The visual impact of fractionated stereotactic conformal radiotherapy on seven eyes with optic nerve sheath meningiomas

Background: Treatment of primary optic nerve sheath meningiomas (ONSMs) remains controversial. Although recent studies have suggested a favorable outcome of radiotherapy, controlled data on the efficacy of fractionated stereotactic conformal radiotherapy (SCRT) in primary ONSMs are still lacking. Methods: Seven eyes treated with SCRT (total dose: 54 Gy) were compared with six eyes that were not treated because of patient or physician preference. The indication for intervention was deterioration of visual function with or without imaging evidence of tumor progression. Patients with secondary ONSMs and those with neurofibrotnatosis type 2 were excluded. The mean follow-up period was 57 months for the treated eyes and 61 months for the untreated eyes. Results: Among the seven treated eyes, visual acuity improved in six, five of which sustained improvement of three or more Snellen lines. One eye deteriorated by two lines. Visual field improved in four eyes, remained stable in two, and deteriorated in one. Four untreated eyes showed worsening of visual acuity and two remained stable. Visual field deteriorated in three eyes and was stable in three. None of the untreated eyes experienced improvement in visual acuity or visual field. No complications of treatment were documented. Conclusions: In agreement with previous reports, these results indicate that SCRT is superior to observation in its impact on visual function in eyes with primary ONSMs.