Everyone above the age of 40 years is at risk for glaucoma, particularly in those with diabetes, a familial history of glaucoma and a history of eye injury. It is one of the dominating causes of blindness in worldwide. Owing to its asymptomatic nature, a significant, irreversible and progressive centripetal visual field loss subsequent to the damage of the optic nerve head and the loss of retinal nerve fiber layer are commonly found in newly diagnosed individuals. Today, the main modifiable treatment option to delay the progression of glaucoma and preserve the visual field remains relying on the reduction of intraocular pressure. However, rigorous control of intraocular pressure in many glaucoma patients failed to prevent the deterioration of glaucomatous changes, and a minuscule proportion of normal tension glaucoma subjects had developed an onset of visual field loss . Therefore, elevated intraocular pressure is now considered as an important, but not the sole risk factor causing retinal ganglion cells death, meaning that certain risk factors must be involved in the pathogenesis of glaucoma.