An accumulating body of evidence suggests the involvement of ET-1 [20], [21], [41]–[43] and ETB receptors [25], [30], [33], [34], [42], [44]–[46] in the pathogenesis of glaucoma, however a causal link of ETB receptors to neurodegeneration has not been clearly established. This evidence concerns the gene EDN1 and glaucoma.