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Ocular Hypertension

What Is Ocular Hypertension?

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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.

Fluid (aqueous) is normally produced within the front portion of the eye and exits the eye through a drainage system located in the angle of the eye. The balance between fluid production and fluid drainage determines the pressure within the eye at any given time.

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 as measured in one or both eyes on two or more occasions. 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.
  • The angle through which the intraocular fluid drains is open. 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, in which a special contact lens is used to examine the drainage angles (or channels) in your eyes to see if they are open, narrowed, or closed.
  • No signs of any other ocular disease are present that could contribute to elevated intraocular pressure. Some eye diseases and medications 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 open-angle glaucoma. Glaucoma is an eye disease in which characteristic optic nerve damage occurs, accompanied by an intraocular pressure that is relatively too high for the eye. Although most patients with glaucoma have ocular hypertension for a period of time prior to the onset of glaucoma, there are often patients who have glaucoma with normal intraocular pressures. The word tension is sometimes used as a synonym for pressure. These patients have what is termed normal tension glaucoma (NTG) or low-tension glaucoma (LTG). Another phrase that is commonly used to describe patients who may develop glaucoma in the future is glaucoma suspect. A glaucoma suspect usually has elevated intraocular pressure, but this group also includes patients with normal pressures whose optic nerve appears to be at risk for glaucomatous damage.

As mentioned above, increased intraocular pressure can result from other eye conditions. However, within this article, ocular hypertension primarily refers to increased intraocular pressure with open angles and no other eye condition that causes elevated intraocular pressure, together with no optic nerve damage or visual loss related to that increase in intraocular pressure.

Last Reviewed 11/20/2017

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