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 Fluorescence Lifetime Imaging Ophthalmoscopy FLIO from Bench to Bedside written by Chantal-Simone Dysli and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two photon Adaptive Optics Fluorescence Lifetime Imaging Ophthalmoscopy written by James A.. Feeks and published by . This book was released on 2018 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: "There are many critical processes involved in keeping the retina functioning properly. Two of these, the visual cycle and the metabolism of the cell, are tied together by their conversion of important molecules from one form to another. In the visual cycle, 11-cis-retinal is regenerated so that it can combine with a rhodopsin molecule and initiate phototransduction. In cellular metabolism, the cell undergoes many steps to generate adenosine triphosphate, the energy unit of the cell. These mechanisms are critical in maintaining a functioning retina, however they have been difficult to directly interrogate in the living eye. A technique which can quantitatively measure these processes could allow researchers and clinicians to examine them in healthy subjects and how they change under conditions of disease. The goal of this work is to develop a technique which will allow us to investigate these measures of retinal function quantitatively and in a repeatable way. Advantageously, molecules which are converted during the visual cycle or cellular metabolism are accessible using adaptive optics aided two-photon fluorescence ophthalmoscopy. Furthermore, I develop a new technique, adaptive optics fluorescence lifetime ophthalmoscopy, which provides a robust and quantitative measure of a key property of retinal fluorescence. Initially, this method was deployed in a new two-photon adaptive optics ophthalmoscope designed for imaging mice. Exogenous fluorophores with known fluorescence lifetimes were used to validate the initial measurements, before using the new technique to establish baseline measurements for a sensor of cellular metabolism in the mouse eye. Following successful implementation in the mouse, the fluorescence lifetime method was translated to a system dedicated to imaging the macaque retina. By measuring the fluorescence lifetime of endogenous fluorescence originating in the photoreceptors, I found that rods and cones exhibit different fluorescence lifetimes. Further development of this technology may advance research in widespread areas including fluorophore identification in the retina, mechanisms of retinal metabolism, and as a clinical diagnostic."--Pages xiii-xiv.

Download or read book Retinal Fluorescence Lifetime Imaging Ophthalmoscopy Measures Depend on the Severity of Alzheimer s Disease written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Monitoring Macular Pigment Changes in Macular Holes Using Fluorescence Lifetime Imaging Ophthalmoscopy written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundus Autofluorescence written by Noemi Lois and published by Lippincott Williams & Wilkins. This book was released on 2012-02-13 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: Featuring over 250 illustrations, this detailed full-color textbook provides up-to-date information on the use of fundus autofluorescence imaging in evaluation of retinal disease. Chapters describe the techniques available to image and quantify fundus autofluorescence and the autofluorescence patterns observed in the healthy eye and in various retinal diseases. Emphasis is on the value of fundus autofluorescence as a diagnostic and prognostic tool and its clinical utility in the context of other imaging techniques, such as fluorescein and indocyanine green angiography and optical coherence tomography. Each chapter also discusses the value of fundus autofluorescence in understanding the pathogenesis of the condition, and provides a comprehensive update on all aspects of the condition. A companion Website will offer the fully searchable text and an image bank.

Download or read book Clinical Application of Fluorescence Lifetime Imaging at the Eye written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fluorescence Lifetime Imaging Ophthalmoscope and Supplement of Agonistic TrkB Antibody in a Glaucoma Model written by Aiwei Liu and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two photon Excited Fluorescence Adaptive Optics Ophthalmoscopy of Retinal Function written by Sarah Eileen Walters and published by . This book was released on 2019 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The retina is the light-sensitive tissue at the back of the eye which carries out the first steps in vision. Specialized neural cells in the retina known as photoreceptors are responsible for detection of light and its transduction by initiating an electrical signal to the brain. Adaptive optics scanning light ophthalmoscopy (AOSLO), which dynamically corrects aberrations of the ocular media in the living eye and affords a lateral resolution of 2 ?m, has revolutionized our ability to visualize photoreceptors and many other microstructures in the retina. The implementation of two-photon excited fluorescence (TPEF) imaging in AOSLO has enabled not only complementary structural information throughout the retina, but an objective, non-invasive measure of visual function in photoreceptors by measuring TPEF kinetics from these cells. The aim of the present thesis is to further develop and apply TPEF ophthalmoscopy as a novel measure of in vivo cellular function in the retina. First, TPEF ophthalmoscopy was used in conjunction with other imaging modalities to evaluate the extent of photoreceptor dysfunction in a non-human primate model of retinal degeneration. TPEF ophthalmoscopy was essential in determining that photoreceptors were non-functional. Second, the sensitivity of TPEF kinetics to detect changes in photoreceptor function in conditions relevant to disease pathogenesis was investigated. Systemic hypoxia was employed in non-human primates as a model of physiological change, reducing oxygen supply to the retina, and TPEF kinetics were shown to be slowed as a consequence. Finally, the capabilities of TPEF ophthalmoscopy were expanded by implementing intrinsic fluorescence lifetime imaging. TPEF lifetime imaging was shown to distinguish retinal cell classes that are functionally disparate, and lifetimes were altered in regions of retinal damage. TPEF ophthalmoscopy has the potential to yield advances in understanding of both the basic physiology and pathology of the retina. If translated successfully into humans, TPEF ophthalmoscopy demonstrates promise as a valuable imaging modality that may, when used in conjunction with other clinical measures, identify early cellular dysfunction and longitudinally track pathological changes. Ultimately, it may assist in timely diagnosis, intervention, and development of treatments or vision restoration methods to combat blindness as a consequence of retinal disease."--Pages xiv-xv.

Download or read book Characterizing and Identifying the Fluorescence Lifetime of the in Vivo Human RPE Cellular Mosaic written by Janet A H. Tang and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The retinal pigment epithelium (RPE) is a cell layer in the back of the eye essential for ocular health. With age, the RPE naturally accumulates autofluorescent material called lipofuscin, just one of many retinal fluorophores. Fluorescence is useful for diagnosing and tracking retinal disease. Beyond measuring intensity fluorescence lifetime imaging ophthalmoscopy (FLIO) varied with fluorophore composition and environmental factors that may provide critical insight into retinal mechanisms. Adaptive optics ophthalmoscopy can target specific retinal layers or individual cells. This thesis characterizes the in vivo human RPE layer using AOFLIO and investigates potential sources of change across the retina and with age. Firstly, it demonstrates the safety and repeatability of AOFLIO in human subjects with green-light excitation at 532 nm. By imaging at both the 532 nm spectral channel and mimicking the clinical device with two blue-light excitation channels - the long spectral channel (LSC) and short spectral channel (SSC) - I found that there was a high correlation between the LSC and 532 nm channel with a near-constant offset between the two lifetimes. That is likely because of a higher relative contribution of melanin to the 532 nm channel. To elucidate how AOFLIO results can be translated into the clinic, some subjects were also imaged with clinical FLIO. The AO LSC was well correlated with the clinical LSC, making the comparison simple between those channels. The AO 532 nm channel and the clinical LSC were not well correlated. The in vivo human signal in all 3 channels was compared to that from endogenous fluorophores in cuvettes. These results indicated that the main sources of fluorescence in the 532 nm channel are lipofuscin, melanin, and FAD where the increase of fluorescence lifetime with age can be attributed to the increase of melanolipofuscin which likely pulls the lifetime signal longer. Lastly, the cell-to-cell dynamics were investigated which found lifetime increases with age and eccentricity. The AO SSC changes were found to also be likely due to melanin changes across the retina. Future work will include applying AOFLIO to disease eyes to begin probing the dynamics of change with retinal degeneration."--Pages xiii-xiv.

Download or read book The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques written by Peng Xiao and published by Frontiers Media SA. This book was released on 2022-12-06 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fluorescence Lifetime Spectroscopy and Imaging written by Laura Marcu and published by CRC Press. This book was released on 2014-07-17 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the past two decades, there has been an increasing appreciation of the significant value that lifetime-based techniques can add to biomedical studies and applications of fluorescence. Bringing together perspectives of different research communities, Fluorescence Lifetime Spectroscopy and Imaging: Principles and Applications in Biomedical Diagnostics explores the remarkable advances in time-resolved fluorescence techniques and their role in a wide range of biological and clinical applications. Broadly accessible, the book captures the state-of-the-art of fluorescence lifetime metrology and imaging and provides current perspectives on their applications to biomedical studies of intact tissues and medical diagnosis. The text introduces these techniques within the wider context of fluorescence spectroscopy and describes basic principles underlying current instrumentation for fluorescence lifetime imaging and metrology (FLIM). It also covers the wide range of methods, including single channel (point) spectroscopy, fluorescence lifetime imaging microscopy, and single- and multi-photon excitation. Edited by pioneers in this field, with contributions from leading experts, the book includes an overview of complementary techniques that help researchers beginning FLIM research. It offers a comprehensive treatment of fundamental principles, instrumentation, analytical methods, and applications. It also provides an overview of the label-free contrast available from lifetime measurements of tissue autofluorescence and the prospects for exploiting this for clinical applications and biomedical research including drug discovery.

Download or read book Multiphoton Microscopy and Fluorescence Lifetime Imaging written by Karsten König and published by Walter de Gruyter GmbH & Co KG. This book was released on 2018-01-22 with total page 785 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph focuses on modern femtosecond laser microscopes for two photon imaging and nanoprocessing, on laser tweezers for cell micromanipulation as well as on fluorescence lifetime imaging (FLIM) in Life Sciences. The book starts with an introduction by Dr. Wolfgang Kaiser, pioneer of nonlinear optics and ends with the chapter on clinical multiphoton tomography, the novel high resolution imaging technique. It includes a foreword by the nonlinear microscopy expert Dr. Colin Sheppard. Contents Part I: Basics Brief history of fluorescence lifetime imaging The long journey to the laser and its use for nonlinear optics Advanced TCSPC-FLIM techniques Ultrafast lasers in biophotonics Part II: Modern nonlinear microscopy of live cells STED microscopy: exploring fluorescence lifetime gradients for super-resolution at reduced illumination intensities Principles and applications of temporal-focusing wide-field two-photon microscopy FLIM-FRET microscopy TCSPC FLIM and PLIM for metabolic imaging and oxygen sensing Laser tweezers are sources of two-photon effects Metabolic shifts in cell proliferation and differentiation Femtosecond laser nanoprocessing Cryomultiphoton imaging Part III: Nonlinear tissue imaging Multiphoton Tomography (MPT) Clinical multimodal CARS imaging In vivo multiphoton microscopy of human skin Two-photon microscopy and fluorescence lifetime imaging of the cornea Multiscale correlative imaging of the brain Revealing interaction of dyes and nanomaterials by multiphoton imaging Multiphoton FLIM in cosmetic clinical research Multiphoton microscopy and fluorescence lifetime imaging for resection guidance in malignant glioma surgery Non-invasive single-photon and multi-photon imaging of stem cells and cancer cells in mouse models Bedside assessment of multiphoton tomography

Download or read book The bh TCSPC Handbook written by Dr. Wolfgang Becker and published by Becker & Hickl GmbH. This book was released on 2021-09-01 with total page 995 pages. Available in PDF, EPUB and Kindle. Book excerpt: Time-Correlated Single Photon Counting Modules SPC-130EMN, SPC-130EMNX, SPC-130IN, SPC-130INX, SPC-150N, SPC-150NX, SPC-150NXX, SPC-160, SPC-160PCIE, SPC-180N, SPC-180NX, SPC-180NXX Detectors, Lasers and Peripheral Devices Simple-Tau Systems Technical Principles TCSPC Applications FLIM Systems Applications in Life Sciences Clinical FLIM Applications SPCM Software SPCImage NG Data Analysis Software Time-correlated single photon counting (TCSPC) is an amazingly sensitive technique for recording low-level light signals with picosecond resolution and extremely high precision.TCSPC originates from the measurement of excited nuclear states and has been used since the late 60s [775, 1250]. For many years TCSPC was used primarily to record fluorescence decay curves of organic dyes in solution. Due to the low intensity and low repetition rate of the light sources and the limited speed of the electronics of the 70s and 80s the acquisition times were extremely long. More important, classic TCSPC was intrinsically one-dimensional, i.e. limited to the recording of the waveform of a periodic light signal. Light sources ceased to be a limitation when the first mode-locked Argon lasers and synchronously pumped dye lasers were introduced. For the recording electronics, the situation changed with the introduction of the SPC-300 modules of Becker & Hickl in 1993. Due to a new analog-to-digital conversion principle these modules could be used at photon count rates almost 100 times higher than the classic TCSPC devices. Moreover, the modules were able to record the photons of a large number of detectors simultaneously. They were thus able to record a photon distribution not only versus the time in a fluorescence decay but also versus aspatial coordinate or the wavelength of the photons. Multi-dimensional TCSPC was born. Within a few years, more dimensions were added to multidimensional TCSPC. Fast sequential recording was introduced with the SPC-430 in 1995, fast scanning with the SPC-535 in 1997. Time-tag recording was introduced with the SPC-431 in 1996; multi-module TCSPC systems followed in 1999. Since then, the Becker & Hickl TCSPC systems became bigger, faster and more flexible. Recent TCSPC modules, like the SPC-150NX or the SPC-180, can be configured for sequential recording, imaging, or time-tag recording by a simple software command. Multi-module systems, like the SPC-134EM and SPC-154, can be used for scanning at unprecedented count rates and acquisition speeds. Nevertheless, TCSPC still has the reputation to be an extremely sluggish technique unable to record any fast changes in the fluorescence or scattering behaviour of a sample. The multidimensional features of modern TCSPC are not commonly understood. Thus, many users do not make efficient use of their SPC modules. However, if appropriately used, multidimensional TCSPC techniques not only deliver superior results but also solve highly sophisticated measurement problems. This handbook is an attempt to help existing and potential users understand and make use of the advanced features of modern TCSPC. After an introduction into the bh TCSPC devices and associated detector, laser, and experiment control modules the principles of advanced TCSPC techniques are described. These include multidetector TCSPC, multiplexed TCSPC, sequential recording techniques, scanning techniques, parameter-tag recording, and multi-module TCSPC techniques. The next chapter describes the architecture of the bh SPC modules. A chapter about detectors gives a review of detector principles and of the parameters used to characterise detectors. It describes a number of detectors commonly used for TCSPC and gives advice about obtaining best performance from them. The implementation of bh SPC devices is described in the next part of the handbook. It includes principles and wiring diagrams for typical experiments, guidelines for first system setup, and advice for system optimisation. It describes dead-time, counting loss, and pile-up effects, detector effects, and effects related to the optical system. The next chapter of the handbook is dedicated to TCSPC applications. The first part of this chapter describes the measurement of fluorescence and anisotropy decay curves, multispectral lifetime experiments, recording of transient fluorescence lifetime phenomena, and measurements of phosphorescence decay curves. The second part of the chapter is dedicated to time-resolved laser scanning microscopy. It contains sections on a wide variety of fluorescence-lifetime imaging (FLIM) experiments and procedures, such as FLIM with various excitation principles, excitation sources, and detection principles, high-speed and time-series FLIM, Z-stack FLIM, simultaneous fluorescence and phosphorescence lifetime imaging (FLIM/PLIM), fluorescence lifetime-transient scanning (FLITS), and FLIM with special microscope configurations. A third part contains FLIM background knowledge: Signal-to-noise ratio, acquisition time, the effect of counting loss and pile-up, photobleaching, and fluorescence depolarisation on the recorded data. The book contains a large chapter on TCSPC applications, most of them in Biology. It contains sections on FLIM of molecular environment parameters in tissue, FLIM-based FRET measurements in cells, autofluorescence FLIM of biological tissue, plant physiology, and clinical FLIM applications. A section about diffuse optical tomography (DOT) by NIRS techniques includes breast imaging, static and functional brain imaging, perfusion measurement in the human brain, diffuse tissue spectroscopy, and small-animal imaging. Picosecond photon correlation, fluorescence correlation spectroscopy, burst-integrated fluorescence lifetime techniques, and photon counting histogram techniques are reviewed in the next sections. The last part of the application chapter gives an review of non-biological TCSPC applications like positron lifetime measurement, measurement of barrier discharges, remote sensing, metrological applications, and characterisation of detectors. The application chapter also includes practical hints about optical systems, detectors, and other technical aspects of the applications described. Another large chapter describes the SPCM operating software of the bh SPC modules. It describes the various user interface configurations, operation modes, the system and control parameters, the handling and display of the multidimensional data recorded by the modules, and the associated data file structure. The TCSPC Handbook also contains a chapter on the SPCImage NG fluorescence decay and FLIM data analysis software. It describes the general principles of fluorescence decay analysis, the calculation of fluorescence decay parameters and lifetime images by various decay models, pseudo-global analysis, multi-wavelength FLIM analysis, batch-processing of FLIM series, and analysis of PLIM data. The handbook ends with a list of more than 1200 references related to TCSPC, most of them being applications of the bh SPC devices.

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 Two photon Excited Fluorescence Lifetime Reveals Differences in Biochemical Composition Between Retinal Cells in the Living Monkey and Mouse written by Khang T. Huynh and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The retina is the light-sensitive, multilayered tissue at the back of the eye responsible for converting light into electrical impulses for visual perception. Dysfunction in even one cell type or layer can result in partial to total blindness. Observing the structural and functional dynamics that underlie dysfunction, especially before cell death, is critical to understanding retinal diseases, developing new diagnostic metrics, and evaluating novel treatments. Adaptive optics scanning light phthalmoscopy (AOSLO), which permits near-diffraction limited imaging by correcting the inherent aberrations of the eye, has enabled in vivo subcellular scale evaluations of the retina. Two-photon excited fluorescence (TPEF) imaging allows the optical probing of molecules spectrally inaccessible with single-photon fluorescence that play important roles in metabolism, the visual cycle, and structure. By combining TPEF with AOSLO, it may be possible to evaluate the biochemistry of different cells and layers throughout the living retina and relate those measurements to function. Previous work has established the instrumentation and workflow to perform TPEF adaptive optics fluorescence lifetime ophthalmoscopy (AOFLIO), an AOSLO modality which measures the time-dependent component of fluorescence aggregated from all contributing endogenous and exogenous fluorophores. The goals of this thesis are to determine how lifetime signatures differ between cells and layers and disambiguate the aggregate lifetimes into their constituent molecular species. First, AOFLIO was deployed in macaque photoreceptors. The phasor method of analysis, a method to visualize fluorescence lifetime decays in two-dimensional frequency space, was incorporated into this workflow. This enabled the separation of S cone, M/L cone, and rod photoreceptor lifetime signatures, an improvement in sensitivity over traditional multiexponential fitting. Second, AOFLIO and phasor analysis were applied to other features in the macaque retina. In vivo fluorescence signatures can be compared to those of known retinal fluorophores with a phasor fingerprint, allowing inferences about the dominant contributing sources. Finally, AOFLIO was deployed in rho-/-retinitis pigmentosa (RP) mice whose retinas expressed a fluorescence lifetime-based sensor of glucose concentration. The first evidence of glucose sequestration in the retinal pigment epithelium, the hypothesized mechanism that causes sequential cone death in RP, was observed. This work has advanced the development of TPEF AOFLIO as a noninvasive probe of biochemical composition in the in vivo retina. This may allow subcellular evaluations of the retina in health, throughout the time course of disease, and in response to therapeutics"--Pages xviii-xix.