Primary open angle glaucoma (POAG) is the most prevalent form of glaucoma, and a major cause of irreversible blindness. POAG is often accompanied by ocular hypertension and characterized by progressive loss of retinal ganglion cells, atrophy of the optic nerve, and visual field loss. To date, at least 20 genetic loci for POAG have been reported. And four causative genes (CYP1B1, MYOC, OPTN, and WDR36) are identified from these loci. In addition, recently, heterozygous NTF4 mutation was associated with the phenotype in a small percentage of patients.