Ocular Complications of Radiotherapy in Uveal Melanoma

SIMPLE SUMMARY: Radiation therapy, comprising brachytherapy, proton beam therapy, stereotactic radiotherapy, and radiosurgery, is the most used eye-sparing treatment for uveal melanoma worldwide. However, radiotherapy is associated with many complications, some of which are vision-threatening. Being aware of the different adverse effects of radiotherapy, the risk factors for their occurrence, their prognosis, and the available treatments for each complication is essential in aiding both the practitioner and patient to make the choice regarding the most appropriate therapy. ABSTRACT: Uveal melanoma is the most common primary malignant intraocular tumor in adults. Radiation therapy has replaced enucleation and is now the preferred treatment in most cases. Nonetheless, around 70% of patients develop radiation-related complications, some of which are vision-threatening. The objective of this review is to present the most important complications associated with radiotherapy in the treatment of uveal melanoma and their pathogenesis, incidence, risk factors, and available preventive and therapeutic measures. The most common complications are cataracts, with a reported incidence ranging from 4% to 69%, and radiation retinopathy, reported in 5–68% of cases. Radiation-related complications are responsible for approximately half of secondary enucleations, the leading cause being neovascular glaucoma. A poor visual outcome is mainly associated with the presence of radiation retinopathy and radiation optic neuropathy. Therapeutic options are available for the majority of complications with the notable exception of optic neuropathy. However, many studies report a final visual acuity of less than 20/200 in more than 60% of treated eyes. Reducing complication rates can be achieved by lowering the dose of radiation, with the use of eccentric, customized plaques and careful planning of the irradiation delivery in order to protect structures vital to vision and by associating radiation therapy with other methods with the aim of reducing tumor volume.