3 Things to Know About Intraocular Pressure (IOP)

Intraocular pressure (IOP) is a measurement that is made at every comprehensive eye examination and is a key risk factor for conditions such as glaucoma. Intraocular pressure is typically high in glaucoma and can lead to damage to the nerve in the back of the eye. If the eye pressure is too low, it can lead to problems with keeping the eyes healthy and intact including having a choroidal detachment. 
 

What Determines the Eye Pressure?

The intraocular pressure is determined by the amount of fluid in the front of the eyes. The fluid is produced from behind the iris and then drains through a structure called the trabecular meshwork. The eye pressure varies based on the rate at which the fluid is produced into the front of the eyes and the rate at which it drains out of the trabecular meshwork. Anything that can increase the rate of production or decrease the drainage rate can lead to an increase in eye pressure. Conversely, anything that causes fluid to drain faster or be produced slower can reduce eye pressure. 
 

Normal Eye Pressure

In most individuals, the eye pressure is between ten and twenty-two. This range is considered to be normal and frequently is used to grade if the eye pressure is abnormal. The scale used for the measurement of eye pressure is based on the pressure in millimeters of mercury. In different individuals, the eye pressure may be abnormally high or low without there being any pathology of any form. These are considered to be normal variations of the range of eye pressure. However, in cases of glaucoma, anterior uveitis, or other eye conditions high eye pressure can be a sign of an eye problem. If the eye pressure is abnormally low, it can be from an injury or damage from surgery. Either way, the eye can lose fluid abnormally and result in lower eye pressure. 
 

How is Intraocular Pressure Measured?

In an eye examination, the eye pressure will be checked in some fashion. There are several options to check eye pressure in an eye examination. The gold standard for determining intraocular pressure is using the Goldmann applanation tonometry method. This uses a yellow dye and numbing agent to evaluate the force it requires to slightly indent the eye. Similarly, the Tonopen method uses a numbing drop and yellow dye to check the eye pressure with a handheld instrument instead. There are methods of checking eye pressure that does not involve the use of any eye drops. The iCare tonometer is a handheld instrument that can check eye pressure with a small probe that cannot be felt as it presses against the front of the eye for a fraction of a second. Another option is a non-contact tonometer or the “air puff” test. This instrument uses a constant force of a small puff of air into the eye and measures the response to determine the eye pressure.

Our eye doctor at The Optical Centre in Longmont, CO excels in the prescription of glasses, contact lenses and the diagnosis of a variety of eye diseases. Call our optometrist at 303-772-6650 or schedule an eye exam appointment online if you would like to learn more about intraocular pressure. Our eye doctor, Dr. Erica Whitmire provides the highest quality optometry services and eye exams in Longmont, Colorado and its surrounding areas.