Viagra – is one of the most well-known drugs that helps men suffering from disorders of potency, return to normal sexual life. Despite the effectiveness and safety, proven over the years, many men are afraid to take Viagra because of some side effects.
One of the side effects of Viagra, found at the stage of clinical trials was the change in the perception of blue and green. Violation of color vision appeared, when Viagra was just beginning to act, and disappeared after a few hours after taking this pill.
The creators of Viagra conducted additional research and found that sildenafil (Viagra’s main active ingredient), temporarily blocks the enzyme phosphodiesterase, not only in the vessels of the penis, but also in blood vessels of the retina. This fact has forced patients to worry: could it have a negative effect on vision?
Recently, scientists one of the pharmaceutical laboratories in Indianapolis conducted test using Viagra and another popular drug for improvement of erection under the name Cialis. The subjects were divided into three groups. The first group of volunteers within six months every day took Cialis (5 mg), the second group – Viagra (50 mg), and the participants of the third group received a placebo. Ophthalmologists monitored vision during treatment, and six months after stopping treatment. Surveys showed that 80% of study participants throughout the study period had no changes in the organs of vision. Interestingly, one participant of the experiment, which was included in the placebo (“dummy”) group, ophthalmic disease developed.
Another popular drug for treating erectile dysfunction – Levitra has not been included in the list of tested drugs, as this was not necessary. The fact is that Levitra acts selectively and does not affect the enzyme phosphodiesterase, which is contained in the retina. Levitra acts only on the phosphodiesterase, which is produced in the vessels of the penis. These enzymes differ in their chemical structure.
Thus, studies have shown that all three drugs are considered safe for health. Buying Viagra, Cialis or Levitra you can be sure that the side effects though there are, but their action is short-lived and goes through a couple of hours after the end of the pill.