Probe as Viagra use linked to blindness

US HEALTH officials are examining 38 reports of blindness among some men using Viagra.

However, the Food and Drug Administration has no evidence yet that the drug is to blame, said spokeswoman Susan Cruzan.

The type of blindness involved - NAION, or non-arteritic anterior ischemic optic neuropathy - can occur in men who are diabetic or have heart disease, the same conditions that can cause impotence and thus lead to Viagra use.

The FDA has had a total 42 reports of the blindness, 38 among users of Viagra and four among users of another drug called Cialis. There were no cases reported among users of Levitra, a third impotence drug.

The FDA is in discussions about the reported cases with the manufacturers of the three drugs in case there is a problem with the class of medication.

Eli Lilly & Co, which manufactures Cialis, refers to vision problems as an uncommon side effect.

Viagra manufacturer Pfizer also refers on its website to some vision issues: “Less common are bluish or blurred vision, or being sensitive to light.”

Pfizer spokesman Daniel Watts said there is no proof that Viagra caused the blindness. He said that men who take Viagra often have high blood pressure and high cholesterol.

Viagra was approved by the US government in 1998. It may aid in the treatment of enlarged hearts that can result from high blood pressure.

Analyst Jason Napodano said he doesn’t think Viagra sales will stumble because the number of cases involved is so small.

Viagra should not be used by men with heart conditions whose doctors have warned them not to have sex.

The drug’s label also warns of erections lasting longer than four hours, painful erections lasting longer than six hours, headache, flushed skin and vision problems.