Viagra and two other popular impotence drugs may cause sudden blindness in one eye in rare cases, the Food and Drug Administration said in a formal alert Friday.

Although the statement said it remains unclear whether the drugs are actually causing the sudden Blindness, it warned men most prone to the ocular condition to discuss the newly identified risk with their doctors. The condition, called non-arteritic anterior ischemic optic neuropathy (NAION), is caused by a blockage of blood to the optic nerve.

In its release Friday, the agency identified men at greater risk of the condition as those older than 50 or who smoke, and those with high blood pressure, Heart disease or High Cholesterol.

The FDA said recently that it had received 43 reports of NAION in men who had recently taken Viagra, Cialis or Levitra. The vision loss is generally not reversible.

Source: Cincinnati Post