Longitudinal progression of visual function metrics in early and intermediate age-related macular degeneration

Abstract

Purpose : The purpose of this study was to examine longitudinal changes in performance on psychophysical tests of visual function over 12 months in subjects with early and intermediate age-related macular degeneration (AMD).

Methods : Prospective cohort study of 101 subjects with AMD age-related eye disease study (AREDS) stage 2 (N=33), AREDS stage 3 (N=47), and age-matched, normal controls (N=21). At baseline, 6 and 12 months, subjects underwent a dilated retinal examination with best-corrected visual acuity (BCVA), mesopic microperimetry with eye tracking (MAIA), dark adaptometry (DA; AdaptDx), low luminance visual acuity (LLVA) testing (standard log 2.0 neutral density filter and computerized), and cone contrast test (CCT). Low luminance deficit (LLD) was calculated as the difference in letters read for BCVA and LLVA. Group comparisons were performed using two-sided significance tests.

Results : 82 subjects completed the 6-and 12-month follow-up visits. The drop-out rate (18.8%) in this aged population is a limitation of the 12 month analysis. However, the intermediate AMD group showed a statistically significant impairment in standard LLVA, standard LLD, and CCT red as compared to the normal group at 12 months (p<0.05). Microperimetry metrics (percent reduced threshold and average threshold), CCT green and blue, and rod intercept on DA remained significantly different between groups at 1 year, similar to the baseline visits (all p<0.05). At 12 months, standard calculated LLD became significantly greater among early (p=0.027) and intermediate (p=0.002) AMD compared to controls. The intermediate group lost the most ETDRS letters of standard BCVA, while the early group lost the least, resulting in a significant difference in BCVA change between the groups at 12 months (p=0.021). The intermediate AMD group also had a significant loss of retinal sensitivity on microperimetry average threshold relative to those with early AMD (p=0.001) or controls (p<0.001). The percent of intermediate patients with greater than 2 standard deviations plus the mean of normal values was significantly higher than in the normal group for both calculated LLD (p=0.022) and percent reduced threshold (p=0.017).

Conclusions : Our study suggests that calculated standard LLD and microperimetry average threshold may be useful functional measures of disease progression in eyes with early and intermediate AMD.

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