Most uveal
melanomas are treated with
radiotherapy. An adequate understanding of the effects of radiation on the tumour and the healthy ocular tissues is necessary. Ionizing radiation damages cell membranes, organelles, and
DNA. Irradiated cells are lysed or undergo apoptosis,
necrosis, and senescence. These effects occur in tumour cells and vascular endothelial cells, resulting in tumour shrinkage, ischaemia,
infarction, exudation, and
fibrosis, which can cause exudative
maculopathy, serous
retinal detachment, rubeosis, and
neovascular glaucoma (ie, 'toxic tumour syndrome'). Such abnormalities must be distinguished from collateral damage to healthy ocular tissues that receive high doses of radiation, and these include radiation-induced retinopathy,
optic neuropathy, choroidopathy,
cataract, and scleral
necrosis. Radiation retinopathy can be treated effectively with
photodynamic therapy, anti-angiogenic agents, and intravitreal
steroid injections. In some patients,
optic neuropathy may improve with intravitreal
steroids or anti-angiogenic agents.
Neovascular glaucoma resolves with intra-cameral
bevacizumab. Exudative
retinal detachment can regress with intra-vitreal
steroid injections.
Cataract is treated in the usual manner. Scleral
necrosis, if severe, may require grafting, possibly using a lamellar flap from the same eye. Depending on the bulk of the residual toxic tumour, treatment can consist of intra-vitreal
steroids and/or anti-angiogenic agents, transpupillary
thermotherapy or
photodynamic therapy to the tumour, or surgical removal of the tumour by endo- or exo-resection. Measures aimed at preventing collateral damage include eccentric placement of
ruthenium plaques or
iodine seeds and delivery of a notched
proton beam. The decision to treat a
uveal melanoma with
radiotherapy requires the ability to manage iatrogenic side effects and complications.