Ocular hypertension means the pressure in your eyes — your intraocular pressure (IOP) — is higher than normal. Left untreated, high eye pressure can cause glaucoma and permanent vision loss in some individuals.
However, some people can have ocular hypertension without developing any damage to their eyes or vision, as determined by a comprehensive eye exam and visual field testing.
Researchers have estimated that ocular hypertension is 10 to 15 times more likely to occur than primary open-angle glaucoma, the most common type of glaucoma.
According to the Ocular Hypertension Treatment Study, 4.5 to 9.4 percent of Americans age 40 or older have ocular hypertension, which increases their risk of developing sight-threatening glaucoma.
You can’t tell by yourself that you have ocular hypertension, because there are no outward signs such as eye pain or red eyes. During a comprehensive eye exam, your eye care practitioner will measure your IOP and compare it with normal levels.
An eye pressure reading of 21 mmHg (millimeters of mercury) or higher generally signifies ocular hypertension.
If you picture your eye as a globe inflated by pressure, you can better understand why ocular hypertension should be monitored. Pressure that is too high or that continues to increase exerts a force within your eye’s interior that can damage the eye’s delicate optic nerve, causing glaucoma.
Excessive aqueous production. The aqueous (or aqueous humor) is a clear fluid that is produced in the eye by the ciliary body, a structure located behind the iris. The aqueous flows through the pupil and fills the anterior chamber of the eye, which is the space between the iris and the cornea.
The aqueous drains from the eye through a structure called the trabecular meshwork, in the periphery of the anterior chamber, where the cornea and iris meet. If the ciliary body produces too much aqueous, the pressure in the eye increases, causing ocular hypertension.