Proton beam irradiation of subfoveal choroidal neovascularisation in age-related macular degeneration

Purpose To assess the safety and potential toxicity of proton beam radiatio n in the treatment of subfoveal choroidal neovascular membrane (CNVM) due t o age-related manner degeneration (ARMD) in a prospective, non-randomised s tudy. Methods Forty-eight eyes of 46 consecutive patients with subfoveal CNVM due to ARMD, not amenable to laser photocoagulation, were treated prospectivel y with a single proton beam exposure. Two dose regimens were evaluated: 8 C GE (Cobalt Gray Equivalent) and 14 CGE. Patients were followed for an avera ge of 22.1 months after proton beam treatment. Results At the 12 month follow-up, 44% of eyes in the 8 CGE group and 75% o f the eyes in the 14 CGE group had stabilised or improved visual acuity. Co mplex size in the 8 CGE group as measured on standard fluorescein angiograp hy (FA), decreased or had no change initially but showed less effect over t ime, while the eyes treated with 14 CGE maintained decreased leakage over t he followup period of 12 months. However, 11 eyes in the 14 CGE group exper ienced radiation retinopathy, with the onset between 3 and 30 months. Seven of these 11 eyes have demonstrated some visual loss but only 1 eye develop ed severe visual loss at 15 months after proton treatment. Conclusions To date, 14 CGE has suggested a favourable influence on visual function and growth inhibition of CNVM. Proton beam irradiation appears to inhibit CNVM growth. The 14 CGE dose regimen appears to have a longer effec t of CNVM growth than does 8 CGE, with overall stabilisation of visual func tion and growth inhibition. Radiation retinopathy has developed over time, but severe visual loss has been limited. On the basis of the incidence of r adiation retinopathy, adjustments in the total radiation dosage and/or frac tionation of the dosage should be considered.