Unilateral Optic Nerve Sheath Fenestration in Idiopathic Intracranial Hypertension: A 6-Month Follow-Up Study on Visual Outcome and Prognostic Markers

Abstract

Loss of vision is a feared consequence of idiopathic intracranial hypertension (IIH). Optic nerve sheath fenestration (ONSF) may be an effective surgical approach to protect visual function in medically refractory IIH. In this study, we evaluate the impact of unilateral superomedial transconjunctival ONSF on bilateral visual outcome using a comprehensive follow-up program. A retrospective chart review of IIH patients who underwent unilateral ONSF between January 2016 and March 2021 was conducted. Patients fulfilling the revised Friedman criteria for IIH and who had exclusively received ONSF as a surgical treatment were included. Main outcomes were visual acuity (VA); perimetric mean deviation (PMD); papilledema grade; and optic nerve head elevation (maxONHE) 1 week, 2 weeks, and 1, 3, and 6 months after surgery. VA (p < 0.05), PMD (p < 0.05), papilledema grade (p < 0.01), and maxOHNE (p < 0.001) were improved after 6 months on both the operated and non-operated eye. Prolonged surgical delay impedes PMD improvement (r = -0.78, p < 0.01), and an increasing opening pressure initiates a greater ganglion cell loss (r = -0.79, p < 0.01). In this small case series, we demonstrate that unilateral superonasal transconjunctival ONSF is a safe procedure with an effect on both eyes. Optic nerve head elevation and PMD are feasible biomarkers for assessing early treatment efficacy after ONSF.

Keywords: automated perimetry; idiopathic intracranial hypertension; optic nerve head; optic nerve sheath fenestration; optical coherence tomography; papilledema.

Figure 1

Optic nerve sheath fenestration and primary outcomes: Continuous data from baseline to 6 months. (a) Mean best corrected visual acuity (BCVA) for the operated and fellow eye improved 6 months postoperatively (p < 0.05). However, an improvement could already be observed after 1 month. (b) Perimetric mean deviation (PMD) improved after 1 month in the operated eye (p < 0.05) and after 6 months in the fellow eye (p < 0.05). There was no further improvement in PMD from 1 month to 6 months in any of the eyes (p > 0.5). (c) The mean modified Frisén papilledema grade improved in both eyes after 2 weeks (p < 0.05) and continued to improve until the 6-month follow-up, with a statistically significant change from 1 month to 6 months. (d) The maximum optic nerve head elevation (maxONHE) obtained from optical coherence tomography was reduced 1 week postoperatively (p < 0.001). In the fellow eye, a statistically significant reduction was reached after 1 month. A further reduction was observed from the 1-month to the 6-month follow-up (p < 0.05). (a–d) Repeated measures mixed-effects model followed by Dunnett’s Test. Data are presented as mean with 95% confidence interval. * = p < 0.05, ** = p < 0.01, *** = p < 0.001, **** = p < 0.0001.