Ocular Hypertension

Ocular hypertension means the pressure inside your eye is higher than normal, but without damage to the optic nerve. While it often causes no symptoms, this condition affects millions of people and requires careful monitoring to prevent vision loss from glaucoma.

Table of contents

• What is ocular hypertension?
• Causes and mechanisms
• Risk factors
• Symptoms and signs
• Difference between ocular hypertension and glaucoma
• Diagnosis and testing
• Treatment options
• Outlook and progression
• Prevention and monitoring

What is ocular hypertension?

Ocular hypertension is a condition where the pressure inside your eye is higher than normal. Your eyes constantly make a clear fluid called aqueous humor that flows in front of your eye and then drains out. Normally, an equal amount goes in and out. If the fluid doesn’t leave your eye when it should, the pressure inside your eye increases.^[1]

Normal eye pressure is 11 to 21 millimeters of mercury (written as mmHg). This is the same type of measurement used in taking your blood pressure. If your eye pressure is higher than 21 mmHg in one or both eyes at two or more visits to your eye care specialist, then you may have ocular hypertension.^[1][2]

Bilateral ocular hypertension happens in both eyes. Unilateral ocular hypertension means that pressure is high in only one eye.^[1]

An estimated 3 million to 6 million people in the United States have ocular hypertension, which puts them at risk for developing glaucoma. Studies show that 4% to 10% of Americans aged 40 and older have this condition.^[2][3]

Ocular hypertension is not caused by, or related to, high blood pressure in your body, although both conditions have similar-sounding names.^[2]

Causes and mechanisms

Ocular hypertension occurs when there is an imbalance in the production and drainage of fluid in your eye. This can happen if too much fluid enters the eye or too little fluid drains from the eye.^[2]

The main causes include problems with your eye’s drainage system, called the anterior chamber angle. The drainage angle is near the front of your eye, located between the iris (the colored part) and the cornea (the clear window at the front).^[1]

If the drainage angle is blocked, it causes fluid and pressure to build up. Several conditions can prevent the aqueous humor from exiting the eye properly:^[2]

• Uveitis (inflammation of the middle portion of the eye)
• Pigment dispersion syndrome, in which tiny flecks of pigment from the iris float around inside the eye, blocking the trabecular meshwork (a spongy tissue in the drainage angle through which aqueous humor passes out of the eye)
• Pseudoexfoliation syndrome, when microscopic bits of protein fiber build up at various sites in the body, including the eye, where they may block fluid from draining out
• A tumor within the eye
• Large cataracts that block drainage routes
• Damage to the eye caused by injury or surgery
• Certain medications, including corticosteroids
• Chronic angle-closure, a condition in which the iris blocks the trabecular meshwork

In some cases, the eye may simply produce too much fluid, leading to increased pressure.^[1]

Risk factors

Several factors can increase your chance of developing ocular hypertension. Some risk factors cannot be changed, like your age, your ethnicity, or having certain medical conditions.^[1]

Risk factors for ocular hypertension include having other conditions, such as:^[1]

• High blood pressure (hypertension)
• Low blood pressure (hypotension)
• Diabetes
• Extreme nearsightedness (myopia)
• A thinner central cornea
• Bleeding at the optic nerve head

Additional risk factors include:^[1][2]

• Being over 40 years of age
• Having a family history of glaucoma or ocular hypertension
• Being Black or Hispanic
• Taking steroid medications for a long time
• Having had previous eye injuries or eye surgeries

Having pigment dispersion syndrome or pseudoexfoliation syndrome can also increase your risk of developing ocular hypertension.^[1]

Symptoms and signs

The tricky thing about ocular hypertension is that it generally doesn’t cause symptoms. This is why regular eye exams are so important. Your healthcare provider can tell if the pressure inside your eye is high when they do their testing.^[1][2]

People who have ocular hypertension might not feel it because their eyesight seems fine. You won’t know you have the condition unless you are diagnosed by an eye doctor during an office visit.^[2]

In some cases, you may feel eye pain with movement of your eyes or touching your eyes. However, ocular hypertension does not usually cause headaches or dizziness, even though some other eye problems may create these symptoms.^[1]

Difference between ocular hypertension and glaucoma

Ocular hypertension can cause glaucoma, but they are not the same condition. Glaucoma happens when high pressure inside your eye damages the optic nerve. These nerves in both eyes connect directly to your brain and transmit electrical signals that your brain turns into images.^[1]

The main difference is that with ocular hypertension, you have elevated eye pressure without any damage to the optic nerve or changes to your vision. With glaucoma, there is actual damage to the optic nerve and vision loss may occur.^[1][5]

If you have glaucoma that’s not treated, you can lose your vision. However, not all people with ocular hypertension will develop glaucoma. Studies show that people with ocular hypertension have an average estimated risk of 10% of developing glaucoma over 5 years.^[3][5]

The Ocular Hypertension Treatment Study showed that treatment with pressure-reducing eye drops can reduce the possibility of glaucoma developing by about 50%. At 5 years, 4.4% of patients in the medication group versus 9.5% in the untreated group developed signs of glaucoma.^[3]

Diagnosis and testing

An eye care professional will review your medical history and do a comprehensive eye exam. Several tests may be done to diagnose ocular hypertension:^[1]

• Measuring intraocular pressure, also called tonometry
• Testing for optic nerve damage with a dilated eye exam and imaging tests
• Checking for areas of vision loss, also known as a visual field test
• Measuring corneal thickness with an exam called pachymetry
• Inspecting the drainage angle, also known as gonioscopy

A doctor uses special equipment to measure your intraocular pressure during an eye exam to assess your eye health. Intraocular pressure levels greater than 21 mmHg confirm a diagnosis of ocular hypertension.^[2]

Ocular hypertension is diagnosed when:^[3]

• Intraocular pressure is greater than 21 mmHg in one or both eyes at two or more office visits
• The optic nerve appears normal
• No signs of glaucoma are seen on visual field testing
• No signs of any eye disease are seen

Treatment options

Once you are diagnosed with ocular hypertension, doctors will assess your risk of developing glaucoma. This assessment helps doctors determine whether or not treatment is needed.^[2]

Whether treatment is considered appropriate or not, all patients with ocular hypertension should be examined on a regular basis, usually every 6 to 12 months. Visual field testing and optic nerve scans are done to watch for early signs of damage.^[15]

Treatment of ocular hypertension with pressure-reducing eye drops can definitely reduce the possibility of glaucoma developing. The study also helps doctors to recognize which patients are at greater risk for glaucoma so that treatment can be given to only patients at greatest risk. These risk factors include optic nerve appearance, visual field testing results, corneal thickness, pressure over 25, and age.^[15]

When appropriate, doctors prescribe eye drops, which help to manage ocular hypertension and reduce the risk of glaucoma. Prescription eye drop medicines include:^[13]

• Prostaglandins, which increase the outflow of fluid in the eye
• Beta blockers, which reduce the production of fluid in the eye
• Other types of medications that help lower eye pressure

In rare cases, surgery may be recommended to lower intraocular pressure. This could include laser treatment or other surgical procedures.^[2]

Following your doctor’s instructions carefully is essential, as inconsistent use of eye drops will reduce their effectiveness. Regular follow-up appointments with your eye doctor are important to monitor the effectiveness of treatment and adjust your treatment plan as necessary.^[12]

Outlook and progression

Most cases of ocular hypertension fortunately do not lead to glaucoma, but unfortunately, some do. Studies over the last 20 years have helped to characterize people with ocular hypertension:^[3]

• They have an average estimated risk of 10% of developing glaucoma over 5 years
• This risk may be decreased to 5% (a 50% decrease in risk) if eye pressure is lowered by medications or laser surgery
• Over a 5-year period, the incidence of glaucoma damage is about 2.6-3% for intraocular pressures of 21-25 mmHg, 12-26% for intraocular pressures of 26-30 mmHg, and approximately 42% for those higher than 30 mmHg

At 20 years, about 49% of those in the control group and 42% of those in the medication group developed glaucoma in the Ocular Hypertension Treatment Study. However, since early treatment was started for the control group during later phases, the full long-term benefit of early treatment is still being studied.^[11]

With careful follow-up and appropriate treatment when indicated, the vast majority of patients with ocular hypertension can be assured that no vision will be lost from glaucoma.^[15]

Prevention and monitoring

Because ocular hypertension typically occurs without symptoms, regular eye exams are essential. A majority of people with ocular hypertension remains undiagnosed. In one study, 75 percent of people with eye pressures greater than 21 mmHg were previously undiagnosed.^[5]

People should see their eye doctors regularly so that the condition can be detected and monitored. Regular comprehensive eye exams allow your healthcare provider to detect high eye pressure before it causes damage.^[2][6]

If you have ocular hypertension, it is essential to have regular comprehensive eye examinations. Not all people with ocular hypertension will develop glaucoma. However, people with ocular hypertension have an increased risk of glaucoma.^[6]

You’ll want to see your provider and follow suggestions about medications and regular eye exams. Your eye doctor will monitor your eyesight by measuring your eye pressure and checking for any early signs of optic nerve damage or vision changes.^[1]