Ophthalmic complications of radiotherapy.

Radiotherapy is a vital tool in the management of benign and malignant conditions affecting the eye, orbit, and surrounding tissues. It may be used alone or in combination with surgery or systemic therapies. While conventional external beam radiotherapy (EBRT) is still indicated for selected orbital and periocular conditions, intraocular tumours are now predominantly managed with plaque brachytherapy, proton therapy, or stereotactic radiosurgery. Despite advances in radiotherapy precision, adjacent normal structures are still often exposed to radiation, resulting in a variety of ophthalmic complications. All radiotherapy modalities carry the risk of cataracts as well as vision-threatening complications such as neovascular glaucoma, radiation retinopathy and radiation optic neuropathy. Plaque brachytherapy, due to its highly localised dose delivery, carries the additional risk of scleral necrosis. In contrast, conventional EBRT exposes a broader area of normal tissues to radiation and has a higher risk of periocular radiation dermatitis, dry eye syndrome and secondary cancers. The incidence and severity of adverse effects are influenced by tumour characteristics, treatment technique, and individual patient factors. Advances in radiotherapy planning, preventative strategies, and early interventions have helped reduce the burden of complications. This review explores the ophthalmic complications of radiotherapy, focusing on their epidemiology, dose-toxicity thresholds, diagnosis, and management.