Eye pressure, also called intraocular pressure (IOP), is a measurement of the fluid pressure inside the eye, and it is measured in millimeters of mercury (mmHg) . Normal eye pressure is usually considered to be between 10 and 21 mmHg. However, the pressure at which eye damage develops is different for each person, and eye damage can develop at a lower or higher pressure for some people. Eye pressure that’s too low or too high can damage vision. Elevated eye pressure with no other symptoms is called ocular hypertension. Some people can have higher eye pressure with no damage, while others may lose vision even if the pressure is in the normal range. It is important to see an eye care specialist to receive a thorough examination and determine if your eye pressure is problematic.