Ocular Hypertension Overview
The term ocular hypertension usually refers to any situation in which the pressure inside the eye, called intraocular pressure, is higher than normal. Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure ranges from 10-21 mm Hg. Ocular hypertension is an eye pressure of greater than 21 mm Hg.
Although its definition has evolved through the years, ocular hypertension is commonly defined as a condition with the following criteria:
- An intraocular pressure of greater than 21 mm Hg is measured in one or both eyes at two or more office visits. Pressure inside the eye is measured using an instrument called a tonometer.
- The optic nerve appears normal.
- No signs of glaucoma are evident on visual field testing, which is a test to assess your peripheral (or side) vision.
- To determine other possible causes for your high eye pressure, an ophthalmologist (a medical doctor who specializes in eye care and surgery) assesses whether your drainage system (called the "angle") is open or closed. The angle is seen using a technique called gonioscopy. This technique involves the use of a special contact lens to examine the drainage angles (or channels) in your eyes to see if they are open, narrowed, or closed.
- No signs of any ocular disease are present. Some eye diseases can increase the pressure inside the eye.
Ocular hypertension should not be considered a disease by itself. Instead, ocular hypertension is a term that is used to describe individuals who should be observed more closely than the general population for the onset of glaucoma. For this reason, another term to refer to a person with ocular hypertension is "glaucoma suspect," or someone whom the ophthalmologist is concerned may have or may develop glaucoma because of elevated pressure inside the eyes. An eye exam may show a glaucoma-damaged optic nerve.
As mentioned above, increased intraocular pressure can result from other eye conditions. However, within this article, ocular hypertension primarily refers to increased intraocular pressure without any optic nerve damage or vision loss. Glaucoma occurs when increased intraocular pressure, optic nerve damage, and vision loss are present.