Particularly, plasma ET-1 levels were higher in primary open-angle glaucoma (POAG) (SMD: 0.87, 95% CI: 0.09–1.65, p < 0.05), normal-tension glaucoma (SMD: 0.86, 95% CI: 0.27–1.46, p = 0.05), and angle-closure glaucoma patients (SMD: 1.03, 95% CI: 0.43–1.63, p < 0.001) compared to healthy controls. This evidence concerns the gene EDN1 and low tension glaucoma.