VAN LINT Michel
To demonstrate a case of radiation toxicity diagnosed only 29 years after orbital radiation therapy.
Our patient is a 29 year old male who was being followed in the ocular surface clinic for keratoconjunctivitis sicca due to previous orbital radiation therapy to the left eye for retinoblastoma. At the age of 5 months he had been diagnosed with bilateral sporadic retinoblastoma. The right eye had been enucleated and for his left eye he had received external orbital radiation therapy. During a follow-up visit he complained of central metamorphopsia that had been present for two weeks. His visual acuity was 20/40. Macular optical coherence tomography (OCT) scan then showed extensive macular edema. No previous OCT scans were available for comparison. Fluorescein angiography failed because of focusing issues secondary to pronounced orbital fat atrophy. The fundus revealed some micro-aneurysms, but no signs of neovascularization or other vascular abnormalities. A blood test ruled out diabetes mellitus.
Intravitreal anti-VEGF injection (bevacizumab) was attempted. The macular edema partially improved, but failed to respond to the second injection. We then switched to intravitreal triamcinolone acetonide. Three weeks later the OCT scan showed only minimal residual intraretinal fluid cysts in the temporal perifoveal area and visual acuity had improved to 20/25.
Radiation retinopathy can present symptomatically as late as 29 years post radiotherapy. In our case, the retinal edema has probably been longstanding since his refractive error changed dramatically after treatment, necessitating a new prescription for his glasses.