Erection Drugs Viagra, Cialis Didnt Show Eye Damage In Study
The erection drugs can cause changes in light perception right away that clear a few hours later, said Raj Maturi, an author of the Lilly-funded research and an ophthalmologist at the Indiana University School of Medicine in Indianapolis.
The study, published online today in the Archives of Ophthalmology, found no evidence of permanent visual changes in patients who took the drugs every day for six months, Maturi said. About 6.2 percent of U.S. men are unable to achieve an erection, with rates rising to 16.7 percent in ages 60 to 69, according to the National Institutes of Health.
“The average patient should be relieved these drugs dont cause significant visual dysfunction,” Maturi said in a telephone interview today. “And he can be comfortable taking them in the long-term.”
The study was sponsored by Indianapolis-based Lilly, which also helped design the research, collect the data and prepare the manuscript. Viagra had sales of 1.9 billion last year for Pfizer, based in New York. Cialis revenue was $1.2 billion for Lilly.
Drug Actions
The chemicals in Viagra and Cialis act on compounds in the blood vessels of the penis, allowing for more blood flow that can lead to an erection, according to background information in the article. Similar compounds exist in the eye.
Researchers examined 244 men, ages 30 to 65, using a test that measured the electrical impulses from their eyes, as well as comprehensive ophthalmologic exams. A third of the patients took Viagra, a third took Cialis and a third took a placebo.
Each patient visited the examiners six times, and were screened before the study began, halfway through the study, and twice after the study was over.
The exams turned up no cases of a rare optic nerve disease that can cause vision loss in one eye, the authors wrote. The ailment, called non-arteritic anterior ischemic optic neuropathy, is caused by lowered blood pressure. A European advisory panel said in 2006 that people with the disorder shouldnt take erectile-dysfunction drugs.
The study didnt aim to find cases of the disease, Maturi said.
The research was done in healthy men, some of whom had mild erectile dysfunction, Maturi said. The results may not apply to patients with diabetes, who may be more sensitive to lowered blood pressure that could damage the optic nerve, the authors wrote.