The risk of developing one of three serious eye conditions increases by 85% for regular users of common erectile dysfunction (ED) medications such as Viagra, Cialis, Levitra and Stendra, new research has found.
The eye conditions include serous retinal detachment (SRD), retinal vascular occlusion (RVO), and Ischemic optic neuropathy (ION).
Two of the three conditions had previously been linked to ED medications only by anecdotal case studies, but those links are now confirmed for the first time by a large, epidemiological study, published in JAMA Ophthalmology.
Researchers at University of British Columbia (UBC) in Vancouver, Canada, analysed health insurance claim records of 213,000 men in the US who had not experienced SRD, RVO or ION in the year before they became regular users of ED medications.
Researchers followed the records to see how many men developed one or more of the three conditions, and how that rate compared to men who didn’t use the medications.
After accounting statistically for other conditions such as hypertension, diabetes and coronary artery disease that are known to be associated with eye problems, they found users of ED medications are 2.58x more likely than non-users to develop SRD, 1.44x more likely than non-users to develop RVO, and 2.02x more likely than non-users to develop ION.
Dr Mahyar Etminan, an associate professor in the department of ophthalmology and visual sciences at the UBC faculty of medicine, said regular users of ED drugs who find any changes in their vision should take it seriously and seek medical attention.
“These are rare conditions, and the risk of developing one remains very low for any individual user. However, the sheer number of prescriptions dispensed each month in the US – about 20 million – means that a significant number of people could be impacted,” he said.
The study showed only the statistical association between eye conditions and use of Viagra, Cialis, Levitra or Stendra. It did not prove that the drugs cause these conditions.
However, ED medications function in a way that suggests some possible explanations.
“These medications address erectile dysfunction by improving blood flow, but we know that they can also hinder blood flow in other parts of the body,” Etminan said.
“So although our study doesn’t prove cause-and-effect, there is a mechanism by which these medications could conceivably lead to these problems. The totality of the evidence points toward a strong link.”
According to UBC, the potential risk of SRD and RVO is not addressed in the information currently provided to patients along with their ED medications, unlike the ION risk which has been demonstrated by previous research.
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