AIM: To evaluate visual outcomes and changes in fluid after administering monthly anti-vascular endothelial growth factor (VEGF) injections to treat neovascular age-related macular degeneration (nAMD) with subretinal fluid (SRF) and pigment epithelial detachment (PED). METHODS: This prospective study included eyes with nAMD previously treated with as-needed anti-VEGF injections. The patients were treated with six monthly intravitreal injections of ranibizumab. Quantitative volumetric segmentation analyses of the SRF and PED were performed. The main outcome measures included best-corrected visual acuity (BCVA), and SRF and PED volumes. RESULTS: Twenty eyes of 20 patients were included in this study. At the 6-month follow-up, BCVA and PED volume did not change significantly (P=0.110 and 0.999, respectively) but the mean SRF volume decreased from 0.53±0.82 mm3 at baseline to 0.08±0.23 mm3 (P=0.002). The absorption rate of the SRF volume was negatively correlated with the duration of previous anti-VEGF treatment (P=0.029). Seven of the 20 eyes (35%) showed a fluid-free macula and significant improvement in BCVA (P=0.036) by month 6. CONCLUSION: Quantifying the SRF can precisely determine the patient’s responsiveness to anti-VEGF treatment of nAMD.