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

Purpose: To use optical coherence tomography angiography (OCTA) derived quantitative metrics to assess the response of choroidal neovascularization to pro-re-nata (PRN) anti-endothelial growth factor (anti-VEGF) treatment in neovascular age-related macular degeneration (AMD). Design: Prospective longitudinal cohort study. Participants: Fourteen eyes from 14 study participants with treatment-naive neovascular AMD were enrolled. Methods: Subjects were evaluated monthly and treated with intravitreal anti-VEGF agents under a PRN protocol for one year. At each visit, two 3x3 mm2 OCTA scans were obtained. Custom image processing was applied to segment the outer retinal slab, suppress projection artifact, and automatically detect CNV. CNV membrane area (mm2) and CNV vessel area (mm2) was calculated. Main outcomes: Individual and mean CNV membrane area and CNV vessel area at each visit; within-visit repeatability determined by coefficient of variation. Results: Eight eyes had entire CNV within 3x3 mm(2) scanning area and had adequate image quality for CNV quantification. One case (case #2) was excluded from analysis due to the presence of a large subretinal hemorrhage overlying the CNV membrane. In the remaining cases, CNV vessel area was reduced by 39%, 50%, 43%, and 41% at months 1, 3, 6, and 12 respectively. CNV 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, while it was statistically significant for CNV membrane area. Neither metric was significantly different compared to baseline at month 12. Individual analyses revealed each CNV had a unique response under PRN treatment. Within-visit repeatability was 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 to baseline after three months. After one year of follow-up, these reductions were no longer statistically significant. When anti-VEGF treatment was held, increasing CNV vessel area over time often resulted in exudation, but it was not possible to exactly when exudation occurs. (C) 2018 by the American Academy of Ophthalmology