Tumour location aVects the incidence of cataract and retinopathy after ophthalmic plaque radiation therapy

Aim—To examine how tumour location aVects ocular morbidity after ophthalmic plaque radiotherapy for uveal melanoma. Methods—69 eyes were irradiated and followed for a mean 42 months. There were 23 anterior uveal melanomas and 46 were posterior to the equator. Anterior and posterior tumours had similar basal dimensions. Their mean apical heights were 4.8 mm (anterior) and 3.5 mm (posterior) which received a mean 88 Gy and 83.4 Gy respectively. Results—Only one patient (4%) plaqued for an anterior uveal melanoma developed secondary retinopathy (cystoid macular oedema). In contrast, 24 (52%) of the posterior choroidal melanoma patients developed retinopathy (p value <0.0001). Cataract developed in 18 (86%) eyes with phakic anterior tumour compared with seven (17%) eyes with posterior tumours (p value <0.0000). No posterior nasal tumours lost more than two lines of vision though 45% developed retinopathy. Conclusion—While plaque radiation of anterior melanomas is more likely to cause reversible vision loss secondary to cataract, treatment of posterior tumours is more likely to be associated with irreversible loss because of retinopathy. Nasal location is also protective against severe loss of vision. (Br J Ophthalmol 2000;84:1068–1070) Enucleation and radiotherapy are the most commonly used treatments for choroidal melanoma. 2 High energy cobalt-60 ophthalmic plaques have been replaced by the lower energy ruthenium-106 (Ru) and iodine-125 (I). Most recently, palladium-103 (Pd) has become available. Though all four radionuclides can be used successfully to treat choroidal melanoma, they diVer in their distribution of radiation. 12 Tumour, and therefore plaque location, aVects the distribution of intraocular radiation. Since the plaque is centred over the tumour during treatment, the radiation dose distribution shifts along with the plaque (Fig 1). Treatment of anterior tumours results in a higher dose to the lens, and irradiation of posterior tumours increases the dose to the macula. This study examines tumour location as a risk factor for ocular complications of plaque radiotherapy. Patients and methods