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[IP] Low blood pressure and vision loss



Isn't this a coincidence, we were talking about how low blood pressure
affects vision tonight, and this post of an article was on another list.
Debbie

                  Nighttime Fall Of Blood Pressure From Medication
Increases
                                           Risk Of Vision Loss

               IOWA CITY, IA -- January 6, 1998 -- Researchers in the
University of Iowa College of Medicine are
               concerned that people who take medications to control
high blood pressure at bedtime or in excessive
               amounts may be at increased risk for an eye disorder
known as anterior ischemic optic neuropathy
               (AION) or stroke of the eye.
               According to Dr. Sohan Hayreh, professor of ophthalmology
and the lead author of a study published in
               the American Journal of Ophthalmology, AION seems to have
become increasingly common since the
               introduction of powerful new blood pressure medications.
               The research indicates that in three-quarters of all AION
cases, the precipitating factor is a drop in blood
               pressure during the night, the clue that led Hayreh and
his team to investigate the relationship between the
               drugs and the condition.
               AION is a condition brought on by a small stroke of the
optic nerve, the result of diminished blood supply
               to the anterior, or front part, of the optic nerve. AION
may cause serious vision impairment.
               Some people with AION may not immediately realise their
vision has been affected. "I had one patient
               recently who did not discover his impairment until he
went hunting and tried to aim his gun," Hayreh said.
               He added 25 percent of those who have an incident in one
eye develop AION in the other eye within
               three years. "One day you are functioning fine and within
a few weeks, you have a serious visual
               disability.
               In their study, the researchers looked at 925 episodes of
the onset of AION to determine the time of day
               and the season of the year in which persons with the
condition discovered their visual loss. More than
               three-quarters of the people reported they discovered
their impairment upon waking, either from a night's
               sleep or from a nap.
               Hayreh, who first described and named the condition in
1974, had previously made the connection
               between the onset of AION and a decrease in blood
pressure during sleep. Blood pressure normally
               drops when a person is asleep. By using a small blood
pressure monitor developed in the last decade,
               Hayreh has recorded steep drops in blood pressure among
those who had AION and glaucoma.
               He found patients taking such medications as
beta-blockers, calcium channel blockers and ACE
               inhibitors, all of which have become popular treatments
for hypertension and other heart conditions in
               recent years, suffered significantly more optic nerve
damage.
               Hayreh added some medications prescribed for enlarged
prostate can also result in significant drops in
               blood pressure during the night.
               "This is cause for concern, since urologists who treat
the prostate condition may not be aware of the
               increased risk for AION," he said, adding that in
addition to the medications, risk factors for AION
               include diabetes, smoking, high blood pressure and high
cholesterol levels.
               The researchers also found that onset of AION occurs
significantly more often during warm months.
               Hayreh said this indicates that a different set of
factors may be at work to cause AION than those that
               precede heart attack and stroke in the brain, both of
which are more common during the winter.
               "We have found no evidence that patients with AION are at
increased risk for heart attack or stroke in
               the brain," he said. "The fact that AION is more common
during warm weather is something that we
               cannot yet explain. More research is needed."