PPT about VISUAL PROSTHESIS, a vision for blind people, which I made for my college purpose. Gathered Information from its official sites.

1. Hariharan Sivadasan.
Asan Memorial College of Engineering and Technology. Chengalpet.
BIONIC EYE VISUAL
PROSTHESIS

2. BIONIC EYE ?
 Bio-electronic eye
 Electronic device which replaces functionality of a part
or whole of the eye
 Used for replacing functionality (or)
 Adding functionality to the eye

3. The Eye
 Human Eye is similar to a camera
 Macula provides the highest
resolution of the image which
we see.
 Macula is comprised of multiple
layers of cells which process
the initial “analog”light energy
entering the eye into “digital”
electrochemical impulses.
 Human eye has nearly
100 million photoreceptors.

4. Structure of the Eye

5. The Retina

6. The Eye with Retina

7. How does healthy vision work
The human eye captures
information that is only
perceived once processed by
the brain.
The eye receives information
via reflected light – it can only
make sense of what is in a
room if there is some light to
illuminate its contents. If it is
pitch black, there is nothing for
the eye to work with.
Reflected light enters the eye
and is focussed on its rear
internal surface, known as the
retina. Light receptors located
on this surface process the
light into electrical signals and
transmit these signals to the
brain along the optic nerve.
When the brain receives this
electrical information from the
optic nerve, it interprets it as an
image.

8. How the eye does it?
Light enters the eye through the cornea,
the clear bulge at the front of the eyeball.
The cornea gathers the light into the pupil,
a hole in the centre of the iris, which is the
structure that gives the eye its colour.
Depending on the amount of light available
to the eye, the iris will contract or expand
to accommodate the amount of light
required, making the pupil smaller or
larger. The more light that is available, the
smaller the pupil becomes; restricting the
amount of light entering the eye. The less
light available, the larger the pupil
becomes; allowing more light to enter the
eye.
Once the light passes through the pupil it
goes through the crystalline lens, which
sits behind the iris. Light then passes
through the vitreous humour, the clear gel
that fills the inside of the eye. Finally, light
comes to focus on the retina.
The retina is a filmy tissue made up of a
number of layers of different types of cells.
One layer of the retina contains light
receptors known as rods and cones. These
light receptors allow the retina to convert
light into electrical impulses, which are
then transmitted along the optic nerve to

9. Measuring vision
 Visual acuity is the measure of how well someone sees. This can be
determined by testing how clearly they can see text at a standard
distance. This is done with a Snellen chart, named after its inventor,
Herman Snellen, a Dutch ophthalmologist who worked at the turn of
the 19th century.
 The Snellen Chart
 The Snellan chart typically features eleven rows of letters, which are
largest on the top row (which usually has one letter only) and smallest
on the final row (which usually has nine letters). Each row indicates a
specific level of acuity; one row represents what is accepted to be
normal vision, a visual acuity of 20/20.
 Many people have visual acuity higher than 20/20 (such as 20/15)
and many have a lower visual acuity (such as 20/40). The larger the
second number, the lower the visual acuity.

10. Bionic Eye

11. Who will it help?
 Technology is aimed at helping people with severe
vision loss due to:
 Retinitis pigmentosa, and
 Age-related macular degeneration.
 To benefit from this technology people will need:
 Some remaining retinal ganglion cells
 A healthy optic nerve and visual cortex
 Very low or no vision
 To have been able to see in the past, so that the
vision processing part of the brain has developed fully.

12. What Might I see?
 A person using a retinal implant to see will not
experience vision in the same way a person with
healthy vision does. Vision will be quite basic to
start with and people will need training to adapt
to the implant. With time, training and patience,
people will be able to use this visual information
to be more independent and mobile.

13. Phosphene vision and The Bionic Eye apps
 The retinal implant bionic eye works by stimulating the perception of
light in a patient. A phosphene is a perceived spot of light in the
visual field. What our technology aims to do is stimulate many of
these phosphenes across the visual field in a way that enables the
patient to put together a picture of what they are looking at. The
more electrodes an implant contains, the more phosphenes are
capable of being generated and the more detail a patient may be
able to see.
 An app to simulate the sort of vision a person with a bionic eye might
experience. Although it is difficult to predict exactly what people with
retinal implants will experience, the app will help you imagine what
vision with phosphenes might be like. You can vary phosphene
number and size to experience different effects, and also record
images of what you are 'seeing' with your bionic vision.

 The bionic eye app is now available for Android and iOS.

14. How does it work?
 The bionic vision system consists of a camera, attached to a
pair of glasses, which transmits high-frequency radio signals
to a microchip implanted in the eye. Electrodes on the
implanted chip convert these signals into electrical impulses
to stimulate cells in the retina that connect to the optic nerve.
These impulses are then passed down along the optic nerve
to the vision processing centres of the brain, where they are
interpreted as an image.
 To benefit from this technology, patients need to have a
functional visual pathway fromthe retina to the brain along
the optic nerve, as well as some intact retinal cells. As such,
the two medical conditions that this technology aims to
address are retinitis pigmentosa and age-related macular
degeneration.

15. Why these Conditions?
 Retinitis pigmentosa (RP) and age-related macular degeneration
(AMD) are two major causes of blindness and low vision in Australia
and worldwide. Both these conditions lead to damage of the
photoreceptor cells in the retina that are crucial to vision, but leave
the optic nerve and visual cortex healthy and intact.
 Approach takes advantage of the healthy parts of the visual system
to maximise the benefits for people with RP and AMD.

16. The BVA devices
 Scientists are simultaneously developing
different bionic eye devices. From 2012 until
2014 research was conducted with a 24-
electrode early prototype that was implanted in
three people.
• 44-electrode prototype
• Wide-View device
• High-Acuity device

17. 44-electrode prototype
 The 44-electrode prototype is designed to help
researchers learn more about how the bionic eye can be
optimised. The device will be fully implantable
and include a patient-worn vision processor. Participants
will be able to take the device out of the lab and into the
real world. Feedback from patients will allow
researchers to develop more sophisticated vision
processing and stimulation techniques.

18. High-Acuity device
 With the High-Acuity device, Scientists hope
patients will be able to recognise faces and
read large print. The first patients for the High-
Acuity device will be people with retinitis
pigmentosa, but scientists are developing the
technology so it will be suitable for people with
age-related macular degeneration.

19. Wide-View device
 The Wide-View device may be most suitable
for patients with retinitis pigmentosa.
Researchers continue work on the device
development and preclinical studies in
preparation for patient tests with this device in
due course.
 The implanted chip has 98 electrodes to
stimulate the retina and enable patients to
perceive vision.
 To provide patients the ability to move around
large objects such as buildings, cars and park
benches and to lead more independent lives.

20. Advantages
 Very Early in the visual pathway
 No Batteries implanted within body
 No complicated surgical procedure
 Power Requirement – ¼ of milliwatt

21. Disadvantages
 Axons b/w electrodes and ganglionic cells
 Other axons get excited – unwanted
perception of large blur
 Extra circuitry required for downstream
electrical input

23. Conclusion
 Its been 40 years since Arne Larsson received the first fully
implanted cardiac pacemaker at the Karolinska Institute in
Stockholm.
 Researchers throughout the world have looked for ways to improve
people's lives with artificial, bionic devices.
 Bionic devices are being developed to do more than replace
defective parts.
 Researchers are also using them to fight illnesses.
 Providing power to run bionic implants and making connections to
the brain's control system pose the two great challenges for
biomedical engineering.
 We are now looking at devices like bionic arms, tongues, noses etc.