The established model used for evaluating potential therapies for retinal disease has significant limitations. A new model is proposed to account for these limitations: the visual adaptation model. The visual adaptation model was developed to provide a novel approach for testing potential treatments for retinal disease, and the work in this thesis provides empirical support for this model. Specifically, we evaluated two potential therapies for retinal degenerative disease and examined their effects on vision and retinal anatomy. In addition, the profile of retinal reorganization and its functional correlates were examined in RCS rats and transgenic rats which express a rhodopsin mutation; however, immunohistological work targeted one specific line (S334ter-4). Collectively, these studies provide evidence that supports the retinal adaptation model. These studies also provide a novel view of retinal and visual function in retinal disease which should be considered when evaluating treatments involving retinal degeneration. / xvii, 205 leaves : ill. ; 29 cm. --

A high speed, high resolution spectral domain optical coherence tomography (SD-OCT) system was used to study in-vivo early morphological changes and optical nerve head (ONH) blood flow in the Long Evans rat retina, induced by administration of sodium iodate (NaIO3). Linear and circular scanned OCT images were acquired at the same location in the retina from healthy control rats and from rats injected with 40mg/kg of NaIO3 solution at 1, 3, 6 12, 24, 72 and 168 hours post drug administration. Morphological OCT images showed changes in the optical reflectance and layer thickness of the photoreceptor IS and OS. The formation of a new low reflective layer between the photoreceptor OS and the RPE was observed in all tested rats. This new layer appeared as early as 1 hour, increased in thickness after 6 hours, and disappeared by 12 hours post NaIO3 injection. The low optical reflectance and the dynamics of this new layer suggest that it was most likely fluid accumulation. Comparison with H&E stained histological sections and IgG immunohistochemistry revealed minimal photoreceptor OS cell swelling at hour 1, detachment of the OS from the RPE by hour 3, and breaking of the blood-retina barrier with significant fluid accumulation by hour 6 post NaIO3 injection. The Doppler Optical Micro-Angiography (DOMAG) algorithm was used to carry out quantitative analysis of the ONH blood flow. Estimation of flow rate on each ONH vessel was done by measurements of the Doppler angle, vessel size and the axial velocity. This study has demonstrated that the capability of UHR-OCT to study optical reflectance and layer thickness changes, rearrangement and detachment of the photoreceptor OS and RPE layers, together with flow rate estimation of retinal blood vessels. Therefore, it can serve as markers in future non-invasive, in-vivo studies of disease or drug induced retinal degeneration in ophthalmic research.

Inherited retinal degenerative diseases can affect various components of the retina leading to blindness. Five different mutant strains of chicken have been studied extensively as potential models for inherited retinal degeneration. The Smoky Joe (SJ) chicken is a sixth genetically blind strain of White Leghorns that shows various degrees of blindness at hatch and by 8 weeks post-hatch, have complete blindness for those that are homozygous. The objective of this study was to characterize the retinal degeneration in these birds by histology, both during embryonic and post-hatch development, and to the retinal function using electroretinograms (ERG). For both embryonic and post-hatch development, a significantly lower number of cells were found in the retina of blind birds compared to sighted (both p<0.0001). The significant contributor to cell number decrease was the loss of amacrine cells located in the inner nuclear layer. Photoreceptors were also found to potentially decrease in number, but at a later stage. ERG recordings revealed decreases in amplitudes of b-waves and oscillatory potentials in blind birds, but not in sighted. Both histology and ERG findings support the idea that the inner retinal cells are affected. The results indicate that degeneration in the Smoky Joe retina occurs mostly within the inner nuclear layer affecting amacrine cells. This hampers the functional capacity of the retina, causing blindness.

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, Göz Hastalıkları Anabilim Dalı, 2007. / Bibliyografya var.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Diabetes; imaging; phosphorescence; retina. Includes bibliographical references (p. 69-70).

Thesis (Ph. D.)--University of Texas at Austin, 2009. / Title from PDF title page (University of Texas Digital Repository, viewed on Sept. 9, 2009). Vita. Includes bibliographical references.

A neuroproteção é um dos tópicos mais relevantes aplicados à neurociência. As junções comunicantes (JC), formadas pelas conexinas (Cx) estão envolvidas na neurodegeneração após lesão. Estudos com animais KO apresentam resultados contraditórios sobre papel das JCs. O objetivo deste trabalho foi analisar o papel das Cxs a partir do trauma mecânico na retina, modelo que permite a visualização do foco, penumbra, e áreas adjacentes à lesão. Observamos regulação distinta das Cx36 e Cx43 durante a neurodegeneração. A Cx36 não se alterou e a Cx43 apresentou desorganização e aumento da imunorreatividade após 7 dias, concomitantemente com GFAP. Células amácrinas apoptóticas encontram-se acopladas a células vizinhas por Cx36. O papel funcional das JCs foi avaliado, utilizando bloqueadores, para verificar a viabilidade/morte de células. Carbenoxolone (CBX), reduziu o espalhamento da apoptose, após 4h, enquanto a quinina, teve o mesmo efeito após 1h. A distribuição de núcleos apoptóticos confirmou que a utilização de bloqueadores de JCs reduz a propagação da apoptose. A quinina, mas não o CBX, diminuiu a expressão de caspases iniciais e efetoras. O controle da permeabilidade de canais de JCs pode participar de estratégias de neuroproteção. / The neuroprotection stands out as one of the most pursued hot topics in applied neurosciences. The gap junctions (GJ), formed by connexin (Cx) are involved in neurodegeneration injury. Studies using KO animal models endowed apparently contradictory results in relation to the role of coupling in neuroprotection. The aim of this study was to analyze the role of Cx-mediated communication in focal lesion induced by mechanical trauma in the retina, a model that alow the visualization of the focus, penumbra and adjacent areas. We observed distinct regulation of Cx36 and Cx43 during neurodegeneration. The Cx36 did not change during the lesion progression and Cx43 showed disorganized pattern and upregulated after 7 days, the same as GFAP. Apoptotic amacrine cells are coupled with health neighborhood cells by Cx36. The functional role of GJ was evaluated using blockers to verify the viability/cell death. Carbenoxolone (CBX) reduced the spread of apoptosis after 4h while quinine had the same effect after 1h. The distribution of apoptotic nuclei confirmed that the use of GJ blockers reduced the propagation of apoptosis. Quinine, but not CBX, decreases initial and effector caspases expression. The control of GJ channels permeability can participate in neuroprotection strategies.

Retinose Pigmentar (RP) é uma doença hereditária que conduz progressivamente à cegueira. Mais de 150 mutações da rodopsina associadas à RP foram descritas, e causam a alteração da sua conformação. Esta tese testou a hipótese de que pequenas moléculas auxiliam na formação da rodopsina e/ou reduzem a morte dos fotorreceptores. As mutações da RP, N15S e P23H, revelaram diferenças quanto às características e gravidade devido à má-formação das proteínas mutantes. Ligação de pequenas moléculas (retinóides, íons metálicos, clorofilas e antocianinas) à rodopsina foi demonstrada in vitro. O derivado da clorofila, Ce6, mostrou-se mais efetivo, conferindo maior estabilidade e foi então testado em ratos submetidos à degeneração por luz ou em modelos de RP (P23H e S334ter). Observou-se uma proteção contra a degeneração por luz e uma significante diminuição da degeneração no P23H. Em contraste, Ce6 causou um aumento na degeneração dos fotorreceptores do S334ter. Finalmente, resultados clínicos, bioquímicos e in vivo foram comparados e mostraram estar altamente relacionados. / Retinitis Pigmentosa (RP) is an inherited disease that progressively leads to blindness. More than 150 mutations associated with RP are known in rhodopsin, causing its misfolding. This thesis tested the hypothesis that small molecules can rescue folded rhodopsin and/or reduce photoreceptor cell death. RP mutations, N15S and P23H, revealed differences in characteristics and severity of misfolding of the mutant proteins. Binding of small molecule classes (retinals, metal ions, chlorophylls and anthocyanins) to rhodopsin was demonstrated in vitro. The chlorophyll derivative, Ce6, was most effective in conferring stability and therefore tested in rats subjected to light-damage and RP rat models, P23H and S334ter. Protection against the light-induced retinal degeneration and more importantly a significant slowing of the photoreceptor degeneration rate in the P23H rat were observed. In contrast, Ce6 increased photoreceptor degeneration in the S334ter rat. Finally, clinical, biochemical and in vivo rat data were compared and it was found to be highly correlated.

The World Health Organization estimates that there are 285 million people suffering from visual impairment worldwide. The top two causes of uncorrectable vision loss are glaucoma and age-related macular degeneration (AMD), with 112 million people anticipated to be impacted by glaucoma by 2040 and nearly 15% of U.S. adults aged 43-86 predicted to be diagnosed with AMD over the next 15 years. To slow the progression of these ophthalmic diseases, the most valuable preventive action is timely detection and treatment by an ophthalmologist. However, over 50% of glaucoma cases go undetected due to lack of timely assessment by a medical expert. This thesis seeks to transform artificial intelligence (AI) into a trustworthy partner to clinicians, aiding in expediting diagnostic screening for obvious cases and serving as corroboration/a ‘second opinion’ in ambiguous cases. In order to develop AI algorithms that can be trusted as team-mates in the clinic, the AI must be robust to data collected at various sites/from various patient populations, its decision-making mechanisms must be explainable, and to benefit the broadest population (for whom expensive imaging equipment and/or specialist time may not be available), it must be portable. This thesis addresses these three challenges (1) by developing and evaluating robust deep learning (DL) algorithms for detection of glaucoma and AMD from data collected at multiple sites or using multiple imaging modalities, (2) by making AI interpretable, through: (a) comparison of image concepts used by DL systems for decision-making with image regions fixated upon by human experts during glaucoma diagnosis, and (b) through odds ratio ranking of clinical biomarkers most indicative of AMD risk used by both experts and AI, and (3) by enhancing theimage quality of data collected via a portable OCT device using deep-learning based super-resolution generative adversarial network (GAN) approaches. The resulting robust deep learning algorithms achieve accuracy as high as 95% at detection of glaucoma and AMD from optical coherence tomography (OCT) and OCT angiography images/volumes. The interpretable AI-concept/expert-eye-movement comparison showed the importance of three OCT-report sub-regions used by both AI and human experts for glaucoma detection. The pipeline described here for evaluating AI robustness and validating interpretable image concepts used by deep learning systems in conjunction with expert eye movements has the potential to help standardize the acceptance of new AI tools for use in the clinic. Furthermore, the eye movement collection protocols introduced in this thesis may also help to train current medical residents and fellows regarding key features employed by expert specialists for accurate and efficient eye disease diagnosis. The odds ratio ranking of AMD biomarkers distinguished the top two clinical features (choroidal neovascularization and geographic atrophy) most indicative of AMD risk that are agreed upon by both AI and experts. Lastly, GAN-based super-resolution of portable OCT images boosted performance of downstream deep learning systems for AMD detection, facilitating future work toward embedding AI algorithms within portable OCT systems, in order for a larger population to gain access to potentially sight-saving technology. By enhancing AI robustness, interpretability, and portability, this work paves the way for ophthalmologist-AI teams to achieve augmented performance compared to human experts or AI alone, leading to expedited eye disease detection, treatment, and thus better patient outcomes.

京都大学 / 0048 / 新制・課程博士 / 博士(医科学) / 甲第18904号 / 医科博第60号 / 新制||医科||4(附属図書館) / 31855 / 京都大学大学院医学研究科医科学専攻 / (主査)教授 小柳 義夫, 教授 吉村 長久, 教授 髙橋 淳 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM