WHAT IS THIS STUDY ABOUT? Glaucoma and ocular hypertension are chronic eye diseases that can damage the optic nerve and lead to vision loss or blindness. The optic nerve acts like an electric cable with over a million wires. This nerve is responsible for carrying images from the eye to the brain. The way glaucoma and ocular hypertension cause blindness depends on many factors, but the most important factor is the increased pressure inside the eye (intraocular pressure).

There is no cure for glaucoma or ocular hypertension. However, lowering the pressure inside the eye has been shown to slow the progression of disease. Intraocular pressure can be lowered by glaucoma medication, laser treatment, or surgery.

You have open angle glaucoma, pseudoexfoliative glaucoma, or ocular hypertension. Researchers want to find out more about how 2 drugs called Cosopt (dorzolamide hydrochloride and timolol maleate) and Xalatan (latanoprost) can help people with these conditions.

Cosopt and Xalatan are both eye drops that are approved by the U.S. Food and Drug Administration (FDA) to reduce intraocular pressure in people with open angle glaucoma and ocular hypertension.

The study doctor will do a laser procedure called Selective Laser Trabeculoplasty (SLT) on people in this study to help lower their intraocular pressure. The FDA has approved SLT to treat open angle glaucoma and ocular hypertension.

Then the study doctor will ask some participants to use either Cosopt or Xalatan, if their intraocular pressure is still too high 4 to 6 weeks after the SLT procedure. The study doctor wants to see which of the 2 study drugs (Cosopt or Xalatan) is better at reducing intraocular pressure after SLT.

It is planned that about 30 people with glaucoma or ocular hypertension who are at least 18 years old will be in this study. Out of the participants whose intraocular pressure is still too high after SLT, half will use Cosopt and half will use Xalatan. You do not have to be in this study to have SLT or to use Cosopt or Xalatan.