Ultrasonography uses sound waves to image the eye and orbit. It was first developed in the 1950s and has since become an important tool for ocular imaging. Ultrasound uses high frequency sound pulses that reflect off structures in the eye to produce images. There are two main types: A-scan which produces a one-dimensional image, and B-scan which produces a two-dimensional cross-sectional image. Ultrasound is useful for evaluating the posterior segment in opaque media, measuring tissue thickness, and detecting intraocular and orbital lesions. It is a non-invasive tool commonly used to diagnose and monitor various ocular diseases.
OCT is used to non-invasively image the retina in cross-section with micrometer-level resolution. It works by measuring the interference of light reflected from retinal structures. OCT was developed in 1991 and uses near-infrared light wavelengths of 840nm and 1310nm. OCT provides high-resolution 2D images of the retina and can integrate data points over depth to form 3D representations. It is useful for diagnosing and monitoring many retinal diseases.
The document discusses B-scan ultrasound, providing a history of its development and describing the technical aspects and clinical applications. It notes that B-scan utilizes high frequency sound waves to produce two-dimensional images, and was first introduced in 1958. The document outlines the physics behind B-scan, describing how sound waves are reflected and the factors that determine resolution. Clinical uses mentioned include evaluating vitreous opacities, retinal detachments, and tumors.
This document discusses ocular biometry and ultrasound. It begins with definitions of biometrics and ultrasound terminology. It then describes the different modes of ultrasound - A-scan, B-scan and M-scan. Key components of ultrasound devices like transducers, amplifiers and velocities of sound through ocular tissues are explained. Factors affecting ultrasound reflection and penetration are outlined. The document concludes with an introduction to ocular biometry procedures and a brief history.
The document provides information on axial length measurement techniques using ultrasound (A-scan) biometry. It discusses average axial lengths, accuracy of measurements, examination procedure, potential sources of error for different techniques, instrument settings, and special measurement considerations. Key points include:
- The average axial length of a normal eye is 23.06mm, ranging mostly from 22-24.5mm.
- Accuracy of A-scan ultrasound is ±0.1mm. Differences between eyes should be ≤0.3mm.
- Potential sources of error include corneal compression, fluid excess, misalignment, inappropriate eye type settings.
- Gates, gain, and eye type settings impact accuracy and must be optimized.
- Special
Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light to obtain high-resolution cross-sectional images of the retina and anterior segment. OCT of the retina provides images similar to a vertical biopsy under a microscope, with micron-level resolution. Applications of OCT include ophthalmology, dermatology, cardiology, endoscopy, and guided surgery. OCT measures reflected light using interferometry, similar to ultrasound but using light instead of sound. It has much higher resolution than ultrasound. OCT is useful for detailed imaging of the retina and anterior segment, while ultrasound can image deeper structures due to its ability to penetrate tissue.
This document discusses the diagnosis of pre-perimetric glaucoma. It begins by defining pre-perimetric glaucoma as optic nerve abnormalities seen on structural tests with normal visual fields. It then discusses the need for early diagnosis before functional changes occur. Various functional tests are described like standard automated perimetry, short wavelength automated perimetry, frequency doubling technology, and others. Structural tests like confocal scanning laser ophthalmoscopy, optical coherence tomography, and their principles are summarized.
This document provides an overview of B-scan ultrasonography. It begins with an introduction to B-scans and their use in providing qualitative and quantitative assessment of the eye and orbit. It then discusses the physics and principles behind ultrasound, including reflection, absorption, resolution and other key concepts. The document outlines the components and use of B-scan ultrasound machines, including different probe orientations and scanning techniques. It concludes with clinical applications and indications for B-scan ultrasonography in evaluating ocular pathology.
Ultrasonography uses ultrasound to image tissues within the body. A-scan ultrasonography provides a one-dimensional view of the eye by measuring the echoes of ultrasound waves. It can be used to detect and measure tumors, assess eye structures for IOL calculation, and interpret pathology. The ultrasound is reflected at interfaces between tissues, appearing as spikes on the display. Immersion techniques provide more accurate measurements than contact techniques by avoiding compression artifacts. Limitations include artifacts, small lesions, missed foreign bodies, and misalignment issues.
OCT is used to non-invasively image the retina in cross-section with micrometer-level resolution. It works by measuring the interference of light reflected from retinal structures. OCT was developed in 1991 and uses near-infrared light wavelengths of 840nm and 1310nm. OCT provides high-resolution 2D images of the retina and can integrate data points over depth to form 3D representations. It is useful for diagnosing and monitoring many retinal diseases.
The document discusses B-scan ultrasound, providing a history of its development and describing the technical aspects and clinical applications. It notes that B-scan utilizes high frequency sound waves to produce two-dimensional images, and was first introduced in 1958. The document outlines the physics behind B-scan, describing how sound waves are reflected and the factors that determine resolution. Clinical uses mentioned include evaluating vitreous opacities, retinal detachments, and tumors.
This document discusses ocular biometry and ultrasound. It begins with definitions of biometrics and ultrasound terminology. It then describes the different modes of ultrasound - A-scan, B-scan and M-scan. Key components of ultrasound devices like transducers, amplifiers and velocities of sound through ocular tissues are explained. Factors affecting ultrasound reflection and penetration are outlined. The document concludes with an introduction to ocular biometry procedures and a brief history.
The document provides information on axial length measurement techniques using ultrasound (A-scan) biometry. It discusses average axial lengths, accuracy of measurements, examination procedure, potential sources of error for different techniques, instrument settings, and special measurement considerations. Key points include:
- The average axial length of a normal eye is 23.06mm, ranging mostly from 22-24.5mm.
- Accuracy of A-scan ultrasound is ±0.1mm. Differences between eyes should be ≤0.3mm.
- Potential sources of error include corneal compression, fluid excess, misalignment, inappropriate eye type settings.
- Gates, gain, and eye type settings impact accuracy and must be optimized.
- Special
Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light to obtain high-resolution cross-sectional images of the retina and anterior segment. OCT of the retina provides images similar to a vertical biopsy under a microscope, with micron-level resolution. Applications of OCT include ophthalmology, dermatology, cardiology, endoscopy, and guided surgery. OCT measures reflected light using interferometry, similar to ultrasound but using light instead of sound. It has much higher resolution than ultrasound. OCT is useful for detailed imaging of the retina and anterior segment, while ultrasound can image deeper structures due to its ability to penetrate tissue.
This document discusses the diagnosis of pre-perimetric glaucoma. It begins by defining pre-perimetric glaucoma as optic nerve abnormalities seen on structural tests with normal visual fields. It then discusses the need for early diagnosis before functional changes occur. Various functional tests are described like standard automated perimetry, short wavelength automated perimetry, frequency doubling technology, and others. Structural tests like confocal scanning laser ophthalmoscopy, optical coherence tomography, and their principles are summarized.
This document provides an overview of B-scan ultrasonography. It begins with an introduction to B-scans and their use in providing qualitative and quantitative assessment of the eye and orbit. It then discusses the physics and principles behind ultrasound, including reflection, absorption, resolution and other key concepts. The document outlines the components and use of B-scan ultrasound machines, including different probe orientations and scanning techniques. It concludes with clinical applications and indications for B-scan ultrasonography in evaluating ocular pathology.
Ultrasonography uses ultrasound to image tissues within the body. A-scan ultrasonography provides a one-dimensional view of the eye by measuring the echoes of ultrasound waves. It can be used to detect and measure tumors, assess eye structures for IOL calculation, and interpret pathology. The ultrasound is reflected at interfaces between tissues, appearing as spikes on the display. Immersion techniques provide more accurate measurements than contact techniques by avoiding compression artifacts. Limitations include artifacts, small lesions, missed foreign bodies, and misalignment issues.
This document discusses optical coherence tomography (OCT) and its use in evaluating the optic nerve head (ONH). It provides details on OCT technology, including how OCT creates high resolution cross-sectional images of the retina and ONH using infrared light. The document compares time domain OCT and spectral domain OCT, and describes applications of OCT such as glaucoma evaluation by examining the ONH, retinal nerve fiber layer, and peripapillary region. Examples of OCT images of the normal ONH and glaucomatous ONH are also presented.
This document discusses the corneal endothelium and techniques for assessing its health and function. The corneal endothelium is a single layer of hexagonal cells that maintains corneal clarity by pumping fluid out of the stroma. Assessment techniques described include specular microscopy, which allows analysis of endothelial cell density, morphology, and patterns under high magnification; confocal microscopy; anterior segment OCT; and ultrasound pachymetry to measure corneal thickness as an indicator of endothelial function. Common indications for assessment include pre- and post-operative evaluation, and evaluation of donor corneas for transplantation.
Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light to capture high-resolution cross-sectional images of the retina. OCT was introduced in 1991 and has since become a widely used tool for ophthalmic diagnosis. It provides 10 micrometer resolution images, allowing visualization of individual retinal layers. Several technological advancements, including Fourier-domain OCT and swept-source OCT, have improved imaging speeds and depths. OCT angiography allows visualization of the retinal and choroidal vasculature without dyes. Precise quantitative and qualitative analysis of OCT images provides crucial information for diagnosing and monitoring many retinal conditions.
1) Fundus autofluorescence imaging provides a noninvasive method to map naturally occurring fluorophores in the eye. The major source of fundus autofluorescence is lipofuscin in the retinal pigment epithelium and melanin.
2) Lipofuscin accumulation over time can be toxic to retinal pigment epithelium cells and interfere with normal cell function. Areas of geographic atrophy in age-related macular degeneration appear as dark regions due to the lack of retinal pigment epithelium and lipofuscin.
3) Abnormal patterns of fundus autofluorescence such as banded or diffuse patterns are associated with more rapid progression of geographic atrophy compared to areas without abnormalities or those with only
This document discusses various biometry instruments and equipment used to calculate intraocular lens (IOL) power for cataract surgery. It describes how keratometry, A-scan ultrasound biometry, and non-contact devices like the IOLMaster measure important ocular dimensions needed for IOL power calculations, including corneal power, axial length, and anterior chamber depth. It also discusses IOL power calculation formulas from first to fourth generation and factors that influence formula choice, such as eye length, anterior chamber depth, and IOL placement in the eye. Accurate biometry is emphasized as key to achieving the desired postoperative refractive outcome.
Ophthalmic ultrasonography uses sound waves to evaluate the eye and orbit. It can assess tumors, retinal detachments, and foreign bodies when the eye is opaque. The A-scan provides one-dimensional measurements of internal structures. The B-scan gives a two-dimensional cross-section, displaying reflections as varying shades of gray. Together they characterize lesions by location, size, internal reflectivity, structure, and vascularity. Ultrasound is used preoperatively for cataract surgery planning and to evaluate intraocular tumors, accurately measuring their dimensions to guide treatment. Common indications also include opaque media evaluation and orbital disorders.
This document discusses ultrasound techniques used in ophthalmology. It begins by providing background on ultrasound waves and the early development of A-scan and B-scan techniques in the 1950s-1970s. It then describes the basic components and mechanisms of A-scan and B-scan ultrasound probes. The remainder of the document details various ultrasound techniques and their applications, including evaluating the vitreous, retina, choroid, tumors, trauma, and performing biometry. It provides guidance on interpreting ultrasound findings and differentiating various pathologies. In summary, this document serves as a comprehensive guide to ophthalmic ultrasound acquisition and interpretation.
BASIC INFO ON FUDUS FLORESCENCE ANGIOGRAPHYNalin Nayan
The document discusses fundus fluorescein angiography (FFA). FFA involves injecting a fluorescent dye called fluorescein and using a retinal camera to take photos of the retina and choroid as the dye circulates. It describes the five phases seen in FFA - choroidal, arterial, capillary, venous, and late phases. Abnormalities that may appear as hyperfluorescence or hypofluorescence on FFA are also outlined.
Glaucoma drainage devices (GDDs) work by creating an alternate pathway for aqueous outflow from the anterior chamber through a silicone tube to a plate under the conjunctiva where fluid is absorbed. The Ahmed valve and Baerveldt implant are two commonly used valved and non-valved devices, respectively. The Ahmed valve uses silicone leaflets to allow one-way flow above a certain pressure threshold, while the Baerveldt implant relies on a fibrous capsule formation around its plate for resistance to outflow. GDDs are indicated for refractory glaucoma when other surgeries have failed.
This document provides an overview of fundus fluorescein angiography (FFA). It begins with a brief history of FFA and describes the properties and pharmacokinetics of fluorescein dye. The document outlines the procedure for FFA, including patient positioning, dye injection, and photographing different phases. Normal FFA phases and angiogram patterns are presented, along with examples of abnormal hypofluorescence, hyperfluorescence, and vascular filling defects. The document concludes with brief descriptions of several common retinal conditions visualized on FFA.
This document provides an overview of ultrasound use for eye and orbit examination. It discusses the history, principles, instrumentation, techniques, indications, advantages, and types of scans (A-scan and B-scan) used. Key points include:
- Ultrasound uses high frequency sound waves to image ocular structures. It is non-invasive and avoids radiation.
- A-scans show echo amplitude over time as a line, while B-scans provide a cross-sectional image in shades of grey.
- Examination involves transverse, longitudinal, and axial scans using contact or immersion techniques.
- Ultrasound is useful for evaluating opaque media, tumors, detachments, injuries,
Keratometry measures the curvature of the cornea using the reflection of light off the corneal surface. There are two main types - manual keratometers using movable mires or prisms to assess curvature, and automated keratometers using photosensors. Keratometry is used to detect astigmatism, monitor corneal conditions, and assist in contact lens and refractive surgery. It provides important information but has limitations as it only measures the central cornea and assumes a symmetrical shape.
IOL power calculation is challenging in eyes with prior refractive surgery or other special situations. In eyes with prior radial keratotomy, standard keratometry overestimates corneal power due to flattening outside the central optical zone. Multiple methods of IOL power calculation should be used, including topography to measure the flattest central corneal power. A study comparing methods in eyes with prior RK found IOL power calculation using topographic keratometry was least accurate compared to formulas from the ESCRS calculator. No single method provided reliable results, highlighting the difficulty in IOL power calculation for eyes with prior refractive surgery.
Fitting Philosophies and Assessment of Spherical RGP lenses Urusha Maharjan
This document discusses the fitting of spherical rigid gas permeable (RGP) contact lenses. It covers preliminary measures like determining corneal curvature and diameter. Forces affecting lens fit like gravity and tear flow are described. Selection of the first trial lens involves choosing the appropriate back optic zone radius, diameter, and power based on factors like corneal curvature and prescription. Dynamic and static fitting criteria are provided. The lens is assessed for proper movement, centration, and vision. Neutralization of corneal astigmatism by about 90% with a spherical RGP lens is explained through an example.
Basic principles of ocular ultrasonographyRohit Rao
Ultrasound has been used in ophthalmology since the 1950s, with early pioneers developing A-scan and B-scan technologies. A-scan uses amplitude to represent echoes as vertical spikes, while B-scan displays echoes as brightness on a two-dimensional screen. Modes include A-scan for biometry and B-scan for diagnostic imaging. Later improvements included Doppler ultrasound and high-frequency ultrasound biomicroscopy. Ultrasound utilizes acoustic waves and principles of reflection and transmission to generate images of the eye and orbit.
B-scan ultrasonography provides two-dimensional images of ocular structures through the use of high frequency sound waves. It can be used to evaluate a variety of conditions, including retinal detachment, vitreous hemorrhage, intraocular tumors, and trauma. Retinal detachment appears on B-scan as an echogenic membrane attached to the optic nerve head, while vitreous hemorrhage shows as fine echo opacities within the vitreous cavity. B-scan is useful for assessing patients with dense cataracts or other opaque media by allowing visualization of the posterior segment.
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/ocular-ultrasound/❤❤
Dear viewers Check Out my other piece of works at___ https://healthkura.com
Ocular Ultrasonography (Ocular USG/ Ophthalmic USG), ophthalmic ultrasound/ ophthalmic ultrasonography/ ocular ultrasound/ Ultrasound of eye and orbit
PRESENTATION LAYOUT
Introduction
History
Physics
Principles & instrumentation
Terminologies
Indications & contraindications
Methods - A-Scan - B-Scan
Interpretation
Definition
Ultrasound Waves are acoustic waves that have frequencies greater than 20 KHz
The human ear can respond to an audible frequency range, roughly 20 Hz - 20 kHz
......................
For Further Reading
Clinical Procedures in Optometry by J. D. Barlett, J. B. Eskridge & J. F. Amos
Ophthalmic Ultrasound: A Diagnostic Atlas by C. W. DiBernardo & E. F. Greenberg Internet
Physics of ultrasound and echocardiographyjeetshitole
The document discusses the history and physics of ultrasound imaging and echocardiography. It covers how ultrasound waves interact with tissues through reflection, scattering, attenuation and absorption. It describes how piezoelectric transducers convert electrical signals to ultrasound and vice versa to produce images. Imaging can be done in various modes like A-mode, B-mode, M-mode and 2D to visualize cardiac structures and function at different resolutions and depths.
This document discusses optical coherence tomography (OCT) and its use in evaluating the optic nerve head (ONH). It provides details on OCT technology, including how OCT creates high resolution cross-sectional images of the retina and ONH using infrared light. The document compares time domain OCT and spectral domain OCT, and describes applications of OCT such as glaucoma evaluation by examining the ONH, retinal nerve fiber layer, and peripapillary region. Examples of OCT images of the normal ONH and glaucomatous ONH are also presented.
This document discusses the corneal endothelium and techniques for assessing its health and function. The corneal endothelium is a single layer of hexagonal cells that maintains corneal clarity by pumping fluid out of the stroma. Assessment techniques described include specular microscopy, which allows analysis of endothelial cell density, morphology, and patterns under high magnification; confocal microscopy; anterior segment OCT; and ultrasound pachymetry to measure corneal thickness as an indicator of endothelial function. Common indications for assessment include pre- and post-operative evaluation, and evaluation of donor corneas for transplantation.
Optical coherence tomography (OCT) is a non-invasive imaging technique that uses light to capture high-resolution cross-sectional images of the retina. OCT was introduced in 1991 and has since become a widely used tool for ophthalmic diagnosis. It provides 10 micrometer resolution images, allowing visualization of individual retinal layers. Several technological advancements, including Fourier-domain OCT and swept-source OCT, have improved imaging speeds and depths. OCT angiography allows visualization of the retinal and choroidal vasculature without dyes. Precise quantitative and qualitative analysis of OCT images provides crucial information for diagnosing and monitoring many retinal conditions.
1) Fundus autofluorescence imaging provides a noninvasive method to map naturally occurring fluorophores in the eye. The major source of fundus autofluorescence is lipofuscin in the retinal pigment epithelium and melanin.
2) Lipofuscin accumulation over time can be toxic to retinal pigment epithelium cells and interfere with normal cell function. Areas of geographic atrophy in age-related macular degeneration appear as dark regions due to the lack of retinal pigment epithelium and lipofuscin.
3) Abnormal patterns of fundus autofluorescence such as banded or diffuse patterns are associated with more rapid progression of geographic atrophy compared to areas without abnormalities or those with only
This document discusses various biometry instruments and equipment used to calculate intraocular lens (IOL) power for cataract surgery. It describes how keratometry, A-scan ultrasound biometry, and non-contact devices like the IOLMaster measure important ocular dimensions needed for IOL power calculations, including corneal power, axial length, and anterior chamber depth. It also discusses IOL power calculation formulas from first to fourth generation and factors that influence formula choice, such as eye length, anterior chamber depth, and IOL placement in the eye. Accurate biometry is emphasized as key to achieving the desired postoperative refractive outcome.
Ophthalmic ultrasonography uses sound waves to evaluate the eye and orbit. It can assess tumors, retinal detachments, and foreign bodies when the eye is opaque. The A-scan provides one-dimensional measurements of internal structures. The B-scan gives a two-dimensional cross-section, displaying reflections as varying shades of gray. Together they characterize lesions by location, size, internal reflectivity, structure, and vascularity. Ultrasound is used preoperatively for cataract surgery planning and to evaluate intraocular tumors, accurately measuring their dimensions to guide treatment. Common indications also include opaque media evaluation and orbital disorders.
This document discusses ultrasound techniques used in ophthalmology. It begins by providing background on ultrasound waves and the early development of A-scan and B-scan techniques in the 1950s-1970s. It then describes the basic components and mechanisms of A-scan and B-scan ultrasound probes. The remainder of the document details various ultrasound techniques and their applications, including evaluating the vitreous, retina, choroid, tumors, trauma, and performing biometry. It provides guidance on interpreting ultrasound findings and differentiating various pathologies. In summary, this document serves as a comprehensive guide to ophthalmic ultrasound acquisition and interpretation.
BASIC INFO ON FUDUS FLORESCENCE ANGIOGRAPHYNalin Nayan
The document discusses fundus fluorescein angiography (FFA). FFA involves injecting a fluorescent dye called fluorescein and using a retinal camera to take photos of the retina and choroid as the dye circulates. It describes the five phases seen in FFA - choroidal, arterial, capillary, venous, and late phases. Abnormalities that may appear as hyperfluorescence or hypofluorescence on FFA are also outlined.
Glaucoma drainage devices (GDDs) work by creating an alternate pathway for aqueous outflow from the anterior chamber through a silicone tube to a plate under the conjunctiva where fluid is absorbed. The Ahmed valve and Baerveldt implant are two commonly used valved and non-valved devices, respectively. The Ahmed valve uses silicone leaflets to allow one-way flow above a certain pressure threshold, while the Baerveldt implant relies on a fibrous capsule formation around its plate for resistance to outflow. GDDs are indicated for refractory glaucoma when other surgeries have failed.
This document provides an overview of fundus fluorescein angiography (FFA). It begins with a brief history of FFA and describes the properties and pharmacokinetics of fluorescein dye. The document outlines the procedure for FFA, including patient positioning, dye injection, and photographing different phases. Normal FFA phases and angiogram patterns are presented, along with examples of abnormal hypofluorescence, hyperfluorescence, and vascular filling defects. The document concludes with brief descriptions of several common retinal conditions visualized on FFA.
This document provides an overview of ultrasound use for eye and orbit examination. It discusses the history, principles, instrumentation, techniques, indications, advantages, and types of scans (A-scan and B-scan) used. Key points include:
- Ultrasound uses high frequency sound waves to image ocular structures. It is non-invasive and avoids radiation.
- A-scans show echo amplitude over time as a line, while B-scans provide a cross-sectional image in shades of grey.
- Examination involves transverse, longitudinal, and axial scans using contact or immersion techniques.
- Ultrasound is useful for evaluating opaque media, tumors, detachments, injuries,
Keratometry measures the curvature of the cornea using the reflection of light off the corneal surface. There are two main types - manual keratometers using movable mires or prisms to assess curvature, and automated keratometers using photosensors. Keratometry is used to detect astigmatism, monitor corneal conditions, and assist in contact lens and refractive surgery. It provides important information but has limitations as it only measures the central cornea and assumes a symmetrical shape.
IOL power calculation is challenging in eyes with prior refractive surgery or other special situations. In eyes with prior radial keratotomy, standard keratometry overestimates corneal power due to flattening outside the central optical zone. Multiple methods of IOL power calculation should be used, including topography to measure the flattest central corneal power. A study comparing methods in eyes with prior RK found IOL power calculation using topographic keratometry was least accurate compared to formulas from the ESCRS calculator. No single method provided reliable results, highlighting the difficulty in IOL power calculation for eyes with prior refractive surgery.
Fitting Philosophies and Assessment of Spherical RGP lenses Urusha Maharjan
This document discusses the fitting of spherical rigid gas permeable (RGP) contact lenses. It covers preliminary measures like determining corneal curvature and diameter. Forces affecting lens fit like gravity and tear flow are described. Selection of the first trial lens involves choosing the appropriate back optic zone radius, diameter, and power based on factors like corneal curvature and prescription. Dynamic and static fitting criteria are provided. The lens is assessed for proper movement, centration, and vision. Neutralization of corneal astigmatism by about 90% with a spherical RGP lens is explained through an example.
Basic principles of ocular ultrasonographyRohit Rao
Ultrasound has been used in ophthalmology since the 1950s, with early pioneers developing A-scan and B-scan technologies. A-scan uses amplitude to represent echoes as vertical spikes, while B-scan displays echoes as brightness on a two-dimensional screen. Modes include A-scan for biometry and B-scan for diagnostic imaging. Later improvements included Doppler ultrasound and high-frequency ultrasound biomicroscopy. Ultrasound utilizes acoustic waves and principles of reflection and transmission to generate images of the eye and orbit.
B-scan ultrasonography provides two-dimensional images of ocular structures through the use of high frequency sound waves. It can be used to evaluate a variety of conditions, including retinal detachment, vitreous hemorrhage, intraocular tumors, and trauma. Retinal detachment appears on B-scan as an echogenic membrane attached to the optic nerve head, while vitreous hemorrhage shows as fine echo opacities within the vitreous cavity. B-scan is useful for assessing patients with dense cataracts or other opaque media by allowing visualization of the posterior segment.
DIRECT DOWNLOAD LINK ❤❤https://healthkura.com/ocular-ultrasound/❤❤
Dear viewers Check Out my other piece of works at___ https://healthkura.com
Ocular Ultrasonography (Ocular USG/ Ophthalmic USG), ophthalmic ultrasound/ ophthalmic ultrasonography/ ocular ultrasound/ Ultrasound of eye and orbit
PRESENTATION LAYOUT
Introduction
History
Physics
Principles & instrumentation
Terminologies
Indications & contraindications
Methods - A-Scan - B-Scan
Interpretation
Definition
Ultrasound Waves are acoustic waves that have frequencies greater than 20 KHz
The human ear can respond to an audible frequency range, roughly 20 Hz - 20 kHz
......................
For Further Reading
Clinical Procedures in Optometry by J. D. Barlett, J. B. Eskridge & J. F. Amos
Ophthalmic Ultrasound: A Diagnostic Atlas by C. W. DiBernardo & E. F. Greenberg Internet
Physics of ultrasound and echocardiographyjeetshitole
The document discusses the history and physics of ultrasound imaging and echocardiography. It covers how ultrasound waves interact with tissues through reflection, scattering, attenuation and absorption. It describes how piezoelectric transducers convert electrical signals to ultrasound and vice versa to produce images. Imaging can be done in various modes like A-mode, B-mode, M-mode and 2D to visualize cardiac structures and function at different resolutions and depths.
This document provides an overview of ultrasonography principles, methods, and interpretation for ophthalmic use. It discusses the history of ultrasonography, describes A-scan and B-scan display methods, and outlines the examination procedure and interpretation of scans. Key points covered include how ultrasound waves are generated and propagated through ocular tissues, factors that affect resolution, and how scans are oriented and labeled to identify anatomical structures.
Ultrasound uses sound waves to produce images of internal organs and tissues. Sound waves are transmitted into the body and the echoes produced by reflections from structures and tissues are detected. Three key points:
1) Ultrasound transducers convert electrical pulses into sound waves which penetrate the body and receive the echoes. Piezoelectric crystals in the transducer perform this function.
2) Reflected sound waves are displayed as images on screen to visualize internal structures. The brightness of each pixel depends on the strength of reflection.
3) Different transducer designs like linear arrays and curved arrays allow imaging of different body regions. Imaging modes like B-mode show anatomical structures while M-mode depicts motion.
Principles and technology of two dimensional echocardiography (2)Kangkan Sharma
Two-dimensional echocardiography uses ultrasound to generate dynamic images of the heart. It works by transmitting ultrasound pulses that reflect off tissues and return to the transducer. The document discusses key topics in ultrasound physics including: how sound waves propagate and interact with tissues through reflection, refraction, scattering and attenuation; transducer design and beam formation; and Doppler techniques for assessing blood flow. It provides technical details on how 2D echocardiography images are formed and displayed to evaluate cardiac anatomy and function.
This document provides an overview of ultrasound basics, including its history, principles of operation, interactions with tissue, machine components, imaging modes, artifacts, Doppler, elastography, and safety. Key points covered include how ultrasound works via the piezoelectric effect, factors that affect resolution, common artifacts and their clinical value, applications of Doppler and elastography, and that diagnostic ultrasound has been deemed safe by medical organizations.
Ultrasound Physics Made easy - By Dr Chandni WadhwaniChandni Wadhwani
History of ultrasound, Principle of Ultrasound.
Ultrasound wave and its interactions
Ultrasound machine and its parts, Image display, Artifacts and their clinical importance
what is Doppler ultrasound, Elastography and Recent advances in field of ultrasound.
Safety issues in ultrasound.
This document provides an overview of ultrasound basics, including its history, principles of operation, interactions with tissue, machine components, imaging modes, artifacts, Doppler, elastography, and safety. Key points covered include how ultrasound works via the piezoelectric effect, factors that affect resolution, common artifacts and their clinical value, applications of Doppler and elastography, and that diagnostic ultrasound has been deemed safe by medical organizations.
The document discusses various topics related to ultrasound and knobology. It begins with an introduction to ultrasound, covering the properties of ultrasound including frequency, wavelength, velocity and attenuation. It then discusses the principles of ultrasound imaging using the pulse-echo technique. The document covers ultrasound tissue interaction through reflection, refraction, absorption and scattering. It also discusses ultrasound instrumentation components including transducers, imaging modes like B-mode and special imaging techniques like harmonic imaging. Finally, it provides a brief introduction to knobology.
Ultrasound physics and image optimization1 (1)Prajwith Rai
This document discusses ultrasound physics and image optimization. It begins with an overview of basic principles, instrumentation, and image optimization techniques. It then describes how ultrasound works, including the generation of sound waves, their interaction with tissues through reflection, refraction, interference and absorption. This determines image quality. Instrumentation components like the transducer, transmitter, receiver and display are explained. Factors affecting the ultrasound beam like frequency, aperture, pulse length and coupling medium are also covered.
Ultrasonography uses high frequency sound waves to produce echoes from interfaces between structures in the eye. It has been used in ophthalmology since the 1950s, originally with A-scan and later developing B-scan technology. Ultrasound can image both clear and opaque ocular tissues. It is useful for evaluating conditions like tumors, retinal detachments, and vitreous hemorrhages. Examination involves different probe orientations and techniques depending on the area of interest. Findings are interpreted based on echo properties like size, reflectivity, and movement.
Basic Physics Of Transoesophageal Echocardiography For The Workshop2Anil Ramaiah
The document discusses the history and physics of ultrasound imaging and echocardiography. It covers how ultrasound interacts with tissues through reflection, scattering, attenuation and absorption. It describes the basic principles of ultrasound including frequency, wavelength, velocity and acoustic impedance. It also summarizes how ultrasound images are formed using piezoelectric transducers and discusses the different imaging modes and applications of Doppler imaging in cardiology.
This document provides an overview of ultrasound physics basics. It discusses how ultrasound uses sound waves between 10-20 MHz to generate images. Sound waves are longitudinal waves that travel through materials at different speeds depending on compressibility and density. Ultrasound imaging works by transmitting pulses into the body and receiving echoes, with transducers converting between electrical and sound signals. Factors like frequency, beam characteristics, and tissue interactions impact the resulting images and potential artifacts. Understanding ultrasound physics principles is important for optimizing scans and interpreting images.
This document provides an overview of ultrasound physics basics. It discusses how ultrasound uses sound waves between 10-20 MHz to generate images. Sound waves are longitudinal waves that travel through materials at different speeds depending on compressibility and density. Ultrasound imaging works by transmitting pulses into the body and receiving echoes, with transducers converting between electrical and sound signals. Factors like frequency, beam characteristics, and tissue interactions impact the resulting images and potential artifacts. Understanding ultrasound physics principles is important for optimizing scans and interpreting images.
This document provides an overview of ultrasound physics concepts including:
- How ultrasound waves interact with tissue through attenuation, reflection, scattering, refraction, and diffraction.
- Key properties of ultrasound waves like wavelength, frequency, amplitude, and acoustic impedance.
- Factors that determine image resolution such as transducer frequency and beam focusing.
- Common artefacts that can occur like reverberation, side lobes, and multi-path artefacts.
- The importance of understanding ultrasound physics principles to optimize image quality and avoid misdiagnosis.
Ultrasonography uses high frequency sound waves to produce images of internal organs and structures. Sound waves are transmitted into the body using a transducer, which converts electrical signals to sound and vice versa. Reflections from tissues are detected and used to construct images showing anatomical structures. Key physics principles include velocity, frequency, wavelength, and reflection based on acoustic impedance differences between tissues. Proper transducer design and focused beams are important for optimizing image quality and resolution.
Here are quick answers to the review questions:
1. Ultrasound is high frequency sound waves that travel well through soft tissues like muscles, organs and fat. It travels poorly through gas pockets or bones.
2. Higher frequency ultrasound has better resolution but poorer penetration. Lower frequency has poorer resolution but better penetration.
3. Pros of ultrasound include lack of radiation, quick exams, ability to see different tissue planes, portability and lower cost compared to other imaging modalities.
4. Probes come in linear, convex, sector and endocavity shapes. Linear probes have a rectangular footprint for long superficial structures. Convex probes have a curved footprint for abdominal exams. Sector probes have a wedge shape for
This document discusses non-thermal effects of diagnostic ultrasound, specifically radiation force and its potential biological effects. It outlines ultrasound basics and physics, defines key terms, and explores mechanical effects not related to heating, including cavitation, acoustic radiation force, and acoustic streaming which can cause fluid movement. Observations of effects on bone, lung, heart, perception, and development are provided, such as ultrasound accelerating bone healing and potentially altering neural migration through radiation force.
Fundamental Physics and Safety Implications.pptxLoisHernan
Ultrasound imaging works by sending sound waves into the body which bounce off structures and return echoes. A transducer converts the echoes into electrical signals which are used to produce an image. The transducer contains piezoelectric crystals which vibrate when electrical current is applied, producing sound waves. Returning echoes are captured by the transducer and converted back into electrical signals. Factors such as tissue impedance and surface properties determine how much sound is reflected or transmitted at tissue borders. Proper control of machine settings such as frequency and depth allow clinicians to obtain diagnostic images with sufficient resolution and detail.
This document provides an overview of ultrasound diagnostics and various ultrasound imaging techniques. It begins with a brief history of ultrasound diagnostics and outlines common ultrasound modalities including ultrasonography (A, B, and M modes), Doppler flow measurement, tissue Doppler imaging, and ultrasound densitometry. The document then discusses physical properties of ultrasound, acoustic parameters of tissues, and interactions of ultrasound with tissues. It provides details on various ultrasound imaging modes and techniques such as B-mode, M-mode, harmonic imaging, and 3D imaging. The document also covers Doppler blood flow measurement principles and different Doppler methods including duplex, color Doppler, and triplex.
This document provides an overview of photochromatic lenses, including:
1. It discusses the working mechanism of photochromatic lenses, which use silver halide compounds that change color when exposed to UV light through a reversible photolytic reaction.
2. It describes the different types of photochromatic lenses, including glass, plastic, and variations like PhotoGray, PhotoSun, and thin and dark lenses.
3. The document outlines factors that influence photochromatic performance such as crystal size, temperature, and UV wavelength exposure.
This document summarizes a review article on progressive addition lenses (PALs). It discusses the design, structures, and optical characteristics of PALs. Key points include:
- PALs provide continuous vision from distance to near without lines or edges by gradually increasing lens power from upper to lower portions.
- Advanced designs incorporate the prescription onto the back surface rather than just the front, reducing distortions and expanding clear vision zones.
- Wavefront technology further optimizes PALs by reducing higher-order aberrations at all distances.
- Different PAL designs are suited for specific needs like reading, computers, or a balance of distances. Patient needs should be considered when selecting a design.
This document discusses various metabolic disorders and their ocular manifestations. It begins by introducing metabolic disorders and how they are generally inherited. It then discusses specific disorders affecting amino acid metabolism, carbohydrate metabolism, and other pathways. For each disorder, it describes the genetic cause, systemic findings, and relevant ocular manifestations such as corneal opacities, cataracts, retinal degeneration, and more. Overall, the document provides an overview of how inborn errors of metabolism can impact eye health through various pathological mechanisms and biochemical lesions.
The optic nerve develops from the embryonic optic stalk and contains axons originating from retinal ganglion cells. It has intraocular, intraorbital, intracanalicular, and intracranial parts. The intraocular part passes through the lamina cribrosa and expands as it acquires a myelin sheath. The optic nerve receives its blood supply from short posterior ciliary arteries and pial vessels.
This document provides an overview of the anatomy, nerve and blood supply of the uvea, which includes the iris, ciliary body, and choroid. It begins with an introduction to the uvea and its embryological development. It then discusses the anatomy and structures of the iris, ciliary body, and choroid in detail. It also reviews the blood supply and some clinical applications related to the uvea. The document is presented as part of an optometry lecture covering this topic in detail over several slides.
Anatomy of Eyelids & Its Clinical CorrelationsSarmila Acharya
This document provides an overview of the anatomy of the eyelids. It discusses the layers of the eyelids from front to back including skin, muscles like the orbicularis oculi and levator palpebrae superioris, the fibrous tarsal plates, and conjunctiva. It also covers the nerve and blood supply, functions of eyelid structures like blinking and tear distribution, and some clinical correlations like entropion and dermatochalasis.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
A Visual Guide to 1 Samuel | A Tale of Two HeartsSteve Thomason
These slides walk through the story of 1 Samuel. Samuel is the last judge of Israel. The people reject God and want a king. Saul is anointed as the first king, but he is not a good king. David, the shepherd boy is anointed and Saul is envious of him. David shows honor while Saul continues to self destruct.
Level 3 NCEA - NZ: A Nation In the Making 1872 - 1900 SML.pptHenry Hollis
The History of NZ 1870-1900.
Making of a Nation.
From the NZ Wars to Liberals,
Richard Seddon, George Grey,
Social Laboratory, New Zealand,
Confiscations, Kotahitanga, Kingitanga, Parliament, Suffrage, Repudiation, Economic Change, Agriculture, Gold Mining, Timber, Flax, Sheep, Dairying,
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
Andreas Schleicher presents PISA 2022 Volume III - Creative Thinking - 18 Jun...EduSkills OECD
Andreas Schleicher, Director of Education and Skills at the OECD presents at the launch of PISA 2022 Volume III - Creative Minds, Creative Schools on 18 June 2024.
This presentation was provided by Racquel Jemison, Ph.D., Christina MacLaughlin, Ph.D., and Paulomi Majumder. Ph.D., all of the American Chemical Society, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
How Barcodes Can Be Leveraged Within Odoo 17Celine George
In this presentation, we will explore how barcodes can be leveraged within Odoo 17 to streamline our manufacturing processes. We will cover the configuration steps, how to utilize barcodes in different manufacturing scenarios, and the overall benefits of implementing this technology.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
3. Introduction
Sound has been used clinically as an alternative to light in
the diagnostic evaluation of variety of conditions
Advantage of sound over light is it can pass through
opaque tissue
An important tool in terms of diagnosis and management
Is a non-invasive investigation of choice to study eye in
opaque media
4. Definition
Ultrasound Waves are acoustic waves that have
frequencies greater than 20 KHz
The human ear can respond to an audible frequency
range, roughly 20 Hz - 20 kHz
5. History
• In 1956
• First time: Mundt and Hughes, American Oph.
• A-scan (Time Amplitude ) to demonstrate various ocular
disease
• Oksala et al in Finland
• Ultrasound Basic Principle (Pulse-Echo Technique)
• Studied reflective properties of globe
• In 1958, Baum and Greenwood
• Developed the first two-dimensional(immersion) (B-scan)
ultrasound instrument for ophthalmology
• In the early 1960s, Jansson and associates, in Sweden,
• Used ultrasound to measure the distances between
structures in the eye
6. In the 1960s, Ossoinig, an Austrian ophthalmologist
First emphasized the importance of standardizing
instrumentation and technique
Developed standardized A-scan
In 1972, Coleman and associates made
First commercially available immersion B -scan
instrument
Refined techniques for measuring axial length, AC
depth, lens thickness
Bronson in 1974 made contact B scan machine
7. Advantages of USG
Easy to use
No ionizing radiation
Excellent tissue differentiation
Cost effectiveness
8. Primary Uses In Ophthalmology
Posterior segment evaluation in hazy media / orbit
Structural integrity of eye but no functional integrity
Detection and differentiation of intraocular and orbital
lesions
Tissue thickness measurements
Location of intra ocular foreign body
Ocular biometry for IOL power calculations
9. Physics
Ultrasound is an acoustic wave that consists of an
oscillation of particles that vibrate in the direction of the
propagation
Longitudinal waves
Consist of alternate compression and rarefaction of
molecules of the media
Oscillation of particles is characterized by velocity,
frequency & wavelength
10. VELOCITY
Velocity=wavelength*frequency
v=λ * μ
Depends on the density of the media
Takes 33 micro sec to come back from posterior pole
to transducer
About 1500 m/sec average velocity in phakic eye and
1532 m/sec in aphakic eye
11. Sound wave velocities through various media
Medium Velocity (m/sec)
Water 1,480
Aqueous/ Vitreous 1,532
Silicon Lens 1,486
Crystalline Lens 1,641
PMMA Lens 2,718
Silicon Oil 986
Tissue 1,550
Bone 3,500
12. Frequency
Ophthalmic ultrasonography uses frequency ranging
from 6 to 20 MHz
High frequency provide better resolution
8 MHz in A scan
10 MHz in B scan
Low frequency (1-2 MHz)used in body scanning gives
better penetration
13. Wavelength
Wavelength is approx. 0.2mm
Good resolution of minute ocular & orbital structures
f α1/λ α resolution α 1/penetration
FREQUENCY VS
PENETRATION
14. Reflectivity
When sound travels from one medium to another medium of
different density, part of the sound is back into the probe
This is known as an echo; the greater the density difference
at that interface
- the stronger the echo, or
- the higher the reflectivity
15. In A-scan USG echoes are represented as spikes arising from
a baseline
The stronger the echo, the higher the spike
In B-scan USG echoes of which are represented as a
multitude of dots that together form an image on the screen
The stronger the echo, the brighter the dot
16. Absorption
Ultrasound is absorbed by every medium through which it
passes
The more dense the medium, the greater the amount of
absorption
The density of the solid lid structure results in absorption
of part of the sound wave when B-scan is performed
through the closed eye thereby compromising the image
of the posterior segment
17. B-scan should be performed on the open eye unless
the patient is a small child or has an open wound
When performing an USG through a dense cataract,
- more of the sound is absorbed by the dense cataractous
lens
- less is able to pass through to the next medium
- resulting in weaker echoes and images on both A-scan
and B-scan
The best images of the posterior segment are obtained when
the probe is in contact with the sclera rather than the corneal
surface, bypassing the crystalline lens or IOL implant
19. Ultrasound Echo
Ultrasound wave
Refraction & reflection
Echo (reflected portion of wave)
Produced by acoustic interfaces
Created at the junction of two media that have
different acoustic impedances
Determined by sound velocity & density
Acoustic impedance = sound velocity × density
20. Factors influencing the returning echo
( Height in A-Scan & Brightness in B-Scan )
1. Angle of the sound beam
2. Interface
3. Size and shape of interfaces
21. Angle at which a sound beam encounters an ocular structure
Sound beam directed perpendicularly to a structure
maximum amount of sound will be reflected back to
the probe
The farther away from the ideal angle
the lower the amplitude
a) Angle of Incidence
22. Relative difference between various tissues that the
sound beam encounters
Strong or weak echoes due to the significance of tissue
interface
For example:
- The difference in interface between vitreous and fresh
blood is very slight resulting in small echo
- The difference between a detached retina and the
vitreous is great producing a large echo
b) Interface
23. Smooth surface like retina will give strong
reflection
Smooth and rounded surface scatters the
beam
Coarse surface like ciliary body or
membrane with folds tend to scatter the
beam without any single strong reflection
Small interface produces scattering of
reflection
c) Texture and Size of Interface
24. Principle
Pulse- Echo System
Emission of multiple short pulses of ultrasound waves with
brief interval to detect, process and display the turning Echoes
ELECTRIC CURRENT
TRANSDUCER
US WAVE
SURFAC
E
25. Ophthalmic USG uses high-frequency sound waves
transmitted from a probe into the eye
As the sound waves strike intraocular structures,
they are reflected back to the probe and converted
into an electric signal
The signal is subsequently reconstructed as an
image on a monitor
26. Emitted Sound Beam
Used in A scan echography
Beam has parallel border
Non-focused Beam Focused Beam
Used in B scan
Examination takes place in a
focal zone
The beam is slightly diffracted
27. 1. Probe
Consists of piezoelectric transducer
Device which converts electrical energy to sound energy
[Pulse ] and vice versa [Echo]
Basic Components :
Piezoelectric plate
Backing layer
Acoustic matching layer
Acoustic lens
Instrumentation
28. Piezoelectric Element
Essential part generates ultrasonic waves
Coated on both sides with electrodes to which a voltage
is applied
Oscillation of element with repeat expansion and
contraction generates a sound wave
Most common: Piezoelectric ceramic ( Lead zirconate,
titanate)
29. Planer crystal
- Produce relatively parallel sound beam (A- Scan)
Acoustic lens
- Produce focused sound beam (B-scan)
- Improves lateral resolution
Shape of the Crystal
30. Backing Layer
(Damping material: metal powder with plastic or epoxy)
Located behind the piezoelectric element
Dampens excessive vibrations from probe
Improves axial resolution
Acoustic Matching Layer
Located in front of piezoelectric element
Reduces the reflections from acoustic impedance between
probe and object
Improves transmission
31. (longitudinal resolution or azimuthal resolution )
Resolution in the direction parallel to the ultrasound
beam
The resolution at any point along the beam is the same;
therefore axial resolution is not affected by depth of
imaging
Increasing the frequency of the pulse improves axial
resolution
Axial Resolution
32. Ability of the system to distinguish two points in the
direction perpendicular to the direction of the ultrasound
beam
Affected by the width of the beam and the depth of imaging
Wider beams typically diverge further in the far field and
any ultrasound beam diverges at greater depth, decreasing
lateral resolution
Lateral resolution is best at
shallow depths and worse
with deeper imaging
Lateral Resolution
33. Receives returning echoes
Produces electrical signal that undergoes complex
processing
Amplification, Compensation, Compression,
Demodulation and Rejection
2. Receiver (computer unit)
34. Gain
Relative unit of Ultrasound intensity
Expressed in Decibel (db)
Adjust of gain doesn't change the amount of energy
emitted by transducer but change in intensity of the
returning echoes for display
Higher the gain – Greater the sensitivity of the instrument
in displaying weaker echoes (i.e Vitreous opacities)
Lower the gain – Weaker the depth of sound penetration
Terminologies
35. Acoustic impedance mismatch
- Resistance of tissue to passage of sound waves
- Difference of two tissues at the interface
Homogeneous (Vitreous)- Sound passes through tissue
with no returning signal
Heterogeneous (Orbital Fat) - Different levels of
acoustic impedance mismatch within tissue
36. Anechoic : No Echo
Attenuation : Sound is absorbed & scattered
Shadowing : Sound is strongly reflected, nothing passes
through it (drusen of optic nerve head, air)
Reverberation : Collection of Reflected sounds bouncing
back and forth between tissue boundaries
(foreign body in eyeball )
41. 1. A-mode Display
Time amplitude USG
One dimensional acoustic display
Tissue boundary
- displayed graphically as function of distance along a selected
axis
Spacing of the spike
- time taken for the sound beam to reach the given interface
and its echo to reach the probe
42. Amplitude of echo on the display is proportional to the
sound energy reflected at specific tissue boundary
8 MHz
Probe emits unfocused beam
The term “A-Scan” is often used to describe this
mode, but it is not an appropriate term, since the
transducer is fixed in one position during biometric
procedure and is not scanning
44. A-mode USG Biometry
Axial length measurement
To obtain the power of IOL
Calculation of the total refracting power of the eye
45. Probe position
Just touch the cornea
Aligned with optical axis of eye
- aimed towards the macula
Corneal compression
- A 0.4mm compression causes 1 D error in the calculated
IOL power
- Contact Vs immersion method
46. Tall echo – cornea, one peak – contact probe, double
peak – immersion probe
Tall echoes – ant. & post. lens capsules
Tall sharply rising echo – retina
Medium tall to tall echo – sclera
Medium to low echoes – orbital fat
A Scan Characteristics
47. 2. M-mode Display
Motion mode or time motion mode
Dilation and constriction of blood vessel
Accommodation fluctuation
Vascular pulsation in ocular tumor
Motion of detached retina
- PVD vs RD
48. 3. B-mode Display
Intensity modulated USG
B Stands for Brightness modulation
Presents a cross sectional or 2D image
True scanning
Probe emits focused beam
10 MHz
Each echo
o Represented as a dot on display screen
o Strength of the echo brightness of the dot
49. Normal B-scan
• Initial line on left: probe tip
• Right side: fundus opposite to
probe
• Upper part: portion of the globe
where probe marker is directed
Interpretation
Based upon three concepts
Real Time
Gray Scale
Three-Dimensional analysis
50. Real Time
Images can be visualized at approximately 32 frames/sec,
allowing motion of the globe and vitreous to be easily
detected
B scan allows real time evaluation of any ocular
pathology
Real time ultrasonic information frequently aids in
vitreoretinal surgery
51. Gray Scale
Displays the returning echoes as a 2D image
Strong echoes are displayed brightly at high gain and
remain visible even when the gain is reduced
Weaker echoes are seen as lighter shades of gray that
disappear when the gain is reduced
Comparing echo strengths during examination is the basis
for qualitative tissue analysis
52. Three-Dimensional Analysis
Developing a mental 3D image or anatomical map from
multiple 2D B-scan images is the most difficult concept
to master
This is essential, because it provides
the vital architectural information that
is the basis for B-scan diagnosis
Especially important in the preoperative evaluation of
complex retinal detachments and intraocular or orbital
tumors
54. Axial
Probe directly over cornea and directed axially
Pt. fixating in primary gaze
Posterior lens surface and optic nerve head are placed in
the centre of the echogram
Optic nerve head is used as an echographic centre section
Easiest to perform
55. Mainly two varieties of axial scans
Horizontal axial scan
Marker at 3 0’clock RE and 9 0’clock LE
Macular region is placed just below the optic disk
Vertical axial scan
Marker at 12 0’clock
Macula is not seen in this scan
Oblique axial scan
Marker always superior
Sections of all other clock hours
can be performed
56.
57. Points to be noted
Higher decibel gain levels are needed to show structures at
the posterior segment
Because of scatter and strong sound attenuation created by
the lens
- In pseudophakia strong artifacts created by the lens
implant hampers the adequate visualization
Significance
Easy orientation and demonstration of posterior pole lesions
and attachments of membranes to optic nerve head
58. Transverse
EYE – looking in the direction of observer’s interest
PROBE –parallel to limbus and placed on the opposite
conjunctival surface
Probe Marker
superior (if examining nasal or temporal) or nasal(if examining
superior or inferior)
6 clock hrs examined at a time
Limbus-to-fornix approach is used to detect from posterior
pole to periphery
Quadrant examination
Gives lateral extent of the lesion
59. The clock hr which the marker faces is always at the top
of the scan
The area of interest in a properly done transverse scan
is always at the centre of the right side of scan
Nasal
Bridge
60.
61. Longitudinal
EYE - looking in the direction of observer’s interest
PROBE – perpendicular to the limbus and placed on the
opposite conjunctival surface
PROBE MARKER - directed towards the limbus
Optic nerve shadow always at the bottom on the right side
1 clock hr per time examination
Determines the antero-posterior (axial) extent of the lesion
Significance
- Best for peripheral tears and documentation of macula
Nasal
Bridge
62.
63. Examination Procedure
Positioning the patient
Topical anesthesia
Techniques
Contact Technique
o Probe is placed directly
on the globe
Immersion Technique
oMethylcellulose - a
coupling medium (B-
Scan)
64. Sources of Error in contact technique
Corneal compression (Shorter Axial length)
- 1mm error in Axial length – 2.5 to 3.0 Ds error in IOL
Power
Misalignment of sound beam
Source of error in immersion technique
Small air bubbles in the fluid gives falsely long AL
measurement
66. Horizontal
Probe placed on the corneal vertex
Marker nasally (as with a horizontal axial scan)
The probe should be aimed straight ahead to center the
macula
The macula will be centered to the right of the
echogram, with the posterior lens surface centered to
the left
67. Vertical
Probe placed on the corneal vertex
Marker is in the 12-o'clock position
The nerve will not appear in these scans because this
is a vertical (instead of horizontal) slice of the macula
68. Transverse
Patient fixes slightly temporally
Probe on nasal sclera with marker at 12’o clock
Optic nerve as the centre of imaged clock macula is
at 9’o clock in right eye and 3’o clock in left
Bypasses the lens
69. Longitudinal
Probe held on sclera, bypassing crystalline lens
Optic nerve is seen at the bottom with macula just
above
70. Orbital Screening
Orbit highly reflective owing to heterogeneity of
orbital fat which produce large acoustic interface
B scan- bright zone
A scan- highly packed tall spike fading from left to right
Three major portions
Orbital soft tissue assessment
Extraocular muscle evaluation
Retrobulbar optic nerve examination
71. Two Approaches
Transocular (through the globe)
- For lesions located within the posterior & mid
aspects of the orbital cavity
Paraocular (next to the globe)
- For lesions located within the lids or anterior orbit
73. A-SCAN B-SCAN
AMPLITUDE MODULATION SCAN. BRIGHTNESS MODULATION SCAN.
FREQUENCY OF ULTRASOUND IS 8
MHERTZ.
FREQUENCY OF ULTRASOUND IS 10
MHERTZ.
ONE DIMENTIONAL IMAGE OF
SPIKES OF VARYING AMPLITUDES
ALONG A BASELINE.
TWO DIMENTIONAL IMAGING OF
SERIES OF DOTS AND LINES THAT
FORM THE ECOGRAM.
EMITS UNFOCOUSED BEAM. EMITS FOCUSED BEAM.
PROVIDES QUANTITATIVE
INFORMATIONS.
PROVIDES TOPOGRAPHIC
INFORMATIONS.
IS A BASIS OF OCULAR BIOMETRY. ALLOWS REAL TIME EVALUATION OF
ANY OCULAR PATHOLOGY.
75. Immersion Technique
Examining the anterior segment with a standard 10
MHz contact probe can be accomplished only with the
use of a scleral shell
This shifts the anterior segment to the right and into
the area of focus of the sound beam, improving
resolution of anterior segment pathology
The shell is filled with methylcellulose or some other
viscous solution to a meniscus, avoiding air bubbles
within the shell
76. The probe is placed on top of the shell
This produces an echolucent area on the left side of the
echogram corresponding to the shell and methylcellulose
Diagnostic A-scan also can be performed through the shell,
directly over the lesion, for tissue differentiation.
77. Immersion B-scan image of
an iris melanoma extending
into the ciliary body
Modified immersionB-scan. Immersion
79. High Resolution Technique
Ultrasound biomicroscopy
Probes ranges from 20MHz to 50
MHz, with penetration depths of
about 10 mm to 5 mm respectively
The zone of focus is quite small
Scleral shell technique is used
Image quality far superior to
immersion technique
High-resolution B-scan images
of an iris melanoma
81. Normal USG Characteristics
Lens : Oval highly reflective structure
Vitreous : Echolucent
Retina , Choroid , Sclera : Each is single highly
reflective structure
Optic Nerve : Wedge shaped acoustic void in
retrobulbar region
Extra ocular muscles : Echolucent to low reflective
fusiform structures
- The SR- LPS complex is the thickest, IR is the
thinnest
- IO is generally not seen except in pathological
conditions
Orbit : Highly reflective due to orbital fat
83. Topographic Echography
Point-like e.g. fresh V.H
Membrane-like e.g. R.D
Mass-like e.g. choroidal melanoma
Opacities produce dots or short lines
Membranous lesions produce an echogenic line
85. Fresh:
oDot-like: Echolucent or low reflectivity
Old:
oMembrane-like: Varying reflectivity & dense
inferiorly
Fresh VH Old VH
86. Multiple, densely packed, homogeneously distributed
echodense dots of medium to high reflectivity with a clear
preretinal space suggestive of Asteroid Hyalosis
AH is highly ecogenic,they are still visible when the gain setting
is reduced upto 60dB whereas VH which usually disappears by
60 dB
87. PVD at high gain (90dB)
PVD (arrowheads) and
retina (arrow)
PVD at low gain (39 dB)
As the gain is reduced, the PVD
(arrowheads) disappears in contrast to the
retina (arrow), which remains visible even
at low gain settings
90. KISSING CHOROIDALS
Smooth, dome shaped,
thick, less mobile with
double high spike
suggestive of Choroidal
Detachment
91. PVD RD CD
Topographi
c
Smooth, with or
without disc
insertion
Smooth or folded
with disc insertion
Smooth without
disc insertion
Quantitativ
e
< 100 % spike 100 % spike Double 100 %
spike
Kinetic Marked Moderate None
92. Differentiating Features of RD
Rhegmatogenous RD Tractional RD Exudative RD
Convex elevation ,
Undulating folds, PVR
Concave
elevation,Fibrous
tractional band
Convex elevation,
Shifting fluid changes
Configuration with
postural change
98. Extremely thin IOFBs (< 100 mm) can be differentiated, localized
Metallic IOFBs are echo dense—even at low gain settings—and
often produce shadowing of intraocular structures and the orbit
99. Transverse B-scan shows marked vitreous opacities and
membrane formation consistent with endophthalmitis
101. Papilloedema
Transverse B-scan shows marked
elevation of the optic disc
Optic Disc Drusen
Longitudinal B-scan shows
highly calcified, round drusen
at the optic nerve head with
shadowing
102. T sign collection of fluid in subtenon space suggestive of
Posterior Scleritis
High reflective thickening of retinochoroid layer and sclera
103. Posterior Staphyloma in High Myopia
Shallow excavation of posterior pole
Smooth edges
106. Conclusion
Knowledge about the anatomy, pathology and
ultrasound signs together with systemic and ocular
approach can provide useful diagnostic
information.
107. References
Clinical Procedures in Optometry by J. D. Barlett, J. B.
Eskridge & J. F. Amos
Ophthalmic Ultrasound: A Diagnostic Atlas by C. W.
DiBernardo & E. F. Greenberg
Internet
Previous presentations