Disease Proof

Fifty reports of ischemic optic neuropathy (ION), usually resulting in irreversible unilateral blindness, in men using the erectile dysfunction (ED) drugs Viagra, Cialis, or Levitra had been received by the US Food and Drug Administration (FDA) by March 2005. But the FDA and the companies have downplayed the link between these drugs and ION, stating, correctly, that the disease also occurs in men with cardiovascular risk factors who do not take erectile dysfunction drugs, but implying that the cause is cardiovascular risk, not the drugs.