Long-term visual acuity outcomes after radiation therapy for sporadic optic pathway glioma.

Abstract

Children with sporadic optic pathway glioma (OPG) commonly experience a decline in visual acuity (VA). This study aimed to quantify long-term VA outcomes after definitive radiation therapy (RT). From 1997 to 2017, 41 patients underwent RT for OPG and had baseline VA testing. All patients underwent serial VA testing every 3-6months during the first 5years and annually thereafter. The cumulative incidence of VA decline or improvement (per eye) was estimated using death as a competing risk. Mean follow-up was 5years. Most tumors (93%) involved the postchiasmatic optic tracts and/or hypothalamus. Of the tumors tested for BRAF alterations (n = 15), 67% had a BRAF fusion. Median time to VA decline was 20months in the eye with worse vision and 22months in the better eye. For the worse eye, the 5-year cumulative incidences of VA decline and improvement were 17.9% [95% confidence interval (CI) 7-32.8%] and 13.5% (95% CI 4.7-26.7%), respectively. For the better eye, the 5-year cumulative incidences of VA decline and improvement were 11.5% (95% CI 3.5-30.7%) and 10.6% (95% CI 2.6-25.2%), respectively. Visual outcomes did not correlate with radiographic evidence of tumor progression. The 5-year cumulative incidence of VA decline was low. VA decline is most likely to occur within the first 2years after RT and is not associated with radiographic progression of disease, highlighting the need for frequent ophthalmologic exams during this period.