Choriocapillaris Perfusion and Retinal Sensitivity in Areas Bordering Geographic Atrophy

Abstract

Purpose : To assess choriocapillaris perfusion and retinal sensitivity in areas adjacent to geographic atrophy (GA) compared to non-adjacent surrounding areas in patients with dry age-related macular degeneration (AMD).

Methods : Choriocapillaris perfusion images were obtained using swept-source optical coherence tomography-angiography (OCTA) and retinal sensitivity was measured using fundus-guided microperimetry with the Macular Integrity Assessment (MAIA) system. Regions of GA were manually identified based on fundus autofluorescence images and drusen were identified using automated algorithms; both were excluded from analysis. Choriocapillaris flow voids (CFV) were analyzed quantitatively in 6mmx6mm OCTA en face images where the choriocapillaris slab was segmented from the outer boundary of Bruch’s membrane (BM) to approximately 20 um below BM. The percentage of CFV in a region was calculated using one standard deviation threshold below the mean of 20 normal subjects with ages from 20-39 years old. Average CFV and mean retinal sensitivity within 1° of the GA border, between 1-2° from the GA border, and greater than 2° from the GA border were compared with each other and with normal values.

Results : 7 patients (9 eyes) with GA secondary to AMD without evidence of choroidal neovascularization and 2 age-similar normal eyes were imaged. 3 patients (5 eyes) were imaged again on follow-up visits ranging from 3-14 months after baseline. CFV were significantly increased within 1° from the GA border compared to 1-2° from the GA border (P ≤ 0.007) and compared to the area greater than 2° from the GA border (P ≤ 0.0001). CFV were also significantly increased 1-2° from the GA border compared to the area greater than 2° from the GA border (P ≤ 0.0001). Retinal sensitivity was significantly decreased within 1° of the GA border compared to 1-2° from the GA border (P ≤ 0.004) and compared to the area greater than 2° from the GA border (P ≤ 0.008). Overall CFV in patients with GA were significantly increased compared to normal eyes (P = 0.001).

Conclusions : Choriocapillaris perfusion and retinal sensitivity were both significantly decreased in areas bordering GA. These results suggest choriocapillaris perfusion loss may precede development or expansion of GA in eyes with dry AMD. Further quantification of choriocapillaris perfusion in patients with dry AMD may provide insight into the mechanisms behind the progression of GA.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.