[Optic neuropathy after proton-beam therapy for malignant choroidal melanoma]

Proton-beam irradiation is a conservative therapy commonly used for the treatment of uveal malignant melanomas. Some adverse effects such as optic neuropathy can compromise the visual outcome. We were interested in determining the risk factors for radiation papillopathy. Since there is currently no effective therapy, this is an interesting way to improve prevention of optic neuropathy. Six hundred sixty-two eyes had more than 24 month follow-up after proton-beam irradiation for uveal melanoma. In five hundred twenty-two cases, the clinical examination of the optic nerve head by ophthalmoscopy was possible. One-hundred eleven optic discs were pathologic, whereas 411 remained disease-free. Retrospective study of these two groups allowed to quantify the risk factors for optic neuropathy. The irradiation of more than 2mm of optic nerve at 30 Grays-equivalents appeared to be the major risk factor for optic neuropathy. For a given irradiation dose, the observed pattern of clinical responses was heterogeneous. These results are discussed and compared to the previous published reports. Visual results and life prognosis are also discussed, considering the optic nerve head status. Proton-beam therapy can preserve the optic nerve when the tumor location allows to keep it away from the irradiation-field. Patients must be informed about the risk of optic neuropathy after proton-beam irradiation.