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Ronald Lai, Raymond J. Lim, George Wu, Jeff Edelman; Longitudinal Study Of Retinal Degeneration In An Experimental Retinal Detachment Model Using Spectral-domain Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2012;53(14):927.
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Detachment of photoreceptors from the retinal pigment epithelium occurs in retinal disorders, such as retinal detachment and age-related macular degeneration, resulting in loss of photoreceptors and vision. Using spectral-domain optical coherence tomography, this study longitudinally examined the course of photoreceptor degeneration, morphological changes and autofluorescence appearance in the retina after experimental retinal detachment in rat.
Retinal detachment was induced in male Brown-Norway rats by subretinal injection of sodium hyaluronate. On day 0, 1, 3, 7, 14 and 30, eyes of the animals were examined using confocal scanning laser ophthalmoscopy (cSLO) for en-face visualization and SD-OCT for cross-sectional imaging of retinal structures (Heidelberg Spectralis HRA +OCT). Autofluorescence was detected using cSLO in the AF mode. At each time point, histology was performed on two animals to correlate structural findings in SD-OCT with microscopic data. TUNEL staining was used to evaluate cell death. Microglial cells were identified with Isolectin-IB4 labeling.
A partial retinal detachment that occupied about 40-50% of the fundus was induced in the right eye of each animal. Separation of the neural retina from the retinal pigment epithelium was confirmed with SD-OCT imaging immediately after retinal detachment induction. By day 3, significant TUNEL staining and microglial cells were observed in the photoreceptor layers. At the immediate junctional detached zone, inner/outer segments (IS/OS) of the detached photoreceptors appeared longer and extended towards the RPE. Seven days after detachment, the photoreceptor layer thickness in the detached area was thinner when compared with that in the non-detached area, while amoeboid-like autofluorescent structures were present in the detached area. Retinal flatmounts labeled with Isolectin-IB4 suggested that these autofluorescent bodies were activated microglial cells, which continued to increase in number and intensity 14 and 30 days after detachment. By day 30, both the photoreceptor layer thickness and the photoreceptor IS/OS of the detached area were markedly reduced.
SD-OCT provides structural imaging for the extent of photoreceptor degeneration, while autofluorescence reflects the progress of degeneration by monitoring activated microglia in the diseased retina. Combining autofluorescence imaging with SD-OCT imaging is therefore useful in monitoring the in vivo progress of photoreceptor degeneration and evaluating drug therapy efficacy.
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