Evaluation of Peripapillary and Macular Vessel Density following Intraocular Pressure Reduction Using Optical Coherence Tomography Angiography

Abstract

Purpose : The effects of intraocular pressure (IOP) reduction on retinal vessel density (VD) in glaucoma patients undergoing treatment are not fully understood. The purpose of this study is to determine if detectable changes in VD, as measured by optical coherence tomography angiography (OCTA), occur as result of IOP lowering therapy from either a prostaglandin analogue (PGA) or trabeculectomy surgery.

Methods : 6x6mm Spectral Domain OCTA images of the superficial macula and the radial peripapillary capillaries were obtained (Zeiss, Dublin, CA, Cirrus 11.0.0.23113). Images were quality graded then quantified using prototype software. OCTA images of primary open angle glaucoma patients who experienced >20% IOP reduction 3-6 months after treatment with a PGA or trabeculectomy were included. The Wilcoxon Signed Rank Test was used to compare VD change before and after treatment initiation. VD change was compared to the within eye coefficient of repeatability (CRw).

Results : 42 surgically treated eyes (37 patients) and 66 PGA treated eyes (35 patients) underwent OCTA imaging at baseline. After exclusion for image quality and follow-up, 18 surgically treated eyes (17 patients) and 12 PGA eyes (9 patients) were included in the final analysis. The median change in peripapillary VD was -0.0084 (min: -0.0660, max: 0.0578) among trabeculectomy eyes (p=0.958) and -0.0073 (-0.0409, 0.0736) for the PGA eyes (p=0.885) after 3-6 months. Change in macular VD was 0.0121 (-0.0174, 0.0254) for trabeculectomy eyes (p=.230) and -0.0018 (-0.0193, 0.0320) for PGA eyes (p=0.493) during the study period. See Table 1. Based on our prior studies (Lee et al 2021, Vorperian et al 2022 in submission), CRw is 0.087 for peripapillary VD and 0.018 for macular VD.

Conclusions : No significant change in peripapillary and macular VD was seen for either group 3-6 months after IOP reduction. The median differences when compared to the CRw per region are lower, suggesting that the observed differences may be attributable to intersession variability. Further study is needed to determine the utility of macular and peripapillary VD on OCTA as a biomarker for monitoring disease progression and therapeutic efficacy after intervention.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Median Change in Vessel Density (VD), Intraocular pressure (IOP), and follow up of eyes per treatment group, trabeculectomy and prostaglandin analog (PGA), in each region.