Vancouver, B.C.—Regular users of common ED drugs, such as Viagra, Cialis, Levitra, and Stendra, appear to have dramatically higher risk of developing a serious eye condition.

The report in the Journal of American Medical Association Ophthalmology, based on a large epidemiological study, suggested the risk of developing serous retinal detachment (SRD, which is a collection of fluid behind the retina with no tears or breaks), retinal vascular occlusion (RVO, which is a blood clot in the veins or arteries of the retina), or ischemic optic neuropathy (ION, which involves compromised blood supply to the optic nerve) is about 85% higher for users of phosphodiesterase type 5 inhibitors (PDE5Is). University of British Columbia (UBC)–led researchers pointed out that those are among the most commonly prescribed drugs in the United States.

"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 U.S.—about 20 million—means that a significant number of people could be impacted," stated Mahyar Etminan, PharmD, MSC, an associate professor in the department of ophthalmology and visual sciences at the UBC faculty of medicine. "Regular users of these drugs who find any changes in their vision should take it seriously and seek medical attention."

Background information in the report noted that several case reports and small epidemiologic studies have quantified the risk of ocular adverse events associated with the use of PDE5Is. Yet, with conflicting results, the risks of conditions such as SRD and RVO have not been clear.

As a result, the study team set out to quantify the risk of those conditions, as well as ION. To accomplish this, researchers used data obtained from the PharMetrics Plus database (IQVIA) of U.S. insurance claims from January 1, 2006, to December 31, 2020.

The more than 200,000 cohort members who were receiving PDE5Is (including sildenafil, tadalafil, vardenafil, and avanafil) were followed up until the first diagnosis of SRD, RVO, ION, or termination of insurance coverage. The case-control analysis included a total of 1,146 cases of SRD (278), RVO (628), ION (240), and 4,584 controls. The mean (SD) age in both groups was 64.6 (13.3) years.

Results indicated that patients with the ophthalmological conditions were more likely to have hypertension, diabetes, coronary artery disease, and sleep apnea. Researchers calculated the adjusted IRR (incident rate ratio) for the composite endpoints of any of the three outcomes at 1.85 (95% CI, 1.41-2.42; incidence, 15.5 cases per 10,000 person-years).

The adjusted IRRs for the conditions were determined to be:

• SRD: 2.58 (95% CI, 1.55-4.30; incidence, 3.8 cases per 10,000 person-years)
• RVO: 1.44 (95% CI, 0.98-2.12; incidence, 8.5 cases per 10,000 person-years)
• ION: 2.02 (95% CI, 1.14-3.58; incidence, 3.2 cases per 10,000 person-years).

"Findings of this cohort study suggest that regular users of PDE5Is might have an increased risk for SRD, RVO, and ION," the authors advised. "Regular users of PDE5Is need to be cognizant of ocular adverse events associated with these drugs and alert their physicians if they experience any visual deficits."

Because the study showed only the statistical association between eye conditions and the use of ED drugs, it could not prove that the drugs cause these conditions, the authors wrote, adding that the function of those medications 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," Dr. Etminan explained. "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."

Researchers called for more warnings on the risk of the drugs.

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