Morphologic Predictors and Temporal Characteristics of Conversion from Nonexudative to Exudative Age-Related Macular Degeneration in the Fellow Eye

Abstract

To describe the systemic and ocular features of fellow eyes' association with nonexudative neovascularization (NV) based on OCT angiography (OCTA) and to identify longitudinal morphologic changes associated with progression to exudation. Cohort study of contralateral eye in patients with neovascular age-related macular degeneration (nAMD) in 1 eye. Patients with nAMD in one eye were eligble for inclusion and enrolled between June 2015 and Jan 2017. The study eye was the contralateral eye that was free of nAMD with a minimum follow-up of 1 year. Progressive multimodal imaging was performed on both eyes. Nonexudative NV was detected on OCTA in the study eye and quantitative changes analyzed. Nonexudative NV eyes were divided into progression to exudation or not during a minimum of 12 months follow-up. Association between systemic and ocular characteristics with nonexudative NV were determined. Change in OCTA size, vessel density, and vessel length density were compared between visits as predictors of progression to exudation. Among 229 study eyes, 21 (9.1%) had nonexudative NV detected on OCTA at baseline. Hyperlipidemia (adjusted odds ratio [AOR], 1.3; 95% confidence interval [CI], 1.10-3.20; P= 0.04), triglycerides (AOR,2.84 per mmol/L; 95% CI, 1.06-4.35 per mmol/L; P= 0.02), and baseline lesion size in the presenting eye (AOR, 1.6 per 500 μm; 95% CI, 1.21-3.25 per 500 μm; P= 0.03) were associated significantly with nonexudative NV in the study eye. In the study eye nonexudative NV group, 8 (38%) progressed to exudation, with a mean timeto exudation of 377 ± 138 days. The progressor group had larger baseline NV size (1834 ± 552.8 μm vs. 910± 461.7 μm; P < 0.01), higher increase in vessel density/year (8.3 ± 4.1%/year vs. 1.1 ± 2.5%/year; P ≤ 0.01), and higher increase in vessel length density/year (15.6 ± 10.6% vs. 1.9 ± 3.6%; P= 0.02). The change in lesion size per year was similar in both groups. Patients with nonexudative NV in the study eye had significant differences in ocular and systemic characteristics. More than a third of study eyes with nonexudative NV at baseline progressed to exudation, suggesting that close monitoring is essential. OCT angiography features associated with exudation include a larger baseline lesion size, increase in vessel density, and vessel length density.