Predictors of visual outcome in Idiopathic Intracranial Hypertension: observations from a retrospective cohort in Germany

Background Idiopathic intracranial hypertension (IIH) is a rare secondary headache disorder. It is characterized by increased intracranial pressure without an identifiable cause and can potentially cause visual impairment due to damage to the optic nerve. This study aimed to evaluate clinical characteristics and to identify risk factors of permanent and progressive deterioration of visual function in a German IIH cohort. Methods This is a retrospective observational study of IIH patients who were diagnosed between 2004 and 2020 at our tertiary care neurological department. Ophthalmologic findings, clinical characteristics and treatment strategies were recorded. Visual outcomes were assessed at a minimum follow-up of 6 months after IIH diagnosis. Regression analysis was utilized to evaluate potential risk-factors of poor visual outcome, defined as 1) worsening of ophthalmologic findings and/or 2) persistent visual impairment. Results The patient cohort comprised 191 consecutive IIH patients. Cohort characteristics and clinical findings were consistent with prior studies. Ophthalmologic follow-up was available in 90 patients. Here, poor visual outcome occurred in 36% of patients. In regression models, male sex was independently associated with a greater risk for poor visual outcome (OR: 7.2, p = 0.028). Patients with moderate papilledema at baseline had a lower likelihood for poor visual outcome than patients with lower degree papilledema (OR: 0.2, p = 0.016). Surgical intervention (primarily by ventriculo-peritoneal shunt) was associated with a lower risk of poor visual outcome (OR: 0.21, p = 0.09), mediating the relation between papilledema and visual outcome. Neither age, BMI nor cerebrospinal fluid opening pressure were associated with the visual prognosis. Conclusions One third of patients in the follow-up cohort experienced worsening of ophthalmologic findings or visual impairment. Male sex may predispose IIH patients to visual impairment. Moderate papilledema at baseline reduced the risk of poor visual outcome, partially due to surgical therapy during the follow-up period. This study highlights the importance of timely intervention in patients with moderate papilledema and the need for reliable outcome predictors in IIH. Trial registrations: Trial registration is not applicable: This observational study reports retrospective documentations of clinical routine data. It does not classify as a clinical trial.