OBJECTIVE The purpose of this study was to compare the observed change in best-corrected visual acuity (BCVA) with the change in central retinal sensitivity pretreatment and 1 month after 3 consecutive treatments with ranibizumab in patients with wet age-related macular degeneration. METHODS Ten consecutive patients with untreated age-related macular degeneration underwent microperimetric and BCVA assessment before and 1 month after 3 consecutive treatments with ranibizumab. Best-corrected visual acuity was assessed at 2 m by using the Early Treatment Diabetic Retinopathy Study chart. Threshold microperimetry was performed using a Goldman III stimulus to 45 points over the central 12 degrees of the macula. Significant visual improvement after treatment was defined as a change in BCVA >/=10 letters or, on microperimetry, a change in mean retinal sensitivity > or = 2 dB. RESULTS One month after treatment, the median change in BCVA was +6 letters (range, -15 to +12), and the mean change in the mean retinal sensitivity was +2.86 dB (standard deviation, 1.55 dB). One patient recorded a significant improvement in BCVA compared with 8 patients who recorded a significant improvement in mean retinal sensitivity (P = 0.016). CONCLUSIONS Compared with microperimetry, BCVA seems to significantly underestimate the change in visual function experienced by patients treated with ranibizumab.