Ocular Hypertension (cont.)
Ocular Hypertension Studies
As of the year 2000, an estimated 2.47 million people in the United States have glaucoma and more than 130,000 are legally blind because of this disease. These statistics alone emphasize the need to identify and closely monitor people who are at risk of developing glaucoma, particularly those with ocular hypertension.
- Studies estimate that 3-6 million people in the United States alone, including 4-10% of the population older than 40 years, have intraocular pressures of 21 mm Hg or higher, without detectable signs of glaucomatous damage using current tests.
- Studies over the last 20 years have helped to characterize those with ocular hypertension.
- Recent data on people with ocular hypertension from the Ocular Hypertension Treatment Study have shown that 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. Future studies will help to further assess this risk of glaucoma development.
- Patients with thin corneas may be at a higher risk for glaucoma development; therefore, your ophthalmologist may use a measuring device, called a pachymeter, to determine your corneal thickness.
- Ocular hypertension is 10-15 times more likely to occur than primary open-angle glaucoma, a common form of glaucoma. That means that out of every 100 people older than 40 years about 10 will have pressures higher than 21 mm Hg, but only 1 of those people will have glaucoma.
- Over a 5-year period, several studies have shown the incidence of glaucomatous damage in people with ocular hypertension to be about 2.6-3% for intraocular pressures of 21-25 mm Hg, 12-26% for intraocular pressures of 26-30 mm Hg, and approximately 42% for those higher than 30 mm Hg.
- 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 mm Hg in people with ocular hypertension and who are older than 65 years is often suggested.
Some studies have found that the average intraocular pressure in blacks is higher than in whites, while other studies have found no difference.
- A 4-year study showed that blacks with ocular hypertension were 5 times more likely to develop glaucoma than whites. Findings suggest that, on average, blacks 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.
- In addition, blacks are considered to have a 3-4 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 40 years is considered to be a risk factor for the development of both ocular hypertension and primary open-angle glaucoma.
- Elevated 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.
Francisco Talavera, PharmD, PhD
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