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:
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...