Three-year follow-up of ranibizumab treatment of wet age-related macular degeneration: influence of baseline visual acuity and injection frequency on visual outcomes

PURPOSE: To determine the effect of ranibizumab on visual acuity (VA) following a 3-year treatment period for patients diagnosed with wet age-related macular degeneration. To establish whether baseline VA and injection frequency influence visual outcomes. PATIENTS AND METHODS: Retrospective review of 70 patients (76 eyes) treated with 0.5 mg intravitreal ranibizumab for 3 consecutive months, and pro re nata thereafter (three + pro re nata protocol), over a 3-year period. VA was measured using Early Treatment Diabetic Retinopathy Study (ETDRS) charts at baseline, 12, 24, and 36 months. The number of injections administered at the end of years 1, 2, and 3 were also recorded. Eyes were stratified according to baseline VA, as well as the number of injections administered at the end of year 1. Linear regression analysis determined the relationship between VA and both baseline VA and injection frequency. P<0.05 was considered statistically significant. RESULTS: At 36 months, VA improved by a mean of 5.3 ETDRS letters (P=0.002), with 29% of eyes (n=22) demonstrating a clinically significant improvement in VA (gain of ≥15 ETDRS letters). Improvements in VA from baseline to 36 months were inversely proportional to the baseline VA (R=0.414, P=<0.001). A positive correlation was observed between injection frequency and change in VA from baseline to 36 months (R=0.244, P=0.036). CONCLUSION: Mean improvement in VA is inversely proportional to baseline VA, and directly proportional to injection frequency.