Ocular Hypertension: Signs, Symptoms, Treatment
Just as we have blood pressure within our arteries, our eyes also have pressure. This pressure comes from the aqueous humor, the medical term for the thick liquid within our eyeballs. This pressure is called IOP for intraocular pressure, which simply means from within the eye.
Hypertension, commonly called high blood pressure or HTN, may occur within our blood vessels or the eye. When it appears in the eye, it’s called ocular hypertension. It may also be called high IOP, elevated IOP, or glaucoma.
The Aqueous Humor and Ocular Hypertension
Produced by an organ called the ciliary body located behind the iris, aqueous humor is a fluid that fills the front part of the eyeball. It gives the eyeball its shape and carries oxygen and nutrients to the lens and cornea.
The eye normally has a system for keeping the IOP from going too high or too low. It does this by regulating the amount of fluid produced by the ciliary body and keeping this in balance within the interior eye’s aqueous drainage system.
Elevated IOP may occur when too much fluid is produced or when it drains too slowly. Although some people may have a naturally higher IOP than others, and some individuals can also tolerate a higher IOP without damage, any eye pressure measured at over 22 milliliters of mercury (mm) is considered medically high IOP.
Elevated IOP, especially when sustained over time, is dangerous because it can cause damage to the optic nerve by compressing the delicate nerve until it can no longer function normally. High IOP can cause permanent vision loss, typically beginning with the peripheral vision first, and even total irreversible blindness.
Measuring IOP: The Tonometer and Puff Air Test
The damage from high IOP, the main feature of glaucoma, is typically painless and unobvious. In most cases, you are unlikely to have eye pain or redness. During a routine eye exam, your eye doctor will measure your IOP. If it’s over 22mm or there is reason to suspect glaucoma or damage from an elevated IOP, your doctor may order a visual field test.
This test measures your side vision to determine whether it’s within normal limits. IOP is measured in one of two ways: using an instrument called a tonometer or with a puff air test. A tonometer is generally more accurate because it measures IOP directly by detecting it through the eyeball.
A tonometer looks like a pen with a disposable pad on one end. The doctor loads a sterile, disposable pad on one end and holds the device by the other. Using a drop of anesthetic eye solution, the doctor briefly touches the eyeball with the tonometer. After a moment, it produces a reading.
The tonometer test is quick and painless. The other test, the puff air test, uses a puff of air from a special machine to measure IOP. Although this gives a fairly accurate IOP reading and is sufficient for routine needs, the tonometer is more precise and will always be used in the case of any suspected kind of ocular hypertension or glaucoma condition.
Ocular Hypertension Risk Factors
Anyone can get elevated IOP or glaucoma, and the exact cause is often unknown. However, those with a family history of these conditions are statistically at a higher risk. African-Americans also have an increased risk of high IOP, and since risk rises with age, so do those over the age of 40.
What Causes Ocular Hypertension?
There are several possible causes of this condition:
Malfunctioning Ciliary Body
If the ciliary body produces too much aqueous humor to the point where it’s flowing out of the organ faster than it can drain, elevated IOP may naturally result.
Even if the ciliary body doesn’t produce too much fluid, high IOP can still result if the eye doesn’t drain properly.
Certain medications are associated with an elevated risk of high IOP. Of particular concern are steroid drugs like prednisone, whether taken orally or in the form of eye drops.
The same is true for oral steroids. These drugs are commonly used to treat asthma and may be prescribed as an inhaled steroid medication. Steroids are sometimes prescribed to relieve inflammatory skin conditions, such as psoriasis and eczema. These may be in oral form or topical form.
Strong topical steroid creams may have systemic effects, including those on the eye. Always inform your eye doctor of all medications you take, but be particularly sure to mention any kind of steroid use, even if it’s not current. Past use of steroid drugs is something your eye doctor should know about.
Steroid medications may not show side effects until they have been taken for a long time, and effects may show suddenly and without warning.
Trauma to the Eye
Certain eye injuries, particularly penetrating ones, may alter the function of delicate structures within the eye associated with the balance of the aqueous humor.
This effect may not be evident immediately, so as with steroid drugs, you must inform your eye doctor of any kind of past eye injury.
Even if the injury seemed minor to you, mention it anyway. Let your doctor decide if the injury is medically significant or not. Past eye damage may take a long time to cause a current problem like elevated IOP.
Don’t take chances with your eyesight. Tell your eye doctor everything about past eye injuries and all medication use.
Other Eye Conditions Associated with Possible High IOP
Pigment Dispersion Syndrome
A rare eye disease called pigment dispersion syndrome may be related to an increased risk of ocular hypertension. Pigment or color in the eye is normally located only within the iris, the colored part of the eye.
However, in pigment dispersion syndrome, tiny bits of pigment become dislocated and begin to stick to other eye structures where they don’t belong. When this happens, these displaced pigmentary fragments may clog the eye’s aqueous drainage system or otherwise interfere with it. In some cases, this may lead to ocular hypertension.
Corneal arcus is another eye condition associated with a higher risk of ocular hypertension. The corneal arcus is a whitish or bluish ring of color surrounding the cornea. This ring doesn’t go all the way around the cornea. Instead, it appears as a broken half-circle along the top and bottom of the circle formed by the cornea.
This ring is composed of fatty material, which may clog and interfere with the eye’s aqueous drainage system. Corneal arcus is also associated with a possibly elevated risk of heart attack and stroke because it may indicate high levels of unhealthy fatty acids in the bloodstream.
Corneal arcus is typically seen most often in elderly persons.
Treatment of ocular hypertension and glaucoma generally consists of medication and surgery. In particular, special laser surgery may relieve some types of this condition by making a tiny hole within the eyeball for the aqueous humor to drain.
Eye drops for ocular hypertension reduce IOP by either slowing the production of the aqueous humor or by increasing its drainage. These drugs, while often effective, may have side effects. Your doctor will determine when and if medicated eye drops for IOP are right for you and when to begin using them.
It’s critical to understand that ocular hypertension can cause blindness. In many cases, it’s treatable and manageable if caught early but is not curable.
Find an Eye Doctor Near You
The threat of ocular hypertension is only one reason for regular eye checkups; you cannot depend on symptoms to warn you. When many people discover they have ocular hypertension, serious and irreversible damage has already occurred.
This damage is often preventable by getting early and regular eye exams.
A simple tonometer or puff air test may save your eyesight. This measurement will always be performed as part of any comprehensive eye exam. Our list of experienced, top-rated physicians practice nationwide, and one or more is sure to be at a location near you.
Make an appointment today to ensure any problems are detected and treated early for the best chance for a lifetime of healthy vision.