OPTN and open-angle glaucoma: Since the first POAG-correlated mutation gene (trabecluar meshwork-inducible glucocorticoid response/myocilin; TIGR/MYOC) was identified in 1997 [5,6], there have been three genes reported to be responsible for POAG, i.e., TIGR/MYOC, OPTN (optic neuropathy inducing gene) [7,8], and WDR36 (WD repeat domain 36 gene) [9], with TIGR/MYOC being the most frequently mutated gene [10-13].