Colleagues, the following is FYI and does not necessarily reflect my own
opinion. I have no further knowledge of the topic.
------------------------
Public release date: 30-Mar-2005
http://www.eurekalert.org/pub_releases/2005-03/uom-uom_1033005.php
Contact: Jonell Rusinko
[log in to unmask]
612-624-5680
University of Minnesota
U of M researcher says Viagra may cause permanent vision loss in some men
Ophthalmologists at the University of Minnesota say that a condition
that causes permanent vision loss has been diagnosed in a small group of
men who have taken the erectile dysfunction drug Viagra. The condition,
nonarteritic ischemic optic neuropathy (NAION), described as "stroke of
the eye," occurs when blood flow is cut off to the optic nerve, which
injures the nerve and results in permanent vision loss. These cases were
published in the March 2005 issue of the Journal of Neuro-ophthalmology.
Seven patients, aged between 50 and 69 years, had typical features of
NAION within 36 hours after ingestion of Viagra for erectile
dysfunction. Seven similar cases have been previously reported.
"For years, we've known that some men who take Viagra will experience
temporary color changes in their vision and see things as blue or
green," said Howard Pomeranz, M.D., associate professor of ophthalmology
at the University of Minnesota Medical School. "NAION is a much more
serious condition because it can lead to permanent vision loss."
All of the patients had at least one arteriosclerotic risk factor,
including hypertension, diabetes, hypercholesterolemia, or
hyperlipidemia. All of the patients also had a low cup to disk ratio,
which is a way doctors measure the small circular indentation where the
optic nerve connects to the eyeball. The low cup to disk ratio means
that the blood vessels and nerves are tightly bundled together into the
small space in the back of the eye.
"Viagra regulates a chemical in the body to constrict the arteries. This
constriction may cut off the blood flow to the optic nerve, especially
in people with a low cup to disk ratio, where the blood vessels and
nerves are tightly bundled provoking NAION," says Pomeranz.
The onset of NAION within hours after ingestion of Viagra in 14 patients
supports an association between the use of the drug and NAION. Based on
the fact that 14 cases of NAION have now been reported soon after the
use of Viagra, the researchers believe that ophthalmologists should ask
all men with NAION about the use of Viagra, and recommend that patients
with a history of NAION in one eye be cautioned that Viagra may increase
the risk of NAION in the fellow eye.
###
The Academic Health Center is home to the University of Minnesota's six
health professional schools and colleges as well as several
health-related centers and institutes. Founded in 1851, the University
is one of the oldest and largest land grant institutions in the country.
The AHC prepares the new health professionals who improve the health of
communities, discover and deliver new treatments and cures, and
strengthen the health economy.
--
Kathrynne Holden, MS, RD < [log in to unmask] >
"Ask the Parkinson Dietitian" http://www.parkinson.org/
"Eat well, stay well with Parkinson's disease"
"Parkinson's disease: Guidelines for Medical Nutrition Therapy"
http://www.nutritionucanlivewith.com/
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