A popular medication prescribed for erectile dysfunction and enlarged prostate may be linked to an increased risk of developing glaucoma, according to a major study.
Tadalafil, widely known by the brand name Cialis, could make patients up to 33 percent more likely to develop the sight-threatening eye condition, researchers have found. Glaucoma damages the optic nerve, which connects the eye to the brain, and is a leading cause of preventable blindness globally.
The study, conducted by scientists from Taiwan and the U.S., analyzed data from 73,854 men over 40. Half of these participants had been prescribed tadalafil or a similar erectile dysfunction drug for up to five years.
The findings indicated that men taking tadalafil were 22 percent more likely to develop glaucoma compared to those not using the drug. The risk for the most common type of glaucoma increased by 33 percent. Additionally, the study showed a 32 percent higher likelihood of developing ocular hypertension, or high pressure within the eye, a known risk factor for glaucoma.
Researchers emphasized that this observational study cannot definitively prove that tadalafil causes glaucoma, but rather indicates an association. They suggested that long-term use of the drug might affect the eyes and warrants further investigation.
Scientists theorize that tadalafil's potential link to glaucoma could stem from long-term use causing temporary increases in intraocular pressure, which might progressively damage the optic nerve. Another proposed mechanism is that the drug could contribute to hypoperfusion, or reduced blood flow, to the optic nerve, though these theories remain unproven.
Tadalafil's known side effects include indigestion, muscle aches, headaches, a stuffy nose, and facial flushing. Headaches, in particular, can be an early warning sign of glaucoma.
Erectile dysfunction affects millions of men worldwide, with hundreds of thousands in the UK alone believed to be prescribed tadalafil. The medication works by enhancing blood flow to the penis to help achieve and maintain an erection. It also relaxes muscles in the prostate and bladder to treat enlarged prostate symptoms.
These findings emerge as projections indicate a significant rise in glaucoma cases in the coming decades. A separate study earlier this year estimated that 1.6 million people in the UK could be living with glaucoma by 2060, a 60 percent increase from current numbers. This projected rise is attributed to an aging population and the growth of at-risk ethnic communities.
Glaucoma often develops slowly, and many individuals may not realize they have the condition, mistaking subtle symptoms like headaches or nausea for other ailments. More pronounced symptoms can include eye pain, redness or tenderness of the eyes, blurred vision, and seeing halos around lights.