Abstract A 62-year-old woman underwent a second surgery for a WHO grade 1 tuberculum sellae meningioma 4 years after her primary resection. The meningioma affected her right optic nerve, and there was a microscopic residual tumor after the second surgery. Due to the history of recurrence, residual tumor, and visual decline, she was offered postoperative radiation therapy of 1.8 Gy in 29 fractions, with a total dose of 52.2 Gy. Maximum doses to the anterior optic pathway structures were 53.7 Gy to the chiasm, 53.3 Gy to the right optic nerve, and 52.3 Gy to the left optic nerve. Following a transient improvement, her vision rapidly worsened 7 to 8 months later, with only finger counting possible in her left eye and a nearly total visual field loss. Visual acuity was reduced to 20/60 in the right eye, the visual field was reduced (especially in the lower 2 quadrants), and radiation-induced optic neuropathy (RION) was suspected. A rare yet disabling condition that may occur following radiation therapy, RION usually presents with painless, rapid visual deterioration in 1 or both eyes. Treatment options are limited, rendering this a devastating radiotherapeutic complication. Systemic steroids were administered to the patient without visual improvement. Bevacizumab was given as a last effort and, after 3 courses, MRI showed some improvement, with regression of presumed inflammatory changes in both optic nerves. However, the patient’s visual function further deteriorated bilaterally. Three additional bevacizumab courses had no effect, neither visually nor radiographically. This case illustrates that despite precautions, including using doses considered relatively safe when planning radiation therapy, RION might develop and may have devastating consequences. Mitigating treatment options are limited.

Radiation-Induced Optic Neuropathy Following Radiation Therapy for a Recurrent Tuberculum Sellae Meningioma: A Case Report