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

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.