Scotopic microperimetric sensitivity and inner choroid flow deficits as predictors of progression to nascent geographic atrophy.

BACKGROUND/AIMS To assess the role of microperimetric retinal sensitivity (MPRS) and inner choroid flow deficits (IC FD) in predicting the development of incomplete retinal pigment epithelial and outer retinal atrophy (iRORA) in intermediate AMD (i-AMD). METHODS Thirty eyes with i-AMD evaluated at the Doheny-UCLA Eye Centres were enrolled in this prospective IRB-approved study. Subjects underwent several diagnostic tests: (a) 6×6 mm swept-source optical coherence tomography angiography (SS-OCTA) with the IC slab used to quantify the FDs, (b) 20°×20° spectral-domain optical coherence tomography (SD-OCT) to monitor progression to iRORA and (c) scotopic MPRS within an area of 18° centred on the fovea. All subjects were followed-up for 24 months. The baseline IC FD and MPRS were correlated with the development of iRORA. At 24-month follow-up, the stage of AMD was re-assessed and the eyes were divided into two sub-groups based on the development of iRORA. RESULTS Twenty-eight eyes completed the 2-year follow-up. At baseline, the mean MPRS was 13.40±4.66 dB and the mean IC FD was 27.55±8.67%. The morpho-functional regression showed a significant correlation between baseline MPRS and IC FD and the development of iRORA within 24 months (R2=0.744, p<0.05). A Kaplan-Meier survival curve was fit to determine the cumulative incidence of iRORA over the 24 months. CONCLUSIONS A lower MPRS and greater IC FD at baseline were predictors of progression to iRORA in eyes with i-AMD. These parameters may be useful biomarkers for risk stratification and prognostication.