Radiotherapy for Nonmalignant Eye Diseases: Graves' Ophthalmopathy - Pseudotumor Orbitae.

Orbital radiotherapy (RT) is an effective treatment for moderate-to-severe Graves´ ophthalmopathy (GO), especially when combined with steroids, as it reduces painful eye symptoms associated with retroorbital and eye lid soft tissue swelling, improves eye movement, and can decrease the need for prolonged steroid therapy. It is generally well-tolerated; common side effects include temporary dryness and conjunctivitis, with rare long-term risks like cataracts and a very small theoretical risk of radiation-induced cancer. RT benefits are rarely immediate and improved symptoms are typically observed several weeks to months after the treatment. GO is treated with the retrobulbar space considered as clinical target volume (CTV). Retrobulbar RT is carried out either with lateral opposing fields or with intensity modulated radiotherapy (IMRT) while protecting the radiosensitive lenses considered as organs at risk (OAR). The dose concept should be adapted to the respective phase of the disease: in the early purely inflammatory phase a single dose 0.3-2.0 Gy applied in 8 daily fractions up to a total dose of 2.4-16 Gy is sufficient and well tolerated; in the more advanced inflammatory to fibrotic phase single doses of 1.8-2.0 Gy applied in 8-10 fractions 5 times weekly up to a total dose of 16-20 Gy are required to gain improvement of symptoms. To avoid severe ophthalmologic symptoms, the efficacy of radiation could also be improved by using a reduced single dose of only 1 Gy and extending the duration of therapy with the radiation applied only once a week. In GO with manifest ocular muscle dysfunction, antiproliferative external beam RT has a Grade B recommendation, supported by Level 2 evidence.