Thanks to the over 1,600 participants in the Ocular Hypertension Treatment Study (OHTS), we have already changed the way doctors care for people worldwide with high eye pressure.

Information for participants

Please contact your clinic for more information about your participation.

Ocular hypertension and glaucoma

Ocular Hypertension is a common condition that occurs in 3 to 8% of Americans over age 40.

The eye makes fluid different from tears which then drains away. When fluid cannot drain, the eye pressure builds up in the system – known as ocular hypertension. This can damage the nerve at the back of the eye, causing glaucoma.

A higher than normal eye pressure does not by itself mean that you have glaucoma. But people with ocular hypertension have a higher risk of developing glaucoma. So some doctors refer to them as “glaucoma suspects.”

Glaucoma is one of the leading causes of blindness in the United States, but little is known about preventing it.

Primary Open Angle Glaucoma (POAG)

Primary Open Angle Glaucoma (POAG) is glaucoma associated with an open anterior chamber angle. It is the most common form of glaucoma. High pressure in the eye damages nerve fibers in back of the eye, which leads to a slow loss of vision, often referred to as tunnel vision.

How has the study helped so far?

The 1,636 participants in the study have changed the management of ocular hypertension in the U.S. and worldwide.

  • We now know that medicated eyedrop treatment can prevent or delay glaucoma, a serious eye problem. And we know that the thickness of the cornea can predict who will develop glaucoma.
  • Medicare now covers the cost of corneal thickness measurements for nearly 1 million patients per year. For many patients, this measure helps decide how often patients should see their eye doctor and if they will need treatment.
  • Most eye doctors around the world now have access to OHTS’ simple, web-based calculator to identify which patients are more likely to develop glaucoma.
  • The major papers from this study are among the most cited in medical research and have improved how doctors manage ocular hypertension and glaucoma.

Phases 1 and 2 are complete

In phase 1 of the study, which began in 1994, we randomly assigned groups of people with high eye pressure and no evidence of glaucoma to either receive or not receive eyedrop medication. In phase 1, the first participant was randomized at Devers Eye Institute on 02/28/1994 and the last participant was randomized at Kresge Eye Institute on 10/31/1996. In phase 2, which ended in 2009, everyone received the drops.

The results of these first two phases showed that the rate of developing glaucoma was reduced by more than 50% in those using eyedrops.

The next phase

We are now beginning phase 3, which involves a 20-year follow-up to this historic study that we believe will lead to new scientific advances in ocular diseases such as glaucoma.

Phase 3 results will help doctors make decisions about the best care for patients with high eye pressure. This includes decisions about how often patients should receive exams and whether or not they will benefit from treatment.