**Background**

# *Ocular Hypertension Treatment Study (African-American Results)*

Glaucoma is a group of diseases that can damage the eye's optic nerve
and result in blindness. Open-angle glaucoma, the most common form, is
one of the leading causes of blindness in the United States,
particularly among African Americans. Glaucoma usually has no early
symptoms, and by the time people experience problems with their vision,
they usually have a significant amount of optic nerve damage.

**How Open-Angle Glaucoma Develops**

Increased pressure inside the eye is frequently associated with
open-angle glaucoma. In the front of the eye is a space called the
anterior chamber. A clear fluid flows continuously in and out of this
space and nourishes nearby tissues. The fluid leaves the anterior
chamber at the angle where the cornea and iris meet. When the fluid
reaches the angle, it flows through a spongy meshwork, like a drain, and
leaves the eye.

Open-angle glaucoma gets its name because the angle that allows fluid to
drain out of the anterior chamber is open. However, for unknown reasons,
the fluid passes too slowly through the meshwork drain. As the fluid
builds up, the pressure inside the eye rises. Elevated eye pressure is
believed to damage the optic nerve, but the mechanism is still unknown.
A healthy optic nerve is necessary for good vision. When the optic nerve
is damaged, vision loss is the result.

At first, open-angle glaucoma has no symptoms. People are not aware that
glaucoma is affecting their vision, and there is no pain. When glaucoma
remains untreated, people may notice that although they see things
clearly in front of them, they miss objects to the side and out of the
corner of their eye. Without treatment, people with glaucoma may find
that they have no side vision. Over time, the remaining vision may
decrease until there is no vision left.

**The Ocular Hypertension Treatment Study**

Initial results of the Ocular Hypertension Treatment Study, published in
2002, found that eye drops used to reduce pressure inside the eye were
effective in delaying the onset of primary open-angle glaucoma.
Researchers found that after five years, treatment reduced the onset of
primary open angle glaucoma by more than 50 percent. The study examined
1636 people 40-80 years of age who had elevated eye pressure but no
signs of glaucoma. Half were assigned daily eye drops, and the other
half were assigned to observation (no medication). In the medication
group, treatment reduced eye pressure by approximately 20 percent. The
Ocular Hypertension Treatment Study was the first large-scale study to
demonstrate that lowering eye pressure can safely and effectively delay
and possibly prevent the disease.

Because glaucoma is a leading cause of blindness and visual impairment
among African Americans, researchers wanted a more definitive answer
about the effects of early treatment in this subgroup. After OHTS'
initial results, researchers continued to follow the African Americans
in OHTS and found that pressure-lowering eye drops reduced the
development of primary open-angle glaucoma by almost 50 percent.

Several significant risk factors are associated with the development of
glaucoma. These include older age, family history of glaucoma, and
diabetes, as well as ocular risk factors, such as higher eye pressure,
certain characteristics in the anatomy of the optic nerve, and thinness
of the cornea. The OHTS underscores the importance of assessing all of
these risk factors in the management of individual patients rather than
relying on the perceived or self-reported "race" of that individual.