Perfused Large Vessel and Capillary Densities in Various Grades of Papilledema Using OCTA Custom Software

Abstract

Purpose : Optical Coherence Tomography Angiography (OCTA) Angioanalytics^TM software has limitations in papilledema including: inaccurate autosegmentation, difficulty identifying the scleral canal border and inability to separate large vessels (LV) from capillaries. The purpose of this study was to apply customized software to overcome these issues and analyze perfused vessel density in various grades of papilledema.

Methods : We performed a prospective cross-sectional analysis of eyes with papilledema using the RTVue XR Avanti^TM OCTA. Images of choroid, radial peripapillary capillary (RPC), nerve head (NH), and vitreous layers were exported to MATLAB^®. The choroid image was used to center a 1.95-millimeter annular ring on the scleral canal opening, and a surrounding 0.75-millimeter peripapillary ring was analyzed. Custom digital subtraction analysis software separated LVs from capillaries and calculated mean perfused LV density (PLVD) and perfused capillary density (PCD) in RPC, NH, and vitreous layers. ANOVAs comparing the results of each layer by papilledema grade were performed, with post-hoc Tukey’s procedure (PHTP) to examine individual relationships.

Results : One eye from each of 56 subjects with papilledema, Frisén grades 0-5 and atrophic papilledema (n = 7, 14, 15, 4, 5, 2, and 9, respectively), was analyzed. ANOVA with LV subtraction analysis revealed significant changes in PCD throughout all three layers (P≤0.04). PHTP showed patterns of decreased PCD in high grade and atrophic papilledema compared to low grade. ANOVA of LV analysis showed significant changes in PLVD within the NH (P=.01) and vitreous (P=0.002) layers. PHTP showed decreased PLVD in high grades within the NH layer and increased PLVD in atrophic subjects within the vitreous layer, when compared to low grade papilledema.

Conclusions : Customized OCTA post-processing software demonstrated significantly decreased PCD across high-grade papilledema and post-papilledema optic atrophy. LV analysis of NH and vitreous layers may reflect changes in LV visibility secondary to changes in peripapillary retinal nerve fiber layer thickness.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

NH Layer - (Left to right) Original OCTA image, OCTA image with vessel separation, and isolated peripapillary ring in low grade (0) and high grade (4) papilledema.