Objective: This study aimed to determine the effect of external beam radiation therapy on choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).
Design: The study design was a nonrandomized clinical trial with an historic control group.
Participants: A total of 91 patients were treated with external beam radiation. These patients were compared retrospectively to the 119 patients in a control group.
Intervention: Patients with subfoveal CNV who did not meet the criteria for laser treatment defined by published reports from the Macular Photocoagulation Study Group or who did not want laser treatment were considered for radiation therapy in a nonrandomized, prospective clinical trial. Additional entry criteria for this prospective study included visual acuity better than or equal to 20/320 on the Early Treatment Diabetic Retinopathy Study chart and a lesion size less than 12 disc areas. The patients were treated with 5 fractions of 200 cGy 6 MV external beam photons.
Main outcome measures: The visual acuity measured at baseline was compared to the visual acuity after 1 year of follow-up.
Results: The mean baseline visual acuity of the 91 patients entered into the Radiation Study was 20/80. After 1 year, 83 patients (91.2%) completed follow-up, and their mean visual acuity dropped to 20/200. By comparison, the mean baseline visual acuity of the control patients also was 20/80, and after 1 year, the control subjects had a mean visual acuity of 20/125. At 1 year of follow-up, 49.4% of patients treated with radiation and 38.1% of the control subjects lost 3 or more lines of visual acuity (P = 0.16).
Conclusions: This study found that external beam radiation using 1000 cGy in 5 fractions, a dose similar to that used in previous studies, was not effective in the treatment of CNV secondary to AMD. These results suggest that patients should not be treated with this dose of external beam radiation for CNV secondary to AMD.