Late retinal complications of radiation therapy for nasal and paranasal malignancies: Relationship between irradiated-dose area and severity

Purpose: Radiation-induced cataract, once a notorious ocular complication o f radiation therapy, is no longer considered a severe complication, because visual acuity can be restored by surgical treatment without significant co mplications. Late retinal complications of retinopathy and glaucoma, for wh ich there is no effective method of treatment, have become serious complica tions of radiotherapy of the head and neck. We retrospectively investigated the risk of late retinal complications of radiotherapy for nasal and paran asal malignancies according to the radiation dose and area of the retina ir radiated. Methods and Materials: Between October 1982 and May 1996, 43 eyes of 25 pat ients were exposed to fractionated external-beam irradiation for treatment of advanced nasal and paranasal cancer. None of the patients had tumor inva sion into the eyes. The patients were followed ophthalmologically for a min imum of 2 years (range 2.0-11, mean 4.5, median 3.3). The radiation dose an d area of the retina irradiated were estimated from the dose distribution f igures calculated using the portal films and CT scan. Results: Major late adverse effects of radiotherapy were observed in the re tina in 9 of 43 eyes (in 8/25 patients). Radiation retinopathy was observed in 7 eyes, and the cumulative incidence was 25%. The median interval befor e the onset of symptoms attributable to retinopathy was 32 months (range 16 -60). Neovascular glaucoma developed in 3 of the 43 eyes, with a cumulative incidence of 7%. The median period to the onset of symptoms attributable t o glaucoma was 22 months (range 16-26), Obstruction of the central retinal artery,vas observed in 1 eye. The irradiation doses to the retinas that dev eloped late complications ranged between 54-75 Gy (mean 61, median 61). No patients who received less than 50 Gy developed retinal complications. The retina in 21 eyes was exposed to a dose of 50 Gy or more. In 13 of the 21 e yes, 60% or more of the retina was irradiated, and 8 of the eyes (62%) in t his group (greater than or equal to 50 Gy, greater than or equal to 60%) de veloped severe retinal complications, whereas such complications only devel oped in 1 of the 8 eyes (13%) in the other group (greater than or equal to 50 Gy, greater than or equal to 60%). The results suggest that the radiatio n dose and area irradiated are the most important factors in the developmen t of severe complications. Conclusion: Radiation-induced retinopathy and glaucoma are more serious lat e complications than cataracts, which are easily treated with surgery. We i nvestigated the risk of late retinal complications of radiotherapy, and our findings suggested that the radiation dose and area irradiated are the mos t important factors in the development of severe complications. We recommen d that the radiation dose and area of the retina irradiated be minimized in patients at risk of eye complications, and the patients should be closely followed by periodic ophthalmologic testing after treatment. (C) 1999 Elsev ier Science Inc.