A Novel Framework to Define and Prognosticate Visual Outcomes Following Fractionated Radiation Therapy for Optic Nerve Sheath Meningiomas

Abstract

Abstract Objective: Optic nerve sheath meningiomas (ONSMs) are rare tumors that can cause significant visual problems due to their location along the optic nerve. Fractionated radiation therapy (RT) is the standard treatment, but data related to the discussion of visual outcomes are limited. No comprehensive guidelines exist to classify or define visual outcomes postoncological therapy. We propose the Wills Eye Visual Outcomes (WEVO) classification system to evaluate visual outcomes based on visual acuity, visual fields, and color vision status. Methods: We retrospectively reviewed visual and radiographic outcomes for 29 ONSMs in 27 patients who were treated with fractionated stereotactic RT between 1997 and 2012. Results: Median radiation dose of 52.2 Gy (range, 50.4-55.8). Median visual and radiographic follow-ups were 7 years (range, 1-22 y) and 6 years (range, 2-18 y), respectively. Ultimately, progression-free survival was 100% at the last follow-up. Using the WEVO criteria, visual outcomes were determined to be improved, unchanged, or worsened. At the last follow-up, 11 cases had improved vision, 10 cases had unchanged vision, and 8 cases had worsened vision. Patients aged > 46, those presenting with large visual field defects, and those with color vision defects were more likely to have worsened visual outcomes following RT. Poor visual acuity at treatment and an observation time of > 6 months from presenting with symptoms to RT did not significantly correlate with worsening visual outcomes. Conclusion: We provide groundwork to predict individualized risk of blindness or worsened visual outcomes in the radiation of ONSMs.