Swept Source OCT Imaging of Choriocapillaris Flow Deficits, Choroidal Thickness, and Choroidal Vascularity in AMD Eyes with Geographic Atrophy and Drusen

Abstract

Purpose : Choriocapillaris (CC) flow impairment, choroidal thickness (CT), and the choroidal vascularity index (CVI) were measured in AMD eyes with geographic atrophy (GA) and drusen using SS-OCT angiography to determine if changes in these measurements at baseline and during follow-up were correlated with the growth of GA and changes in drusen volume.

Methods : Patients with GA and drusen secondary to non-exudative AMD were enrolled in an IRB-approved prospective SS-OCT imaging study (PLEX^® Elite 9000, Carl Zeiss Meditec). Both 6x6mm and 12x12mm scan patterns were performed. GA and drusen area measurements and drusen volume measurements were obtained using selected SS-OCT slabs. From the same scans, the CC was visualized and flow deficits (FDs) quantified using a validated SS-OCT angiographic algorithm. CT and CVI measurements were obtained using an automated and validated algorithm

Results : In 36 eyes from 25 patients with GA, the annual square root enlargement rates (ERs) ranged from 0.07 to 0.75 mm/year. While the highest CC FD measurements were found within a 600-micron region adjacent to the GA, the correlations between the ERs and the CC FD measurements were stronger when regions further away from the margins were included. The best correlations were obtained by measuring the CC FDs from the total scan area minus the area of GA (p<0.001). While no significant correlations existed between the ER of GA and CT measurements or the presence of reticular pseudodrusen, a statistically significant correlation was found between the ER of GA and a decreased CVI outside the area of GA (p<0.035). In 8 eyes from 8 patients with drusen volumes exceeding 0.03 mm³ that were followed for over a year, no significant correlations were found between changes in the CC FDs beneath drusen and longitudinal changes in drusen.

Conclusions : Contrary to expectations, the strongest correlations between the ER of GA and CC FDs were found when the regions away from the edge of GA were correlated with the ERs compared with the regions immediately adjacent to the GA where the CC FDs were the highest. Moreover, in this region away from the edge of GA, the CVI was lower, and this decreased CVI correlated with both the CC FDs and the ER of GA. Additional patients with non-exudative AMD are being recruited and followed in this study.

This is a 2020 ARVO Annual Meeting abstract.