What Everyone Should Know About Eye Pressure

When giving an annual eye exam, ophthalmologists check many aspects of vision and eye health, including intraocular eye pressure. Eye doctors measure eye pressure because elevated pressure—aka ocular hypertension—can damage the optic nerve and cause permanent vision loss.

There are several methods for testing eye pressure; each is a form of tonometry. Tonometry tools and techniques vary. The most well known may be the one involving a puff of air being blown at the eye, called non-contact or air-puff tonometry.

No matter which tool an ophthalmologist uses, the important thing is that they measure eye pressure.

Facts About Normal Eye Pressure

Our eyes are filled mostly with a fluid called vitreous humor. Toward the front of the eye, just behind the cornea, there is another fluid called aqueous humor. Aqueous humor drains from the eye as equal amounts of new aqueous humor refill that space.

In healthy eyes with normal intraocular eye pressure (IOP), aqueous humor drainage and refill remain equal and constant. Normal eye pressure would measure between 12 and 21 mmHg (millimeters of mercury).

Pressure above 21 mmHg could cause damage to the optic nerve, leading to irreversible vision loss.

Causes of Elevated Eye Pressure

When too much aqueous humor is produced, intraocular eye pressure increases. This pressure can also increase when aqueous humor fails to drain correctly.

Patients with eye conditions, such as pigment dispersion syndrome and a few others that indirectly block or slow aqueous fluid drainage, can also experience increased eye pressure. These patients should have their eye pressure regularly monitored through routine eye exams.

Injury or trauma to the eye can also dangerously elevate eye pressure.

Other causes of increased eye pressure include certain medications, particularly steroids. Consequently, anyone who has sustained a blow to the eye or is taking steroids for any reason should get their eye pressure checked.


Glaucoma is an eye disease that causes optic nerve damage, resulting in vision loss. Elevated intraocular eye pressure is the most common indicator of glaucoma, particularly of primary open-angle glaucoma (POAG), as we discussed in our earlier Concise Guide to Glaucoma here on the blog.

However, elevated eye pressure is not the only symptom of glaucoma—this disease can be present in eyes with normal eye pressure. Normal-tension glaucoma can be more challenging to spot, which is a big reason why routine eye care is so vital for all adults. In both types, patients with glaucoma don’t feel any eye pain. In fact, even when eye pressure is elevated, patients don’t feel it.

Often patients don’t know anything is wrong with their eyes until they start to lose peripheral vision. At that point, the optic nerve degeneration has already begun.

Glaucoma Treatment

Whether you have glaucoma that presents with normal tension or elevated intraocular eye pressure, the treatment is similar: reduce the eye pressure using either prescription eye drops or surgery to halt or slow your vision loss.

Although there is no cure for glaucoma, it can be managed, and vision can be saved so long as the disease is diagnosed early enough. Anyone can develop glaucoma, but those at greater risk include anyone over age 40 and those with a family history of glaucoma.

Campus Eye Center Offers Comprehensive Routine Eye Care for Adults and Children

Early diagnosis of many different eye diseases and disorders, including diabetic retinopathy, various infections, macular degeneration, and more can be key to saving a patient’s vision, which is why everyone should have their eyes examined annually. That exam should always include a test of intraocular eye pressure.

Here at Campus Eye Center, we help our valued Lancaster, PA area patients live better by seeing better. If it’s been a while since you’ve had an eye exam with tonometry or you have concerns about the management of glaucoma and other eye diseases, we invite you to make an appointment to visit one of our two convenient locations today.