Anterior Segment Complications After Helium Ion Radiation Therapy for Uveal Melanoma

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Abstract
Objective: To delineate the factors in the development of visually significant cataract after helium ion irradiation of eyes with uveal melanomas. Design: Retrospective analysis with multivariate analysis using life tables and Cox proportional hazard models in addition to other nonparametric techniques. Patients: All patients with a noncataractous other eye and adequate dosimetry data who were treated with helium ion irradiation. Results: Significant cataracts (grade 3+ or 4+ on a Oto 4+ scale) developed in 129 patients (44%). The risk of cataract development peaked at 3 years (25% per personyear) and then declined to a sustained level of 7% to 9% per year after 7 years. In multivariate analysis, the percentage of lens included in the treatment port was the predominant predictive correlate with time to significant cataract (relative risk of 2.97 for a 25% increase in the percentage of lens in the treatment port). Patient age, preexisting cortical opacity, and ultrasound tumor height were also significant; ciliary body involvement and tumor dose had smaller effects. Kaplan-Meier analysis demonstrated an increased rate of cataractogenesis with each increment of the percentage of lens in the treatment port; when more than half of the lens was in the beam, the risk of cataract exceeded 90% within 7 years. Conclusions: Cataract development after helium ion irradiation is a function of the amount of the lens in the beam. Unlike neovascular glaucoma that develops mainly in the first few years after treatment, cataract continues to develop during the entire length of follow-up.

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