To evaluate the predictive characteristics of fellow-eye geographic atrophy (GA) without neovascularization in patients with unilateral Type 3 macular neovascularization.

This retrospective study included 84 patients who were diagnosed with unilateral Type 3 macular neovascularization. Patients who developed fellow-eye neovascularization and those exhibiting GA without neovascularization at the final follow-up were included in the neovascularization and GA groups, respectively. The patient demographics and baseline fellow-eye characteristics were compared between the two groups.

The mean follow-up period was 40.5 ± 11.5 months after diagnosis. Patients included in the GA group (n = 28) were significantly older (mean 77.4 ± 5.2 years vs. 74.2 ± 5.8 years, P = 0.016), had significantly thinner subfoveal choroidal thickness (mean 109.4 ± 36.8 µm vs. 173.1 ± 77.6 µm, P < 0.001), and had a significantly higher incidence of baseline GA (39.3% vs. 16.1%, P = 0.019) than those included in the neovascularization group (n = 56). In the multivariate analysis, subfoveal choroidal thickness showed a close negative association with the risk of GA rather than neovascularization (P = 0.004, β = 0.982, 95% confidence interval = 0.970–0.994).

In patients with unilateral Type 3 macular neovascularization, older age, the presence of GA, and a thin choroid in the fellow eye were found to be indicative of a higher probability of progression toward fellow-eye GA instead of neovascularization may be potential candidates for future complement inhibitor treatments targeting fellow-eye GA.