1 I INTRODUCTION
Radiation therapy (RT) has played an essential role in significantly improving outcomes for many pediatric brain tumors.1-5However these cures come at a cost, with significant radiation-related late effects including neurocognitive deficits,6second neoplasms,7 cerebral vasculopathy and endocrinopathies,8 even with newer modalities of radiation like protons.
The Childhood Cancer Survivor Study (CCSS) reported that when compared to their siblings, survivors of childhood cancer, more than 5 years off-therapy, had more than ten times the risk for cataracts, and more than double the risk of developing glaucoma, legal blindness and double vision.9 There was a significant dose-associated risk for these ocular complications, with radiation to the eye. There is an increased risk of cataract with radiation to the lens, at doses as low as 50 cGy.10 The literature describes an increased risk of ocular complications like cataract after total body irradiation (TBI) prior to bone marrow transplant,11-16 and after orbital radiation for other childhood cancers like sarcomas,17 and retinoblastoma.18However data regarding these complications for children with brain tumors who receive radiation, is more limited. Moreover, the existing literature pertains to patients treated with “photon” radiation, treated largely prior to the advent of modern techniques which deliver radiation more precisely. There is very limited data regarding the incidence of ocular complications after treatment with protons, a newer modality of radiation, which is now widely used for the treatment of children with brain tumors, due to absence of an exit dose and the potential to spare healthy tissue that is not in the target field.19
The primary aim of our study was to determine the incidence, timing and risk factors for the development of ocular complications in children with brain tumors after proton radiation, to better inform screening and follow-up, as well as to devise strategies to minimize the risk of these late-effects. The secondary aim was to describe the visual function of children after the completion of treatment that included cranial radiation, for brain tumors.