Risk factors for radiation maculopathy after ophthalmic plaque radiation for choroidal melanoma

Abstract

Purpose: To determine how tumor characteristics and radiation dose affect the incidence of radiation maculopathy (RM).

Design: Retrospective, consecutive case series.

Methods: A consecutive case series of 384 uveal melanomas irradiated (mean apical dose, 71.2 Gy) were followed up for a mean 47.2 months. Tumor locations included: 122 (32%) centered anterior to the equator, 27 (7%) equatorial, and 235 (61%) posterior. Tumor sizes were American Joint Committee on Cancer class T1 (n = 180), T2 (n = 150), T3 (n = 47), and T4 (n = 7).

Results: RM occurred in 8 (7%) eyes with anterior uveal melanomas. In contrast, it was found in 82 (41%) eyes with posterior tumors. Multivariate analysis revealed the risk related to posterior location was greater compared with anterior location with a hazard ratio of 6.66 (95% confidence interval [CI], 4.94 to 22.50; P = .0001). Tumor height (> 6.0 mm) also demonstrated a high risk for RM (hazard ratio, 4.5; 95% CI, 2.68 to 10.17; P = .0001). A significant dose-response relationship was found between dose to fovea and RM (P = .0005, for trend). As compared with a dose of < 35 Gy, the risk of RM was 1.74 (95% CI, 0.98 to 3.1) for doses from 35 to 70 Gy, and the risk of RM was 2.43 (95% CI, 1.48 to 4.0) for doses of 70 Gy or more. Of interest, those anterior melanomas with RM had a mean apical height of 9.4 mm, as compared with a mean height of 3.3 mm for anterior tumors not associated with RM. Visual acuity was preserved if the fovea dose was less than 35 Gy.

Conclusions: This study suggests that tumor location, tumor thickness, and radiation dose to the fovea are risk factors for the development of RM.