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Alexander E Salmon, Benjamin S Sajdak, Thomas B Connor, Alfredo Dubra, Joseph Carroll; High resolution imaging of retinal detachment in the cone-dominant ground squirrel. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1154. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify changes in reflectance and distribution of individual photoreceptors after experimental retinal detachment.
Baseline optical coherence tomography (OCT), scanning light ophthalmoscopy (SLO), and adaptive optics SLO (AOSLO) images were acquired before saline was infused into the subretinal space of thirteen-lined ground squirrels (13-LGS; n=3). The detached region was then imaged at several time points over 6 months. Cone inner segments were identified using the non-confocal split-detection or dark-field AOSLO image. Cone density, Voronoi cell area regularity (VCAR), and confocal reflectance intensity (normalized by detector gain) was measured at 14 days post-detachment at the edge of the bleb and compared to isoeccentric regions at baseline.
Cone photoreceptors were visible inside much of the re-attached area in split-detector and dark-field images. Hyperreflective lesions and diffuse, graded opacities were common at the photoreceptor layer within the detached region which obscured cone visualization. Changes in confocal reflectance intensity and cone density values were variable (Table). The mosaic exhibited a significant reduction in VCAR after detachment (p = 0.0071, paired t-test, n = 3). In other regions, cone death gave rise to visibility of the underlying RPE cells (Figure). On OCT, disruption of the laminar appearance of the outer retinal layers occurred in the detached areas and hyper-reflectivity was evident in the inner retina.
Increased variability in reflectance intensity for cones with intact inner segments may represent degeneration of outer segments, improper realignment, cell debris, or changes to the reflective and absorptive substrates in the RPE. The marked reduction in cell density for squirrel DM_160303 (Table) may be related to an inner retinal hemorrhage that did not occur in the other two animals. An overall reduction in VCAR at the edge of the bleb suggests an inability to remodel past this physical barrier.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
(A) SLO image of the detached region (t: 180d). Confocal (B) split-detector (C), and dark-field (D) images from the outlined area in (A). (B-D) RPE cells are visible (left) adjacent to surviving cones. Images have been contrast adjusted for display purposes. Scale bars: 750µm (A) and 50µm (B-D).
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