Abstract
Purpose :
Generally orbital radiation with a cumulative dose of 20 Gy (10x2 Gy fractions) and external beam radiotherapy with a cumulative dose of 30 Gy (10 x 3 Gy) is regarded as safe with respect to the development of radiation retinopathy. 2 cases were observed in whom radiation retinopathy was diagnosed 15 years after orbital irradiation and 3 years after whole-brain radiation. In both cases the above mentioned protocols were applied.
Methods :
Clinical evaluation, including general ophthalmological examination, SD-OCT and fluoresceine angiography.
Results :
Case 1: A 55-year-old woman was referred for a cystoid macular oedema (ME) on the left eye (OS). She reported reduced visual acuity (VA) for 1 year. 15 years ago she received radiation for endocrine orbitopathy of the left orbit (total dose: 20Gy, 10x2Gy, within 12 days). BCVA (Snellen) was 1.0p on the right eye (OD) and 1/20 OS. OCT revealed extensive foveal cystoid edema (CFT: 714µm), subfoveal fluid and areas of hyperreflectivity (hard exsudates). Fluorescein angiography (FA) indicated enlargement of the central avascular zone, microaneurysms, teleangiectatic vessels, and a cystic ME. Case 2: A 55-year-old woman was referred for a macular ME on both eyes (OU) after a history of metastatic breast cancer. 3 years ago she underwent whole-brain radiation (total dose: 30Gy, 10x3Gy within 12 days). VA was reduced for 6 months OU. BCVA (Snellen) was 0,5 OD and 0,4 OS. SD-OCT presented a cystoid ME (CFT OD: 479 µm, OS: 737 µm), intraretinal hard exudates and a small line of subretinal fluid OS. FA revealed pericentral microaneurysms, teleangiectatic leaky capillaries OU, and ischemic retinal areas (approx. 2.5 discs) OS. Late phase indicated a cystoid and partially diffuse ME. Intravitreal anti-VEGF-injection in combination with focal laser photocoagulation was indicated.
Conclusions :
The pertinent and clinically relevant problem of precise safety limit definition of radiation seems not to be solved so far. Since our patients did not present any risk factors associated with increased susceptibility to radiation retinopathy (vascular diseases, hypertonia, diabetes mellitus), it may be concluded that the standard doses of orbital radiation or whole brain radiotherapy cannot be regarded as safe. Regular screening of surviving patients after orbital or whole-brain radiation should be performed.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.