Peripapillary Choroidal Vascularity Index for Differentiating Papilledema from Pseudopapilledema: A Deep Learning–Based Approach

Purpose: To compare the peripapillary choroidal vascularity index (PPCVI) in eyes with papilledema secondary to idiopathic intracranial hypertension (IIH) and pseudopapilledema due to optic disc drusen (ODD) using a novel deeplearning algorithm. Design: Retrospective observational cohort study. Subjects: The study included 30 eyes of 15 patients with papilledema secondary to IIH, 30 eyes of 15 patients with ODD, and 78 eyes of 39 age- and sex-matched healthy controls. All cases of IIH and ODD were confirmed with lumbar puncture and B-scan ultrasonography, respectively. Methods: Optical coherence tomography (OCT) was performed using a 3.4 mm diameter 360-degree peripapillary circle scan. Choroidal segmentation was automatically performed with a deep-learning ResUNet model and a volumetric smoothing algorithm. The CVI was quantified in each peripapillary scan. Statistical comparisons were made between groups, and in IIH patients before and after resolution of papilledema. Linear mixed models were used for analysis. Main Outcome Measures: Mean PPCVI, expressed as a percentage, across study groups and longitudinally in IIH eyes. Results: There were no significant differences among groups regarding age, sex, visual acuity, or intraocular pressure (p > 0.05). Mean PPCVI was significantly reduced in the papilledema group compared to the pseudopapilledema and control groups (31.7% ± 8.4% vs. 39.0% ± 8.1% and 40.7% ± 5.6%, respectively; p < 0.001). After a mean follow-up of 36 ± 12.1 months, IIH patients with resolved papilledema showed a significant increase in PPCVI (34.8% ± 8.0% vs. 31.7% ± 8.4%, p = 0.033), although values remained lower compared to pseudopapilledema and control groups (p < 0.001). Conclusions: Reduced PPCVI could be a potential biomarker for differentiating papilledema from pseudopapilledema. Increase in PPCVI following resolution of papilledema supports its utility as a potential parameter for monitoring disease activity.