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Eye
Drops May Delay or Prevent Glaucoma in African-Americans
Washington University Press Release Embargoed
until 3 p.m. CT, Monday, June 14, 2004
St. Louis,
June 14, 2004 — Eye drops that reduce elevated
pressure inside the eye can delay or prevent the
onset of glaucoma in African-Americans at high risk
for developing the disease, according to a study
led by researchers at the University of Maryland
Medical Center and Washington University School
of Medicine in St. Louis.
The researchers
say that means it is important to identify African-Americans
with elevated eye pressure, so they can receive
prompt medical treatment. The results are reported
in the June 2004 issue of Archives of Ophthalmology.
“This
analysis of the data revealed both good news and
bad news,” says Michael A. Kass, M.D., national
chair of the 22-center study and head of the Department
of Ophthalmology and Visual Sciences at Washington
University School of Medicine. “African-Americans
do better when they are treated with pressure-lowering
drops, but even with treatment, they tend to have
a higher risk than other groups.”
Daily
pressure-lowering eye drops reduced the development
of primary open-angle glaucoma in African-Americans
by almost 50 percent. Primary open-angle glaucoma
is the most common form of glaucoma and one of the
nation’s leading causes of blindness.
Of the
African-American study participants who received
the eye drops, 8.4 percent went on to develop glaucoma.
By comparison, 16.1 percent of the African-American
study participants who did not receive the eye drops
went on to develop the disease.
The African-American
subjects were part of a larger study called the
Ocular Hypertension Treatment Study (OHTS). The
new results are a follow up to initial results released
two years ago. In those earlier findings, researchers
discovered that treating people with elevated eye
pressure could delay or prevent the onset of glaucoma.
At that time, results for African-Americans trended
in the same direction, but now investigators have
been able to separate out data from the African-American
participants in the national study and consider
their risks as a group.
During
the original OHTS study, 1,636 subjects between
the ages of 40 and 80 were divided into two groups.
All had elevated pressure in the eye — ocular
hypertension — but did not have glaucoma,
and about half were randomly selected to use eye
drops each day. The others were closely monitored
by eye specialists for a minimum of five years but
did not use drops.
This
new analysis looked in detail at the outcomes for
the 408 African-Americans who participated in the
OHTS study. Researchers also compared the African-American
subjects to the rest of the subjects in the study
and found that among patients in the observation
group — those who did not use pressure-lowering
eye drops — about 11 percent developed glaucoma
during the course of the study. But the percentage
of African-Americans who did not receive drops and
developed the disease was 16.1 percent.
Looking
at patients who received the pressure-lowering drops,
the investigators found that 8.4 percent of African-Americans
developed glaucoma, but only 4.4 percent of the
other patients using drops developed the disease.
“We’ve
known for some time that glaucoma is about four
times more common in African-Americans than in Caucasians,
and blindness from glaucoma is about six times more
common in African-Americans,” Kass says. “This
study suggests that even when treatment is identical,
the risk for African-Americans is still higher,
even though treatment does help. We believe there
must be other factors that help explain the differences,
but the full explanation is not available right
now.”
The study
suggests there may be anatomical differences that
explain some of the increased risk. For instance,
some African-American patients have thinner corneas
and a slightly different anatomical appearance to
the optic nerve than other populations. Eve Higginbotham,
M.D., first author on this study and head of the
Department of Ophthalmology at the University of
Maryland Medical Center, says those differences
should be considered when prescribing treatment
for African-American patients at risk for glaucoma.
To determine
why some African-Americans are at increased risk,
a team of Washington University scientists has launched
a new study that will compare gene expression in
the optic nerves of African-Americans to age-matched
Caucasians. That study, funded by a five-year, $3.4
million grant from the National Eye Institute, will
be headed by M. Rosario Hernandez, D.D.S., professor
of ophthalmology and visual sciences at Washington
University School of Medicine.
“We
believe that gene-based differences between African-Americans
and Caucasians may be what underlies susceptibility
to glaucoma,” Hernandez says. “We plan
to test that hypothesis over the next few years
by studying the behavior of human cells taken from
the two groups. If we find that certain genes are
more active in optic nerve cells from African-Americans,
we also might find that those same genes are overactive
in Caucasians who develop the disease, providing
a potential genetic target for assessing risk.”
Hernandez
and colleagues also will compare differences in
growth factors, nerve cell proliferation and cell
migration in optic nerve tissues from African-Americans
and Caucasians. They will pay particular attention
to the optic nerve head, the likely target of stress
generated by high pressure in the eye.
“Our
main goal is to determine how cells called astrocytes
contribute to optic nerve degeneration in glaucoma,”
Hernandez says. “Astrocytes are the major
cell type in the optic nerve, providing structural
and metabolic support to the nerve fibers.”
But until
Hernandez and her colleagues can identify genetic
and other types of risk that make cells more vulnerable
to damage from high pressure and glaucoma, researchers
from the OHTS study say early detection and treatment
of glaucoma is the key to a good outcome. Both for
African-Americans and for members of other ethnic
groups, this latest study reaffirms that drops can
slow the progression of the disease.
“When
determining treatment, doctors should take into
account several risk factors, including the specific
anatomical characteristics of the optic nerve and
the cornea,” Higginbotham says. “While
African-Americans participating in our study were
more likely than others to have these specific physical
characteristics, the study results underscore the
importance of measuring these ocular risk factors
rather than relying solely on the race or ethnicity
of the individual.”
Primary
open-angle glaucoma
Primary open-angle glaucoma affects about 2.2 million
Americans age 40 and over. Half of them are not
aware they have the disease. Vision loss from glaucoma
occurs when the optic nerve is damaged. In most
cases, elevated eye pressure, also called ocular
hypertension, contributes to this damage. This causes
gradual loss of peripheral (side) vision.
As the
disease progresses, the field of vision gradually
narrows and blindness can result. Glaucoma has no
early symptoms, and by the time people experience
problems with their vision, they usually have a
significant amount of optic nerve damage. However,
if detected early, glaucoma can usually be controlled
and serious vision loss prevented. Comprehensive
dilated eye examinations are recommended at least
once every two years for African Americans over
age 40 and all people over age 60.
###
Higginbotham
EJ, Gordon MO, Beiser JA, Drake MV, Bennett GR,
Wilson MR, Kass MA. The Ocular Hypertension Treatment
Study: Topical medication delays or prevents primary
open-angle glaucoma in African American individuals.
Archives of Ophthalmology, June 2004, pp. 813-820.
The Ocular
Hypertension Treatment Study was sponsored by the
National Eye Institute (NEI) and the National Center
on Minority Health and Health Disparities (NCMHD)
of the National Institutes of Health (NIH). The
study also was supported by Research to Prevent
Blindness and Merck Research Laboratories.
The full-time
and volunteer faculty of Washington University School
of Medicine are the physicians and surgeons of Barnes-Jewish
and St. Louis Children's hospitals. The School of
Medicine is one of the leading medical research,
teaching and patient care institutions in the nation,
currently ranked second in the nation by U.S. News
& World Report. Through its affiliations with
Barnes-Jewish and St. Louis Children's hospitals,
the School of Medicine is linked to BJC HealthCare.
Eye
Drops Can Delay Onset of Glaucoma
Washington University Press Release June 13, 2002
St. Louis,
June 13, 2002 -- A study led by investigators at
Washington University School of Medicine in St.
Louis has found that drops that lower eye pressure
can delay the onset of glaucoma. The eye drops reduced
the development of open-angle glaucoma by more than
50 percent. The study appears in the June 2002 issue
of the Archives of Ophthalmology.
"The
fundamental question we asked was whether you can
delay or prevent people from developing glaucoma,"
says Michael A. Kass, M.D., national chair of the
22-center study and head of the Department of Ophthalmology
and Visual Sciences at Washington University School
of Medicine. "There are millions of people in the
United States (and in other countries) who are at
risk of developing glaucoma because they have high
pressure in their eyes. This study provides the
first good evidence that treating those people may
delay, or possibly even prevent, the blinding eye
disease, glaucoma."
The study,
called the Ocular Hypertension Treatment Study (OHTS),
examined 1,636 people between the ages of 40 and
80. All had elevated pressure in the eye (ocular
hypertension) but did not have glaucoma. About half
(817) were randomly selected to use eye drops each
day. The other patients (819) were closely monitored
by eye specialists for a minimum of five years.
Patients
who received treatment were given commercially available,
pressure-lowering eye drops, either a single type
of drop or a combination of more than one. The drops
reduced pressure in the eye by approximately 20
percent.
"I think
it is very significant that reducing pressure in
the eye by only 20 percent reduced risk by as much
as it did," Kass says. "A modest drop in pressure
makes a big difference."
Open-angle
glaucoma is the most common form of glaucoma and
one of the leading causes of blindness in the United
States. It is the number one cause of blindness
among African Americans and affects a total of about
2.2 million Americans age 40 and over. As many as
2 million more may have the disease, but they have
not been diagnosed. Because glaucoma rarely has
early symptoms, by the time they experience vision
problems, most people already have significant,
irreversible damage.
As with
heart disease, diabetes and high blood pressure,
glaucoma develops over many years. The idea of attacking
glaucoma before damage could occur has been an attractive
one, but there was no clear evidence to support
this approach. The current study addressed this
issue by clearly identifying factors that put people
at risk for the disease.
Several
risk factors are associated with the development
of glaucoma, including older age and African descent,
particular characteristics in the anatomy of the
optic nerve, and thinness of the cornea.
Fluid
regularly flows into and out of the eye. High pressure
results when that fluid drains too slowly. Between
3 and 6 million Americans have elevated eye pressure
and are at risk for open-angle glaucoma. Approximately
1.5 million people in the United States who have
elevated eye pressure but do not have glaucoma already
are being treated with medications that lower intraocular
pressure, but prior to this study, there was no
convincing evidence that the treatment has any long-term
benefit. These findings change that.
"During
the five-year study period, we found that only 4.4
percent of the study patients who received the eye
drops developed glaucoma," says Mae E. Gordon, Ph.D.,
director of the OHTS Coordinating Center and professor
in the Department of Ophthalmology and Visual Sciences
and the Division of Biostatistics at Washington
University School of Medicine. "By comparison, 9.5
percent of the study participants who did not get
pressure-lowering drops developed glaucoma."
Although
high pressure in the eye is a strong risk factor
for glaucoma, patients aren't considered to have
the disease until they also have damage to their
optic nerve. The damage causes loss of peripheral
(side) vision. As glaucoma worsens, a patient's
field of vision gradually narrows, and they can
become almost blind. But if the disease is detected
early through a comprehensive eye exam, glaucoma
usually can be controlled and serious vision loss
prevented. The American Academy of Ophthalmology
recommends comprehensive eye exams for all people
over 60 and for African Americans over 45. African
Americans are three to four times more likely to
develop glaucoma than Caucasians. Because of that
high risk, 25 percent of the participants in the
OHTS were African American.
Even
though drops succeeded in reducing the rate of glaucoma,
Kass believes not all patients with high eye pressure
should automatically receive treatment. "Before
simply putting a patient on drops, doctors need
to consider the patient's general health status,
their individual risk factors and their life expectancy,"
he says. "It's important to remember that even in
the study group that did not receive treatment,
90 percent of the people did not develop glaucoma."
Because
some eye drops cause side effects and because daily
treatment can be inconvenient and expensive, Kass
believes some patients may want to opt for close
observation rather than active treatment. He says
doctors should use the results of this study as
only one of several factors when designing a treatment
strategy for an individual patient.
"The
availability of many different types of pressure-lowering
eye drops will allow eye-care professionals to choose
the safest regimen for each individual patient,"
he says. "We found no increase in health problems
among patients who received eye drops, but different
regimens of drops are more appropriate to some patients
than others, depending upon individual risk and
the general health of the patient."
Kass
says researchers hope to continue the study to determine
the long-term benefits of treatment and to improve
accuracy of the early diagnosis of glaucoma. But
now that the initial phase is complete, those participants
who were randomly assigned to receive observation
rather than eye drops will be offered eye drop medication.
The
Ocular Hypertension Treatment Study was sponsored
by the National Eye Institute (NEI) and the National
Center on Minority Health and Health Disparities
(NCMHD) of the National Institutes of Health (NIH).
The study also was supported by Research to Prevent
Blindness and Merck Research Laboratories.
The full-time
and volunteer faculty of Washington University School
of Medicine are the physicians and surgeons of Barnes-Jewish
and St. Louis Children's hospitals. The School of
Medicine is one of the leading medical research,
teaching and patient care institutions in the nation.
Through its affiliations with Barnes-Jewish and
St. Louis Children's hospitals, the School of Medicine
is linked to BJC HealthCare.
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June
2004 Release