Repeatability Of Measuring The Vessel Density In Patients With Retinal Vein Occlusion: An Optical Coherence Tomography Angiography Study

Purpose To determine the repeatability of superficial vessel density measurements using Spectral domain Ocular coherence tomography angiography(SD-OCTA) in patients diagnosed with retinal vein occlusion(RVO). Design Prospective observational study. Subjects Patients who visited our retinal clinic from August 2017 to August 2018, diagnosed with RVO were recruited for the study. Methods Two consecutive 3x3 mm pattern scans were performed using the Cirrus HD-OCT 5000 along with AngioPlex software (Carl Zeiss Meditec) in each eye by single skilled examiner. All scans were analyzed using en face OCTA images to measure vessel density (VD) automatically. For further analysis of the effect of central macular thickness(CMT), eyes were divided into two groups according to CMT of 400 mu m (Group 1: CMT > 400 mu m, Group 2: CMT < 400 mu m). To identify factors affecting the repeatability of VD measurements, linear regression analyses were conducted for the coefficient of variation (CV) of VD by investigating demographics and ocular variables. Main outcome measures The intraclass correlation coefficient (ICC), coefficient of variation (CV) of VD measurements. Results A total of 57 eyes from 57 patients were examined: 35 eyes with BRVO and 22 eyes with CRVO. In all 57 eyes with RVO, the ICC and CV of the full VD(VD of 3mm diameter circle) were 0.800 and 10.61%, respectively. Univariate analyses showed that the mean CMT (B, 0.001; p<0.001) and mean ganglion cell-Inner plexiform layer (GC-IPL) thickness (B, -0.002; p = 0.020) were significant factors that affected the repeatability. Multivariate analyses of these two factors showed that only mean CMT was a significant factor. The ICC and CV of the full VD in group 1 (CMT > 400 mu m) were 0.348 and 22.55% respectively. In group 2 (CMT < 400 mu m), the ICC and CV of the full VD were 0.910 and 7.76%, respectively. Conclusions The repeatability of VD measurement in eyes with RVO was reasonably comparable to previous studies. Repeatability of VD measurement was significantly affected by central macular thickness.