The Age-Related Macular Degeneration Radiotherapy Trial (AMDRT): 1 Year Results

Abstract

Abstract: : Purpose: To determine the efficacy of external beam irradiation for subfoveal choroidal neovascularization (CNV) complicating age-related macular degeneration. Methods: Ten centers enrolled 89 patients who were randomized to radiotherapy (5 X 4 Gy fractions=20Gy; 6 MeV) versus no radiotherapy (sham treatment or observation). Eligibility criteria included visual acuity greater than or equal to 20/320 and CNV not amenable to MPS laser photocoagulation or photodynamic therapy with verteporfin. Randomization was stratified by lesion type: new CNV (N=80) and recurrent CNV (N=9). The primary outcome measure was change in visual acuity. Secondary outcome measures were fluorescein angiographic lesion size change and incidence of side effects. Results: At baseline, the radiation and no radiation groups were not different with respect to age (mean 77), gender (58% females), race (99% caucasian), and systemic hypertensive status (57% hypertensive). Baseline visual acuity was not different between the groups (47% greater than or equal to 20/80) at baseline. Fluorescein angiographic features did not differ between the groups (84% minimally classic or occult CNV; 74% comprised of <25% blood; 81% comprised of <25% fibrosis). At 6 months follow-up, 26% of radiated and 50% of eyes not radiated demonstrated loss of greater than or equal to 3 visual acuity lines (p=0.04; stratified Χ2 test). At 12 months follow-up, 43% of radiated eyes and 50% of eyes not radiated demonstrated loss of greater than or equal to 3 visual acuity lines (p=0.60). No eyes developed radiation retinopathy or optic neuropathy. Conclusions: External beam irradiation at a dose of 5 X 4 Gy has a very modest and short-lived (6 month) benefit in preserving visual acuity. No obvious safety concerns were observed with this dose. Radiotherapy at similar doses or fraction sizes may be studied as an adjuvant, rather than primary, treatment for subfoveal CNV.

Keywords: age-related macular degeneration • choroid: neovascularization • radiation therapy