Relevant bibliographies by topics / Functional retinal imaging

Academic literature on the topic 'Functional retinal imaging'

Author: Grafiati
Published: 10 December 2022
Last updated: 29 January 2023

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Journal articles on the topic "Functional retinal imaging"

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Ganekal, Sunil. "Retinal functional imager (RFI): Non-invasive functional imaging of the retina." Nepalese Journal of Ophthalmology 5, no. 2 (September 25, 2013): 250–57. http://dx.doi.org/10.3126/nepjoph.v5i2.8738.

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Retinal functional imager (RFI) is a unique non-invasive functional imaging system with novel capabilities for visualizing the retina. The objective of this review was to show the utility of non-invasive functional imaging in various disorders. Electronic literature search was carried out using the websites www.pubmed.gov and www.google.com. The search words were retinal functional imager and non-invasive retinal imaging used in combination. The articles published or translated into English were studied. The RFI directly measures hemodynamic parameters such as retinal blood-flow velocity, oximetric state, metabolic responses to photic activation and generates capillary perfusion maps (CPM) that provides retinal vasculature detail similar to flourescein angiography. All of these parameters stand in a direct relationship to the function and therefore the health of the retina, and are known to be degraded in the course of retinal diseases. Detecting changes in retinal function aid early diagnosis and treatment as functional changes often precede structural changes in many retinal disorders. Nepal J Ophthalmol 2013; 5(10): 250-257 DOI: http://dx.doi.org/10.3126/nepjoph.v5i2.8738
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Hunter, Jennifer J., William H. Merigan, and Jesse B. Schallek. "Imaging Retinal Activity in the Living Eye." Annual Review of Vision Science 5, no. 1 (September 15, 2019): 15–45. http://dx.doi.org/10.1146/annurev-vision-091517-034239.

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Retinal function has long been studied with psychophysical methods in humans, whereas detailed functional studies of vision have been conducted mostly in animals owing to the invasive nature of physiological approaches. There are exceptions to this generalization, for example, the electroretinogram. This review examines exciting recent advances using in vivo retinal imaging to understand the function of retinal neurons. In some cases, the methods have existed for years and are still being optimized. In others, new methods such as optophysiology are revealing novel patterns of retinal function in animal models that have the potential to change our understanding of the functional capacity of the retina. Together, the advances in retinal imaging mark an important milestone that shifts attention away from anatomy alone and begins to probe the function of healthy and diseased eyes.
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Yao, Xincheng, Taeyoon Son, Tae-Hoon Kim, and Yiming Lu. "Functional optical coherence tomography of retinal photoreceptors." Experimental Biology and Medicine 243, no. 17-18 (November 27, 2018): 1256–64. http://dx.doi.org/10.1177/1535370218816517.

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Age-related macular degeneration (AMD) is the leading cause of severe vision loss and legal blindness. It is known that retinal photoreceptors are the primary target of AMD. Therefore, a reliable method for objective assessment of photoreceptor function is needed for early detection and reliable treatment evaluation of AMD and other eye diseases such as retinitis pigmentosa that are known to cause photoreceptor dysfunctions. Stimulus-evoked intrinsic optical signal (IOS) changes promise a unique opportunity for objective assessment of physiological function of retinal photoreceptor and inner neurons. Instead of a comprehensive review, this mini-review is to provide a brief summary of our recent in vitro and in vivo optical coherence tomography (OCT) studies of stimulus-evoked IOS changes in animal retinas. By providing excellent axial resolution to differentiate individual retinal layers, depth-resolved OCT revealed rapid IOS response at the photoreceptor outer segment. The fast photoreceptor-IOS occurred almost right away (∼ 2 ms) after the onset of retinal stimulation, differentiating itself from slow IOS changes correlated with inner neural and hemodynamic changes. Further development of the functional IOS instruments and retinal stimulation protocols may provide a feasible solution to pursue clinical application of functional IOS imaging for objective assessment of human photoreceptors. Impact statement Retinal photoreceptors are the primary target of age-related macular degeneration (AMD) which is the leading cause of severe vision loss and legal blindness. An objective method for functional assessment of photoreceptor physiology can benefit early detection and better treatment evaluation of AMD and other eye diseases that are known to cause photoreceptor dysfunctions. This article summarizes in vitro study of IOS mechanisms and in vivo demonstration of IOS imaging of intact animals. Further development of the functional IOS imaging may provide a revolutionary solution to achieve objective assessment of human photoreceptors.
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Barliya, Tilda, Ron Ofri, Shai Sandalon, Dov Weinberger, and Tami Livnat. "Changes in Retinal Function and Cellular Remodeling Following Experimental Retinal Detachment in a Rabbit Model." Journal of Ophthalmology 2017 (2017): 1–14. http://dx.doi.org/10.1155/2017/4046597.

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Purpose.To explore functional electroretinographic (ERG) changes and associated cellular remodeling following experimental retinal detachment in a rabbit model.Methods.Retinal detachment was created in ten rabbits by injecting 0.1 ml balanced salt solution under the retina. Fundus imaging was performed 0, 3, 7, 14, and 21 days postoperatively. ERGs were recorded pre- and 7 and 21 days postoperatively. Eyes were harvested on day 21 and evaluated immunohistochemically (IHC) for remodeling of second- and third-order neurons.Results.Retinal reattachment occurred within two weeks following surgery. No attenuation was observed in the photopic or scotopic a- and b-waves. A secondary wavefront on the descending slope of the scotopic b-wave was the only ERG result that was attenuated in detached retinas. IHC demonstrated anatomical changes in both ON and OFF bipolar cells. Bassoon staining was observed in the remodeled dendrites. Amacrine and horizontal cells did not alter, but Muller cells were clearly reactive with marked extension.Conclusion.Retinal detachment and reattachment were associated with functional and anatomical changes. Exploring the significance of the secondary scotopic wavefront and its association with the remodeling of 2nd- and 3rd-order neurons will shade more light on functional changes and recovery of the retina.
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Azuma, Shinnosuke, Shuichi Makita, Deepa Kasaragod, Satoshi Sugiyama, Masahiro Miura, and Yoshiaki Yasuno. "Clinical multi-functional OCT for retinal imaging." Biomedical Optics Express 10, no. 11 (October 14, 2019): 5724. http://dx.doi.org/10.1364/boe.10.005724.

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Nguyen, Van, and Yannis Paulus. "Photoacoustic Ophthalmoscopy: Principle, Application, and Future Directions." Journal of Imaging 4, no. 12 (December 12, 2018): 149. http://dx.doi.org/10.3390/jimaging4120149.

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Photoacoustic ophthalmoscopy (PAOM) is a novel, hybrid, non-ionizing, and non-invasive imaging technology that has been used to assess the retina. PAOM can provide both anatomic and functional retinal characterizations with high resolution, high sensitivity, high contrast, and a high depth of penetration. Thus, ocular diseases can be precisely detected and visualized at earlier stages, resulting in an improved understanding of pathophysiology, improved management, and the improved monitoring of retinal treatment to prevent vision loss. To better visualize ocular components such as retinal vessels, choroidal vessels, choroidal neovascularization, retinal neovascularization, and the retinal pigment epithelium, an advanced multimodal ocular imaging platform has been developed by a combination of PAOM with other optical imaging techniques such as optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO), and fluorescence microscopy. The multimodal images can be acquired from a single imaging system and co-registered on the same image plane, enabling an improved evaluation of disease. In this review, the potential application of photoacoustic ophthalmoscopy in both research and clinical diagnosis are discussed as a medical screening technique for the visualization of various ocular diseases. The basic principle and requirements of photoacoustic ocular imaging are introduced. Then, various photoacoustic microscopy imaging systems of the retina in animals are presented. Finally, the future development of PAOM and multimodal imaging is discussed.
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Hugo, Juliette, Marie Beylerian, Eric Denion, Aurore Aziz, Pierre Gascon, Danièle Denis, and Frédéric Matonti. "Multimodal imaging of torpedo maculopathy including adaptive optics." European Journal of Ophthalmology 30, no. 2 (February 8, 2019): NP27—NP31. http://dx.doi.org/10.1177/1120672119827772.

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Purpose: The etiology of torpedo maculopathy remains unknown, but it has been recently suggested that it could represent a persistent defect in the development of the retinal pigment epithelium. As retinal pigment epithelium and photoreceptors form a functional unit, an alteration of photoreceptor distribution or function is predictable. The aim of this study is to describe multimodal imaging, including adaptive optics, in three cases of torpedo maculopathy, and discuss its pathogenesis. Methods: Multimodal imaging is presented, including fundus photographs, optical coherence tomography, adaptive optics, autofluorescence, fluorescein angiography, and ultra-widefield retinal imaging in three cases of torpedo maculopathy. Results: An oval-shaped well-delimited chorioretinal lesion both hypopigmented centrally and with a hyperpigmented border in the temporal macula, consistent with torpedo maculopathy, was observed in three patients. Optical coherence tomography showed a preservation of the inner retina, a mild atrophy of the outer retina, an alteration of the ellipsoid zone and of the retinal pigment epithelium layer, and a neurosensory detachment. These lesions were hypoautofluorescent with a hyperautofluorescent border. Fluorescein angiography showed a hyperfluorescence by window effect. Adaptive optics imaging showed an alteration of the cone mosaic within the lesions, with a lower cone density and a higher spacing between cones. Conclusion: The alteration of the cone mosaic suggested by adaptive optics in torpedo maculopathy has never been described and could be explained by the alteration of the retinal pigment epithelium. Our results support the existing hypothesis on the pathogenesis of torpedo maculopathy that a persistent defect in the development of the retinal pigment epithelium may be responsible for this clinical entity.
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Gao, Guanjie, Liwen He, Shengxu Liu, Dandan Zheng, Xiaojing Song, Wenxin Zhang, Minzhong Yu, Guangwei Luo, and Xiufeng Zhong. "Establishment of a Rapid Lesion-Controllable Retinal Degeneration Monkey Model for Preclinical Stem Cell Therapy." Cells 9, no. 11 (November 13, 2020): 2468. http://dx.doi.org/10.3390/cells9112468.

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Background: Retinal degenerative disorders (RDs) are the main cause of blindness without curable treatment. Our previous studies have demonstrated that human-induced pluripotent stem cells can differentiate into retinal organoids with all subtypes of retina, which provides huge promise for treating these diseases. Before these methods can be realized, RD animal models are required to evaluate the safety and efficacy of stem cell therapy and to develop the surgical tools and procedures for cell transplantation in patients. This study involved the development of a monkey model of RD with controllable lesion sites, which can be rapidly prepared for the study of preclinical stem cell therapy among other applications. Methods: Sodium nitroprusside (SNP) in three doses was delivered into the monkey eye by subretinal injection (SI), and normal saline was applied as control. Structural and functional changes of the retinas were evaluated via multimodal imaging techniques and multifocal electroretinography (mfERG) before and after the treatment. Histological examination was performed to identify the target layer of the affected retina. The health status of monkeys was monitored during the experiment. Results: Well-defined lesions with various degrees of retinal degeneration were induced at the posterior pole of retina as early as 7 days after SNP SI. The damage of SNP was dose dependent. In general, 0.05 mM SNP caused mild structural changes in the retina; 0.1 mM SNP led to the loss of outer retinal layers, including the outer plexiform layer (OPL), outer nuclear layer (ONL), and retinal pigment epithelium (RPE); while 0.2 mM SNP impacted the entire layer of the retina and choroid. MfERG showed reduced amplitude in the damaged region. The structural and functional damages were not recovered at 7-month follow-up. Conclusion: A rapidly induced lesion site-controllable retinal degeneration monkey model was established by the subretinal administration of SNP, of which the optimal dose is 0.1 mM. This monkey model mimics the histological changes of advanced RDs and provides a valuable platform for preclinical assessment of stem cell therapy for RDs.
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Yao, Xincheng, and Tae-Hoon Kim. "Fast intrinsic optical signal correlates with activation phase of phototransduction in retinal photoreceptors." Experimental Biology and Medicine 245, no. 13 (June 19, 2020): 1087–95. http://dx.doi.org/10.1177/1535370220935406.

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Quantitative assessment of physiological condition of retinal photoreceptors is desirable for better detection and treatment evaluation of eye diseases that can cause photoreceptor dysfunctions. Functional intrinsic optical signal (IOS) imaging, also termed as optoretinography (ORG) or optophysiology, has been proposed as a high-resolution method for objective assessment of retinal physiology. Fast IOS in retinal photoreceptors shows a time course earlier than that of electroretinography a-wave, promising an objective marker for noninvasive ORG of early phototransduction process in retinal photoreceptors. In this article, recent observations of fast photoreceptor-IOS in animal and human retinas are summarized, and the correlation of fast photoreceptor-IOS to five steps of phototransduction process is discussed. Transient outer segment conformational change, due to inter-disc space shrinkage correlated with activation phase of phototransduction, has been disclosed as a primary source of the fast photoreceptor-IOS. Impact statement As the center of phototransduction, retinal photoreceptors are responsible for capturing and converting photon energy to bioelectric signals for following visual information processing in the retina. This article summarizes experimental observation and discusses biophysical mechanism of fast photoreceptor-intrinsic optical signal (IOS) correlated with early phase of phototransduction. Quantitative imaging of fast photoreceptor-IOS may provide objective optoretinography to advance the study and diagnosis of age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and other eye diseases that can cause photoreceptor dysfunctions.
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de Carvalho, Emanuel R., Richelle J. M. Hoveling, Cornelis J. F. van Noorden, Reinier O. Schlingemann, and Maurice C. G. Aalders. "Functional Imaging of the Ocular Fundus Using an 8-Band Retinal Multispectral Imaging System." Instruments 4, no. 2 (May 7, 2020): 12. http://dx.doi.org/10.3390/instruments4020012.

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Application of functional imaging in ophthalmology requires efficient imaging techniques that can detect and quantify chromophores to visualise processes in vivo. The aim of the present study was to develop and evaluate a fast and affordable imaging system. We describe an eight-band retinal multispectral imaging (MSI) system and compare it with a hyperspectral imaging (HSI) device. Determination of blood oxygen saturation was studied as proof of principle. Reflectance of incident light is measured as 1/absorbance at different wavelengths between 440 nm and 580 nm. Both devices have incorporated optical bandpass filters in a mydriatic fundus camera. The MSI system scans the retina at eight pre-defined wavelengths specific for the spectrum of haemoglobin. The HSI system acquires a full scan from 480 to 720 nm in 5 nm steps. A simple assessment of the ratio between the absorbance peaks of oxygenated haemoglobin (HbO2) and reduced haemoglobin (HbR) was not suitable for generating validated oxygenation maps of the retina. However, a correction algorithm that compares the measured reflectance with reflectance spectra of fully oxygenated and fully deoxygenated blood allowed our MSI setup to estimate relative oxygen saturation at higher levels, but underestimated relative oxygen saturation at lower levels. The MSI device generated better quality images than the HSI device. It allows customisation with filter sets optimised for other chromophores of interest, and augmented with extrinsic contrast imaging agents, it has the potential for a wider range of ophthalmic molecular imaging applications.
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Dissertations / Theses on the topic "Functional retinal imaging"

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Dombrowski, Francis J. "Functional specifications to an automated retinal scanner for use in plotting the vascular map." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23243.

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Approved for public release; distribution is unlimited
The connection between eye disease and diabetes is proven and is no longer a point of conjecture. In focusing attention on the retina, profound inroads have been made in the fight against this dreaded disorder of the blood. By carefully imaging the blood vessels in the eye, medical professionals can make accurate diagnoses based upon the changes and abnormalities observed. In addition, because the vasculature in the retina is extremely sensitive to fluctuations in normal bodily processes, often the first indication of diabetes and many other diseases manifest themselves here and are found during routine eye examinations. This thesis will explore the possibilities of a new method of retinal imaging by the blending and application of existing technologies. With the use of an automated, infrared-based imaging system, problems related to human error and the limitations of existing methods can be readily resolved and the groundwork can be laid for a new standard of accuracy in retinal imaging. Most importantly, it will automate the entire procedure providing medical specialists heretofore unavailable accuracy in their diagnoses.
http://archive.org/details/functionalspecif00domb
Lieutenant, United States Navy
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Heise, Erich A. "Development and Commercialization of Functional, Non-Invasive Retinal Imaging Device Utilizing Quantification of Flavoprotein Fluorescence for the Diagnosis and Monitoring of Retinal Disease." Case Western Reserve University School of Graduate Studies / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1458921113.

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Martin, Carlos Gías. "Functional characteristics of rat visual cortex using optical imaging techniques : application to retinal transplantation." Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419268.

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Gofas, Salas Elena. "Manipulation of the illumination of an Adaptive Optics Flood Illumination Ophthalmoscope for functional imaging of the retina in-vivo High loop rate adaptive optics flood illumination ophthalmoscope with structured illumination capability In vivo near-infrared autofluorescence imaging of retinal pigment epithelial cells with 757 nm excitation." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS195.

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L’œil étant la seule fenêtre optique transparente de notre corps, il donne un accès unique à l’observation de réseaux neuronaux et vasculaires. Mais aujourd’hui une nouvelle ère s’ouvre pour l’imagerie haute résolution, qui ne doit plus se contenter de donner accès aux structures des tissus, mais aussi d’en apprécier les fonctions. En effet, on peut trouver dans l’imagerie rétinienne des biomarqueurs du fonctionnement de l’ensemble du corps humain. Des maladies neurodégénératives (Parkinson,Alzheimer) ou l’hypertension artérielle pourraient être ainsi précocement diagnostiquées par une imagerie de haute précision de la rétine. L’optique adaptative, adaptée à l’imagerie rétinienne dès 1997, a amélioré nettement la résolution spatiale des images rétiniennes entraînant la multiplication des études de rétine par ophtalmoscope. Elle a notamment été couplée avec l’ophtalmoscope à balayage, qui devint le choix le plus populaire par sa supériorité en résolution spatiale et sectionnement optique par rapport au plein champ. Cependant, contrairement aux systèmes à balayage, l’ophtalmoscope plein champ produit des images grand champ à forte cadence d’acquisition et sans distorsion. Dans mon travail de thèse, j’ai cherché à montrer qu’un tel système, associé à des modalités d’imagerie jouant sur la géométrie d’éclairement, pourrait apporter à la recherche sur la rétine. Pour atteindre cet objectif ambitieux, nous avons modifié l’ophtalmoscope plein champ construit au Centre Hospitalier National des Quinze-Vingts avec un traitement d’image spécifique et deux nouveaux instruments inspirés de la microscopie plein champ. Nous avons intégré ces instruments dans le trajet d’illumination de l’ophtalmoscope afin de manipuler la géométrie de l’éclairage de la rétine. Ces nouvelles implémentations nous permettent de mettre en œuvre des techniques d’imagerie plus avancées, comme par exemple l’imagerie en champ sombre ou l’angiographie non invasive en proche infrarouge. Ces modalités d’imagerie ont été exploitées pour imager la rétine de façon fonctionnelle. Nous nous sommes intéressés principalement à la fonction de couplage de lumière des photorécepteurs et à la perfusion sanguine
As the only transparent optical window of our body, the eye gives a unique access to the observation of neural and vascular networks. Today however, a new era is opening up for high-resolution imaging, which should no longer be limited to giving access to tissue structures, but may also tackle their functions. In fact, biomarkers for the functioning of the whole human body can be found in retinal imaging. Neurodegenerative diseases (Parkinson's, Alzheimer's) or arterial hypertension could thus be diagnosed early by high precision imaging of the retina. In my thesis work, I intended to show how the full-field ophthalmoscope, associated to imaging modalities adjusting geometrical settings of the illumination, could contribute to research on the retina. To achieve this ambitious goal, we modified the full-field ophthalmoscope built at the National Hospital Center of Quinze-Vingts with a specific image processing and two new instruments inspired by full-field microscopy. We have integrated these instruments into the illumination path of the ophthalmoscope to manipulate the geometry of the retinal illumination. These new implementations allow us to make use of more advanced imaging techniques, such as dark field imaging or noninvasive near infrared angiography. These imaging modalities have been exploited to image the retina functionally. We focused mainly on the light coupling function of photoreceptors and on blood perfusion
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Wolsley, Clive. "Structure-function studies of the retina using retinal imaging and multifocal electroretinography." Thesis, University of Ulster, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.554273.

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In recent years there has been a great deal of interest in describing the relationships between the structure and function of the retina at a local level. Techniques such as the multifocal electroretinogram (mfERG) provide objective measures of localised retinal function and could provide new information about structure- function comparisons. Novel studies relating mfERGs with eo-localised structure and subjective function information have been undertaken in two ocular conditions, myopia and retinitis pigmentosa (RP). Measurements include peripheral resolution acuity, retinal thickness from optical coherence tomography (OCT), cone counts from confocal scanning laser ophthalmoscopy (CSLO) and ocular length at different eccentricities. In myopia where there is axial elongation of the eye, co-localised loss of mfERG function and reduced retinal cell density occur in regions where retinal laminar structure is thinned. This relationship is more evident in the peripheral retina rather than the central retina. In RP, where chronic deformation of the retina is likely, thinning of the photoreceptor layer and thickening of the inner retinal layers occurs. Only in some regions of the retina are these changes associated with a localised loss of retinal function. Preliminary data from images of the photoreceptor mosaic using CSLO suggests a strong correlation between co-localised cone counts and mfERG amplitude. These studies demonstrate a close association between changes in structure and function in myopia due to retinal stretching, but also suggest important underlying differences in myopic cell function. The structure- function relationship in RP is not always linear, but is dependent on retinal location and the precise nature of the measurements used. Empirical measures of cone density from retinal images could enhance evaluation of retinal structures in myopia and RP. Combining complementary measurements from ocular imaging and psychophysics with mfERG amplitude and timing demonstrates great potential for evaluating local retinal structure-function and function-function relationships in different eye conditions.
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Srinivasan, Vivek Jay. "High-speed Fourier domain Optical Coherence Tomography for structural and functional imaging of the retina." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45748.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
Includes bibliographical references.
Optical Coherence Tomography (OCT) is an emerging optical biomedical imaging technology that enables cross-sectional imaging of scattering tissue with high sensitivity and micron-scale resolution. In conventional OCT, the reference arm path length in a Michelson interferometer is scanned in time to generate a profile of backscattering versus depth from the sample arm. In conventional OCT, a broadband, low coherence light source is used to achieve high axial resolution. However, clinical and research applications of conventional OCT have been limited by low imaging speeds. Recently, new Fourier domain OCT detection methods have enabled speeds of ~20,000-40,000 axial scans per second, which are ~50-100x faster than conventional OCT. These methods are called "Fourier domain" because they detect the interference spectrum and do not require mechanical scanning of the reference arm path length in time. In this thesis, two different technologies for Fourier domain OCT are investigated. The first technology, called spectral OCT, uses a broadband light source and a spectrometer to measure the interference spectrum. The second technology, called swept source OCT, uses a rapidly tunable narrowband laser to measure the interference spectrum over time. Applications of these new technologies for retinal imaging are illustrated, including three-dimensional retinal imaging in animal models, clinical imaging of retinal pathologies, quantification of photoreceptor morphology, and functional imaging of intrinsic stimulus-induced scattering changes in the retina. Finally, using a rapidly tunable laser, ultrahigh-speed swept source OCT imaging at 249,000 axial scans per second, roughly three orders of magnitude faster than conventional OCT, is demonstrated. This technology is applied for three-dimensional snapshots of the retina and optic nerve head and unprecedented visualization of retinal anatomy.
by Vivek Jay Srinivasan.
Ph.D.
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Denniss, Jonathan. "Diagnostic imaging and the structure-function relationship in glaucoma." Thesis, University of Manchester, 2010. https://www.research.manchester.ac.uk/portal/en/theses/diagnostic-imaging-and-the-structurefunction-relationship-in-glaucoma(24b94e53-d0b9-4437-a639-8ea739049d22).html.

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This thesis describes a series of investigations into the use of optic nerve head (ONH) imaging in primary open-angle glaucoma (POAG), and its relation to visual function. Accurate diagnosis is a key issue in POAG, particularly the difficult task of separating those with early disease from those healthy individuals who display signs of POAG. The purpose of this work is to improve diagnostic methods in glaucoma through use of ONH imaging and its relationship with visual field (VF) loss. First, the performance of a group of expert clinicians evaluating ONH photographs for glaucomatous damage was investigated. The results showed that even when their assessments are combined discrimination between eyes with and without POAG (based on VF loss) is far from perfect, highlighting the need for improvements in diagnosis. The possibility of combining structural and functional data to aid diagnosis was then considered. This requires VF loss and ONH damage to be strongly topographically related. The strength of this relationship was evaluated in 185 patients with POAG. 10,000 computer-generated maps between the ONH and VF were tested and the topographic relationship measured with each of these was compared to that using a published structure-based map. The weak topographic relationships found suggest that the application of these maps to individual patients is limited with current measures. The next chapter describes how a multispectral imaging (MSI, also called hyperspectral imaging) system was set-up for spatial evaluation of ONH oxygenation using a Beer-Lambert law model. Test-retest repeatability was tested and found to be acceptable for the purposes of the following studies. The MSI system was then used for an investigation of the relationship between ONH oxygenation and VF loss. 33 eyes of 18 patients underwent VF testing, MSI and HRT3 imaging. Superior-inferior asymmetries in VF sensitivity were compared to superior-inferior asymmetries in ONH oxygenation measured by MSI and in neuroretinal rim (NRR) area measured by HRT3. This way we take advantage of the typical progression of POAG and each eye acts as its own reference, negating the effect of a wide normal range and overlap between health and disease. This study found, for the first time, a strong association between ONH oxygenation and VF sensitivity. A re-analysis of the 33 ONH oxygenation maps was then performed to assess oxygenation only in the area of the NRR as defined by the HRT. Superior-inferior asymmetries in NRR oxygenation were then compared to superior-inferior asymmetries in VF loss, and the associations found were similarly strong. This study shows that MSI is capable of detecting areas of NRR deemed healthy tissue by structural imaging techniques, which are in fact poorly oxygenated and associated with VF defects. These findings show that NRR oxygenation measured by MSI is strongly related to VF loss. This important information complements existing technologies and may aid in the future diagnosis and management of patients with POAG.
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Tan, Wylie. "Localizing Structural and Functional Damage in the Neural Retina of Adolescents with Type 1 Diabetes." Thesis, 2012. http://hdl.handle.net/1807/33569.

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Studies demonstrate neuro-retinal damage in patients with diabetes and no clinically visible diabetic retinopathy. It is unknown which retinal regions are most vulnerable to diabetes. We hypothesized that the standard and slow-flash (sf-) multifocal electroretinogram (mfERG) and adaptive optics (AO) imaging will localize retinal regions of vulnerability. Fifty-five adolescents with diabetes and 54 controls underwent mfERG testing to isolate predominately retinal bipolar cell activity and sf-mfERG testing to isolate three oscillatory potentials (OPs) from intraretinal amacrine and interplexiform cells. Greatest mfERG delays were in the superior temporal quadrant and at 5°-10° eccentricity. Greatest sf-mfERG delays were found at different eccentricities for each OP. Twenty adolescents with diabetes and 14 controls underwent AO imaging. No significant differences in cone photoreceptor density were found; however, patients showed a trend towards reduced density in the superior nasal region. Inner retinal structures may be more susceptible to damage by diabetes than outer retinal structures.
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Bower, Bradley A. "Functional Spectral Domain Optical Coherence Tomography Imaging." Diss., 2009. http://hdl.handle.net/10161/1311.

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Spectral Domain Optical Coherence Tomography (SDOCT) is a high-speed, high resolution imaging modality capable of structural and functional resolution of tissue microstructure. SDOCT fills a niche between histology and ultrasound imaging, providing non-contact, non-invasive backscattering amplitude and phase from a sample. Due to the translucent nature of the tissue, ophthalmic imaging is an ideal space for SDOCT imaging.

Structural imaging of the retina has provided new insights into ophthalmic disease. The phase component of SDOCT images remains largely underexplored, though. While Doppler SDOCT has been explored in a research setting, it remains to catch on in the clinic. Other, functional exploitations of the phase are possible and necessary to expand the utility of SDOCT. Spectral Domain Phase Microscopy (SDPM) is an extension of SDOCT that is capable of resolving sub-wavelength displacements within a focal volume. Application of sub-wavelength displacement measurement ophthalmic imaging could provide a new method for imaging of optophysiology.

This body of work encompasses both hardware and software design and development for implementation of SDOCT. Structural imaging was proven in both the lab and the clinic. Coarse phase changes associated with Doppler flow frequency shifts were recorded and a study was conducted to validate Doppler measurement. Fine phase changes were explored through SDPM applications. Preliminary optophysiology data was acquired to study the potential of sub-wavelength measurements in the retina. To remove the complexity associated with in-vivo human retinal imaging, a first principles approach using isolated nerve samples was applied using standard SDPM and a depth-encoded technique for measuring conduction velocity.

Results from amplitude as well as both coarse and fine phase processing are presented. In-vivo optophysiology using SDPM is a promising avenue for exploration, and projects furthering or extending this body of work are discussed.


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Bruce, A., I. E. Pacey, J. A. Bradbury, A. J. Scally, and B. T. Barrett. "Bilateral changes in foveal structure in individuals with amblyopia." 2013. http://hdl.handle.net/10454/5894.

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PURPOSE: To examine foveal structure in amblyopia using spectral-domain optical coherence tomography (SD-OCT). DESIGN: Prospective, cross-sectional study. PARTICIPANTS AND CONTROLS: Two subject groups were recruited to the study: 85 amblyopes (34 adults, 51 children) and 110 visually normal controls (44 adults, 66 children). METHODS: A detailed eye examination, including an SD-OCT scan, was performed in all participants. A total of 390 eyes of 195 subjects were imaged using a 3-dimensional (3D) macula scan covering a nominal 6 x 6-mm area with a resolution of 256 x 256 (65,536 axial scans). Data from the B-scans bisecting the fovea both horizontally and vertically were fitted with a mathematical model of the fovea to determine a range of foveal parameters. MAIN OUTCOME MEASURES: Foveal thickness, foveal pit depth, and foveal pit slope. RESULTS: Bilateral differences between the eyes of amblyopes compared with visually normal controls were found. The difference between foveal structure in amblyopic participants relative to structure in subjects with normal vision persisted even when variables such as age, ethnicity, axial length, and sex were taken into account. Amblyopes showed increased foveal thickness (+8.31 mum; P = 0.006) and a reduction in pit depth in the horizontal meridian (-10.06 mum; P = 0.005) but not in the vertical meridian (P = 0.082) when compared with subjects with normal vision. Foveal pit slopes were found to be approximately 1 degree flatter in the nasal (P = 0.033) and temporal (P = 0.014) meridians in amblyopes, but differences between amblyopes and controls in the superior (P = 0.061) and inferior (P = 0.087) meridians did not reach statistical significance. No statistically significant interocular differences were found in the foveal structure between amblyopic and fellow eyes. CONCLUSIONS: Differences were found in the foveal structure in both eyes of amblyopes compared with subjects with normal vision. These differences consisted of increased foveal thickness, reduced pit depth when measured along the horizontal meridian, and flattening of the nasal and temporal sides of the foveal pit.
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Book chapters on the topic "Functional retinal imaging"

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Yao, Xin-Cheng, and Yi-Chao Li. "Functional Imaging of Retinal Photoreceptors and Inner Neurons Using Stimulus-Evoked Intrinsic Optical Signals." In Retinal Development, 277–85. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-848-1_20.

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Cheong, Soon K., Wenjun Xiong, Jennifer M. Strazzeri, Constance L. Cepko, David R. Williams, and William H. Merigan. "In Vivo Functional Imaging of Retinal Neurons Using Red and Green Fluorescent Calcium Indicators." In Retinal Degenerative Diseases, 135–44. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75402-4_17.

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Michelson, Georg, Jürgen Welzenbach, Istvan Pal, and Joana Harazny. "Functional imaging of the retinal microvasculature by Scanning Laser Doppler Flowmetry." In Laser Scanning: Update 1, 145–53. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-010-0322-3_24.

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Duan, Jinming, Weicheng Xie, Ryan Wen Liu, Christopher Tench, Irene Gottlob, Frank Proudlock, and Li Bai. "OCT Segmentation: Integrating Open Parametric Contour Model of the Retinal Layers and Shape Constraint to the Mumford-Shah Functional." In Shape in Medical Imaging, 178–88. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-04747-4_17.

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Lin, Julie Qiaojin, and Jean-Michel Cioni. "Live Imaging of RNA Transport and Translation in Xenopus Retinal Axons." In Methods in Molecular Biology, 49–69. New York, NY: Springer US, 2022. http://dx.doi.org/10.1007/978-1-0716-1990-2_3.

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AbstractIn neurons, specific mRNAs are transported into axons, where their local translation supports essential cellular functions. Over the years, our knowledge of the molecular mechanisms underlying axonal mRNA translation has rapidly expanded. However, tools to study mRNA localization and translation in real time with high spatial precision were not available until recently. Here, we present a live imaging approach to examine axonal mRNA trafficking and translation simultaneously in Xenopus retinal ganglion cells (RGCs), using in vitro synthesized fluorescently labeled mRNAs coupled with a genetically encoded protein tagging system to visualize synthesizing peptides at single-molecule resolution. We further describe the process of image analysis in detail, thus providing a methodology that can be used to investigate new research questions in the field.
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Abdallah, Walid, and Amani Fawzi. "Functional Retinal Imaging." In Emerging Technologies in Retinal Diseases, 15. Jaypee Brothers Medical Publishers (P) Ltd., 2009. http://dx.doi.org/10.5005/jp/books/10256_2.

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Fawzi, Amani. "Chapter-05 Compress Functional Retinal Imaging Evaluation in Retinal Diseases." In Optical Coherence Tomography in Macular Diseases and Glaucoma�Advanced Knowledge, 65–82. Jaypee Brothers Medical Publishers (P) Ltd, 2012. http://dx.doi.org/10.5005/jp/books/11829_5.

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Lestak, Jan, and Martin Fůs. "Neuropathology in Hypertensive Glaucoma." In Ocular Hypertension [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96034.

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Hypertensive glaucoma is still defined as a disease where, at high intraocular pressure, retinal ganglion cell axons are impaired with excavation at the optic disc and changes in the visual field. In single cases, the study highlights the importance of knowledge of neuropathology not only at the level of the retina but the entire visual pathway, including the visual centres in the brain. It uses the issue of neurotransmission in the visual analyser and its pathology, but mainly the results of electrophysiological examinations and functional imaging of the brain using Positron Emission Tomography and Functional Magnetic Resonance. It does not overlook the imaging methods of the eye (nerve fibre layer, vessel density). On the basis of this information, therapy is recommended as well.
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Mayer, Hylton R., and Marc L. Weitzman. "Automated Perimetry in Glaucoma." In Visual Fields. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195389685.003.0009.

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Clinical experience and multiple prospective studies, such as the Collaborative Normal Tension Glaucoma Study and the Los Angeles Latino Eye Study, have demonstrated that the diagnosis of glaucoma is more complex than identifying elevated intraocular pressure. As a result, increased emphasis has been placed on measurements of the structural and functional abnormalities caused by glaucoma. The refinement and adoption of imaging technologies assist the clinician in the detection of glaucomatous damage and, increasingly, in identifying the progression of structural damage. Because visual field defects in glaucoma patients occur in patterns that correspond to the anatomy of the nerve fiber layer of the retina and its projections to the optic nerve, visual functional tests become a link between structural damage and functional vision loss. The identification of glaucomatous damage and management of glaucoma require appropriate, sequential measurements and interpretation of the visual field. Glaucomatous visual field defects usually are of the nerve fiber bundle type, corresponding to the anatomic arrangement of the retinal nerve fiber layer. It is helpful to consider the division of the nasal and temporal retina as the fovea, not the optic nerve head, because this is the location that determines the center of the visual field. The ganglion cell axon bundles that emanate from the nasal side of the retina generally approach the optic nerve head in a radial fashion. The majority of these fibers enter the nasal half of the optic disc, but fibers that represent the nasal half of the macula form the papillomacular bundle to enter the temporal-most aspect of the optic nerve. In contrast, the temporal retinal fibers, with respect to fixation, arc around the macula to enter the superotemporal and inferotemporal portions of the optic disc. The origin of these arcuate temporal retinal fibers strictly respects the horizontal retinal raphe, temporal to the fovea. As a consequence of this superior-inferior segregation of the temporal retinal fibers, lesions that affect the superotemporal and inferotemporal poles of the optic disc, such as glaucoma, tend to cause arcuateshaped visual field defects extending from the blind spot toward the nasal horizontal meridian.
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Asad, Ahmed Hamza, Ahmad Taher Azar, and Aboul Ella Hassanien. "A New Heuristic Function of Ant Colony System for Retinal Vessel Segmentation." In Medical Imaging, 2063–81. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0571-6.ch083.

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The automatic segmentation of blood vessels in retinal images is the crucial stage in any retina diagnosis systems. This article discussed the impact of two improvements to the previous baseline approach for automatic segmentation of retinal blood vessels based on the ant colony system. The first improvement is in features where the length of previous features vector used in segmentation is reduced to the half since four less significant features are replaced by a new more significant feature when applying the correlation-based feature selection heuristic. The second improvement is in ant colony system where a new probability-based heuristic function is applied instead of the previous Euclidean distance based heuristic function. Experimental results showed the improved approach gives better performance than baseline approach when it is tested on DRIVE database of retinal images. Also, the statistical analysis demonstrated that was no statistically significant difference between the baseline and improved approaches in the sensitivity (0.7388± 0.0511 vs. 0.7501±0.0385, respectively; P = 0.4335). On the other hand, statistically significant improvements were found between the baseline and improved approaches for specificity and accuracy (P = 0.0024 and 0.0053, respectively). It was noted that the improved approach showed an increase of 1.1% in the accuracy after applying the new probability-based heuristic function.
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Conference papers on the topic "Functional retinal imaging"

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Węgrzyn, Piotr, Dawid Borycki, Sławomir Tomczewski, Kamil Liżewski, Egidijus Auksorius, Andrea Curatolo, and Maciej Wojtkowski. "Functional and Structural Imaging of Retinal Tissue with Spatio-Temporal Optical Coherence Tomography (STOC-T)." In Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.fw7d.2.

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We report on a novel human retina imaging system based on Spatio-Temporal Optical Coherence Tomography (STOC-T). We present structural images and spatially-resolve functional responses of the retinal tissue to white light stimulation.
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Ts’o, Daniel Y., Jesse Schallek, Randy Kardon, and Qian Du. "Intrinsic Signal Functional Imaging of the Retina: Outer Retinal Origins." In Frontiers in Optics. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/fio.2013.ftu5i.1.

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Ramos-Soto, Oscar, Erick Rodriguez-Esparza, Marco Pérez-Cisneros, and Sandra E. Balderas-Mata. "Inner limiting membrane segmentation and surface visualization method on retinal OCT images." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor S. Gimi and Andrzej Krol. SPIE, 2021. http://dx.doi.org/10.1117/12.2580910.

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Pan, Lingjiao, Liling Guan, Fei Shi, Xinjian Chen, Weifang Zhu, and Baoqing Nie. "Detection and registration of vessels for longitudinal 3D retinal OCT images using SURF." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor Gimi and Andrzej Krol. SPIE, 2018. http://dx.doi.org/10.1117/12.2292970.

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Zhang, Min, Lei Zhang, Jia Yang Wang, Jun Feng, and Yi Lv. "Deep convolutional network based on rank learning for OCT retinal images quality assessment." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor Gimi and Andrzej Krol. SPIE, 2019. http://dx.doi.org/10.1117/12.2513689.

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Zabihollahy, Fatemeh, Aidan Lochbihler, and Eranga Ukwatta. "Deep learning based approach for fully automated detection and segmentation of hard exudate from retinal images." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor Gimi and Andrzej Krol. SPIE, 2019. http://dx.doi.org/10.1117/12.2513034.

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Tavakoli, Meysam, and Mahdieh Nazar. "Comparison different vessel segmentation methods in automated microaneurysms detection in retinal images using convolutional neural networks." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor S. Gimi and Andrzej Krol. SPIE, 2020. http://dx.doi.org/10.1117/12.2548359.

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Roy, Priyanka, Mohana Kuppuswamy Parthasarathy, John Zelek, and Vasudevan Lakshminarayanan. "Comparison of Gaussian filter versus wavelet-based denoising on graph-based segmentation of retinal OCT images." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor Gimi and Andrzej Krol. SPIE, 2018. http://dx.doi.org/10.1117/12.2292479.

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Wang, Jui-Kai, Michelle R. Tamplin, Mona K. Garvin, Isabella M. Grumbach, and Randy H. Kardon. "A superpixel-histogram method to analyze retinal, optic nerve, and choroidal blood flow using laser speckle flowgraphy." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor S. Gimi and Andrzej Krol. SPIE, 2022. http://dx.doi.org/10.1117/12.2611850.

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Liu, Jianfei, Yoo-Jean Han, Tao Liu, and Johnny Tam. "Spatially aware deep learning improves identification of retinal pigment epithelial cells with heterogeneous fluorescence levels visualized using adaptive optics." In Biomedical Applications in Molecular, Structural, and Functional Imaging, edited by Barjor S. Gimi and Andrzej Krol. SPIE, 2020. http://dx.doi.org/10.1117/12.2549290.

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Reports on the topic "Functional retinal imaging"

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Choi, S., N. Doble, J. Hardy, S. Jones, J. Keltner, S. Olivier, and J. Werner. In-vivo imaging of the photoreceptor mosaic in retinal dystrophies and correlations with visual function. Office of Scientific and Technical Information (OSTI), October 2005. http://dx.doi.org/10.2172/886664.

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