At your regular eye exam, one thing your eye doctor always checks is your intraocular pressure. It gives an important picture of your eye health and can find signs of optic nerve damage that might affect your eyesight.
Your eyes are filled with fluid that helps keep them inflated like a ball. The “normal” pressure in the eyes can change during the day and differ from person to person. In healthy eyes, the fluids drain freely to keep the eye pressure steady.
If your eye pressure is consistently too high or too low, it could be a warning that you may have problems with your vision.
Eye Pressure Check
A tonometry test measures your intraocular pressure. It’s like pressing a balloon to check for air. It shows how firm your eyeball is with the same measurement units used to check blood pressure. The normal range for intraocular pressure is about 10-20 mm HG.
Why Eye Pressure Matters
Normal intraocular pressure helps support the shape of the eye, which in turn supports the 2 million parts of the eye that help you see.
High pressure. When the fluid in the front of your eye doesn’t drain as well as it should, pressure can get too high. Your doctor may call this ocular hypertension.
It can lead to glaucoma, a group of eye diseases that causes blindness. High eye pressure is one of the top reasons people get it. Glaucoma doesn't hurt, and you can have it for years without noticing any changes in your vision. So checking for high eye pressure can help you catch it early.
You might get ocular hypertension after an eye injury or disease. Some medications, such as steroids, also can raise your eye pressure. It might also happen after certain medical procedures, such as when you get a tube put into your throat. If yours is already high, a spike may damage your vision.
Low pressure. This is a less common concern than high eye pressure. Often, people get low pressure because of a leak in the eye after surgery.
For some people, very low pressure can bring on blurry vision or other problems. Others can see just fine with it.
When the pressure is below 5 mm HG, doctors call it ocular hypotony. It can make you more likely to get several eye problems, including:
- Swelling in the cornea, the clear outer dome of your eyes
- Damage to the macula, the light-sensing part of the retina that allows you to see
Unlike with blood pressure, the danger zones for eye pressure can be tricky to pin down. People can have different ranges for what’s normal. One in 3 people with glaucoma never have “high” eye pressure, while others can have higher-than-normal pressure without damaging their optic nerves. That’s one reason for you to see an ophthalmologist or another eye care provider regularly.