Viagra risks cut down by one as study finds blood flow in eyes unaffected by sex drive drug
When Viagra was introduced in 1999, the drugs manufacturer warned of a number of visual side effects, including possible nerve damage to the eyes. But a UC Irvine College of Medicine study rules out some of these risks -- even when the drug is taken in high doses.
According to Dr. Tim McCulley, assistant professor of ophthalmology, blood flow in the eye does not seem to be reduced by even high doses of the popular erectile dysfunction drug. Since Viagra lowers blood pressure overall, there was persistent suspicion that the drug might cause decreased optical blood flow, which can cause nerve damage.
McCulleys study appears in the January 2003 issue of Ophthalmologica.
"Viagra can change blood vessel structure as well as general blood pressure, so we needed to answer the question whether the drug could change blood vessels in the eye," McCulley said. "Our study may have had a small group of participants, but it showed very little change in blood vessels or blood flow in nearly all the patients."
McCulleys team conducted the trial with 13 men at Stanford University and found that high doses of Viagra by and large preserved the thickness of the eyes choroids layer, which supplies the eyeball with blood. However, the team did find some small variations in thickness, which indicated that some people with underlying vascular diseases may indeed have changes in vision.
In addition, the researchers found no connection among blood flow choroid thickness and changes in color vision, a common side effect of taking Viagra.
McCulleys team confirmed these side effects, finding that Viagra users had a harder time discriminating among subtle changes in color. But they also found that Viagra users reported problems in picking out any number of colors, not just the blue-green variety reported during the drugs clinical trials.
Andrew Porterfield | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
Larsen C Ice Shelf rift finally breaks through
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision
Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...