What is intraocular pressure? Intraocular pressure, or intraocular pressure, is the pressure inside the eye, which is the equalized pressure exerted by the contents of the eye on the wall of the eye. What is normal IOP? Normal intraocular pressure is a statistical concept that is derived from the distribution curve of intraocular pressure in a large number of normal people, and then the 95% confidence interval is calculated, which is the range of intraocular pressure in 95% of normal people. The normal range for Chinese people is 10-21 mmHg. Does high IOP necessarily mean glaucoma? Not necessarily. Normal IOP is the IOP range of 95% of normal people, and there are still 5% of normal people with IOP outside this normal range. In the middle of the period, 4.5% of people with IOP higher than the normal range, but the fundus optic nerve and visual field are normal, this part of the population is called hypertensive eye disease. Does a normal IOP necessarily mean that it is not glaucoma? Not necessarily. In fact, glaucoma is divided into two types: high IOP glaucoma and normal IOP glaucoma (also called low IOP glaucoma). Nearly half of all glaucoma in China is normal pressure. In this group, the IOP is never higher than normal, but there is progressive damage to the optic nerve and visual field in the fundus of the eye. Of course, this group of people must first undergo a brain examination and a brain MRI to exclude central neuropathy.