The normal value for intraocular pressure is around 11-21mmHg. If it is below 11mmHg, there is often not much of a problem in the eye, and usually people who have undergone corneal laser surgery will have a lower IOP. If the IOP is higher than 21mmHg, a detailed examination is needed. High intraocular pressure is a common manifestation of glaucoma, and high intraocular pressure may cause glaucoma to develop. If the IOP is higher than 21 mmHg, regular follow-up examinations are needed to find the cause of the high IOP, most commonly visual field and optic nerve OCT examinations. If there is a problem with both tests, a 24-hour IOP curve is needed. If the IOP curve fluctuates widely at the same time, glaucoma is highly suspected. If there is significant damage to the visual field, and the visual field progresses significantly after several follow-up visits, the diagnosis of glaucoma is confirmed. At this point, medication is needed to lower the IOP and maintain it at a normal level in order to slow down the progression of glaucoma.