Studies by Aung et al. [48],Yao et al. [55] and Liu et al. [56] revealed that the association of OPA1 variants with POAG may be limited to patients with normal tension glaucoma, suggesting that a genetic mechanism favoring OPA1 would have a greater role in the pathophysiology of NTG than HTG. This evidence concerns the gene OPA1 and open-angle glaucoma.