Correlation between optical coherence tomography angiography measured vessel density and retinal nerve fiber layer thickness in moderate primary open angle glaucoma cases and normal controls

: Aim of this study was to establish a correlation between findings obtained from Optical Coherence Tomography Angiography (OCT-A) and Retinal Nerve Fiber Layer (RNFL) thickness measurements in a series of moderate Primary Open Angle Glaucoma (POAG) cases and normal controls. In this observational cross-sectional study a total of 100 eyes were included, comprising 50 eyes with glaucoma and 50 control eyes without glaucoma. All participants underwent comprehensive anterior and posterior segment evaluations, intraocular pressure (IOP) measurement using Goldmann applanation tonometer, gonioscopy, visual field testing, and OCT imaging, which included OCT-A. The OCT-A imaging was performed using the RTvue XR Avanti by Optovue. Two types of analysis were conducted: a comparative analysis between the normal and glaucomatous groups using an unpaired t-test to assess differences in RNFL thickness and vessel density values, and a correlation analysis within each group to examine the strength of correlation between RNFL loss and reduction in vascular density. The results showed a significant reduction in vessel density index in all quadrants of glaucomatous eyes compared to normal eyes. Moreover, this reduced vessel density was found to be significantly correlated with the reduction in RNFL thickness in glaucoma patients. Specifically, the uperior and inferior quadrants exhibited the strongest correlation with each other. The severity of vascular compromise demonstrated a significant correlation with the extent of retinal nerve fiber loss in patients with glaucoma. OCT-A can serve as a valuable adjunct in the diagnosis of glaucoma and monitoring its progression.