Diagnostic ability of superficial vascular density measured by optical coherence tomography angiography to differentiate high myopic eyes from eyes with primary open angle glaucoma.

Purpose: To determine if high myopia and glaucoma can be differentiated based on the measurement of superficial vascular density in the peripapillary and macular areas by using Optical Coherence Tomography Angiography (OCTA). Methods: This prospective, observational, cross-sectional, comparative study was conducted on patients between 40 and 60 years of age diagnosed as primary open-angle glaucoma (POAG) or high myopia and compared with age-matched controls. The main outcome measures were the difference in SVD% in peripapillary and macular areas in POAG and high myopic eyes. Detailed ophthalmic examination and OCTA of the disc and peripapillary area and macula were performed. The SVD in each zone was calculated using ImageJ software and their difference were analyzed. Results: In total, 128 eyes of 70 patients were enrolled. Peripapillary SVD% in controls was 45.07 ± 3.44, 40.36 ± 8.27 in high myopia, and 31.80 ± 9.008 in POAG. The mean difference in peripapillary SVD% of POAG to control was - 13.479, of POAG to high myopia was -8.777 (both P < 0.001), and of high myopia to controls was -4.701 (P = 0.012). Macular SVD% in controls was 27.30 ± 3.438, 22.33 ± 6.011 in high myopia, and 21.21 ± 5.598 in POAG. The mean difference in macular SVD% of POAG to controls was -6.088, of high myopia to controls was -4.965 (both P < 0.001), and of POAG to high myopia was -1.122 (P = 0.984; not statistically significant). Conclusion: OCTA is a useful diagnostic tool in distinguishing glaucomatous and myopic eyes. The measurement of peripapillary SVD has a greater discriminatory ability than that of the macular area.