A miniscule fraction of Cialis users reported vision loss. It was generally attributable to other causes, however.
In addition to the relatively minor eye problems of things appearing blue tinted, blurred vision, and difficulty distinguishing between green and blue, there have been a small number of reports of sudden vision loss. In these rare cases, a condition called non-arteritic anterior ischemic optic neuropathy (NAION) has been diagnosed. A total of 43 cases of NAION have been reported among users of erectile dysfunction drugs in the PDE-5 inhibitor class.
More specifically 38 Viagra users have reported it, as have four Cialis users and one Levitra user. This is a tiny number of people compared to the tens of millions of men who have safely taken these drugs over the past decade-plus.
What is the likeliest explanation for the problems?
The problem with attributing NAION to erectile dysfunction drugs like Cialis is that there’s no evidence that it was the drug that caused the vision problem. This form of blindness is among the most common causes of sudden loss of vision in older Americans. An estimated 1,000 to 6,000 cases are reported each year. Older Americans are not only the most likely to experience NAION, they’re the most likely to take drugs like Cialis, Viagra, and Levitra.
Complicating matters further, two of the main conditions that lead to NAION are diabetes and heart disease, which is significant because diabetes and heart disease are two leading causes of erectile dysfunction. In other words, it’s hard to say whether these men would have experienced vision loss if they hadn’t been taking erectile dysfunction drugs.