A man has taken too much medicine for erectile dysfunction. Then his vision became red

According to a new report on his case, a man in New York had an unexpected side effect due to a high dose of a liquid medicine for erectile dysfunction.

Indeed, two years after the incident, the human vision remains impaired, according to the case report published Oct. 1 in the journal Retinal Cases & Brief Reports.

The 31-year-old man visited the urgent care clinic at the Mount Sinai Infirmary in New York City two years ago. (Contrast of vision refers to the ability to distinguish an object from its surroundings, based on differences in light and color.) [‘Eye’ Can’t Look: 9 Eyeball Injuries That Will Make You Squirm]

He told doctors that he had bought a liquid erectile dysfunction drug online and drank it straight out of the bottle. The drug contained sildenafil citrate compound, which is the generic version of Viagra. Because the man drank the drug straight out of the bottle, he did not know how much he had consumed … but he guessed it was a lot more than what was indicated.

Eye imaging and other tests have shown that he had damaged cells on his outer retina, which is the back part of the eye. Specifically, it damaged its photoreceptors – cells in the retina that turn light into electrical signals that allow us to see. There are two types of photoreceptors: the cones, which allow us to see in color, and the rods, which allow us to see in dim light. Imaging tests revealed that the man had damaged the cones sensitive to color.

In fact, a common side effect of sildenafil citrate involves vision changes, said Dr. Richard Rosen, senior case author, who treated the man. Indeed, a previous preclinical study conducted by Pfizer (manufacturers of Viagra) had shown that high doses (200 mg) of these drugs caused vision problems in 50% of subjects, according to the case report.

But usually, these problems go away in 24 hours, Rosen told Live Science. It is also more common for people to develop a blue vision, rather than a red vision, although the latter has already been reported, as has the yellow vision, he added.

Rosen pointed out that the drug that the man had purchased online had not been approved by the US Food and Drug Administration for the purity and accuracy of the concentrations of chemicals used, even though 39 it contained the same generic medicine as Viagra. This means that the drug could have even greater toxicity, the authors wrote in the report. In fact, the bottle, which according to Rosen called "Iron Man", indicates that it should not be consumed by people, he added.

These drugs, which act on the enzyme involved in maintaining an erection, can also cross-react with an enzyme very similar to that found in the eye that is involved in vision. "The enzymatic systems of the eye are very delicate" and "extremely sensitive to any toxic substance," said Rosen.

This is why a number of drugs can cause adverse effects to the eyes, he added.

The case report serves as a "telling story for people," said Rosen. A common myth is that a "a little, that's good, a lot, it's a lot better," he said, but that certainly does not apply to medications against the ED bought online. And although the symptoms of the man improve, his vision is not completely back to normal. It could have permanent damage, said Rosen.

Originally posted on Live Science.