Correlation Between Optic Disc Peripapillary Capillary Network and Papilledema Grading in Patients With Idiopathic Intracranial Hypertension: A Study of Optical Coherence Tomography Angiography

Background: The continued increase in idiopathic intracranial hypertension (IIH) prevalence has many implications for societal health care. Its potential vision-threatening consequences make ophthalmologists key players in its diagnosis and management. Newer technology such as optical coherence tomography angiography (OCT-A) enables evaluation of the branching complexity of the peripapillary capillary plexus, a region where accurate imaging via fluorescein angiography was previously limited. Methods: A cross-sectional, observational study of 23 (46 eyes) consecutive patients with IIH. Peripapillary total vasculature was recorded using commercial OCT-A en face vessel density mapping. In addition, OCT-A blood flow slab was compared with papilledema grading. OCT-A images were analyzed using a customized image analysis protocol using ImageJ software (v1.51w) and Photoshop software (Adobe Systems, CA). SPSS software version 25 was used for statistical analysis (SPSS Inc, IBM, Chicago, IL). Results: Skeletonized vessel density peripapillary capillary plexus was significantly associated with Frisen papilledema grades, OCT retinal nerve fiber layer (RNFL), and macular ganglion cell layer (GCL) thickness with a P < 0.001, P = 0.022, and P = 0.006, respectively. Every point increase in grade was correlated with a decrease of 9.1 pixels/mm2 in vessel density (R = 0.512, β = -0.115 ± 0.029; P < 0.001). Increased papilledema was correlated with an increased retinal blood flow percentage (R = 0.300, β = 2.114 ± 1.013; P < 0.05) and decreased choroidal blood flow (CBF) percentage (R = 0.300, β = 2.114 ± 1.013; P < 0.05). Every point increase in grade was correlated with a decrease in CBF by 47.4%, as calculated using a linear best-fit line inclusive for all of the data points. Conclusions: OCT-A allows for effective visualization and quantification of the peripapillary retinal vasculature. Our results demonstrate a correlation between skeletonized peripapillary density and papilledema grading, OCT RNFL thickness, and GCL thickness. In addition, we show a significant negative correlation between CBF and papilledema grading. These changes provide key findings regarding the pathophysiology of optic neuropathy in papilledema and highlight the potential of OCT-A as a diagnostic tool for papilledema and a clinical marker for detecting early optic nerve damage.