Abstract
Purpose :
Low luminance deficit (LLD) has previously been shown to be a predictor of visual acuity loss in subjects with geographic atrophy (GA) secondary to age-related macular degeneration (AMD). We conducted a prospective, interventional clinical study in which we explored the relationship between baseline LLD and subsequent normal luminance best-corrected visual acuity (NL-BCVA) changes over 24 months in subjects with GA treated with placebo.
Methods :
A multicenter, randomized, double-masked, placebo-controlled, 24-month treatment study was conducted to evaluate the efficacy and safety of emixustat hydrochloride in subjects with GA secondary to AMD. Visits included screening, baseline, and month 1, 2, 3, 6, 9, 12, 15, 18, 21, 24, and 25. BCVA was measured at each visit under both low and normal luminance, and the results were reported as a total letter score (0-100). Low luminance BCVA (LL-BCVA) was measured using a 2.0-log unit neutral density filter placed in front of the eye being tested, which transmits 1% of incident light. To investigate the disease-related changes in BCVA, only subjects in the placebo arm who completed 24 months were included in this analysis. The LLD was defined as the NL-BCVA score minus the LL-BCVA score at a given exam.
Results :
Of the 508 subjects randomized to one of the 4 treatment arms, a total of 136 subjects were randomized to placebo and 108 of these subjects completed the 24-month treatment period. In the study eye, a statistically significant linear relationship was observed between the changes from baseline in NL-BCVA score at month 24 and the LLD at baseline (P=0.0002). Larger LLD values at baseline were associated with larger decreases in NL-BCVA score at month 24. When the baseline LLD was divided into the following 4 categories: 1) <10 letters; 2) ≥10 and <20 letters; 3) ≥20 and <30 letters; and 4) ≥30 letters, the mean (SE) changes in NL-BCVA score at month 24 were +0.3 (1.61), -4.2 (2.53), -11.2 (3.60), and -18.0 (3.58) letters, respectively, and the median changes were 0.0, -2.0, -8.5, and -14.0 letters, respectively.
Conclusions :
Results of our study support the results of a prior study that showed baseline LLD to be a strong predictor of subsequent NL-BCVA changes in subjects with GA secondary to AMD. The expected amount of this change has been quantified based on the LLD at baseline.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.