Her vision changed after taking a medicine for erectile dysfunction.

According to a case study published this month, the 31-year-old woman bought an unspecified form of sildenafil citrate – the same active ingredient contained in Viagra – from a "non-pharmaceutical source" online . He drank directly into the bottle and immediately began to see flashes of light in both eyes, and his vision became tinged with red.

"It's important to remember that you need to use medications at the right doses." Sildenafil is extremely safe at the usual doses, "said Dr. Raj Maturi, Ophthalmologist, Associate Professor in the Faculty of Medicine at the University. from Indiana, who practices at the Midwest Eye Institute. Maturi was not involved in the new report, although he did study the effects of sildenafil on the eyes.

"We have not found any problems at all – in fact, no case that looks like this – we had some patients who had blurred vision, but that almost always disappeared in a few hours," said Maturi, also spokesperson. for the American Academy of Ophthalmology. "However, this is quite possible if the dose that is taken is maybe four or five, or even 10 times the normal dose."

According to Maturi, when patients have visual symptoms after taking sildenafil, there is often something else. For example, when the drug is taken with drugs for hypertension, the blood pressure may drop to the point that "there is not enough blood in the optic nerve", which causes a transient loss of vision.

The findings of the report's authors suggest that the drug was toxic to light-sensitive human eye cells.

In order to treat erectile dysfunction, sildenafil acts on an enzyme of the penile tissues. But a similar enzyme exists in the eye. Drugs such as Cialis and Levitra and, to a lesser extent, Viagra, may have a lesser effect, said Maturi.

The authors of the new document also acknowledge that there is some uncertainty as to the exact content of the bottle that the man has ordered on the Internet. "The purity of the active substance and the accuracy of the concentration are of concern," they wrote.

Maturi said that it was an edifying tale against the purchase of drugs on some websites because they could contain unknown ingredients that increase their potency and have no side effects. desired. "The good news is that these drugs are relatively inexpensive," he added, in generic forms in pharmacy.

"Companies on the Internet do different things that are absolutely not approved by the FDA and that cause problems for patients," he said.