The human eye is like a camera. The cornea and lens are transparent windows, equivalent to the lens of a camera, which converge light into the eye. The retina is a very thin layer of tissue located at the base of the eye, like the negative of a camera, and is very sensitive to light, which shines onto the retina for imaging. The optic nerve carries the information from the retina to the brain. The optic nerve is like a cable with numerous “wires” called nerve fibers wrapped around it. Optic nerve fibers are very delicate and are easily damaged by high intraocular pressure and various other adverse neurovascular factors. There is a certain amount of pressure in the eye that we call intraocular pressure or IOP. The anterior segment of the eye is filled with a fluid called atrial fluid, which is colorless and transparent. The atrial fluid is constantly produced and drained to maintain a constant pressure within the eye. Most of the atrial fluid is drained out of the eye through a structure called the atrial horn, and if the drainage of atrial fluid is obstructed, the pressure in the eye increases. This is similar to how the pressure inside a water pipe increases when we plug the opening with our finger. Normal intraocular pressure is important for maintaining the visual functions of the eye, such as maintaining the shape of the eye, the optical properties of the refractive imaging system of the eye, and the circulation of blood within the eye. It is commonly believed that when intraocular pressure exceeds a certain limit, it can compress the optic nerve, causing optic nerve atrophy and impairment of visual function. Glaucoma is a disease in which the optic nerve is damaged, usually caused by high intraocular pressure, and its visual impairment is mainly characterized by a characteristic visual field defect, which is a reduction or loss of the spatial extent seen by the eye. This damage is irreversible, which means that the atrophied optic nerve of glaucoma patients cannot be restored to function at this time, so early detection and timely treatment are necessary. Glaucoma, like hypertension, coronary heart disease, diabetes and other familiar systemic diseases, is a lifelong disease that must be treated for life as long as the disease is present. It is generally believed that glaucoma will not cause blindness as long as it is detected early, treated early, and followed up regularly.