Radiation retinopathy after the application of a cobalt plaque. Report of three cases.

Radiation damage to the retinal vascular system has been held responsible for small vessel occlusion, neovascularization, haemorrhages, and exudates when the whole eye has been involved during the course of therapeutic irradiation for the treatment of retinoblastoma (Martin and Reese, I945; Howard, i966), basal cell carcinoma of eyelids or nose, and carcinoma of the paranasal sinuses (Perrers-Taylor, Brinkley, and Reynolds, i965; Chee, I968; Gass, I968). Local radiation treatment for intraocular neoplasms was introduced by Foster Moore (1935) using radon seeds. From 1948 onwards, the physical principles established by Innes (i964), working in conjunction with Stallard, led to the development of the cobalt 6o-applicators, which are now used in many centres throughout the world, not only for the treatment of retinoblastoma but also in certain cases of malignant melanoma of the choroid (Stallard, i968). Retinal vascular complications after this form of therapy have been noted in the literature (Stallard, i96i, i966) but have received little emphasis. However, in a recent study from this unit of ocular complications associated with various types of therapeutic irradiation (MacFaul and Bedford, I 970), attention was drawn to certain vascular lesions which, in some cases, may result in loss of vision in the treated eye. The purpose of this paper is to report three cases of choroidal malignant melanoma treated with a cobalt 6o-applicator and investigated by fluorescein angiography, in which delayed visual loss was associated with retinal vascular occlusions of varying degree.