Abstract
Purpose:
To explore the impact of the baseline difference in visual acuity measured in normal and low luminance conditions (BCVA-LLVA gap) on the capacity of patients with neovascular age-related macular degeneration (AMD) to gain vision with ranibizumab therapy.
Methods:
The HARBOR study (NCT00891735) evaluated the efficacy and safety of intravitreal ranibizumab 0.5 mg and 2.0 mg given monthly or as-needed (PRN) in patients with neovascular AMD. LLVA was measured by placing a 2.0-log-unit neutral density filter in front of the study eye and having the participant read the normally illuminated ETDRS chart. For this analysis, the study participants (N=1084) were pooled and divided into quartiles based on the magnitude of the BCVA-LLVA gap at baseline. The association between BCVA-LLVA gap and BCVA gains was analyzed using a general linear model.
Results:
The baseline BCVA-LLVA gap was negatively correlated with BCVA gain at Month 24 (P<0.0001); the significant association remained after controlling for baseline BCVA, as well as after stratifying by ranibizumab treatment group (0.5 mg or 2.0 mg; monthly or PRN). Patients with the narrowest BCVA-LLVA gap (smallest difference in vision under low luminance) at baseline gained, on average, 13.4 letters in BCVA at Month 24 (versus 2.4 letters in patients with the widest BCVA-LLVA gap at baseline) (Figure). Almost twice as many patients with the smallest baseline BCVA-LLVA gap gained ≥15 letters at Month 24 (49%) compared with patients with the widest baseline BCVA-LLVA gap (26%). Patients with the widest BCVA-LLVA gap at baseline also had the greatest PED, lesion, CNV and subretinal fluid thickness at baseline (P<0.05, based on a general linear model).
Conclusions:
The BCVA-LLVA gap at baseline was prognostic for treatment response in patients with neovascular AMD. A narrow BCVA-LLVA gap may be a manifestation of milder retinal impairment and a predictor of greater capacity for visual function recovery with ranibizumab therapy. There is a good association between function as measured by the baseline visual gap and structure as measured by baseline OCT.