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

La retina es un tejido nervioso que parece tener una mayor tolerancia ante situaciones de hipoxia que el resto del sistema nervioso central (SNC). Sin embargo, las consecuencias funcionales derivadas de la privación de flujo sanguíneo son graves y en la mayoría de los casos irreversibles. Se han realizado numerosas investigaciones con el fin de conocer las alteraciones morfológicas y funcionales de la retina ante situaciones de isquemia de diferente intensidad, sin embargo se carecen de estudios que caractericen específicamente el comportamiento de las células ganglionares de la retina (GCR) ante la isquemia utilizando métodos que nos permiten cuantificar la muerte de las (GCR). Queremos determinar su grado de tolerancia ante la isquemia, y estudiar el patrón de muerte de estas células tras someterlas a diferentes periodos de isquemia transitoria basándonos en técnicas neuroanatómicas. Hemos marcado las CGR con un trazador neuronal fluorescente, el fluoro-Gold, que aplicado en los principales núcleos de proyección de la vía óptica de la rata adulta nos ha permitido distinguir y diferenciar las CGR.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains viii, 56 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 50-54).

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

Thesis (Ph.D.)--University of Western Australia, 2005.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [76]-93).

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (doctoral)--Lund University, 1998. / Added t.p. with thesis statement inserted. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains viii, 99 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 82-99).

Made available in DSpace on 2015-12-10T14:23:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-28. Added 1 bitstream(s) on 2015-12-10T14:29:18Z : No. of bitstreams: 1 000852681.pdf: 1224340 bytes, checksum: 7e3993edae8f0d4badfed835114ffa9b (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Purpose: The aims of this study were to better understand the mechanism of cell death by apoptosis in a glaucoma model (ischemia / reperfusion) and evaluate the role of apoptosis in this model and if treatment with Sildenafil helps prevent apoptosis. Methods: 36 rats, from 4 to 6 months, males, Lewis and weighing ± 350g were divided in 5 groups: control group (6 animals) and for groups with ischemia / reperfusion (7 and 21 days), two groups consisting of ten animals treated with sildenafil and two groups of Five animals treated with placebo. Paracentesis of the anterior chamber with needle 30G coupled to saline (0.9%) was made and maintained for 60 minutes. Intraocular pressure was measured by rebound tonometer (Tonovet®). There was histological, morphometric by hematoxylin and eosin and, immunohistochemical staining and qRT-PCR analysis by Caspase-7, Caspase-6, Caspase-9, Tnf-r2, Fas-l, Bcl-2 and Bax. For statistic analysis we used ANOVA and t-test for morphometric analysis and, for immunohistochemistry and qRT-PCR, Fisher exact test was employed with a statistical significance level of p <0.05 Results: Histology and morphometric analysis, proved more changes in the untreated group compared to the treatment and control group. Analysis of immunohistochemistry and qRT-PCR observed the more significant expression in untreated eyes. Conclusion: Sildenafil apperead to be protective to ganglion cell apoptosis. Cell survival was evident in histology and morphometry. For immunohistochemistry and RT-PCR was observed protective effect in the apoptosis pathways with similar or below expression compared to the control