Objective-To present visual acuity findings and related outcomes from eyes of patients enrolled in a randomized trial conducted by the Submacular Surgery Trials (SST) Research Group (SST Group H Trial) to compare surgical removal vs observation of subfoveal choroidal neovascular lesions that were either idiopathic or associated with ocular histoplasmosis.Methods-Eligible patients 18 years or older had subfoveal choroidal neovascularization (new or recurrent) that included a classic component on fluorescein angiography and best-corrected visual acuity of 20/50 to 20/800 in 1 eye ("study eye"). Patients were examined 3, 6, 12, and 24 months after enrollment to assess study outcomes and adverse events. Best-corrected visual acuity was measured by a masked examiner at the 24-month examination. A successful outcome was defined a priori as 24-month visual acuity better or no more than 1 line (7 letters) worse than at baseline. Results-Among 225 patients enrolled (median visual acuity 20/100), 113 study eyes were assigned to observation and 112 to surgery. Forty-six percent of the eyes in the observation arm and 55% in the surgery arm had a successful outcome (success ratio, 1.18; 95% confidence interval, 0.89-1.56). Median visual acuity at the 24-month examination was 20/250 among eyes in the observation arm and 20/160 for eyes in the surgery arm. The prespecified subgroup of eyes with visual acuity worse than 20/100 at baseline (n=92) had more successes with surgery; 31 (76%) of 41 eyes in the surgery arm vs 20 (50%) of 40 eyes in the observation arm examined at 24 months (success ratio, 1.53; 95% confidence interval, 1.08-2.16). Five (4%) of 111 eyes in the surgery arm subsequently had a rhegmatogenous retinal detachment. Twenty-seven (24%) of 112 initially phakic eyes in the surgery