High pressure in the eyes

The higher the pressure in the eye, the greater the chance of damage to the optic nerve. However, some people who have higher-than-normal pressure in their eyes do not develop glaucoma.

Normal intraocular pressures range from about 10 millimeters of mercury (mm Hg) to about 21 mm Hg.

• Many people who have intraocular pressures consistently above 27 mm Hg develop optic nerve damage unless the pressure is lowered by medication.
• Some people have intraocular pressures consistently higher than 21 mm Hg but do not develop optic nerve damage. This condition is called ocular hypertension.

Some people who have optic nerve damage from glaucoma have normal intraocular pressures. This condition is called normal or low-tension glaucoma. However, what is normal for one person may not be normal for another person.

Health professionals also measure the thickness of the clear front surface of the eye (cornea). Cornea thickness, along with pressure inside the eye, helps determine your risk of developing glaucoma.