A 20-year multicentre retrospective review of optic nerve sheath fenestration outcomes

Abstract

Background: Optic nerve sheath fenestration (ONSF) longitudinal outcomes remain unclear and are vital in the assessment of vision failure in patients with raised intracranial pressure (ICP). Furthermore, limited observational data exists regarding its use in other causes of raised ICP.

Objective: To determine the efficacy and safety of ONSF for idiopathic intracranial hypertension (IIH), cerebral venous sinus thrombosis (CVST), and other indications.

Method: Multicentre study from a tertiary hospital and specialty eye referral hospital in Melbourne, Australia, from July 2000 to December 2020. A total of 116 eyes from 70 patients undergoing ONSF were retrospectively reviewed with patient demographics, surgery indications, visual acuity (VA), visual fields, fundus photos of optic discs, retinal nerve fibre layer (RNFL) thickness, average thickness of optic discs on optical coherence tomography (OCT), and complications recorded. Parametric tests were used to compare the treatment groups pre- and post-operatively.

Results: A total of 116 eyes from 70 patients underwent ONSF, which involved 92 eyes with IIH, 9 eyes with CVST, and 15 eyes with other aetiologies ('Other'). Post ONSF, there was a best corrected visual acuity (BCVA) improvement or stabilisation in 84% of patients in all groups, with 50% achieving a BCVA of 6/6 or better at the final follow-up. RNFL, visual fields, and fundus grades all trended towards improvement, with most improvement noted by day 360. Common complications included transient diplopia (n = 29, 25%) and worsening of visual function requiring further cerebrospinal fluid (CSF) diversion procedures (n = 20, 17%). Complications were most significant in the 'Other' group with 1/3 of eyes requiring further CSF diversion procedures.

Conclusion: Our data demonstrates effectiveness in the use of ONSF in papilloedema with visual failure due to IIH or CVST and when other CSF diversion procedures or medical therapies have failed.

Keywords: cerebral venous sinus thrombosis; idiopathic intracranial hypertension; optic nerve sheath fenestration.

Figure 1.

Visual acuity of all optic nerve sheath fenestration eyes. (a) Longitudinal VA (logMAR) with pre- and post-operative recordings, (b) VA changes from baseline to last follow-up, (c) best corrected visual acuity at final follow-up. VA, visual acuity.

Figure 2.

Visual field MD of (a) Overall ONSF group over time and (b) proportions of patients with improvements in MD from baseline. IIH, idiopathic intracranial hypertension; MD, mean deviation; ONSF, optic nerve sheath fenestration.

Figure 3.

Peripapillary RNFL of (a) overall ONSF group over time and (b) subgroup of IIH patients, whereby the values depicted are the mean measured in micrometers. IIH, idiopathic intracranial hypertension; ONSF, optic nerve sheath fenestration; RNFL, retinal nerve fibre layer.

Figure 4.

Fundus grading of (a) overall ONSF group over time and (b) fundus gradings in the IIH patients, whereby the values depicted on the plot are the mean. IIH, idiopathic intracranial hypertension; ONSF, optic nerve sheath fenestration.