Effect of optic nerve sheath fenestration on papilledema of the operated and the contralateral nonoperated eyes in idiopathic intracranial hypertension.

PURPOSE To evaluate the effect of optic nerve sheath fenestration (ONSF) on papilledema grade in the operated eyes and the contralateral nonoperated fellow eyes in patients with idiopathic intracranial hypertension (IIH). DESIGN Retrospective review. PARTICIPANTS A total of 78 patients underwent ONSF, and 20 patients served as controls. METHODS Charts of patients with IIH who had ONSF at the University of Iowa Hospital and Clinics were reviewed for age, gender, body mass index, and clinical findings. Optic disc photographs were graded by a masked observer using the Frisén papilledema grading scale at preoperative baseline and postoperatively at 2 weeks, 3 months, 6 months, and 12 months follow-up. Wilcoxon signed-rank test was used to examine the change in papilledema grade in both operated and nonoperated eyes at each time point. MAIN OUTCOME MEASURES Grade of papilledema. RESULTS Sixty-two patients (52 women and 10 men) with a mean age of 32 years (range, 13-57 years) underwent unilateral ONSF. The median grade of papilledema for operated and nonoperated eyes was 3 and 2, respectively, at preoperative baseline. Postoperatively the grade was 2 in each eye at 2 weeks (P<0.0001 and <0.0002 for operated and nonoperated eyes, respectively), 1 in each eye at 3 months (P<0.0001 for both operated and nonoperated eyes), 1 in each eye at 6 months (P<0.0001 for both operated and nonoperated eyes), and 0.5 and 1 for operated and nonoperated eyes, respectively, at 12 months follow-up (P<0.0001 for both operated and nonoperated eyes). There was no significant difference in grade of disc edema or reduction of disc edema on the basis of age, gender, or body mass index. CONCLUSIONS Unilateral ONSF significantly decreases the grade of papilledema in both ipsilateral (operated) and contralateral (unoperated) eyes. The reduction of the papilledema and the stability of visual field in the contralateral (nonoperated) eyes suggest that bilateral ONSF may not always be necessary in patients with bilateral visual loss and papilledema due to IIH.