Analysis and comparison of the natural history of visual field changes in ten untreated and ten irradiated chiasmal gliomas revealed (1) no consistent relationship between the pattern and severity of field defects and the location, size, or extent of the tumor, and (2) a monotonously stable course of field defects and visual acuity in most cases. Over prolonged periods of follow up, the untreated patients fared as well as the irradiated group. There was no clinical evidence to support the alleged efficacy of radiation therapy for these indolent congenital tumors.
Glaser JS, Hoyt WF, Corbett J. Visual Morbidity With Chiasmal GliomaLong-Term Studies of Visual Fields in Untreated and Irradiated Cases. Arch Ophthalmol. 1971;85(1):3-12. doi:10.1001/archopht.1971.00990050005002