[Proton therapy of occult neovessels in age-related macular degeneration]

The interest of radiation therapy in the management of age-related macular degeneration inaccessible to photocoagulation is still controversial. Our purpose was to demonstrate the feasibility and the possible efficacy of a single dose delivered to the macular region using a 65-MeV proton beam.

A phase II trial was set up using the cyclotron in Nice, France. Fifty-eight patients were included after signing an informed consent. All patients presented with occult subfoveal choroidal neovascularization. A single dose of 9.1 Gy (i.e., 10 Gy cobalt equivalent) was delivered to the macular region.

The results were analyzed 3, 6, 12 and, 18 months after proton therapy. At 3 months, the visual acuity was stable or enhanced for 86% of patients, at 6 months for 82.3%, at 12 months for 80%, and at 18 months for 61%. For 22 patients at follow-up at 18 months, the reasons for a decrease in visual acuity were a macular hemorrhage for 4 patients and a progression of the neovascular membrane for 3 patients. No secondary effects related to the treatment have been observed. Regarding the lesions visible on the angiographies (i.e., hemorrhage, exudates, subretinal detachment), we observed a stabilization or a decrease in two-thirds of the cases.

Preliminary results of single-dose proton therapy are at least comparable to those obtained by other teams. A second study is in progress comparing 3 dose levels, looking for a dose-effect relationship. Furthermore, a randomized study comparing a single proton dose to a placebo will be necessary to assess the long-term value of proton treatment.