Long-term visual outcome after chemotherapy for optic pathway glioma in children: Site and age are strongly predictive.

Background: Optic pathway gliomas (OPGs) are commonly noted in pediatric oncology services. Radiotherapy is effective at controlling tumors, but has many undesirable late effects, especially in patients with neurofibromatosis. Chemotherapy is commonly used to preserve vision and delay or eliminate the need for radiotherapy. Despite visual threat being a common reason to initiate chemotherapy in patients with OPG, reports of visual outcome after chemotherapy are not common and reports of long-term visual outcome are even scarcer.

Methods: In a single institution, all patients with OPG who had received chemotherapy or radiotherapy between 1996 and 2013 were identified from hospital databases. Visual, treatment, and radiological data were recorded. Categorized visual acuity was the primary outcome measure.

Results: Of 43 patients identified, visual data were available for 42 patients. Approximately 14% of patients experienced an improvement in visual acuity during therapy, 9% of patients experienced a deterioration, and the remainder were stable. At a mean follow-up of 78 months, 26% of patients were legally blind. Children aged <2 years and patients with a chiasmatic/hypothalamic tumor site were overrepresented in this category. An intraconal location was predictive of poor visual outcome for that eye but was unilateral with normal vision in the contralateral eye.

Conclusions: Risk factors for long-term visual deterioration are young age, chiasmatic/hypothalamic tumor site, and intraconal tumor site for the involved eye. The most common visual outcome for children with OPG after treatment with chemotherapy is stability. This stability is maintained over the long term for >90% of children without these risk factors.