the animal. Only 114 electrodes were functioning post
implantation. The receptive field coordinates for each implanted
electrode were estimated and a phosphene was generated in that
location. The macaque received a reward if its eye position
moved within 2° of the known receptive field for that electrode.
Retinal stimulation
The most common nonpreventable reason for blindness in the
developed world is age-related macular degeneration. This con-
dition affects the retina at the back of the eye, while leaving the
remaining components of the visual system intact. Retinal pros-
thesis research aims to use the remaining visual pathway com-
ponents to provide partial restoration of sight. An Australian
researcher, in 1956, was the first to describe placing a light sen-
sitive selenuium plate behind the retina of a blind individual
and restoring some intermittent light sensation [43].
There are significant advantages to the retinal approach to
AHV. Implantation of a cortical prosthesis requires intercranial
neurosurgery, which may expose a patient to higher risk. At a
fine scale, the mapping of a stimulus to the appropriate place on
the cortex may be variable between subjects [44]. An alternate
approach is to stimulate the eye rather than the brain. A retinal
prosthesis could assist people who still have a functioning optic
nerve. In post-mortem examinations of people without light
perception, 80% of the optic nerve and approximately 30% of
the ganglion cell layer was found to be functioning [45]. How-
ever, there may also be continual remodeling by the retina which
could lead to spatial corruption and cryptic synapse formation
after a retinal implant has been attached [46].
The two types of retinal prosthesis, discussed in the following
sections, are subretinal and epiretinal.
Subretinal stimulation
There are approximately 130 million receptors in the retina,
which are reduced down to 1 million fibers in of the optic
5. Artificial human vision
www.future-drugs.com 5
nerve. This information reduction takes place in the inner
nuclear layer (consisting of amacrine, bipolar and horizontal
cell nuclei) of the retina. Targeting this layer, a subretinal
implant is located behind the photoreceptor layer of the retina
and in front of the pigmented layer called the retinal pigment
epithelium. Therefore, the subretinal approach, unlike the
epiretinal, may be capable of utilizing the information reduc-
tion functions in the retina, provided the electric field produced
does not interfere with other retina components (such as the
ganglion cell layer).
Optobionics Corp.
Since the 1980s Alan and Vincent Chow have been investigat-
ing subretinal microphotodiodes for subretinal stimulation [47]
and their company, Optobionics Corp. (USA), was awarded the
original patent for an artificial subretinal device in 1991 [48].
In an early animal experiment, an implanted strip electrode
was inserted behind the photoreceptor layer in a rabbit’s eye.
The evoked electrical response of stimulation to the operated
eye was compared with the normal eye by presenting a flash of
light and then measuring the response from the scalp over the
visual cortex. It was found that a brief electrical spike was gen-
erated during stimulation [49]. This experiment demonstrated
the feasibility of converting light into electrical energy using
subretinal stimulation to produce a cortical electrical evoked
response [50].
A further animal experiment focused on the long-term bio-
compatibility of subretinal stimulation [51]. Cats were selected
for this study as they have both retinal and choroidal circula-
tion (unlike rabbits). The implants, approximately 50 µm in
thickness, with a diameter of 2–2.5 mm, consisted of a doped
and ion implanted silicon substrate, surrounded by a gold elec-
trode layer. Following implantation in the cat’s right eye, the
arrays were evaluated over 10 to 27 months. During this time, a
gradually decreased response to light was found, due to the dis-
solution of the gold electrode layer. In addition, the silicon sub-
strate blocked choroidal nourishment to the retina, which led
to a degeneration of the photoreceptors, which are highly
dependent on blood supply for oxygenation. The loss of pho-
toreceptors may not be important as they may be damaged any-
way. However, design work commenced on a fenestrated design
in order to improve the flow of nutrients from the choroid to
the retina [51]. The positive findings from this study were that
the implant maintained a stable position over time and there
was no rejection, inflammation or degeneration of the retina
outside the location of the implant [52].
By June 2000, Optobionics received approval from the US
Food and Drug Administration (FDA) to commence safety and
feasibility trials in six patients [53]. The artifical silicon retina
(ASR), consisting of 5000 microelectrode-tipped microphoto-
diodes in a 2-mm diameter device, was implanted into the right
eyes of six legally blind patients with RP. During a follow-up
period of 6–18 months, all ASRs were found to function elec-
trically and there were no signs of rejection, inflammation, ero-
sion, retinal detachment or migration of the device. During this
study it was found that all patients experienced improvements
in visual function (such as improved color perception) and
there were also unexpected improvements in retinal areas dis-
tant from the implant. These improvements may have been due
to neurotropic effects, rather than the device and further stud-
ies are intended to explore this improvement. Additional
planned research will examine the implant and age-related mac-
ular degeneration, and whether the neurotropic effect can be
effective in earlier stages of RP [53].
An issue with the Optobionics research has been the lack of an
experimental control (by implanting an inactive device or con-
ducting sham surgery) to evaluate against the ASR. Pardue and
colleagues have recently conducted research addressing this issue
[54]. Their experiment involved 15 RCS rats, which have a
genetic mutation resulting in photoreceptor degeneration over
approximately 77 days. The rats received either the ASR device,
an inactive device, sham surgery or no surgery. The outer retinal
function was assessed with weekly electroretinogram (ERG)
recordings. After 4–6 weeks there was a 30–70% higher b-wave
amplitude response with the ASR compared with the inactive
device, indicating that the ASR device appears to produce some
temporary improvement in retinal function. However, after
8 weeks, there was no significant difference in b-wave amplitude
response between the inactive and active devices. At 8 weeks,
there was a significantly greater number of photoreceptors
remaining for rats who had received either the ASR or inactive
device compared with those rats that had undergone sham sur-
gery or no surgery. Pardue and colleagues suggest that enhanced
protective effects from the ASR may be possible by altering the
design to increase current levels or by increasing environmental
light levels to produce higher stimulation levels [54].
MPDA project
After collaborating with the Optobionics group between 1994
and 1995 [55], a Southern German team led by the University
Eye Hospital in Tübingen, was formed in 1995 to develop a sub-
retinal prosthesis. In 1996, the Institute of Micro-Electronics in
Stuttgart developed a prototype microphotodiode array
(MPDA) containing 7600 microelectrodes on a 3-mm disc, 50
µm in diameter [56]. In vitro techniques have been predominantly
reported by the German subretinal project.
The first generation of MPDAs were tested using a sandwich
technique, which involved the retinae from newly hatched
chickens being adhered to a recording multielectrode array (the
ganglion cell side was adhered). The photoreceptor outer seg-
ments were then damaged and an MPDA placed onto the ret-
ina. This technique allowed the recording of stimuli from the
MPDA [56]. A later study examined degenerated rat retinae [57].
The retinae were removed and cut into 5 × 5 mm
segments, then attached to a 60-electrode microelectrode
array. Beams of white light were flashed onto the MPDA and it
was found that intrinsic ganglion cell activity could be recorded
even with a highly degenerated retinal network. Further experi-
ments have demonstrated that it should be possible to transform
the basic features of images, such as points, bars and edges into
6. Dowling
6 Expert Rev. Med. Devices 2(1), (2005)
activity of the existing retinal network; which suggests that shape
perception and object location may be possible with a subretinal
device [58]. However, recent epiretinal results from Rizzo and col-
leagues have not confirmed the pattern perception of phosphenes
from patterned electrical stimulation of the retina [59].
Further tests have been conducted in order to test the bio-
compatibility stability of the MPDA. Various materials were
placed in Petri dishes with the retinae of pigmented rats. For
comparison, a control dish containing only the retinae and
solution was used. None of the MPDA materials demonstrated
a toxic effect. Retinal cell cultures from rats were also used by
Guenther and colleagues to screen for technical implant mate-
rial [60]. Although most materials (including iridium and silica)
showed good biocompatibility, a reduced biocompatibility was
found for titanium materials. Interestingly, a later paper by
Hammerle and colleagues found that titanium nitrate had
excellent biostability, both in vivo and in vitro [61].
Similarly to the Optobionics research, electroretinography
was performed in rabbits and rats in order to measure the effec-
tiveness of the MPDA. As the MPDA are sensitive to infrared
light, it is possible to stimulate the retina and measure the cur-
rent discharged from the MPDA. This method should be useful
for the localizing electrical responses from an MPDA.
As with the early Optobionics MPDA [49], Zrenner and col-
leagues found in their early work that metabolic processes in
the photoreceptor layer can be disrupted by the MPDA and
they placed very thin holes in their device to allow nutrients to
be passed [56].
As natural photoreceptors are far more efficient than photo-
diodes, visible light is not powerful enough to stimulate the
MPDA. Therefore, infrared enhancement of the photodiode
arrays (by inserting an additional layer in the array) has been
suggested to enhance the stimulation current [43].
The German team commenced in vivo experiments in 2000,
when evoked cortical potentials were measured from Yucantan
micropigs and rabbits. The micropigs have eyes which are com-
parable in size and function with human eyes [62]. At 14 months
post implantation, the implant and retina surrounding it were
examined and there were no noticeable changes to anatomical
integrity [63]. However, because the existing MPDA does not
function in ambient light conditions, an electrode foil prototype
with similar properties was implanted. The micropigs required a
higher threshold level than the rabbits [64], however, the implants
were successful in producing evoked cortical potentials in half of
the animals tested. The thresholds identified in this study were
similar to those required in epiretinal stimulation [64].
The latest reports from this group concern the results of
in vivo experiments in cats. Volker and colleagues described the
use of optical coherence tomography to examine the morpho-
logic and circulatory conditions of the cat neuroretina and it’s
interface with an implanted MPDA [65].
Other subretinal methods
A team of Japanese researchers, led by Tohru Yagi of Nagoya
University has been investigating the attachment of cultured
neurons onto electrodes and then guiding the axons towards
the CNS. As this hybrid retinal implant will not require retinal
ganglion cells or an optic nerve, it could be useful for patients
with diseases in these components of the visual pathway.
Results of an experiment with neural cells obtained from the
spinal cords of a 3–4- week-old rat are described by Ito and col-
leagues [66]. Another study by this team investigated electrical
stimulation requirements by stimulating the lateral geniculate
nucleus in a cat. Recordings of the evoked potentials from the
cat’s cortex found that pulse amplitude was a more important
factor than pulse duration and that a biphasic pulse pattern was
the most effective stimulation pattern [67]. Further studies have
suggested using a computer model for the 3D configuration of
electrode arrays [68].
Peterman and colleagues are also investigating the use of
directed cell growth and localized neurotransmitter release for a
retinal interface. They have been successful in directing the
growth of neurons in a defined direction, using micropatterned
substrates [69] and have demonstrated that the localized chemi-
cal stimulation of excitable cells is feasible. The authors suggest
that chemical stimulation can have a similar spatial resolution
as an electrical stimulation but with the ability to mimic the
major functions of synaptic transmission [70].
An interesting design for a MPDA has been recently reported
by Ziegler and colleagues, who propose a device where each pixel
acts as an independent oscillator whose frequency is controlled
by light intensity [71].
Kanda has suggested an alternative stimulation method for a
retinal device: suprachoroidal-transretinal stimulation (STS),
which does not involve the attachment of electrodes to the ret-
ina [72]. This should result in less complicated surgery for blind
patients. The anodic-stimulating electrode is located on the
choroidal membrane and the cathode is located in the vitreous
body. This technique has been used in animal experiments
where evoked potentials were recorded from the superior collic-
ulus in rats. The authors are planning long-term, in vivo bio-
compatability studies [72]. However, it has been demonstrated
that neural cells should not be separated from electrodes by
more than a few µm, due to overheating, crosstalk between
neighboring pixels and electrochemical erosion [73]. The thick-
ness of the choroid is approximately 400 µm, therefore, supra-
choroidal placement precludes close proximity between elec-
trodes and cells, which will limit the potential visual acuity of
the STS approach.
Epiretinal stimulation
An epiretinal device involves a neurostimulator chip being
implanted against the ganglion cells in the retina. This approach
attempts to stimulate the remaining retinal neurons of patients
who are blind from end-stage photoreceptor diseases.
Retinal implant
Formerly from the Wilmer Ophthalmological Institute, John
Hopkins Hospital, Mark Humayun and Eugene De Juan Jr are
currently based at the Doheny Retina Institute at the University
7. Artificial human vision
www.future-drugs.com 7
of Southern California (CA, USA). Humayun’s PhD thesis
demonstrated that a visually impaired person could perceive
phosphenes during stimulation of the retina [74]. The engineer-
ing aspects of developing electronic stimulators and supporting
electronics have been mainly conducted by Wentai Liu and his
team at North Carolina State University [75].
In the first experiment to demonstrate successful phosphene
perception from local electrical stimulation of the retina,
14 patients (12 with RP, and two with age-related macular
degeneration) had their inner retinal surface electrically stimu-
lated under local anaesthesia [76]. The responses were retinotop-
ically correct in 13 of the patients, with the remaining patient,
blind from birth, unable to distinguish anything apart from
flashing light. The phosphenes were perceived exactly with the
timing of the electrical stimulation [76]. Flicker fusion was
tested in two subjects and found to occur at approximately
50 Hz; the phosphenes also appeared brighter at higher fre-
quency [77]. An earlier paper also reported on five of these
patients [78].
In 1999, a further experiment was reported on nine subjects,
involving nine or 25 electrode array electrodes [45]. The elec-
trodes were placed against the retinal surface and handheld in
place using a silicon-coated cable with the guidance of a surgi-
cal microscope. The flicker fusion frequency was found to be
50 Hz in two subjects and 40 Hz in another two subjects (the
remaining subjects were not tested). By scanning with the head-
mounted camera, subjects were able to perceive simple shapes
in response to stimulation (e.g., horizontal and vertical lines
and ‘U’ and ‘H’ shapes).
A report on the long-term biocompatibility of an implanted,
inactive epiretinal device was also published in 1999 [79], in
which 25 platinum disc-shaped electrodes in a silicon matrix
were implanted into the retinal surface of four normally sighted
dogs. The arrays were held in place using metal alloy tacks.
Over a 6-month period the implants were biologically tolerated
well, mechanically stable and could be securely attached to the
retinal surface [79].
A design for a functioning retinal prosthesis system has been
described in joint papers by Liu and colleagues at North Caro-
lina State University and the John Hopkins team in 1999 [80,81].
The proposed device, termed the multiple unit artificial retina
chipset (MARC), consists of the extraocular unit containing the
video camera and video processing board, connected by a tele-
metric inductive link to the intraocular unit. The power and
signal transceiver, stimulation driver and electrode array are
contained in the intraocular unit.
In 2003, after obtaining FDA approval, the Doheny Eye
Institute team and Second Sight (CA, USA), a company
formed by former North Carolina State University team
member, Robert Greenberg and Alfred Mann, developed the
first human epiretinal implant. A subject with advanced RP
received an implanted 4 × 4-electrode array, connected by a
subcutaneous cable to an extraocular unit which was surgi-
cally attached to the temporal area of the skull. A wireless
link transferred data and power from a belt-worn visual-
processing unit to the extraocular unit. All 16 electrodes
produced phosphenes and the subject was able to detect
ambient light, motion and correctly recognize the location
of phosphenes (e.g., left vs. right or upsidedown). Future
plans are to develop more complex stimulation control and
provide a higher number of electrodes [82]. The use of micro-
wire glass is also being investigated as a method to assist
with the mapping of flat microelectric stimulator chips and
curved neuronal tissue [83].
Retinal prosthesis project
Following earlier collaborative work with Humayan and
deJuan, Wentai Liu and his team have continued with the
development of an epiretinal prosthesis. A 60-electrode stimu-
lating chip, which integrates power transfer and back telemetry,
has been developed [84]. One of the advantages of this system
would be removing the requirement for the cable connecting
the intraocular and extraocular units described in the Doheny
Eye Institute team implant [82].
Second Sight
Second Sight is a company formed by Robert Greenberg (from
the Retinal Prosthesis Project led by Wentai Lui) and Alfred
Mann (also the founder of the Cochlear Implant company
Advanced Bionics). Second Sight developed the epiretinal device
implanted into a blind patient by the Doheny Eye Institute team,
as described previously [82].
Boston retinal implant project
This project is a collaboration between Joseph Rizzo (Massa-
chusetts Eye and Ear Infirmary, Harvard Medical School,
MA, USA) and John Wyatt (Massachusetts Institute of Tech-
nology, MA, USA) to develop an epiretinal prosthesis. The
main difference between their approach and Humayun and
colleagues, is the use of a miniature laser, located in a pair of
glasses, to transfer power and data to a stimulator chip.
Although the laser is required to be accurately directed to the
implant and needs to cope with blinking, it will not be
effected by electronic noise interference (unlike radiofre-
quency transmission) [85]. Electrically invoked cortical poten-
tials have been successfully recorded from stimulation of a
rabbit retina [86].
Recently, the microelectrode arrays have been tested with
six patients, five of them legally blind from RP. The sixth
patient was normally sighted, however their eye required
removal due to orbital cancer. All patients were able to per-
ceive phosphenes in response to stimulation, however, the
results were mixed. Threshold charge densities were found
to be significantly higher and above safe levels, in blind
patients compared with the normally sighted patient [59]. In
this study, it was often found that multiple phosphenes
would be presented when a single electrode was stimulated,
for example, 60% of tests in one subject. In addition, multi-
ple-electrode stimulation did not reliably produce matching
phosphenes [87].
8. Dowling
8 Expert Rev. Med. Devices 2(1), (2005)
EPI-RET
Rolf Eckmillar from the University of Bonn (Germany), leads
the German EPI-RET project, which involves 14 research
groups. The aim of their first epiretinal device is to allow blind
people to identify the location and shape of large objects [88].
Their approach involves replicating a healthy retina with a reti-
nal encoder device, which consists of a photosensor array of
10,000–100,000 pixel inputs and simulated output of
100–1000 ganglion cells. Eventually, this project aims to embed
this encoder into a contact lens. The output from the encoder is
then sent to an implanted retinal stimulator. Eckmilliar and col-
leagues suggest that a future epiretinal prosthesis will be tuned
(to optimize phosphene perception) during a dialog between a
subject and their retinal encoder [89–92]. More recently, a learn-
ing active vision encoder (LAVIE) has been proposed to com-
pensate for spontaneous eye (drift or nystagmus) and head
movements in the absence of vision. A smooth pursuit function
is also being investigated [93].
Flat platinum microelectrodes have been developed for the
EPI-RET project and evoked cortical potentials have been
recorded after stimulation in rabbits [94]. In 2000, Hesse and
colleagues reported problems with the fixation of the electrode
film and the retina in a cat experiment, partly due to the very
thin posterior sclera [95]. Research into alternate electrode shape
and fixation techniques is planned.
The company Intelligent Implants was formed in 1998 to
commercialize research by the EPI-RET group [93].
University of NSW and University of Newcastle Vision
Prosthesis Project
Australian research on an epiretinal prosthetic vision system is
occurring at the Vision Prosthesis Project at the Universities of
NSW and Newcastle, led by Gregg Suaning and Nigel Lovell.
This project aims to extend concepts from the development of
cochlear prostheses.
A 100-channel neurostimulator circuit for the retina has been
developed, which uses bidirectional radiofrequency telemetry
for transferring data and power [16,44]. A data format protocol
has been introduced. The 100-channel neurostimulator was
found to function and successfully produce evoked potentials
in sheep [96–98]. An inexpensive technique for manufacturing
platinum spherical electrodes has also been proposed [99].
Recently, an hexagonal mosaic of intraocular electrodes has
been suggested by Hallum and colleagues to optimize the place-
ment of electrodes and therefore improve visual acuity in pros-
thesis patients [100]. A prototype for an epiretinal system, capa-
ble of 840 stimulating events per second, using this electrode
placement combined with a filtering approach to image
processing, has also been described [101].
Optic nerve devices
The optic nerve is a collection of 1 million individual fibers
running from the retina to the lateral geniculate body. This
nerve can be reached surgically and could provide a suitable
location for implanting a stimulation electrode array.
Microsystems-Based Visual Prosthesis & OPTIVIP projects
(ESPRIT programme of the European Union)
The Microsystems-Based Visual Prosthesis (MiVip) team, led
by Claude Veraat of the Neural Rehabilitation Engineering
Laboratory, Université Catholique de Louvain in Belgium,
has developed a prosthesis system which includes a spiral cuff
silicon electrode to stimulate the optic nerve.
In February 1998, a 59-year-old blind patient was implanted
with the optic nerve visual prosthesis. Localized phosphenes
were successfully produced throughout the visual field and
changing pulse duration or amplitude could alter their bright-
ness. After training it was reported that the patient could per-
ceive different shapes, line orientations and even letters [102].
However, this system only displays one phosphene at a time and
pattern recognition was achieved by the subject scanning with a
head-mounted camera over a time period of up to 3 min. An
interesting feature of this study has been the different phos-
phene shapes that have been generated; if these could be reliably
replicated they might add a useful dimension to prosthetic
vision. The cuff electrode consists of four platinum contacts and
is able to adapt continuously to the diameter of the optic nerve.
Initially a subcutaneous connector conducted stimulation of the
electrode, however, in August 2000, a neurostimulator and
antenna were implanted and connected to the electrode. An
external controller with telemetry was then used for stimulating
the cuff electrode. Recently, an adaptive neural network tech-
nique has been proposed to classify the phosphenes generated by
this device [103,104].
AHV simulation studies
Due to the difficulty in obtaining experimental participants
with an AHV device implanted, a number of simulation studies
have been conducted with normally sighted subjects. However
the simulation approach assumes that normally sighted people
are receiving the same experience as a blind recipient of an
AHV system. Weiland and Humayun have stated that human
implant studies are the only method of verifying the effective-
ness of a visual prosthesis and have questioned the validity of
simulation studies [105].
A frequently cited prosthetic vision simulation was con-
ducted in 1992 at the University of Utah by Cha and col-
leagues, in order to calculate the minimum number of phos-
phenes required for adequate mobility [106]. The pixelized
vision simulator device consisted of a video camera connected
to a monitor in front of the subject’s eyes. A perforated mask
was placed on the monitor to reproduce the effect of individual
phosphenes. The artificial environment consisted of an indoor
maze, which contained paper column obstacles. Walking speed
and frequency of contact were used as dependant variables.
This research found that a 25 × 25 array of phosphenes, with a
field of view of 30° would be required for a successful device.
The simulation display employed by Cha and colleagues
used a simple television-like display. Hayes and colleagues have
described a more sophisticated approach [107], in which two
different image-processing applications were used to display
9. Artificial human vision
www.future-drugs.com 9
simulated phosphenes to a seated subject, who wore a head-
mounted display. The first image processing application used a
simple square phosphene array, where each phosphene con-
sisted of a solid grey scale value equal to the mean luminance
of the contributing image pixels. The second image processing
application used a Gaussian filter. Array size, contrast level,
dropout percentage, simulated phosphene size and back-
ground noise were adjustable features of the simulation.
Object recognition (including plate, cup and spoon), reading,
candy pouring and cutting accuracy tasks were conducted
under different simulation conditions. The main result was to
conclude that the phosphene array size would be the most
important factor in a useable prosthesis.
Another image processing approach investigated the require-
ments for AHV facial recognition in [108]. A low vision
enhancement system connected to a PC and driven by a visual
basic program was used to display the images. Subjects were
required to select which simulation image best matched a set of
four normal images of human faces (the images of the same
person were varied by head angle and whether the person was
smiling or serious). All images displayed occupied a visual field
of 13° horizontally and 17° vertically. The simulation display
was presented in a circular dot mask, rather than the contigu-
ous square blocks. Electrode properties (such as dropouts; size
and gaps), contrast and grey levels could be varied experimen-
tally. The grid sizes used in this study varied from 10 × 10 to 32
× 32 phosphenes. The authors found high accuracy for all high
contrast tests (except those with significant dropout and two
gray levels) and suggest that reliable face recognition using a
crude pixelized grid is feasible.
Research at the Queensland University of Technology (Aus-
tralia), has examined the use of various image-processing
techniques (such as enhancing edges, using different grey
scales and extracting the most important image features) to
identify a recognition threshold for low-quality stationary
images [109]. These images are used to represent the limited
number of phosphenes available to the subject (typically a 25
× 25 array). This research has found that at these low infor-
mation levels the use of image- processing techniques is not
helpful in the identification of static scenes, although an auto-
matic zoom feature did aid image understanding. Additional
research at Queensland University of Technology is investigat-
ing methods for the assessment and enhancement of mobility
for AHV system users [110].
Expert opinion
With our current understanding of neuronal mechanisms in
the visual system, AHV systems do not appear likely to
replace the functioning of normal human vision. It is not
likely that a regularly organized array of phosphenes will
occur as a result of current technology microelectrodes [21].
While the development of AHV systems continues, research
into retinal transplantation, growth factors and gene therapy
has commenced which may also provide alternative treatment
options for blindness.
AHV systems are likely to offer benefits in the areas of mobility
and reading. An important question is whether the benefits from
these systems are worth the cost. Despite the overloading of
another sensory input channel, traditional mobility aids and ETA
devices (such as the vOICe system from Peter Meijer [201]), are
probably cheaper, less invasive and may require a similar amount
of training to AHV systems. Additionally, most people who are
classified as blind are elderly and still have some remaining
vision, and therefore are probably not suited to an AHV system.
The need for standard psychophysical assessment methods
have been noted by a number of AHV researchers [101,111]. To
inform consumers on the benefits of an AHV system compared
with other technical aids for the blind, future research compar-
ing the effectiveness of these devices would be useful. The lack
of a method to compare mobility has also been raised by
Dobelle [13]. However, there are a number of mobility assess-
ment methods presented in the Orientation and Mobility Liter-
ature which could be useful for comparison of AHV systems
and other devices [112–114].
AHV research offers important insight regarding the function-
ing of the human visual system and in brain-computer interface
technology. The subretinal device from Optobionics has shown
impressive results, however, these results may be due to neuro-
trophic effects rather than the microphotodiode implant used.
Current research in other AHV systems is promising, however,
there appears to be significant development required before they
can provide useful mobility and reading. Excellent additional
review papers on AHV include [38,50,115,116].
Five-year view
The subretinal implants demonstrate the greatest promise in
restoring some vision, however, there are doubts over whether
the improvements in vision are due to neurotrophic effects or
the device itself. Further tests to determine the reason for the
improvements are planned. If the device is responsible, it is
conceivable to see these implants available in the next 5 years.
The cortical implant system from the Dobelle institute is
commercially available; however it has not been approved by
the FDA. A 5-year view on this system is not possible, as infor-
mation regarding the system and patient outcomes are not
made public. A recent article in the Wall Street Journal [117]
reported a 33-year-old female recipient who paid US$100,000
for the Dobelle system and was only able to use it for 15 min
per day (as it was tiring and caused head pain).
The remaining cortical and optic nerve systems are still in
varying stages of preliminary human or animal testing. Prelimi-
nary research has also commenced on microstimulation of the
lateral geniculate nucleus [118]. Although progress will be made,
it does not appear likely that a commercial system using these
methods will be available in the next 5 years.
Acknowledgements
This research was supported by Cochlear Ltd and the Aus-
tralian Research Council through ARC Linkage Grant project
0234229.
10. Dowling
10 Expert Rev. Med. Devices 2(1), (2005)
Information resources
Main contacts and project websites:
• Bionic Eye Research Project (Cortical Neuroprosthesis, Uni-
versity of New South Wales, Australia)
Vivek Chowdhury and John Morley
http://ophthalmology.med.unsw.edu.au/bioniceye.htm
• Cortical Implant for the Blind (CORTIVIS, Europe)
Edwardo Fernandez
http://cortivis.umh.es/
• EPI-RET (Retina implant research in Cologne, Germany)
Rolf Eckmiller
www.medizin.uni-koeln.de/kliniken/augenklinik/epi-
ret3e.htm
• Intracortical visual prosthesis (Illinois Institute of Technol-
ogy)
Phillip Troyk
http://neural.iit.edu/intro.html
• Microsystems-Based Visual Prosthesis (MiVip, ESPRIT pro-
gram of the European Union, now OPTIVIP)
Claude Veraart
www.md.ucl.ac.be/gren/Projets/mivip.html
• OPTIVIP projects (ESPRIT program of the EU)
Claude Veraart
www.dice.ucl.ac.be/optivip/
• Optobionics Corporation (USA)
Alan Chow and Vincent Chow
www.optobionics.com
• Retinal Implant (Doheny Retina Institute, University of
Southern California, USA)
Mark Humayun and Eujene De Juan Jr
www.usc.edu/hsc/doheny/
• Retinal Implant & Biohybrid Implant (Japan)
Tohru Yagi
www.bmc.riken.jp/~ yagi/retina/
• Retinal Implant-AG (was SUB-RET project, Germany)
Eberhart Zrenner
www.retina-implant.de/tour/
• Retinal Prosthesis Project (North Carolina State University)
Wentai Liu
www.icat.ncsu.edu/projects/retina/
• Retinomorphic chip (University of Pennsylvania, USA)
www.neuroengineering.upenn.edu/boahen/pub/fs_pub.htm
• Second Sight (CA, USA)
Alfred E Mann and Robert Greenberg
www.2-sight.com/
• The Boston Retinal Implant Project (USA)
John Wyatt and Joseph Rizzo
www.bostonretinalimplant.org/
• The Dobelle Institute (Lisbon, Portugal)
William Dobelle
www.dobelle.com/
• University of Utah (Intracortical prosthesis, USA)
Richard A Normann
www.bioen.utah.edu/cni/projects/blindness.htm
• Vision Prosthesis Project (Retinal prosthesis, Universities of
NSW and Newcastle, Australia)
Gregg Suaning
http://bionic.gsbme.unsw.edu.au/
Key issues
• Artificial human vision (AHV) involves the electrical
stimulation of a component of the human visual system,
which may invoke the perception of a phosphene or point
of light.
• Four locations for AHV implants are currently utilized;
subretinal, epiretinal, optic nerve and the visual cortex
(using intra- and surface electrodes).
• The only commercially available system is the cortical
surface stimulation device from the Dobelle Institute.
• The most impressive gains in vision have been reported
from the subretinal device developed by the Optobionics
Corp., however, these results may not be related to the
microphotodiode device used.
• Psychophysical and mobility assessment standards would
help in comparing AHV systems with other technical aids
for the blind.
References
1 Hambercht FT. The history of neural
stimulation and its relevance to future
neural prostheses. In: Neural Prostheses:
Fundamental Studies. Agnew WF,
McCreery DB (Eds). Prentice Hall, NJ,
USA (1990).
2 World Health Organization (WHO).
Blindness and visual disability: seeing ahead
– projections into the next century. WHO
Fact Sheet 146 (1997).
3 World Health Organization. Blindness and
visual disability: other leading causes
worldwide. WHO Fact Sheet 44 (1999).
4 World Health Organization. Blindness and
visual disability: major causes worldwide.
WHO Fact Sheet 143 (1999).
5 Chawla H. Essential Opthamology.
Churchill Livingstone, Edinburgh, UK
(1981).
6 World Health Organization. Blindness and
visual disability: socioeconomic aspects.
WHO Fact Sheet 145 (1997).
7 Rosen S. Kinesiology and sensorimotor
function. In: Foundations of Orientation and
Mobility. 2nd Edition. Blasch BB, Weiner
WR (Eds). American Foundation for the
Blind, NY, USA (1997).
8 Farmer LW, Smith DL. Adaptive
technology. In: Foundations of Orientation
and Mobility. 2nd Edition. Blasch BB,
Weiner WR (Eds). American Foundation
for the Blind, NY, USA (1997).
9 Dodds A. Rehabilitating Blind and Visually
Impaired People. Chapman and Hall,
London, UK (1993).
10 Soong GP, Lovie-Kitchin JE, Brown B.
Preferred walking speed for assessment of
mobility performance: sighted guide versus
nonsighted guide techniques. Clin. Exp.
Optom. 83, 279–282 (2000).
11 Dagnelie G. Toward an artificial eye. IEEE
Spectrum 22–29 (1996).
11. Artificial human vision
www.future-drugs.com 11
12 Pelayo FJ, Martinez A, Romero S et al.
Cortical visual neuro-prosthesis for the
blind: retina-like software/hardware
preprocessor. Proceedings of the First
International IEEE EMBS Conference on
Neural Engineering (2003).
13 Dobelle W. Artificial vision for the blind by
connecting a television camera to the brain.
ASAIO J. 46, 3–9 (2000).
14 Boahen KA. A retinomorphic vision
system. IEEE Micro. 16, 30–39 (1996).
15 Normann RA, Maynard EM, Guillory KS,
Warren DJ. Cortical implants for the blind.
IEEE Spectrum 33, 54–59 (1996).
16 Suaning GJ, Lovell NH. CMOS
neurostimulation system with 100
channels, scaleable output and bi-
directional radio frequency telemetry.
IEEE Transac. Biomed. Eng. 48, 248–260
(2001).
17 Troyk PR, Schwan MAK. Closed-loop class
E transcutaneous power and data link for
MicroImplants. IEEE Transac. Biomed. Eng.
39, 589–599 (1992).
18 Cornsweet TN. Visual Perception.
Academic Press, NY, USA (1970).
19 Gregory RL. Eye and Brain: The Psychology
of Seeing. 5th Edition. Oxford University
Press, Tokyo (1998).
20 Levine MD. Vision in Man and Machine.
McGraw-Hill Publishing Company, NY,
USA (1985).
21 Troyk P, Bak M, Berg J et al. A model for
intracortical visual prosthesis research. Artif.
Organs 27, 1005–1015 (2003).
22 Hubel DH, Exploration of the primary
visual cortex, 1955–1978. In: Cognitive
Neuroscience: A reader. Gazzaniga MS (Ed.).
Blackwell, MA, USA (2000).
23 Ronner SF. Electrical excitation of CNS
neurons. In: Neural Prostheses: Fundamental
Studies. Agnew WF, McCreery DB (Eds).
Prentice Hall, NJ, USA (1990).
24 Brindley GS, Lewin WS. The sensations
produced by electrical stimulation of the
visual cortex. J. Physiol. 196, 479–493
(1968).
25 Suaning G, Lovell N, Schindhelm K,
Coroneo A. The bionic eye (electronic
visual prosthesis): a review. Aust. NZ J.
Ophthamol. 26, 195–202 (1998).
26 Dobelle WH, Mladejovsky MG.
Phosphenes produced by electrical
stimulation of human occipital cortex, and
their application to the development of a
prosthesis for the blind. J. Physiol. 243,
553–576 (1974).
27 Dobelle WH, Mladejovsky MG, Evans JR,
Roberts TS, Girvin JP. ‘Braille’ reading by a
blind volunteer by visual cortex
stimulation. Nature 259, 111–112 (1976).
28 Chowdhury V, Morley JW, Coroneo MT.
An in vivo paradigm for the evaluation of
stimulating electrodes for use with a visual
prosthesis. Aust. NZ J. Surg. 74, 372–378
(2004).
29 Chowdhury V, Morley JW, Coroneo MT.
Surface stimulation of the brain with a
prototype array for a visual cortex
prosthesis. J. Clin. Neurosci. 11, 331–341
(2004).
30 Bak M, Girvin JP, Hambrecht FT et al.
Visual sensations produced by intracortical
microstimulation of the human occipital
cortex. Med. Biol. Eng. Comp. 28, 257–259
(1990).
31 Schmidt EM, Bak MJ, Hambrecht FT et al.
Feasibility of a visual prosthesis for the
blind based on intracortical
microstimulation of the visual cortex. Brain
119, 507–522 (1996).
32 Rizzo JF, Wyatt J, Humayun M et al.
Retinal prosthesis: an encouraging first
decade with major challenges ahead.
Ophthalmology 108, 13–14 (2001).
33 Normann RA. A penetrating, cortical
electrode array: design considerations.
Proceedings of IEEE International Conference
on Systems, Man and Cybernetics (1990).
34 Rousche PJ, Normann RA. A System for
impact insertion of a 100 electrode array
into cortical tissue. Proceedings of the 12th
Annual International Conference of the IEEE
Engineering in Medicine and Biology Society
(1990).
35 Normann RA. Visual neuroprosthetics-
functional vision for the blind. IEEE
Engineering in Medicine and Biology
Magazine 14, 77–83 (1995).
36 Maynard EM, Nordhausen CT,
Normann RA. The Utah intracortical
electrode array: a recording structure for
potential brain- computer interfaces.
Electroencephalogr. Clin. Neurophysiol.
102, 228–239 (1997).
37 Normann RA, Warren D, Koulakov A.
Representations and dynamics of
representations of simple visual stimuli by
ensembles of neurons in cat visual cortex
studied with a microelectrode array.
Proceedings of the First International IEEE
EMBS Conference on Neural Engineering
(2003).
38 Maynard EM. Visual prostheses. Ann. Rev.
Biomed. Eng. 3, 145–168 (2001).
39 Fernandez E, Ahnelt P, Rabischong P et al.
Towards a cortical visual neuroprosthesis
for the blind. Proceedings of the IFMBE,
Vienna 3, 1690–1691 (2002).
40 Fernandez E, Alfaro A, Tormos JM et al.
Mapping of the human visual cortex using
image-guided transcranial magnetic
stimulation. Brain Res. Protocols 10,
115–124 (2002).
41 Pelayo FJ, Romero S, Morillas CA et al.
Translating image sequences into spike
patterns for cortical neurostimulation.
Proceedings of the Annual Computational
Neuroscience Meeting, Alicante, Spain
(2003).
42 Fernandez JM, Alfaro A, Bonomini P et al.
Brain plasticity: feasibility of a cortical
visual prosthesis for the blind. Proceedings of
the 25th Annual International Conference of
the IEEE Engineering in Medicine and
Biology Society. (2003).
43 Schubert MB, Hierzenberger A, Lehner
HJ, Werner JH. Optimizing photodiode
arrays for the use as retinal implants.
Sensors and Actuators A: Physical. 74,
193–197 (1999).
44 Suaning GJ, Lovell NH. A 100 channel
neural stimulator for excitation of retinal
ganglion cells. Proceedings of the 20th
Annual International Conference of the IEEE
Engineering in Medicine and Biology Society.
20, 2232–2235 (1998).
45 Humayun MS, de Juan E Jr, Weiland JD
et al. Pattern electrical stimulation of the
human retina. Vision Res. 39, 2569–2576
(1999).
46 Marc RE, Jones BW, Watt CB, Strettoi E.
Neural remodeling in retinal
degeneration. Prog. Retinal Eye Res. 22,
607–655 (2003).
47 Chow AY, Chow VY, Pardue MT et al. The
semiconductor-based microphotodiode
array artificial silicon retina. Proceedings of
the IEEE International Conference on
Systems, Man and Cybernetics (1999).
48 Chow A. Artificial retina device.
Optobionics Corporation USA (1991).
49 Chow AY, Chow VY. Subretinal electrical
stimulation of the rabbit retina. Neurosci.
Lett. 225, 13–16 (1997).
50 Margalit E, Maia M, Weiland JD et al.
Retinal prosthesis for the blind. Survey of
Ophthalmol. 47, 335–356 (2002).
51 Chow AY, Pardue MT, Chow VY et al.
Implantation of silicon chip
microphotodiode arrays into the cat
subretinal space. IEEE Transactions on
Neural Systems and Rehabilitation
Engineering. 9, 86–95 (2001).
52 Pardue MT, Stubbs J, Evan B et al.
Immunohistochemical studies of the retina
following long-term implantation with
subretinal microphotodiode arrays. Exp. Eye
Res. 73, 333–343 (2001).
12. Dowling
12 Expert Rev. Med. Devices 2(1), (2005)
53 Chow A. First trials and future technologies
for artificial retinas. Proceedings of the 14th
Annual Meeting of the IEEE Lasers and
ElectroOptics Society (2001).
54 Pardue MT, Phillips MJ, Yin H et al.
Neuroprotective effect of subretinal
implants in the RCS rat. Invest.
Ophthalmol. Vision Sci. (2004). In Press.
55 Chow AY, Peachey NS. The subretinal
microphotodiode array retinal prosthesis.
Ophthalmic Res. 30, 195–198 (1998).
56 Zrenner E, Miliczek K-D, Gabel VP et al.
The development of subretinal
microphotodiodes for replacement of
degenerated photoreceptors. Ophthalmic
Res. 29, 269–280 (1997).
57 Zrenner E, Stett A, Weiss S et al. Can
subretinal microphotodiodes successfully
replace degenerated photoreceptors? Vision
Res. 39, 2555–2567 (1999).
58 Stett A, Barth W, Weiss S, Haemmerle H,
Zrenner E. Electrical multisite stimulation
of the isolated chicken retina. Vision Res.
40, 1785–1795 (2000).
59 Rizzo J, Wyatt J, Loewenstein J, Kelly S,
Shire D. Methods and perceptual
thresholds for short-term electrical
stimulation of human retina with
microelectrode arrays. Invest. Ophthalmol.
Visual Sci. 44, 5355–5361 (2003).
60 Guenther E, Troger B, Schlosshauer B,
Zrenner E. Long-term survival of retinal
cell cultures on retinal implant materials.
Vision Res. 39, 3988–3994 (1999).
61 Hammerle H, Kobuch K, Kohler K et al.
Biostability of micro-photodiode arrays for
subretinal implantation. Biomaterials 23,
797–804 (2002).
62 Zrenner E. The subretinal implant: can
microphotodiode arrays replace
degenerated retinal photoreceptors to
restore vision? Ophthalmologica 216(Suppl.
1), 8–20 (2002).
63 Gekeler F, Schwahn H, Stett A, Kohler K,
Zrenner E. Subretinal microphotodiodes to
replace photoreceptor-function. A review of
the current state. In: Vision, sensations et
environnement. Doly M, Droy M-T, Christen
Y (Eds). Irvinn, Paris, France, 77–95 (2001).
64 Schwahn HN, Gekeler F, Kohler K et al.
Studies on the feasibility of a subretinal
visual prosthesis: data from Yucatan
micropig and rabbit. Graefe’s Archive Clin.
Exp. Ophthalmol. 239, 961–967 (2001).
65 Volker M, Shinoda K, Sachs H et al. In vivo
assessment of subretinally implanted
microphotodiode arrays in cats by optical
coherence tomography and fluorescein
angiography. Graefe’s Archive Clin. Exp.
Ophthalmol. Epub ahead of print (2004).
66 Ito Y, Yagi T, Kanda H et al. Cultures of
neurons on microelectrode array in hybrid
retinal implant. Proceedings of the IEEE
International Conference on Systems, Man
and Cybernetics (1999).
67 Kanda H, Yagi T, Nakatsu T, Watanabe M,
Uchikawa Y. A study on electrical
stimulation to visual nervous system in
visual prosthesis. Proceedings of the 26th
Annual Conference of the IEEE (2000).
68 Kanda H, Yagi T, Ito Y et al. Efficient
stimulation inducing neural activity in
retinal implant. Proceedings of IEEE
Systems, Man, and Cybernetics 4, 409–413
(1999).
69 Peterman MC, Bloom DM, Lee C et al.
Localized neurotransmitter release for use
in a prototype retinal interface. Invest.
Ophthalmol. Visual Sci. 44, 3144–3149
(2003).
70 Peterman MC, Mehenti NZ, Bilbao KV
et al. The artificial synapse chip: a flexible
retinal interface based on directed retinal
cell growth and neurotransmitter
stimulation. Artif. Organs 27, 975–985
(2003).
71 Ziegler D, Linderholm P, Mazza M et al.
An active microphotodiode array of
oscillating pixels for retinal stimulation.
Sensors and Actuators A: Physical 110, 11–17
(2003).
72 Kanda H, Morimoto T, Fujikado T et al.
Electrophysiological studies of the
feasibility of suprachoroidal-transretinal
stimulation for artificial vision in normal
and RCS rats. Invest. Ophthalmol. Visual
Sci. 45, 560–566 (2004).
73 Palanker D, Huie P, Vankov A et al.
Attracting retinal cells to electrodes for
high-resolution stimulation. Ophthalmic
Technol. SPIE 5314 (2004).
74 Humayun MS. Is surface electrical
stimulation of the retina a feasible approach
towards the development of a visual
prosthesis? PhD thesis, University of North
Carolina at Chapel Hill (1992).
75 Liu W, McGucken E, Vitchiechom K
et al. Dual unit visual intraocular
prosthesis. Proceedings of the 19th Annual
International Conference of the IEEE
Engineering in Medicine and Biology
Society (1997).
76 Humayun MS, Sato Y, Propst R, de Juan Jr
E. Can potentials from the visual cortex be
elicited electronically despite severe retinal
degeneration and a markedly reduced
electroretinogram? German J. Ophthalmol.
4, 57–64 (1995).
77 Humayun MS, de Juan E. Artificial vision.
Eye 12, 605–607 (1998).
78 Humayun MS, De Juan E Jr, Dagnelie G
et al. Visual perception elicited by electrical
stimulation of retina in blind humans.
Arch. Ophthalmol. 114, 40–46 (1996).
79 Majji AB, Humayun MS, Weiland JD et al.
Long-term histological and
electrophysiological results of an inactive
epiretinal electrode array implantation in
dogs. Invest. Ophthalmol. Visual Sci. 40,
2073–2081 (1999).
80 Liu W, McGucken E, Vichienchom K et al.
Retinal prosthesis to aid the visually
impaired. Proceedings of the IEEE
International Conference on Systems, Man
and Cybernetics (1999).
81 Liu W, McGucken E, Cavin R et al., A
retinal prosthesis to benefit the visually
impaired. In: Intelligent Systems and
Technologies in Rehabilitation Engineering.
Teodorescu H-NL, Jain LC (Eds). CRC
Press, FL, USA (2001).
82 Humayun MS, Weiland JD, Fujii GY et al.
Visual perception in a blind subject with a
chronic microelectronic retinal prosthesis.
Vision Res. 43, 2573–2581 (2003).
83 Johnson L, Perkins FK, O’Hearn T et al.
Electrical stimulation of isolated retina with
microwire glass electrodes. J. Neurosci.
Meth. (2004). In Press.
84 Liu W, Sivaprakasam M, Singh PR,
Bashirullah R, Wang G. Electronic visual
prosthesis. Artif. Organs 27, 986–995
(2003).
85 Rizzo JF, Wyatt J. Prospects for a visual
prosthesis. The Neuroscientist 3, 251–262
(1997).
86 Rizzo JF, Miller S, Denison T, Wyatt J.
Electrically-evoked cortical potentials
from stimulation of rabbit retina with a
microfabricated electrode array. Invest.
Ophthalmol. Visual Sci. 37, S707
(1996).
87 Rizzo J, Wyatt J, Loewenstein J, Kelly S,
Shire D. Perceptual efficacy of electrical
stimulation of human retina with a
microelectrode array during short-term
surgical trials. Invest. Ophthalmol. Visual
Sci. 44, 5362–5369 (2003).
88 Eckmiller R. Learning retina implants with
epiretinal contacts. Ophthalmic Res. 29,
281–289 (1997).
89 Eckmiller R, Becker M, Hunermann R.
Dialog concepts for learning retina
encoders. Proceedings of the International
Conference on Neural Networks (1997).
90 Becker M, Braun M, Eckmiller R. Retina
implant adjustment with reinforcement
learning. Proceedings of the 1998 IEEE
International Conference on Acoustics, Speech
and Signal Processing (1998).
13. Artificial human vision
www.future-drugs.com 13
91 Becker M, Eckmiller R, Hunermann R.
Psychophysical test of a tunable retina
encoder for retina implants. Proceedings of
the International Joint Conference on Neural
Networks (1999).
92 Baruth O, Eckmiller R, Neumann D.
Retina encoder tuning and data encryption
for learning retina implants. Proceedings of
the International Joint Conference on Neural
Networks (2003).
93 Eckmiller R, Becker M, Hunermann R.
Towards a learning retina implant with
epiretinal contacts. Proceedings of the IEEE
International Conference on Systems, Man
and Cybernetics (1999).
94 Walter P, Heimann K. Evoked cortical
potentials after electrical stimulation of the
inner retina in rabbits. Graefe’s Archive Clin.
Exp. Ophthalmol. 238, 315–318 (2000).
95 Hesse L, Schanze T, Wilms M, Eger M.
Implantation of retina stimulation
electrodes and recording of electrical
stimulation responses in the visual cortex of
the cat. Graefe’s Archive Clin. Exp.
Ophthalmol. 238, 840–845 (2000).
96 Suaning GJ, Lovell NH, Kerdraon YA.
Physiological response in Ovis aries
resulting from electrical stimuli delivered by
an implantable vision prosthesis.
Proceedings of the 23rd Annual International
Conference of the IEEE Engineering in
Medicine and Biology Society (2001).
97 Suaning GJ, Lovell NH, Kerdraon Y. Trans-
retinal electrical stimulation using a
neuroprosthesis: the effects of damage to
the R-Membrane. Proceedings of the Second
Joint Annual Conference and the Annual Fall
Meeting of the Biomedical Engineering
Society (2002).
98 Hallum L, Tsafnet G, Lovell N, Suaning G.
Artificial vision for the blind. Australasian
Sci. 30, 21–23 (2003).
99 Suaning GJ, Lovell NH, Kwok CY.
Fabrication of platinum spherical electrodes
in an intraocular prosthesis using high-
energy electrical discharge. Sensors and
Actuators A: Physical 108, 155–161 (2003).
100 Hallum LE, Taubman DS, Suaning GJ,
Morley JW, Lovell NH. A filtering approach
to artificial vision: a phosphene visual tracking
task. Proceedings of the World Congress on
Medical Physics and Biomedical Engineering
(WC2003), Sydney, Australia (2003).
101 Suaning GJ, Hallum LE, Chen SC, Preston
PJ, Lovell NH. Phosphene vision:
development of a portable visual prosthesis
system for the blind. Proceedings of the 25th
Annual International Conference of the
IEEE/EMBS, Cancun, Mexico (2003).
102 Veraart C, Wanet-Defalque M-C, Gérard B,
Vanlierde A, Delbeke J. Pattern recognition
with the optic nerve visual prosthesis. Artif.
Organs 27, 996–1004 (2003).
103 Archambeau C, Delbeke J, Verleysen M.
Classification of visual sensations generated
electrically in the visual field of the blind.
Proceedings of the 5th IFAC symposium on
Modeling and Control in Biomedical Systems,
Melbourne, Australia (2003).
104 Archambeau C, Delbeke J, Veraart C,
Verleysen M. Prediction of visual
perceptions with artificial neural networks
in a visual prosthesis for the blind. Artif.
Intel. Med. (2004). In Press.
105 Weiland JD, Humayun MS. Past, present,
and future of artificial vision. Artif. Organs
27, 961–962 (2003).
106 Cha K, Horch K, Normann R. Mobility
performance with a pixelised vision system.
Vision Res. 32, 1367–1372 (1992).
107 Hayes JS, Yin VT, Piyathaisere D et al.
Visually guided performance of simple
tasks using simulated prosthetic vision.
Artif. Organs 27, 1016–1028 (2003).
108 Thompson R, Barnett G, Humayun M,
Dagnelie G. Facial recognition using simulated
prosthetic pixelized vision. Invest. Ophthalmol.
Vision Sci. 44, 5035–5042 (2003).
109 Boyle JR, Maeder AJ, Boles WW. Can
environmental knowledge improve
perception with electronic visual
prostheses? Proceedings of the World Congress
on Medical Physics and Biomedical
Engineering (WC2003), Sydney (2003).
110 Dowling J, Maeder A, Boles W. Mobility
enhancement and assessment for a visual
prosthesis. Proceedings of SPIE International
Symposium on Medical Imaging, San Diego,
CA, USA (2004).
111 Loewenstein JI, Montezuma SR, Rizzo III
JF. Outer retinal degeneration: an electronic
retinal prosthesis as a treatment strategy.
Arch. Ophthalmol. 122, 587–596 (2004).
112 Lovie-Kitchin J, Mainstone J, Robinson J,
Brown B. What areas of the visual field are
important for mobility in low vision
patients? Clin. Vision Sci. 5 (1990).
113 Geruschat D, Turano KA, Stahl JW.
Traditional measures of mobility
performance and retinis pigmentosa.
Optometry Vision Sci. 75, 525–537 (1998).
114 Haymes S, Guest D, Heyes A, Johnston A.
Mobility of people with retinitis
pigmentosa as a function of vision and
psychological variables. Optometry Vision
Sci. 73, 621–637 (1996).
115 Warren DJ, Normann RA, Visual
neuroprostheses. In: Handbook of
Neuroprosthetic Methods. Finn WE, LoPresti
PG (Eds). CRC Press, FL, USA (2003).
116 Uhlig CE, Taneri S, Benner FP, Gerding H.
Elektrostimulation des visuellen Systems.
Ophthalmologe 98, 1089–1096 (2001).
117 Naik G, Regalado A. An inventor struggles
to restore sight. In: Wall Street Journal, NY,
USA, B1 (2003).
118 Pezaris JS, Reid RC. Microstimulation in
LGN produces focal visual percepts. To be
presented at the 34th Annual Meeting of
the Society for Neuroscience. 23–27
October, San Diego, CA, USA (2004).
Website
119 Meijer PBL. Vision technology for the
totally blind (2003).
www.seeingwithsound.com/
(Accessed December, 2004)
Affiliation
• Jason Dowling
Queensland University of Technology, School of
Electrical and Electronic Systems Engineering,
Faculty of Built Environment and Engineering,,
Brisbane, Australia
Tel.: +617 3864 1608
Fax: +617 3864 1516
j.dowling@qut.edu.au