OCT Angiography and Cone Photoreceptor Imaging in Geographic Atrophy

PURPOSE: To compare cone spacing and choriocapillaris (CC) perfusion adjacent to geographic atrophy (GA) in patients with age-related macular degeneration (AMD) and age-similar normal eyes. METHODS: Subjects were imaged using adaptive optics scanning laser ophthalmoscopy (AOSLO), fundus autofluorescence (FAF), and swept-source optical coherence tomography angiography. The GA border was identified using FAF images; CC flow void was analyzed in 1° regions extending from the GA border. A grader masked to CC perfusion selected regions of interest (ROIs) with unambiguous cone mosaics in AOSLO images. At each ROI, cone spacing and CC flow void were converted to Z-scores (standard deviations from the mean of 12 normal eyes aged 50 to 81 years for cone spacing, and 60 normal eyes age 51 to 88 years for CC flow void). RESULTS: Excluding regions of GA and drusen, CC flow void in eight eyes of six patients with AMD was significantly greater than in four age-similar normal eyes (exact permutation test, P = 0.024). CC flow void was negatively correlated with distance from the GA margin (r = −0.35; 95% confidence interval [CI], −0.53 to −0.12). Increased cone spacing was significantly correlated with CC flow void (r = 0.33; 95% CI, 0.12 to 0.59). Cone spacing was increased in 39% of ROIs, while CC flow void was increased in 96% of ROIs. CONCLUSIONS: In eyes with GA due to AMD, CC hypoperfusion was significantly correlated with, and more extensive than, cone photoreceptor loss. The results suggest that reduced CC perfusion contributes to the development of GA.