Glaucoma is a group of clinical signs or eye diseases that threaten the visual function of the optic nerve and are primarily associated with elevated intraocular pressure. Typical manifestations are high intraocular pressure, sunken atrophy of the optic nerve papillae, and visual field defects. IOP is the pressure of the contents of the eye acting on the wall of the eye. The statistically normal IOP value is 10-21 mmHg, which represents the physiological IOP range for 95% of the normal population. Clinically glaucoma is divided into three categories: 1. primary glaucoma 2. secondary glaucoma 3. developmental glaucoma Primary glaucoma is the main type of glaucoma and is divided into: closed-angle glaucoma and open-angle glaucoma. Closed-angle glaucoma is further divided into acute and chronic closed-angle glaucoma. Typical signs and symptoms of acute closed-angle glaucoma are severe eye pain, headache, nausea, vomiting, decreased vision, conjunctival congestion, corneal edema, shallow anterior chamber, narrow atrial angle, often dilated pupil, and increased intraocular pressure of 80 mmHg or more. In chronic closed-angle glaucoma, there is no corresponding symptom of rapid increase in IOP. In the early stage, IOP, fundus and visual field are normal, and with the expansion of atrial angle adhesions, IOP increases to a moderate degree, often in the range of 40-50 mm Hg. In the middle and late stages of the disease, there is typical glaucomatous optic nerve papillary damage in the fundus and glaucomatous visual field damage. Primary open-angle glaucoma is also known as chronic open-angle glaucoma and chronic simple glaucoma. It has the following characteristics: (1) the IOP in at least one of the two eyes is consistently ≥ 21 mmHg; (2) the atrial angle is open; and (3) there is typical glaucomatous optic nerve papillary damage and visual field damage. Open-angle glaucoma has a slower progression and is mostly asymptomatic, not easily detected early, and has a greater risk. The concept of hypertension The atrial angle is open, the IOP is usually 21-30 mmHg, and long-term follow-up does not show damage to the optic nerve or visual field. If hypertension is suspected, central corneal thickness measurement should be done. corneal thickness above the standard IOP setting of 520um can overestimate IOP by up to 7~10mmHg. with 5 years of follow-up, 5~10 % develop open angle glaucoma. Glaucoma is a bifocal disease (can develop simultaneously or sequentially), a lifelong progressive, irreversible and blinding eye disease. However, as long as glaucoma is detected early and treated appropriately, most patients can maintain some visual function for life. The following are fundus images of optic nerve damage in progressive glaucoma. a Normal optic nerve cup-to-disc ratio (C/D=0.3) b Pathological cup-to-disc ratio