According to the University of Illinois Eye and Ear Infirmary, normal eye pressure, also called intraocular pressure, ranges from 10 to 21 mmHg (millimetres of mercury).
How is eye pressure measured?
A tonometer measures intraocular pressure. The most accurate type of tonometer is the applanation tonometer. Your eye doctor numbs your eyes with eye drops and applies the tonometer gently to the front surface of the eye to get a pressure reading. The other type of tonometer, called a noncontact tonometer, sends a warm puff of air into the eye to measure pressure.
Ocular hypertension is an eye pressure greater than 21 mmHg. Although ocular hypertension is not considered a disease by itself, it increases the risk of glaucoma. Glaucoma is vision loss that occurs when the optic nerve fibers die from a lack of blood supply.
Risks for ocular hypertension
Although anyone can develop ocular hypertension, people at high risk are those of African descent, people over 40, individuals with a family history of ocular hypertension or glaucoma, people with diabetes and people who are highly nearsighted.
Treating ocular hypertension
Some eye doctors prescribe eye drops to lower high intraocular pressure. However, these medications can have side effects, so other doctors monitor intraocular pressure and only provide treatment if other signs of glaucoma develop.