Quantitative Evaluation of Choroidal Neovascularization under Pro Re Nata Anti–Vascular Endothelial Growth Factor Therapy with OCT Angiography

Purpose: To use OCT angiography (OCTA)-derived quantitative metrics to assess the response of choroidal neovascularization (CNV) to pro re nata (PRN) anti–vascular endothelial growth factor (VEGF) treatment in neovascular age-related macular degeneration (AMD). Design: Prospective, longitudinal cohort study. Participants: Fourteen eyes from 14 study participants with treatment-naïve neovascular AMD were enrolled. Methods: Participants were evaluated monthly and treated with intravitreal anti-VEGF agents under a PRN protocol for 1 year. At each visit, two 3 × 3-mm² OCTA scans were obtained. Custom image processing was applied to segment the outer retinal slab, suppress projection artifact, and automatically detect CNV. Choroidal neovascularization membrane area and CNV vessel area were calculated. Main Outcome Measures: Individual and mean CNV membrane area and CNV vessel area at each visit; within-visit repeatability determined by coefficient of variation. Results: Eight eyes showed the entire CNV to be within the 3 × 3-mm² scanning area and had adequate image quality for CNV quantification. One patient (patient 2) was excluded from analysis because of the presence of a large subretinal hemorrhage overlying the CNV membrane. In the remaining patients, CNV vessel area was reduced by 39%, 50%, 43%, and 41% at months 1, 3, 6, and 12, respectively. Choroidal neovascularization membrane area was reduced by 39%, 51%, 54%, and 45% at months 1, 3, 6, and 12. At month 6, mean change from baseline was not statistically significant for CNV vessel area, whereas it was statistically significant for CNV membrane area. Neither metric was significantly different compared with baseline at month 12. Individual analyses revealed each CNV had a unique response under PRN treatment. Within-visit repeatability was 7.96% (coefficient of variation) for CNV vessel area and 7.37% for CNV membrane area. Conclusions: In this small exploratory study of CNV response to PRN anti-VEGF treatment, both CNV vessel area and membrane area were reduced compared with baseline after 3 months. After 1 year of follow-up, these reductions were no longer statistically significant. When anti-VEGF treatment was withheld, increasing CNV vessel area over time often resulted in exudation, but it was not possible to determine exactly when exudation occurs.