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.