To evaluate the visual outcome of optical coherence tomography-based ranibizumab monotherapy in Korean patients with retinal angiomatous proliferation and identify prognostic factors of visual outcome. A prospective single-arm clinical study of 31 retinal angiomatous proliferation patients who underwent 3 consecutive monthly intravitreal ranibizumab injections was conducted. Additional treatment was given based on optical coherence tomography at monthly follow-ups over 24 months. Best-corrected visual acuity improved from 48.7 ± 19.3 to 56.3 ± 19.1 letters at 24 months (P = 0.010). Total cumulative numbers of injection were 5.5 ± 2.2 and 7.7 ± 3.4 times at 12 and 24 months, respectively. Older age, larger choroidal neovascularization size, and poor initial best-corrected visual acuity were associated with poor visual outcome. Final best-corrected visual acuity was significantly worse with Stage 3 disease (70.4 ± 5.1, 62.3 ± 11.6, 46.2 ± 22.3 letters improved in each stage; P = 0.015). Among factors associated with poor visual outcome, only the stage of retinal angiomatous proliferation remained statistically significant on multiple linear regression analysis (P = 0.006). Although baseline best-corrected visual acuity was similar, Stage 3 patients exhibited limited visual improvement despite anatomical improvement, and more recurrences requiring more injections. Retinal angiomatous proliferation may be successfully managed with ranibizumab monotherapy in Korean patients, with the number of treatments required comparable to other forms of neovascular age-related macular degeneration. However, visual improvement was limited in late-stage RAP.