Category: 

What Is Normal Eye Pressure?

The pressure of fluid behind the cornea is tested in an eye exam.
A tonometer measures the pressure of the fluid behind the cornea.
Routine eye exams are painless and can help detect vision or eye problems -- such as signs of eye pressure -- early.
Normal eye pressure usually increases with age.
Article Details
  • Written By: N. Freim
  • Edited By: Melissa Wiley
  • Last Modified Date: 25 November 2014
  • Copyright Protected:
    2003-2014
    Conjecture Corporation
  • Print this Article
Free Widgets for your Site/Blog
A red blood cell can pass through a person's entire body in 20 seconds.  more...

December 19 ,  1998 :  President Bill Clinton was formally impeached by the House of Representatives.  more...

During an eye exam, a tonometer will measure the pressure of the fluid behind the cornea. To be considered normal eye pressure, the measurement should be between 10 to 20 mmHg. The reading can vary by body position, time of day, and factors like medication or fluid intake. An increased pressure can be a warning sign of problems, most notably glaucoma.

The cornea of the eye is filled with a thick liquid called the aqueous humor. This fluid helps keep the cornea curved and inflated. The eye constantly produces new aqueous humor and drains the old. The pressure of the fluid is measured with a tonometer, which gauges the amount of force needed to flatten an area of the cornea. The thickness of the individual cornea can affect the results.

There are a variety of ways to measure eye pressure. Some tonometers involve direct contact with the eye, which usually requires a topical anesthetic, and are regarded as the more reliable method. Several non-contact methods involve a tonometer that pushes a puff of air at the cornea and measures the force of the air as it hits. This style is good for children or people who are nervous about having a machine touch their eyes.

Ad

The tonometer measures normal eye pressure in millimeters of mercury (Hg). The healthy range is from 10 to 20 mmHg, with the average being about 14 to 16 mmHg. The amount of pressure can vary throughout the day and can change depending on the position of the body. Factors that normally affect general health, such as exercise, medicine, or alcohol intake, can also affect eye pressure.

Although normal eye pressure usually increases with age, a marked increase or a difference in pressure in each eye can be warning signs for health problems. High pressure is often seen with glaucoma, although the disease can develop without it. Eye pressure above 21 mmHg can damage the optic nerve and can lead to blindness. If glaucoma is caught early, doctors may be able to slow the disease. Once the eye is damaged, however, it is difficult to repair. This is why it is important to have regular checkups to measure normal eye pressure and catch problems early.

Ad

More from Wisegeek

You might also Like

Discuss this Article

Post your comments

Post Anonymously

Login

username
password
forgot password?

Register

username
password
confirm
email