Pfizer said yesterday that a review of its erectile dysfunction drug, Viagra (sildenafil), has concluded that there is no evidence of an increased risk of blindness amongst users [[31/05/05a]].

Nevertheless, the world’s largest pharmaceutical company said that it was in discussions with the US Food and Drug Administration over updating the drug’s label to reflect rare reports of nonanterior ischemic optic neuropathy – a type of stroke affecting the eye – in some men who have used the medicine. While the firm said that the FDA had concluded that no causal relationship between Viagra and NAION has been established, it had agreed to include the fact of these reports in the Viagra label to help inform physicians and patients. Pfizer believes that the FDA has asked that similar information be included in the labels of all oral ED medicines.

The news hit the headlines earlier this year and was portrayed by many as a major issue for one of the world’s most notorious drugs. However, Pfizer’s chief medical officer, Dr Joseph Feczko, said: “Men taking Viagra are at no greater risk for blindness – including vision loss from NAION – than men of similar age and health not taking the medicine.”

Pfizer notes that NAION is among the most common acute optic nerve diseases in older adults, and shares a number of common risk factors with erectile dysfunction: over 50 years of age, high blood pressure, high cholesterol, and diabetes. The company adds that most of the reported NAION cases occurred in Viagra users with underlying risk factors associated with the development of the condition.