CONTACT: BECKY SOGLIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-6660; fax (319) 335-8034
Release: Nov. 3, 1999
UI study adds evidence: Common glaucoma treatment may
contribute to other eye risks
IOWA CITY, Iowa -- Beta-blocker eyedrops, commonly
used to treat glaucoma, may put some people with the condition at increased
risk for further visual loss by aggravating the fall of blood pressure during
sleep, according to a University of Iowa Health Care study.
This excessive nighttime fall in blood pressure in
susceptible individuals can interfere with optic nerve circulation which,
in turn, may worsen glaucoma damage and produce an optic nerve stroke, known
as anterior ischemic optic neuropathy, said Sohan Singh Hayreh, M.D., Ph.D.,
D.Sc., UI professor emeritus of ophthalmology and visual sciences, and lead
"Blood pressure normally falls during sleep in
all of us, and it is not a problem if there are no other risk factors,"
Hayreh said. "However, if a person with glaucoma is taking beta-blocker
eyedrops to lower eye pressure, the blood pressure could fall even more and
potentially reduce blood circulation through the optic nerve in susceptible
Although these beta-blocker eyedrop side effects had
been previously documented, the UI planned study is the first to examine the
problem on a large-scale by continuous blood pressure monitoring over a 24-hour
period. The UI team studied 275 white patients, 161 with glaucoma and 114
who had experienced an eye stroke. The participants had their blood pressure
monitored every 10 minutes during the daytime and every 20 minutes during
the nighttime for 24 hours.
"We were surprised to find that patients with
normal tension glaucoma, also known as low tension glaucoma, had much greater
decreases in blood pressure than patients who were known to have the optic
nerve stroke," Hayreh said.
Patients using beta-blocker eyedrops had much greater
decreases in nighttime diastolic blood pressure, lower minimum nighttime diastolic
blood pressure and lower minimum nighttime heart rate than patients who were
not using the medication. Thus, beta-blocker eyedrop use may put individuals
at risk for optic nerve stroke or worsened glaucoma damage.
Previous studies led by Hayreh have shown a significant
association between progressive vision deterioration and nighttime blood pressure
fall in patients with glaucoma or optic nerve stroke who also had high blood
pressure and were on blood pressure lowering medication.
Beta-blockers are one of many types of pills used
to lower high blood pressure. The UI studies seem to suggest that beta-blockers
taken orally as a pill or in eyedrop form can cause excessive blood pressure
fall during sleep, particularly when the medication is taken at bedtime or
in the evening. The excessive blood pressure decrease is then a risk factor
for glaucoma damage or optic nerve stroke. These risks also hold true for
other blood pressure-lowering medicines.
Lowering the eye pressure in people with glaucoma
is absolutely essential to prevent visual loss. Beta-blocker eyedrops lower
the eye pressure very effectively in the vast majority of people; hence, their
use since the early 1970s has become almost the first option for glaucoma
treatment, Hayreh said.
"It is absolutely essential for people with glaucoma
to lower their eye pressure," he said. "However, the present research
study suggests that for some individuals beta-blocker eyedrops may not be
the ideal medication to use.
"If a person with glaucoma is using beta-blocker
eyedrops and yet is still losing vision in spite of low eye pressure, the
nighttime blood pressure decrease may be the underlying factor. In that case,
it is better to switch to other glaucoma drops that do not decrease the blood
pressure too much during sleep."
Hayreh cautioned that people using beta-blockers,
whether in eyedrop form for glaucoma or pill form for high blood pressure,
should not stop taking their medication on their own because that can be extremely
dangerous. Instead they should consult with their ophthalmologist or other
physician about whether they are at increased risk for problems and should
thus adjust their treatment.
Approximately 2 million Americans have glaucoma. Overall,
it is the second most common cause of legal blindness. Glaucoma painlessly
destroys side vision, thus limiting a persons ability to perform most
day-to-day activities such as walking, driving or carrying out manual tasks.
A person with glaucoma can deceptively believe that his or her eyes are fine
because central vision is generally lost only in the late stages of the disease.
Left untreated, glaucoma damage is irreversible and progressive, ultimately
resulting in complete blindness.
Optic nerve stroke is one of the most common causes
of sudden visual loss in the middle-aged and elderly population. Haryeh first
postulated the connection between optic nerve strokes and blood pressure fall
during sleep in 1974. He reported in 1998 that three of every four patients
who had an optic nerve stroke noticed sudden loss of vision after they had
slept. The recent 24-hour blood pressure monitoring study lends support to
the connection between eye stroke and nighttime blood pressure decreases.
The UI findings on beta-blocker eyedrops and glaucoma
were published in the September issue of the American Journal of Ophthalmology.
The UI team also included Patricia Podhajsky, a research
nurse in ophthalmology and visual sciences, and M. Bridget Zimmerman, Ph.D.,
a biostatician in the UI College of Public Health.
The study was supported by grants from the National
Institutes of Health, and Research to Prevent Blindness, Inc. based in New
York. Hayreh is also a Research to Prevent Blindness Senior Scientific Investigator.
University of Iowa Health Care describes the partnership
between the UI College of Medicine and the UI Hospitals and Clinics and the
patient care, medical education and research programs and services they provide.