At your regular eye exam, one thing your eye doctor always checks is your intraocular pressure. That’s the pressure inside your eyes. It gives an important picture of your eye health and can find signs of optic nerve damage that might affect your sight.
Your eyes are filled with fluid that keeps 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 eye pressure steady.
Ocular hypertension is when the pressure inside the eye is higher than normal. 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.
Ocular hypertension usually has these signs:
- An intraocular pressure of 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, which is a test to assess your peripheral (or side) vision.
- No signs of any eye disease are seen.
Ocular hypertension should not be considered a disease by itself. But if you have it, you may be more likely to develop glaucoma.
Studies over the last 20 years have helped to characterize those with ocular hypertension:
1). 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. However, the risk may become even less than 1% per year because of significantly improved techniques for detecting glaucomatous damage. This could allow treatment to start much earlier, before vision loss occurs.
2). Patients with thin corneas may be at a higher risk for glaucoma development. Therefore, your eye doctor might measure your corneal thickness.
3). Over a 5-year period, the incidence of glaucomatous damage in people with ocular hypertension 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.
4). In approximately 3% of people with ocular hypertension, the veins in the retina can become blocked (called a retinal vein occlusion), which could lead to vision loss. Because of this, keeping pressures below 25 mmHg in people with ocular hypertension and who are older than age 65 is often suggested.
Some studies have found that the average intraocular pressure in Black and Hispanic people is higher than in white people, while other studies have found no difference.
5) A 4-year study showed that black individuals with ocular hypertension were five times more likely to develop glaucoma than whites. Findings suggest that, on average, black individuals have thinner corneas, which may account for this increased likelihood to develop glaucoma, as a thinner cornea may cause pressure measurements in the office to be falsely low.
6)In addition, blacks are considered to have a three to four times greater risk of developing primary open-angle glaucoma. They are also believed to be more likely to have optic nerve damage.
Although some studies have reported a significantly higher average intraocular pressure in women than in men, other studies have not shown any difference between men and women.
- Some studies suggest that women could be at a higher risk for ocular hypertension, especially after menopause.
- Studies also show that men with ocular hypertension may be at a higher risk for glaucomatous damage.
Intraocular pressure slowly rises with increasing age, just as glaucoma becomes more prevalent as you get older.
- Being older than age 40 is a risk factor for both ocular hypertension and primary open-angle glaucoma.
- Elevated eye pressure in a young person is a cause for concern. A young person has a longer time to be exposed to high pressures over a lifetime and a greater likelihood of optic nerve damage.
Ocular Hypertension Causes
High pressure inside the eye is caused by an imbalance in the production and drainage of fluid in the eye. The channels that normally drain the fluid from inside the eye do not function correctly. More fluid is being made but cannot cannot drain. This results in an increased amount of fluid inside the eye, thus raising the pressure.
Another way to think of high pressure inside the eye is to imagine a water balloon. The more water that is put into the balloon, the higher the pressure inside the balloon. The same situation exists with too much fluid inside the eye: The more fluid, the higher the pressure. Also, just like a water balloon can burst if too much water is put into it, the optic nerve in the eye can be damaged by too high of a pressure.
People with very thick but normal corneas often have eye pressure measuring at the high levels of normal or even a little bit higher. Their pressures may actually be lower and normal, but the thick corneas cause a falsely high reading during measurements.
Ocular Hypertension Symptoms
Most people with ocular hypertension do not have any symptoms. For this reason, regular eye examinations with an eye doctor are very important to rule out any damage to the optic nerve from the high pressure.
Questions to Ask the Doctor
1). Is my eye pressure elevated?
2). Are there any signs of eye damage due to an injury?
3.)Has my optic nerve been damaged?
4). Is my peripheral vision normal?
5). Is treatment necessary?
6). How often should I get follow-up examinations?
Exams and Tests
- Visual acuity using eye chart.
- Slit Lamp.
- Tonometry.
- Optic Nerve Examination.
- Gonioscopy.
- Visual Field Testing.
- Pachymetry.
Ocular Hypertension Treatment
- Medication.
- Surgery.
Next Steps
Depending on the amount of optic nerve damage and the level of intraocular pressure control, people with ocular hypertension may need to be seen from every 2 months to yearly, even sooner if the pressures are not being adequately controlled.
Glaucoma should still be a concern in people who have elevated intraocular pressure with normal-looking optic nerves and normal visual field testing results or in people who have normal intraocular pressure with suspicious-looking optic nerves and visual field testing results. These people should be observed closely because they are at an increased risk for glaucoma.
Prevention
Ocular hypertension cannot be prevented, but through regular eye examinations with an eye doctor, its progression to glaucoma can be prevented. Depending on the amount of optic nerve damage and the level of intraocular pressure control, people with ocular hypertension may need to be seen from every 2 months to yearly, even sooner if the pressures are not being adequately controlled.
