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Katharina G Foote, Nicholas Rinella, Nicolas Bensaid, Qinqin Zhang, Ruikang K Wang, Travis Porco, Austin Roorda, Jacque L Duncan; Multimodal imaging in choroideremia. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1540.
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© ARVO (1962-2015); The Authors (2016-present)
Choroideremia (CHM) is associated with progressive degeneration affecting retinal pigment epithelium (RPE), choriocapillaris (CC) and photoreceptors. Symptoms include nyctalopia, reduced peripheral vision, eventual loss of visual acuity and legal blindness. Delivery of potential treatments for patients with mutations in the CHM gene requires identification of the cell type affected earliest in retinal degeneration.
Four CHM patients (8 eyes) and 2 normal eyes were studied. A combination of imaging techniques including fundus-guided microperimetry, confocal and non-confocal adaptive optics scanning laser ophthalmoscopy (AOSLO), spectral domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF) and swept-source OCT angiography (OCTA) was used to analyze macular sensitivity, cone photoreceptor outer and inner segment structure, RPE structure and CC health, respectively. Loss of capillary vascular density called flow voids (areas of reduced perfusion) accompanies retinal degeneration and is visible in CC. OCTA images were compared to a database of 20 normal subjects; areas with threshold lower than 1 standard deviation (SD) below the normal mean were considered CC flow voids. Margins of preserved FAF were manually delineated and flow voids were quantified in 3 regions: R1, region of central preserved FAF extending to 1° inside the preserved FAF edge; R2, 1° inside the FAF edge to the preserved FAF edge; and R3, 1° beyond the FAF edge.
The percent area with CC flow voids in R1 (mean ± SD 14±7.3%) was significantly greater than in the 2 normal eyes (7.2±0.1%) (P=0.039). The flow voids increased progressively in regions R2 (22±8.0%) and R3 (37±6.1%) compared to R1, and were different from the normal eyes (P=0.008). Sensitivity decreased progressively from R1 (21±2.1 dB) to R2 (16±2.4 dB) to R3 (6±3.1 dB) (P= 0.031). However, CC flow voids were not significantly correlated with retinal sensitivity in any of the regions (P>0.5).
In eyes with CHM, CC flow voids were greater than normal in regions of preserved FAF, and increased progressively from 1° inside the edge of the preserved FAF to 1° external to the edge of the preserved FAF. Visual sensitivity decreased as CC flow voids increased approaching and beyond the edge of the preserved FAF. The findings suggest that both CC nonperfusion and visual sensitivity accompany retinal degeneration in eyes with CHM.
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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