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Vera L Bonilha, Brent A Bell, Mary E Rayborn, Joe G Hollyfield, Stephanie A Hagstrom, Gayle J Pauer; Geographic Atrophy: Correlation Between Confocal Scanning Laser Ophthalmoscopy (SLO), Histology and Immunohistology of Retinal Sections in the Region of Expanding Lesions.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2443.
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© ARVO (1962-2015); The Authors (2016-present)
Geographic atrophy (GA) represents the atrophic late-stage of dry AMD. AMD pathology affects the RPE physiology and results in several noticeable morphological features in these cells. Funduscopy images identify hypopigmented areas, in which larger choroidal vessels may become visible due to the absence of the RPE and the choriocapillaris. Visible light SLO autofluorescence (VAF-SLO) imaging visualizes the accumulation of the autofluorescent lipids composing lipofuscin at the level of the RPE monolayer in patients. Whereas near-infrared SLO autofluorescence (IRAF-SLO) has been introduced to visualize the distribution of melanin. Here, we characterized the GA from several donors by VAF- and IRAF-SLO and correlated it to histological and immunohistological findings of retinal sections.
SLO, and fundus macrography (FM) were used to identify and measure the extent of GA lesions from 28 fixed donor eyes. Adjacent areas of the retina/RPE/choroid from the margins of the GA border were cut to generate four smaller fragments: two were processed for epon embedding while the others were processed for cryosectioning and immunofluorescence in the green-red and near-IR (NIR) channels that closely matched SLO images. Cryosections were also reacted with antibodies to activated microglia (anti-Iba-1). These donor eyes were compared to several age-matched normal eyes in the perimacula. DNA was obtained from blood samples or fixed eye tissue of the donors and genotyped for single nucleotide polymorphisms (SNPs) previously shown to be associated with GA (rs2842992, near SOD2; rs1789110, near MBP; rs722782, near C80rf42).
The majority of the GA donors displayed association with at least two of the risk alleles on SOD2, MBP, and C80rf42. The cytoplasm of RPE cells at the GA margins contained similar amounts of fluorescent granules visible in both NIR and green-red channels. RPE cells at the border of the GA display loss of apical localization of dark pigmented non-fluorescent granules. Borders of medium size GA lesions are enriched in Iba-1 positive cells.
GA eyes can be sub-grouped together based on the IRAF-SLO, presence of distribution of fluorescent granules within the RPE, and presence of microglia cells.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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