Background. Extension of cavernous sinus meningiomas can compromise vision by compressing the optic nerves and chiasm. Surgical tumour removal aims to protect vision in the long-term. However, the risks of surgery include transient or permanent damage to the anterior visual pathways. This study aims to 1) analyse the visual status in unilateral cavernous sinus meningioma with extra-cavernous extension, before and after removal of the extra-cavernous portion, without any adjuvant treatment with radiotherapy, 2) identify pre-surgical and early post-surgical prognostic factors for long-term visual outcome and 3) compare these results to previous studies.

Methods. This is a retrospective study of 30 consecutive patients who underwent surgery between 1989 and 2004. Visual acuity, visual fields, and fundi were evaluated before surgery and during the mean follow-up period of 2 years.

Findings. Total visual loss occurred in the ipsilateral eye following surgery in 10% of patients. There was improvement in vision in 23%, no significant change in 27% and worsening in 50% of patients. Pre-surgical visual acuity was not predictive of final visual outcome, but initial optic disc pallor was a poor prognostic factor. In pre-operatively normal contralateral eyes, 10% developed a mild visual deficit (visual acuity = 20/32 or better, and visual field defect ≤4 dB) post-operatively. Where vision in the contralateral eye was affected pre-operatively, 57% improved and 43% were unchanged. Overall, 93% of patients retained good visual function (mild or no visual deficit) in at least one eye, and 40% retained good visual function in both eyes after surgery.

Conclusion. Visual handicap is rare after conservative surgery for cavernous sinus meningioma with supra/laterosellar extension. Since surgery protects contralateral visual pathways from local compression, it may preserve long-term vision in the contralateral eye. Visual outcome in the ipsilateral eye is unpredictable, and may significantly worsen after surgery.