Peripapillary Vessel Density Measurement of Quadrant and Clock-Hour Sectors in Primary Angle Closure Glaucoma Using Optical Coherence Tomography Angiography

Background: The purpose of this study was to investigate peripapillary vessel density of primary angle closure glaucoma (PACG) eyes in quadrant and clock-hour sectors, and the diagnostic ability of peripapillary vessel density was also studied. Methods: : This was a cross-sectional study on forty-one PACG patients(50 eyes)and twenty-seven healthy subjects(27 eyes). The optic disc was imaged using a 1050-nm-wavelength swept-source optical coherence tomography system (DRI OCT Triton, TOPCON). Peripapillary vessel density was quantified by imageJ software. Characteristics of peripapillary vessel density of quadrant and clock-hour sectors were analyzed, and diagnostic capability was evaluated by areas under the receiver operating characteristics curves (AUCs). Results: Compared to the control group, four quadrants and each clock-hour sectors of peripapillary vessel density of glaucomatous group decreased to different degrees, and vessel density reduced most at 7 o'clock. Except 4 o'clock, there was not any statistical difference between the diagnostic ability of peripapillary vessel density and peripapillary retinal nerve fiber layer thickness. The inferior quadrant peripapillary vessel density had the best diagnostic value (AUCs0.944), followed by 7 o'clock vessel density (AUCs0.937), average vessel density (AUCs0.926) and 7 o'clock RNFL thickness (AUCs0.922). Conclusions: : In PACG, the diagnostic ability of peripapillary vessel density is equivalent to peripapillary retinal nerve fiber layer thickness. Understanding spatial characteristics of peripapillary vessel density in PACG may be helpful for clinical diagnosis and treatment.