To maintain normal function, the eye must maintain a certain pressure, which we call intraocular pressure. The maintenance of intraocular pressure depends mainly on the continuous production and drainage of a clear fluid (atrial fluid) in the eye. If the atrial fluid is not drained properly, the intraocular pressure will rise and the optic nerve and visual function will be damaged, even leading to blindness. Normal IOP ranges from 10-21 mmHg, with an average value of 16 mmHg. Glaucoma is a group of diseases characterized by optic nerve atrophy and visual field defects, and pathologically increased IOP is its main risk factor. Glaucoma is now recognized as one of the major blinding eye diseases, has a genetic predisposition, and is the second leading cause of blindness. The damage to visual function caused by glaucoma is irreversible. In many early stages of glaucoma, there is often no obvious manifestation, so it is easy to be ignored by the patient, and by the time the patient realizes it, the condition is often very serious, so glaucoma has a significant impact on vision. If glaucoma is detected early and treated effectively, it is possible to maintain useful visual function throughout the patient’s life. It is important to note that there is a type of glaucoma in which the patient’s IOP is never high, but glaucoma can also develop because the optic nerve is less tolerant of IOP.