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Eye Pressure: What You Need To Know

Written by Dr. Dovbakh Olga Dmitrivna on Fri, 11 November 2022

Key Highlights

  • High eye pressure may or may not cause glaucoma
  • Intraocular pressure depends on age and blood pressure
  • Low eye pressure can result from eye surgeries
  • Aerobic exercises lower the eye pressure
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After reading this article's title, did you just raise your eyeballs? Well, our eyes are present in the shape of balls. The eyes are closed balls that have a jelly-like substance called vitreous humor filling most of the back part of the eye. A more-watery liquid called aqueous humor also is present.

Much of the aqueous humor is in the front part of the eye, behind the cornea, and in front of the iris. In a healthy eye, a small amount of new aqueous humor is constantly entering the eye while an equal amount drains out. Most of the aqueous humor flows out of the eye through the drainage angle, in front of the iris. This equal flow maintains a stable pressure.

What exactly is eye pressure?

The eye is a closed ball filled with clear jelly in the back behind the lens and clear fluid in the front, between the iris and the cornea. The aqueous humor is in continuous circulation throughout the front part of the eye before it drains out and this fluid helps keep the eye "inflated" just like air inside a balloon. 

We can measure the pressure of the eye just like you can gauge how full a balloon is by poking the balloon with your finger. The less air or pressure in the balloon, the easier it will be to poke, and conversely, the more air or pressure in the balloon, the stiffer the balloon will be and the harder it will be to poke it.

Eye pressure also called intraocular pressure or IOPβ€”is a measurement of the fluid pressure inside the eye. Measuring it is like measuring blood pressure. Eye pressure is measured in millimeters of mercury, like the way a thermometer measures temperature using mercury. Normal eye pressure is usually between 10 and 20 millimeters of mercury (mmHg). 

1. High or low: Normal range of eye pressure

Normal eye pressure is something that falls within the normal range. Having eye pressure that's too low or too high can damage your vision.  Low eye pressure may be defined as less than 8 mm Hg. In general, the eye can see fine still at these low pressures, though the risk of blurred vision increases significantly with eye pressures under 6 mm Hg. The primary issue is whether the low eye pressure is causing any problems for the eye or the vision. What pressure an eye can tolerate varies greatly among different individuals. 

When the eye pressure is lower than what the eye can tolerate, it is like a ball that is low on air, were part of the ball can begin to collapse. For some individuals that can begin to happen with an eye pressure of even 10 mm Hg, while someone else may be perfectly fine without visual symptoms with a pressure of 2 mm Hg. If you have low eye pressure or are concerned about your vision you should discuss this with your ophthalmologist.

Elevated eye pressure with no other symptoms is ocular hypertension. Some people can have higher eye pressure with no damage. Other people may lose vision even if the pressure is in the normal range. When someone has glaucoma, eye pressure damages the optic nerve. This damage can permanently reduce vision and if left untreated, can cause total blindness.  Eye pressure can vary with the thickness of the cornea.

Low eye pressure in and of itself does not cause pain. In contrast, high eye pressure often causes eye pain, especially when it is acute, meaning the eye pressure has suddenly risen. However, after having eye surgery, low eye pressure can be associated with other changes to the eye anatomy that will stimulate your eye's pain nerve fibers and cause some pain. Low eye pressure is a less common concern than high eye pressure.

2. Cause of eye pressure?

Ocular hypertension refers to a situation within which the pressure inside the eye is beyond the statistical norm. The increase in pressure can damage the optic nerve and may cause loss of vision. Elevated intraocular pressure is a major risk factor for the development or progression of glaucoma, an eye disease in which the optic nerve gets damaged and may lead to blindness. IOP physiologically depends on a multitude of systemic and ocular factors including age and blood pressure. 

If the aqueous humor does not flow out of the eye properly, pressure builds up and causes ocular hypertension. If high pressure causes damage to the optic nerve, it leads to glaucoma which may further aid in vision loss. Although increased IOP can cause glaucoma, the reverse is also possible due to a mutual relationship between the two. The cause of an increased IOP is the imbalance in the system of production and the discharge of the aqueous humor.

Several factors work to elevate your IOP:

  • Factors increase IOPAge - It is more common at the age of 40 years or more
  • Race - It is more common among African-Americans and the Hispanics
  • Genetic factors - It may commonly occur in those with a family history of increased IOP or glaucoma
  • Osmotic pressure of blood - Both high and low blood pressure may cause an increase in IOP
  • Medicines - Certain medications like steroids and corticosteroids may increase the IOP
  • Eye diseases - Eye diseases like myopia, glaucoma, uveitis,  and ocular inflammation, may elevate the IOP
  • Eye surgery
  • Diabetes
  • Trauma - Blows to the eye or bruises in the eyes can also elevate the IOP
  • Stress - Reading for long hours, over-working, emotional stress, and exam stress, all can elevate your IOP
  • Other factors - include anesthetics, dyslipidemia, migraine, metabolic syndrome, cigarette smoking, and drinking caffeine-containing beverages

3. What are the symptoms of high eye pressure?

High eye pressure itself is a symptom of an underlying eye disease like glaucoma. Ocular hypertension usually does not show any evident signs and symptoms. However, the high eye pressure may cause you to have blurry vision, headache, pain, rainbow-colored halos around lights, and nausea. Regular eye examinations are a good way to keep a check on your eye pressure.

How can you diagnose high eye pressure?

High eye pressure is diagnosed by an opthalmologist, who measures the pressure of your eyes. During this procedure, your eyes are numbed with eye drops, and your doctor uses an instrument called a tonometer to measure how your cornea resists slight pressure. This helps him to measure your eye pressure. Your ophthalmologist will also check for glaucoma. He will examine your optic nerve for signs of damage, and check your side (peripheral) vision.

How is high eye pressure treated?

Lowering the high pressure on your eyes is crucial to avoid more complications like glaucoma. If your eye pressure is only slightly elevated, your ophthalmologist may decide not to start treatment immediately. He or she will monitor pressure with regular testing instead. The treatment options for glaucoma and high eye pressure coincide as high eye pressure may further cause glaucoma. These include;

  • Treatment Option for IOPPrescription eye drops - Those with prostaglandins like latanoprost and travoprost increase the fluid outflow of your eyes thereby reducing the eye pressure. Beta-blockers like timolol reduce the production of fluid in your eye, thereby lowering the pressure in your eyes. 
  • Oral medications - If eye drops fail to bring your eye pressure down, then your doctor may prescribe oral medicine like a carbonic anhydrase inhibitor which reduces the production of fluid in your eye.
  • Surgeries - Laser trabeculoplasty is an option if you have open-angle glaucoma. It's done in your doctor's office. Your doctor uses a small laser beam to open clogged channels in the trabecular meshwork. Filtering surgery or trabeculectomy is a surgical procedure, where your doctor creates an opening in the white of the eye (sclera) and removes part of the trabecular meshwork.

Drainage tubes are where your eye surgeon inserts a small tube shunt in your eye to drain away excess fluid to lower your eye pressure.

Minimally invasive glaucoma surgery (MIGS) procedures generally require less immediate postoperative care and have less risk than trabeculectomy or installing a drainage device.

How can you prevent high pressure in your eyes? 

Prevention of high eye pressure is usually achieved through lowering the increased eye pressure. Eating a healthy diet benefits your overall health and may also be good for your eye health. Regular exercise also helps to lower your eye pressure. Moderate aerobic exercises like jogging, walking, and bicycling have been shown to reduce intraocular eye pressure in healthy individuals. These exercises also reduce IOP following the installation of medication eye drops in glaucoma patients.

Food to reduce eye pressure?

Foods Decrease IOPVarious foods can help reduce your eye pressure and further reduce the risk of developing glaucoma. These include antioxidant-rich foods such as green leafy vegetables, tomatoes, and peppers, fruits like blueberries and cherries, lean meat, tofu, soy, beans, etc.

Avoid refined foods, such as white bread, pasta, and sugar. Eat fewer red portions of meat, and reduce or eliminate trans fatty acids, found in such commercially-baked goods as cookies, crackers, cakes, donuts, processed foods, and margarine. Avoid coffee and other stimulants, alcohol, and tobacco. These may increase eye pressure. Drink 6 to 8 glasses of filtered water daily. All these measures may lower your eye pressure.

Conclusion

Eye pressure is maintained in our eyes by a liquid substance called aqueous humor. It enables the eyes to remain in the shape of circular, inflated balloons. This pressure may change due to various factors such as increasing age, stress, smoking, caffeinated beverages, etc. Eye pressure can be lower or higher than normal, however, high eye pressure is a cause of concern.

The high pressure may cause eye damage to the optic nerve leading to glaucoma that results in permanent blindness. It may also cause headaches, nausea, and vomiting. Before the condition worsens, it is essential to lower the eye pressure and this can be achieved via using medicated eye drops, oral medicines, or surgical procedures. High eye pressure should not be ignored and when controlled, it can save your vision.

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Dr. Dovbakh Olga Dmitrivna

Dr. Dovbakh Olga Dmitrivna is a Clinical Psychologist based out of Ukraine. She graduated from the Bukovinian State Medical University, Ukraine back in 2009. Driven by a thirst of knowledge and with a keen interest in matters of the mind, Dr. Dovbakh Olga Dmitrivna went back to University in 2021 to specialise in psychiatry.

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