Optic nerve sheath fenestration in IIH associated with improved visual function and reduced papilledema

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Frontiers in Medicine Published April 6, 2026 Medically reviewed April 26, 2026 DOI ↗ By Dr. Lars van Dijk, PhD · Surgical, Procedural & Diagnostic

Key Takeaway

Consider OCT metrics for monitoring IIH patients post-ONSF, but note evidence is from a retrospective case series.

A retrospective case series evaluated 35 patients (70 eyes) with idiopathic intracranial hypertension who underwent bilateral optic nerve sheath fenestration. Structural and functional outcomes were assessed at baseline and at 6, 12, and 24 weeks postoperatively using optical coherence tomography (OCT) metrics and visual field testing.

Optic nerve head swelling measures and peripapillary retinal nerve fiber layer (RNFL) thickness showed significant reductions over time (p < 0.05). Best-corrected visual acuity and visual field mean deviation improved during follow-up. However, macular ganglion cell layer metrics declined, and cup volume did not show statistically significant change. Correlations between RNFL/macular metrics and visual field indices strengthened over time and were strongest by 24 weeks.

Safety and tolerability data were not reported. Key limitations include the retrospective, single-arm case series design without a control group. The authors note that early RNFL values may be confounded by edema, and macular GCL decline may reflect delayed neuroaxonal loss or unmasking as edema resolves rather than edema resolution alone.

For practice, this suggests OCT-derived parameters, particularly RNFL and macular ganglion cell metrics, may be useful for longitudinal postoperative monitoring in IIH patients after ONSF. However, the observational nature of this evidence and lack of comparative data limit definitive conclusions about the procedure's effectiveness relative to other treatments.

Study Details

Study typeCohort

EvidenceLevel 3

PublishedApr 2026

View Original Abstract ↓

BackgroundIdiopathic intracranial hypertension (IIH) is characterized by elevated intracranial pressure (ICP) without an identifiable cause and may lead to optic nerve damage and permanent vision loss. We evaluated longitudinal structural and functional outcomes after optic nerve sheath fenestration (ONSF) and how Optical Coherence Tomography (OCT)–visual function relationships evolve over early postoperative follow-up.MethodsThis retrospective case series included 35 patients (70 eyes) with IIH who underwent bilateral ONSF. Structural and functional measures were assessed at baseline and at 6, 12, and 24 weeks postoperatively, including best-corrected visual acuity (BCVA) recorded on a 0–10 decimal chart, standard automated perimetry indices (mean deviation (MD), visual field index (VFI, pattern standard deviation), and spectral-domain OCT metrics (peripapillary retinal nerve fiber layer (RNFL) thickness and macular ganglion cell layer (GCL) measures. Pearson correlations were used to evaluate associations between OCT parameters and visual function at each time point.ResultsOCT demonstrated significant reductions in optic nerve head swelling measures and peripapillary RNFL thickness over time (p < 0.05), consistent with postoperative improvement in papilledema. Macular GCL metrics also declined over follow-up, which may reflect delayed neuroaxonal loss and/or unmasking as edema resolves rather than edema resolution alone. BCVA and MD improved over follow-up, with several endpoints showing the largest change by approximately 12 weeks followed by stabilization through 24 weeks. Correlations between RNFL/macular metrics and visual field indices (VFI and MD) strengthened over time and were strongest by 24 weeks, consistent with increasing structure–function concordance as postoperative edema improves. Cup volume did not show statistically significant change.ConclusionONSF was associated with improvement in papilledema-related structural measures and visual function in vision-threatening IIH. OCT-derived parameters, particularly RNFL and macular ganglion cell metrics, are useful for longitudinal postoperative monitoring; early RNFL values may be confounded by edema, while later measurements better reflect axonal status and align more closely with visual function.