Normal intraocular pressure ranges from 10-21mmHg. If it exceeds 21mmHg, it is considered to be increased intraocular pressure. Main symptoms of high intraocular pressure include eye distension, eye pain, tearing, photophobia, blurred vision, nausea, vomiting, headache, etc. High intraocular pressure is a primary diagnostic criterion for glaucoma, but it is not the only standard. Glaucoma can be divided into primary glaucoma, secondary glaucoma, congenital glaucoma, and mixed glaucoma. Primary glaucoma can further be subdivided into open-angle glaucoma and angle-closure glaucoma. Only during an acute attack of angle-closure glaucoma does the intraocular pressure increase, whereas open-angle glaucoma generally does not affect intraocular pressure. Therefore, the diagnosis of glaucoma mainly relies on a comprehensive assessment of the angle of the anterior chamber, intraocular pressure, visual field, visual acuity, and the condition of the optic disc.