Download or read book High Resolution Retinal Imaging to Evaluate Laser and Light Safety in the Retina for Near and Long Term Health Effects written by Ginger Madeleine Pocock and published by . This book was released on 2012 with total page 426 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this research was to investigate detect and monitor laser-tissue interactions at threshold and potentially sub-threshold levels of injury. High resolution imaging modalities can provide a deeper understanding of candidate biomarkers disease and injury at the molecular, cellular, and tissue-levels which can be used to identify and diagnose early stages disease and damage. In addition, multi-scale and multi-modal imaging have also been used to identify inherent biomarkers of retinal disease and injury. Monitoring tissue changes can be mapped back to biological changes at the cellular and sub-cellular level. Diseases often alter tissue on the ultra-structural level yet retinal clinical diagnosis often monitor changes in tissue at the organ level. If injury and disease is detected and diagnosed during an "early" stage of development, treatments and drug interventions may prevent further spread of the pathology. Non-invasive imaging is expected to be a valuable tool for in vivo medical research as well as for the diagnosis and management of disease. In addition to developing new imaging tools and techniques to image the retina, the identification of inherent biomarkers of disease and health using diagnostic methods are almost equally as important. Using the inherent optical properties of retinal tissue, we can non- invasively quantify differences in the absorption and reflection of light to gauge the risk for visual disability or worse yet irreversible vision loss as a result of retinal disease and chronic light exposure. The research presented with in this dissertation is three separate studies aimed at identifying light injury and potential biomarkers indicating the risk of light mediated development of disease.

Download or read book High Resolution Imaging in Microscopy and Ophthalmology written by Josef F. Bille and published by Springer. This book was released on 2019-08-13 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book provides a comprehensive overview of the application of the newest laser and microscope/ophthalmoscope technology in the field of high resolution imaging in microscopy and ophthalmology. Starting by describing High-Resolution 3D Light Microscopy with STED and RESOLFT, the book goes on to cover retinal and anterior segment imaging and image-guided treatment and also discusses the development of adaptive optics in vision science and ophthalmology. Using an interdisciplinary approach, the reader will learn about the latest developments and most up to date technology in the field and how these translate to a medical setting. High Resolution Imaging in Microscopy and Ophthalmology – New Frontiers in Biomedical Optics has been written by leading experts in the field and offers insights on engineering, biology, and medicine, thus being a valuable addition for scientists, engineers, and clinicians with technical and medical interest who would like to understand the equipment, the applications and the medical/biological background. Lastly, this book is dedicated to the memory of Dr. Gerhard Zinser, co-founder of Heidelberg Engineering GmbH, a scientist, a husband, a brother, a colleague, and a friend.

Download or read book Ryan s Retinal Imaging and Diagnostics E Book written by Stephen J. Ryan and published by Elsevier Health Sciences. This book was released on 2013-08-13 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: Access all of the latest advances in imaging techniques of the retina and posterior segment on your favorite eReader with Ryan's Retinal Imaging and Diagnostics eBook. 12 chapters from the landmark reference Retina, 5th Edition offer the foundations to better understand, apply, and optimize new and emerging retinal imaging technologies. Examine and evaluate the newest diagnostic technologies and approaches that are changing the management of retinal disease, including future imaging technologies which will soon become the standard. Put the very latest diagnostic imaging methods to work in your practice, including optical coherence tomography (OCT), fluoroscein angiography, indocyanine angiography autofluorescence imaging, ophthalmic ultrasound and more. Benefit from the extensive knowledge and experience of esteemed editor and ophthalmologist, the late Dr. Stephen Ryan, and a truly global perspective from the world authorities. Consult this title on your favorite e-reader, conduct rapid searches, and adjust font sizes for optimal readability. Compatible with Kindle®, nook®, and other popular devices.

Download or read book High Spatiotemporal Resolution Mapping of Retinal Physiology written by Qiuxiang Zhang and published by . This book was released on 2014 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of my PhD dissertation research is to explore high resolution imaging of retinal function using transient intrinsic optical signals (IOSs) correlated with retinal physiological activation. The retina is responsible for capturing photons and preliminary visual information processing. Functional examination of retinal neural cells is important for eye disease detection and treatment evaluation. It is known that different diseases can target different retinal cell types, and thus high resolution imaging of retinal function is desirable. Fast IOSs with time courses comparable to retinal electroretinogram (ERG) kinetics can act as a unique biomarker to map physiological distortions correlated with eye diseases. In vitro IOS imaging of wild-type and mutant mouse retinas has revealed IOS distortions correlated with retinal diseases. In order to achieve in vivo IOS imaging, a rapid line-scan confocal ophthalmoscope was constructed. Confocal IOS imaging of laser-injured frog eyes unambiguously detected localized (30 mm) functional lesions in the retina before morphological abnormality is detectable. Comparative IOS and ERG measurement revealed a close correlation between the observed optical response and retinal electrophysiological dynamics, particularly the ERG a-wave, which has been widely used to evaluate photoreceptor function. To further uncover the anatomic source of fast IOSs in retinal photoreceptors, a functional spectral domain optical coherence tomography (SD-OCT) system was constructed to provide depth-resolved IOS mapping at subcellular resolution. High spatiotemporal resolution OCT disclosed that fast IOSs was predominantly confined to the outer retina, particularly in the photoreceptor outer segment. Comparative study of dark- and light-adapted retinas demonstrated the feasibility of functional OCT mapping of rod and cone photoreceptors, with great potential for early disease detection and improved treatment evaluation of age-related macular degeneration (AMD) and other eye diseases that can cause photoreceptor damage. In addition to functional retinal imaging, we also applied the SD-OCT system for in vivo dynamic observation of light-driven melanosome translocation in RPE. Comparative OCT examination of dark- and light- adapted frog eyes verified that RPE melanosomes are the primary source of reflectivity in the RPE band. To the best of our knowledge, this is the first time demonstration of the feasibility of dynamic OCT monitoring of sub-cellular RPE translocation. Thus, SD-OCT is a versatile tool to assess posterior segment dynamics that may have relevance in the clinical setting.

Download or read book Evaluation of Retinal Damage Produced by Long Term Exposure to Laser Radiation written by William D. Gibbons and published by . This book was released on 1975 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study reported here was designed with two objectives. The first objective was to determine whether or not photopigments may be involved in the production of 'nonthermal' lesions, and the second objective was to extend argon ED50 measurements for 'nonthermal' lesions to 1000-sec exposures. To accomplish the first objective, exposures were made for 120 seconds using a wavelength of 1060 nm. This wavelength, when absorbed at the retina, can produce a temperature rise but is inefficient in bleaching photopigments. Thus, lesions produced by these exposures should stem primarily from thermal changes. The results of these exposures were then compared to those obtained from exposure to a wavelength of 514.5 nm which readily interacts with photopigments.

Download or read book Functional Measurements of Retinal Phototoxicity Using Photopigment Densitometry and Adaptive Optics written by Benjamin David Masella and published by . This book was released on 2013 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Recent advances in high-resolution retinal imaging have led to the discovery of retinal changes caused by light exposures below previously published damage thresholds. These effects were discovered by imaging the retinal pigment epithelium (RPE) with adaptive optics (AO). The changes observed were a transient decrease in RPE autofluorescence (AF reduction) and a disorganization of RPE autofluorescence (RPE disruption). The origins of these changes are not fully understood and their functional consequences have not been previously investigated. Understanding these phenomena is critical for the field of ophthalmic imaging; yet, research to date has been limited to techniques that measure retinal structure and provide little information about function. Photopigment densitometry is a measure of retinal function that can be implemented in a reflectance imaging system and has been used to study the retina for over 60 years. With the advent of near diffraction-limited ophthalmoscopes, which can resolve individual photoreceptors, it is now possible to apply this technique to investigations requiring high spatial resolution. This thesis describes a study that combined high-resolution retinal imaging with photopigment densitometry to investigate the functional consequences of AF reduction and RPE disruption. An adaptive optics scanning laser ophthalmoscope was adapted to measure the density and regeneration rate of the photopigment rhodopsin. Rhodopsin kinetics were measured before and after a series of radiant exposures that caused various degrees of RPE disruption. No measurable change in rhodopsin recovery rate was found at any exposure level and RPE disruption was found to be visible at exposure levels that did not produce a significant reduction in rhodopsin density. However, such a reduction in rhodopsin density was measured at the highest exposure levels. Additionally, a new effect caused by near-infrared (NIR) illumination was discovered: a decrease in infrared autofluorescence (IRAF) measured after exposure to NIR illumination at levels well below recommended limits. Because many retinal imaging systems rely on NIR illumination to avoid potentially harmful exposures at shorter wavelengths, understanding the source of this IRAF reduction is important for both scientific and clinical imaging. This thesis provides the first description of IRAF reduction, as well as an examination of its basic properties"--Pages viii-ix.

Download or read book Digital Teleretinal Screening written by Kanagasingam Yogesan and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Digital retinal imaging performed by primary care providers and nurses, followed by remote image interpretation (teleretinal imaging), is rapidly acquiring a crucial role in many parts of the world as it permits the detection of major diseases, such as diabetic retinopathy and glaucoma, in patients who would otherwise be beyond the reach of a trained ophthalmologist. In this book, experts from around the world describe how digital teleretinal screening can be set up and optimally utilized. Technical issues are discussed, and the appropriate use of screening for different diseases and in different age groups is explained. The major part of the book draws upon the clinical experience of leading practitioners in a wide range of teleretinal applications. The result is a comprehensive source of high-quality information for clinicians and other health professionals who are involved in eye care delivery, so that they can assess how teleretinal screening might be applied to their working practice.

Download or read book Analysis of Retinal Function Following Laser Irradiation written by and published by . This book was released on 1992 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposure of the fovea to single or multiple pulses of coherent light (532 nm) can produce both transient and permanent changes in the eye's ability to resolve fine spatial detail. The immediate effects for extended duration exposures (>50 msec) are often large, producing acuity deficits as great as 90% of its pre-exposure level. The size of these deficits often reflect a total loss of foveal functioning although, depending upon the energy and duration of the exposure, these changes are reversible. Permanent changes in acuity can be noted in the absence of gross morphological damage and at power densities below the ED50 level provided the area of involvement is large. On the other hand, at power densities above the ED50 level, little if any permanent or consistent visual deficits are noted if the damage is restricted to relatively isolated areas within either the foveal or parafovea. Multiple pulses which increase the area of total involvement are more effective in permanently shifting postexposure acuity than are the single pulse conditions. Cumulative effects of repetitive exposures separate in time by as much as several al days are possible. The exact parameters of any observed loss in visual performance of course is dependent upon the discrimination task and its ability to depict subtle changes in the retina mosiac. Laser safety (MPE), Visual acuity, Nd/YAG, Rhesus monkey, Flash effects, Long-term visual deficits, Light-induced damage, RA 3.

Download or read book Autofluorescence Imaging of Retinal Pigment Epithelial Cells in the Living Human Eye written by Charles E. Granger and published by . This book was released on 2020 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The lens and cornea of the eye enable vision by focusing images of the world on the light-sensitive retina. In turn, they can be conveniently utilized as an objective lens, allowing visualization and imaging of the retina in ophthalmoscopy. This technique is used every day to non-invasively diagnose and monitor retinal disease and injury, to allow retinal surgery, and study fundamentals of vision science. The implementation of adaptive optics technology further enables ophthalmoscopy by measuring and correcting the eye's aberrations and allowing high-resolution imaging of retinal cells in the living eye. Cellular-scale in vivo imaging has provided greater insight into the study of disease, physiology, and even allowed advanced techniques for probing neuronal function. Despite the resolution improvement, many retinal cells critical to vision remain difficult to image with traditional reflected light, requiring the implementation and development of advanced microscopy imaging techniques where possible. One such layer of cells is the retinal pigment epithelium (RPE), which maintains the health and normal function of rod and cone photoreceptors, and is affected in many retinal diseases that cause blindness. While these cells cannot be visualized using standard reflectance imaging, they are unique from other retinal cells in that they contain relatively strong endogenous fluorophores, namely lipofuscin and melanin. The work in this thesis aims to advance methods of autofluorescence imaging of the RPE in the living human eye through adaptive optics ophthalmoscopy. This includes single-photon fluorescence intensity imaging techniques, utilizing both visible and near-infrared excitation, allowing for structural analysis of cells in human subjects. Structural analysis is then complemented by the implementation of fluorescence lifetime imaging, potentially providing functional analysis of cells and a more effective method of assessing cell health. These imaging techniques provide a set of tools for characterizing and studying RPE cells with structural and functional biomarkers in both healthy and diseased human eyes"--Pages xiii-xiv.

Download or read book Nonlinear Optical Effects on Retinal Damage Thresholds in the 1200 1400 Nm Wavelength Range written by Francesco Jozac Echeverria and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent changes in the maximum permissible exposure (MPE) limits for near-infrared (NIR) laser exposures are analyzed in light of nonlinear optical phenomena. We have evaluated the thresholds for supercontinuum (SC) generation for ultra-short (femtosecond) laser exposures in the NIR region and compared these values with the MPEs listed in the American National Standard for Safe Use of Lasers 2014 Edition (ANSI Z136.1-2014). Due to the strong increase in ocular absorption in the 1.2 to 1.4 micrometer (i.e. 1200-1400 nm) range, evaluation of the SC generation phenomenon is necessary because any shift in laser energy within the eye to shorter wavelengths (i.e. greater frequency) could lead to unforeseen increases in hazards to the retina. The findings of this research do in fact indicate a shift in laser energy to shorter wavelengths for femtosecond pulsed lasers. In addition, an analysis involving spectral measurements through a water cuvette leads to estimations involving the eye configuration that show radiant exposures exceeding the ANSI thresholds for visible wavelengths. The implications of these findings are such that enough NIR energy is converted to visible energy near the retina when dealing with femtosecond pulsed lasers, warranting further studies in examining what the effects caused by nonlinear optical phenomena due to ultrashort pulsed lasers have on MPE thresholds established for eye safety. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155191

Download or read book Retinal Image Based Eye Tracking Using the Tracking Scanning Laser Ophthalmoscope written by Christy Kathleen Sheehy and published by . This book was released on 2015 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: The tracking scanning laser ophthalmoscope (TSLO) was designed, built and characterized for high-resolution eye-tracking, imaging, and targeted retinal stimulus delivery. Eye-tracking is done via an image-based software program that monitors the image of the retina over time while simultaneously logging the displacements of the eye. Currently, this system is the most accurate, fast and functional eye-tracking system used in a standard ophthalmic instrument. The TSLO has the ability to non-invasively track the eye at 960 Hz (with an accuracy of 0.2 arcminutes or roughly 1 micron) and present stimuli to the retina at the resolution of single cone photoreceptors (0.66 arcminutes, which is roughly 3 microns). The combination of structural imaging and functional testing allows one to begin to more thoroughly understand retinal disease progression, as well probe specific retinal locations in order to test new treatment efficacies. This level of accuracy is unprecedented in the clinic and is crucial when monitoring minute changes in eye motion, structure, and function. Additionally, the system is capable of providing external eye-tracking for other high-resolution imaging systems, such as optical coherence tomography (OCT) and adaptive optics scanning laser ophthalmoscope (AOSLO) systems through the active steering of an imaging beam. This feature allows the imaging raster or stimuli to stay on target during fixational eye motion. This dissertation steps through all of the above-mentioned uses of the TSLO and further elaborates on the optimal design and system test performance capabilities of the system.

Download or read book Ultrahigh Resolution Optical Coherence Tomography for Non invasive Imaging of Outer Retina Degeneration in Rat Retina written by Sepideh Hariri and published by . This book was released on 2013 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project initiated with the aim for improving the ultrahigh resolution optical coherence tomography (UHR-OCT) system performance by considering the limitations to the axial OCT resolution for in vivo imaging of human and animal retina. To this end, a computational model was developed to simulate the effect of wavelength-dependant water absorption on the detected spectral shape of the broad-bandwidth light source used in UHR-OCT at 1060nm wavelength region, which effectively determines the axial OCT resolution in the retina. For experimental verification of the computational model, a custom built light source with a re-shaped spectrum (Superlum Inc.) was interfaced to the state-of-the-art UHR-OCT system. About 30% improvement of the axial OCT resolution in the rat retina and ~12% improvement of the axial OCT resolution in the human retina was achieved compared to the case of the almost Gaussian shaped spectrum of the standard, commercially available SLD. Although water absorption in the 1060nm spectral region strongly affects the sample beam, selecting a suitable light source with specific spectral shape can compensate for the undesired water absorption effect and thus result in significantly improved axial resolution in in vivo OCT retinal images. To demonstrate the advantages of the state-of-the-art OCT technology for non invasive retinal imaging, an established animal model of outer retina degeneration (sodium iodate (NaIO3)-induced retina degeneration) was employed for longitudinal monitoring of the degeneration and investigation of possible early and dynamic signs of damage undetected by other imaging modalities. The long-term (up to 3 months) and short-term (up to 12 hours) effect of sodium iodate toxicity on the layered structure of retina was monitored longitudinally and in vivo for the first time using OCT. An initial acute swelling of the retina, followed by progressive disruption and degeneration of outer retina was observed as a result of sodium iodate-induced damage. Changes in the thickness and optical reflectivity of individual retinal layers were extracted from the OCT images to quantify the changes occurring at different stages of the disease model. Results from this project present the theoretical and practical limits to the highest axial OCT resolution achievable for retina imaging in the 1060nm spectral range both in small animals and humans, and provided a framework for future development of novel light sources. Furthermore, UHR-OCT imaging was shown to be an effective and valuable modality for in vivo, non invasive investigation of retina degenerative disease.

Download or read book Wavefront Sensing and High Resolution Adaptive Optics Imaging in the Living Rodent Eye written by Ying Geng and published by . This book was released on 2011 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The rodent has become an increasingly valuable model for human diseases and development due to its availability for genetic manipulations. Non-invasive microscopic imaging of the rodent retina would allow tracking of retinal development, disease progression, and the efficacy of therapy in single animals. Correction of the eye's aberrations using adaptive optics (AO) could improve the resolution of in vivo rodent retinal images, but previous attempts have been limited by the small size of its eye and the difficulty in measuring its aberrations due to poor Shack-Hartmann wavefront sensor (SHWS) spot quality. The work in this thesis describes methods developed to measure the rodent eye optics and to optimize its retinal image quality in vivo. Our first attempt was modifying a confocal fluorescence adaptive optics scanning laser ophthalmoscope (AOSLO) originally built for imaging the primate and human eye to accommodate the rat eye. Despite achieving in vivo resolution sufficient to resolve sub-cellular structures in fluorescent ganglion cells, problems were identified with aberration measurements and AO image quality. We then constructed a SHWS customized for the small mouse eye, and found a solution to the aberration measurement problem. The custom designed SHWS can favor light from a specific retinal layer and provide good wavefront spot quality. This wavefront sensor was incorporated into a confocal AOSLO custom designed for the mouse eye. High quality images were obtained in the mouse retina revealing multiple cell layers, including the photoreceptor mosaic, nerve fiber bundles, fine capillaries/blood flow, and ganglion cell bodies and fine processes. The in vivo resolution of the system was directly characterized to be sub-[micrometer] laterally, and ~10 [micrometers] axially. This fine resolution has allowed classification of ganglion cells in vivo. The value of the instrument was also demonstrated in two functional imaging scientific studies"--Leaves vii-viii.

Download or read book Fluorescence Lifetime Imaging Ophthalmoscopy written by Martin Zinkernagel and published by Springer. This book was released on 2019-07-29 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the emerging non-invasive imaging technique of Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO). FLIO reveals unique information on retinal diseases, ranging from age-related macular degeneration and vascular diseases to hereditary retinal dystrophies. Fluorescence lifetimes enable the evaluation of disease progression before irreversible structural changes occur. The image acquisition is suitable for diagnostic purposes and follow-up examinations to investigate the natural course of disease, and to monitor the effects of possible therapies. This book fills the gap between available literature and gives state-of-the-art guidance on the principles of the FLIO technique, image acquisition, and data analysis. Written by a team of expert leaders within this field, this book will be relevant for scientists and clinicians with an interest in ophthalmoscopy.

Download or read book Fundus Fluorescein Angiography written by Amresh Chopdar and published by Butterworth-Heinemann. This book was released on 1996 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorescein angiography provides the ophthalmologist with valuable diagnostics information on retinal blood flow, and permits diagnosis of a wide range of eye disorders including macular disease, diabetes, tumours and retinal detachment. This book, now retitled, has been completely updated, revised and redesigned to give more details on techniques and the interpretation of results obtained. New to this book: * the existing text has been expanded and updated * there is a new chapter on digital and video angiography * there is a new section on pitfalls * the layout has been redesigned for greater clarity * the book contains more information on fundus angiography in clinical practice * there is more information on the anatomy of the ocular vascular system * there are two new chapters on diabetes and age related macular degeneration The book will continue to be an indispensible guide for the practising and trainee ophthalmologist.

Download or read book Pathologic Myopia written by Richard F. Spaide and published by Springer Nature. This book was released on 2021-07-28 with total page 461 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pathologic Myopia is a major cause of severe vision loss worldwide. The mechanisms for vision loss include cataract, glaucoma, retinal detachment, and above all, myopic maculopathy within the posterior staphyloma. The first edition of Pathologic Myopia is one of the only current books to specifically address this disease and discusses recent developments in imaging technologies and various approaches to treatments, such as laser photocoagulation, photodynamic therapy, pharmaco-therapeutic injections in the vitreous, and surgery. This new edition is a timely update to the standard reference in the field, with new chapters on advanced refractive error correction, genetics, developing a classification system, and special surgical approaches for pathologic myopia. Complete with even more high-quality color images and informative tables, this book is written and edited by leaders in the field and is geared towards ophthalmologists, including residents and fellows in training, glaucoma and cataract specialists, and vitreoretinal macula experts.

Download or read book Handbook of Advanced Lighting Technology written by Robert Karlicek and published by Springer. This book was released on 2016-05-08 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Advanced Lighting Technology is a major reference work on the subject of light source science and technology, with particular focus on solid-state light sources – LEDs and OLEDs – and the development of 'smart' or 'intelligent' lighting systems; and the integration of advanced light sources, sensors, and adaptive control architectures to provide tailored illumination which is 'fit to purpose.' The concept of smart lighting goes hand-in-hand with the development of solid-state light sources, which offer levels of control not previously available with conventional lighting systems. This has impact not only at the scale of the individual user, but also at an environmental and wider economic level. These advances have enabled and motivated significant research activity on the human factors of lighting, particularly related to the impact of lighting on healthcare and education, and the Handbook provides detailed reviews of work in these areas. The potential applications for smart lighting span the entire spectrum of technology, from domestic and commercial lighting, to breakthroughs in biotechnology, transportation, and light-based wireless communication. Whilst most current research globally is in the field of solid-state lighting, there is renewed interest in the development of conventional and non-conventional light sources for specific applications. This Handbook comprehensively reviews the basic physical principles and device technologies behind all light source types and includes discussion of the state-of-the-art. The book essentially breaks down into five major sections: Section 1: The physics, materials, and device technology of established, conventional, and emerging light sources, Section 2: The science and technology of solid-state (LED and OLED) light sources, Section 3: Driving, sensing and control, and the integration of these different technologies under the concept of smart lighting, Section 4: Human factors and applications, Section 5: Environmental and economic factors and implications