Optic nerve sheath fenestration (ONSF) has gained attention as surgical method of choice in patients with idiopathic intracrial hypertension (IIH) and progressive visual loss despite medical treatments. However, effect of different factors on visual outcome has remained illusive. In this study we aimed to investigate the effect of different pathophysiologic factors in patients with IIH that underwent ONSF.

this was a prospective interventional study on patients with IIH that were referred to Oculo-Facial clinic of one senior oculofacial surgeon (F.P.) and underwent ONSF from May 2013 to December 2016. All patients with established diagnosis of IIH based on modified Dandy criteria that showed papilledema and progressive optic neuropathy or acute/subacute profound visual loss were enrolled. Comprehensive ophthalmology exam including best corrected visual acuity, extra-ocular movements, fundus exam and assessment of papilledema based on Frisen grading, OCT, visual field perimetry, and also neurology evaluations including exam, brain MRI and measurement of ICP were performed before and after ONSF.

Thirty three patients were enrolled. Mean age was 33.4 (SD 15) year. Mean BCVA improved after ONSF (p=0.027). Papilledema in operated (p=0.0001) and opposite eye (p=0.005) improved after ONSF. Multivariate analysis showed that time between visual symptoms and ONSF was the independent factor that showed negative and significant correlation with the visual outcome. No remarkable complication was observed.

ONSF was effective and safe in treatment of patients with IIH papilledema and progressive visual loss. Earlier ONSF was associated with better visual outcome.