Effect of Mydriatic Administration on Retinal Hemodynamics in Glaucoma: An Optical Coherence Tomography Angiography Study

Abstract

Precis: Pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine resulted in a statistically significant decrease in foveal avascular zone (FAZ) metrics in glaucoma eyes. This observation emphasizes the critical role of pupillary status in interpreting glaucomatous vascular alterations detected by optical coherence tomography angiography (OCTA). Purpose: The purpose of this study was to evaluate the influence of mydriatic eye drops on OCTA parameters in patients with primary open angle glaucoma (POAG). Materials and Methods: A total of 20 POAG eyes and 20 control eyes were recruited in the study. The imaging area on the fundus was visualized by AngioPlex (Cirrus 5000 HD-OCT) using en face view of 3x3 mm and 6x6 mm preview scans. Images were generated before and after the instillation of topical 0.5% tropicamide and 2.5% phenylephrine. Optic nerve head (ONH) perfusion, ONH flux index, macular perfusion density, macular vessel density, and FAZ measurements were consecutively obtained for each session. Differences between the predilation and postdilation measurements were evaluated in POAG patients and controls. Results: POAG eyes showed a statistically significant decrease in the FAZ area from a mean of 0.29-0.25 mm(2) (P=0.037) and FAZ perimeter from a mean of 2.27-2.09 mm (P=0.045) in the OCTA 6x6 mm scan area after tropicamide/phenylephrine instillation. Predilation and postdilation measurements of ONH perfusion and ONH flux index were significantly lower in the glaucoma group compared with controls (P<0.05, for all). Conclusions: Topical pupillary dilation with 0.5% tropicamide and 2.5% phenylephrine results in a statistically significant reduction in the FAZ area and FAZ perimeter in POAG eyes. Further OCTA studies are needed for the diagnostic value of vascular changes due to pupil dilation in glaucoma.