Study Findings that State Eye Drops Delay Onset of Glaucoma in People
at Higher Risk
have discovered that eye drops used to treat elevated pressure inside
the eye can be effective in delaying the onset of glaucoma. These results
mean that treating people at higher risk for developing glaucoma may
delay -- and possibly prevent -- the disease. These findings are reported
in the June 2002 issue of Archives of Ophthalmology.
At the Emory Eye Center in
Atlanta, where nearly 100 patients have been followed for up to nine
years, Allen Beck, MD, a principal investigator in the study, was very
encouraged by the results.
"I think these results will
have a major impact on the way we regard and treat patients with elevated
eye pressure," said Dr. Beck. "This large nationwide study better defines
the risk factors for glaucoma and will have a lasting benefit to our
patients. When treatment to lower eye pressure in an ocular hypertensive
patient is recommended, we will have confidence that we can significantly
lower that patient's risk of developing glaucoma," he concluded.
Scientists found that pressure-lowering
eye drops reduced by more than 50 percent the development of primary
open-angle glaucoma, the most common form of glaucoma and one of the
nation's leading causes of vision loss. Researchers noted that 4.4 percent
of the study participants who received the eye drops developed glaucoma
within five years. By comparison, 9.5 percent of the study participants
who did not receive the eye drops developed glaucoma. Additionally,
several significant risk factors were found to be associated with the
development of glaucoma in study participants. These included personal
risk factors, such as older age and African descent, 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.
Elevated eye pressure results
when the fluid that flows in and out of the eye drains too slowly, gradually
increasing pressure inside the eye. It is estimated that between three
and six million people in the U.S. -- including between four and seven
percent of the population above age 40 -- have elevated eye pressure
and are at increased risk for developing open-angle glaucoma. Until
now, doctors did not know if treating elevated eye pressure before glaucoma
developed could delay the onset of the disease. Some doctors treat people
with elevated eye pressure, others do not. This study provides some
important information to consider in reaching a decision about treatment.
"This study showed that treating
elevated eye pressure delays or prevents the onset of glaucoma in some
people," said Paul A. Sieving, M.D., Ph.D., director of the National
Eye Institute (NEI), a component of the Federal government's National
Institutes of Health (NIH) and one of the study's sponsors. "The study
clearly makes a connection between elevated eye pressure and the onset
of glaucoma. However, not all people with elevated eye pressure should
be treated with the eye drops. If you are at risk for glaucoma, see
your eye care professional to receive a comprehensive eye exam and find
out if eye drops might help."
The study -- called the Ocular
Hypertension Treatment Study examined 1,636 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.
"It is significant that this
modest 20 percent reduction in eye pressure had such an important protective
effect in the development of glaucoma," said Michael Kass, M.D., of
the Washington University Department of Ophthalmology and Visual Sciences
and chair of the study.
Dr. Kass sounded a cautionary
note. "Eye care professionals should not prescribe eye drops for all
people who have elevated eye pressure with no sign of glaucoma," he
said. "Doctors should take into account several factors, including the
simple fact that 90 percent of participants in the observation group
did not develop glaucoma within the five-year study period. An individual's
risk of developing glaucoma, along with their health status and life
expectancy, should be considered. The burden of daily treatment, including
cost, inconvenience, and possible side effects, are other factors that
the doctor and patient should discuss."
Dr. Kass said that study
researchers prescribed commercially available eye drops, either singly
or in combination, to reduce eye pressure. "The availability of many
different types of pressure-lowering eye drops allows eye care professionals
to choose the safest regimen for each patient," he said. In the study,
the group receiving the eye drops did not show increased evidence of
health problems in comparison to the observation group.
Open-angle glaucoma affects
about 2.2 million Americans age 40 and over; another two million may
have the disease and don't know it. Glaucoma occurs when the optic nerve
is damaged. In most cases, increased pressure in the eye plays an important
role in this damage. The damage to the optic nerve causes loss of peripheral
(side) vision. As the disease worsens, the field of vision gradually
narrows and blindness can result. However, if detected early through
a comprehensive eye exam, glaucoma can usually be controlled and serious
vision loss prevented. Comprehensive eye examinations are recommended
for all people over age 60, and African Americans over age 40.
Glaucoma is the leading cause
of blindness in African Americans, according to John Ruffin, Ph.D.,
director of the National Center on Minority Health and Health Disparities
(NCMHD), part of NIH and another study sponsor. "Glaucoma is three to
four times more likely to develop in African-Americans than whites,"
Dr. Ruffin said. "This study took that into account: 25 percent of study
participants were African American."
Dr. Sieving said this clinical
trial is among the studies supported in the National Eye Institute's
glaucoma research program. "We will continue to conduct and support
research aimed at finding better ways to detect, treat, and possibly
prevent glaucoma," he said.
In addition to support from
the NEI and NCMHD, the Ocular Hypertension Treatment Study was supported
by Research to Prevent Blindness and Merck Research Laboratories. The
study was conducted at 22 clinical centers across the country.