Eye pressure is measured in millimeters of mercury (mmHg). Normal eye pressure ranges from 10 to 21 mmHg. Ocular hypertension is an eye pressure of greater than 21 mmHg.
While the average eye pressure is approximately 15 mm Hg (millimeters of mercury), the range of normal eye pressure is much larger. About 90 percent of people will fall between a pressure of 10 and 21.
Measuring Eye Pressure
Normal eye pressure ranges from 12-21 mm Hg, and eye pressure of greater than 21 mm Hg is considered higher than normal. When the IOP is higher than normal but the person does not show signs of glaucoma, this is referred to as ocular hypertension. High eye pressure alone does not cause glaucoma.
While not everyone has the same IOP, the standard or “normal” range of pressure is between 10 to 21 mm Hg.
Normal IOP is usually between 12 and 22 mm Hg. Similar to using inches as a way to report length, mm Hg refers to millimeters of mercury and is a way to report pressure. An eye is considered hypotonous when the IOP drops below 10 mm Hg. However, hypotony may not be a problem unless the IOP drops below 5 mm Hg.
Treatment options include argon laser photocoagulation, cryotherapy, external diathermy, ciliary body suturing, and vitrectomy with endotamponade. Clefts can spontaneously close and result in a dramatic rise in IOP.
Some individuals may not experience any symptoms at all, despite their low eye pressure. When symptoms of low IOP do appear, they can lead to vision loss or distortion. Low IOP may also cause an individual to be slightly more farsighted than before.
Age-related change in IOP
In the cross-sectional analysis, average IOP increased from 12.7 mm Hg in subjects in their 20s to 14.0 mm Hg in those in their 40s. Then IOP decreased from 13.9 mm Hg in those in their 60s to 13.1 mm Hg in those in their 70s.
“Pressure is highest typically in the morning, when you're just waking up, and lowest in the afternoon,” says Johnson. “So if you have a 4:00 pm. appointment at the doctor's office, that particular pressure may be the lowest pressure you'll have that day.”
Ocular hypotony can arise from several causes, including trauma, surgery, intraocular inflammation, and the use of systemic and topical medications. It can result in severe vision loss, especially if complicated by hypotony maculopathy or hypotony keratopathy.
Whether you develop glaucoma depends on the amount of pressure your optic nerve can handle — and this amount is different for each person. For most people, eye pressure above 21 is higher than normal. Getting regular dilated eye exams can help your eye doctor figure out what level of eye pressure is normal for you.
Drinking a quart of water in less than five minutes has been shown to increase intraocular pressure; instead, advise your patients to drink small amounts of water often to stay hydrated.
Normal intraocular pressures average from 12-21 mm Hg. The “mm Hg” refers to millimeters of mercury, a scale for recording eye pressure. Anything that exceeds 21 mm Hg is considered hypertensive. A problem in the drainage of fluid produced in the eye causes increased pressure.
Stress can interfere with your sleep, skin and digestion. But did you also know it can affect your eyes? Your eyes undergo changes such as increased intraocular pressure (IOP) when you're stressed or anxious, whether for a short time or on a regular basis.
Measurements were taken by Goldmann applanation tonometer, after a complete rest for at least 15 minutes and always first in the right eye. Results: Mean intraocular pressure increases progressively with age until 60 years.
iCare HOME Tonometer is the only FDA approved eye pressure device available to patients for measuring eye pressure (intraocular pressure) at home that does not require using prescription eye drops to take your own pressure.
Doctors know that increased blood pressure results in increased eye pressure, possibly because high blood pressure increases the amount of fluid the eye produces and/or affects the eye's drainage system.
Symptoms of High Eye Pressure
Blurred vision. Blind spots in the visual field. Red eyes.
Intraocular pressure may become elevated with muscle exertion, changes in body position and increased respiratory volumes, especially when Valsalva manoeuver mechanisms are involved. All of these factors may be present during physical exercise, especially if hydration levels are increased.
Can you have glaucoma without having increased pressure inside the eye? Elevated eye pressure increases the risk of developing glaucoma; however, the disease can occur in people with normal or even lower-than-normal eye pressure. It is optic nerve damage that can lead to vision loss and possible blindness.
Glaucoma with “Normal” Eye Pressure
Another form of glaucoma is called normal-tension glaucoma. If someone has normal-tension or normal-pressure glaucoma, their eye pressure has never been recorded above 21 mmHg, yet they still have optic nerve damage.
Dehydration also causes disbalance in our eye pressure. Our eyes normally maintain a pressure for the proper functioning of it. But due to lack of water, this balance is disturbed creating an increase in the fluid pressure in our eyes.