Tadalafil, the active ingredient in the erectile dysfunction drug Cialis and a medication for enlarged prostate symptoms, may be linked to an increased risk of glaucoma, a serious eye condition that can lead to vision loss. The findings come from a study published in the British Journal of Ophthalmology.
Researchers analyzed the health records of nearly 74,000 men aged 40 and older who had lower urinary tract symptoms. Tadalafil is prescribed to treat both erectile dysfunction and benign prostatic hyperplasia (BPH), commonly known as an enlarged prostate, which can cause difficulties with urination.
The five-year study compared men who were prescribed tadalafil with those who did not take the drug. The analysis aimed to determine if there was a correlation between tadalafil use and the development of glaucoma or increased intraocular pressure, a precursor to vision problems.
The study found that men taking tadalafil were 22 percent more likely to develop glaucoma compared to men who did not use the medication. Furthermore, those on tadalafil showed a 32 percent higher likelihood of developing high pressure inside the eye and a 33 percent increased chance of developing primary open-angle glaucoma, the most prevalent form of the disease.
Glaucoma is a group of conditions that damage the optic nerve, often due to fluid buildup and subsequent pressure within the eye. Without treatment, it can result in permanent vision loss and blindness.
While the study did not definitively establish a causal link, the authors suggested that tadalafil's mechanism of action might play a role. The drug widens blood vessels and lowers blood pressure, which can improve circulation for erectile dysfunction. However, researchers theorize this could potentially reduce blood flow to the optic nerve at critical times. Changes in blood flow to the eye's blood vessels may also contribute to elevated eye pressure.
The observational nature of the study means it can only show an association, not cause and effect. The researchers noted that the increased risk may be more pronounced in individuals with pre-existing risk factors for glaucoma. These include a history of glaucoma or high eye pressure, other optic nerve conditions, or a family history of the disease.
Based on their findings, the study's authors recommended that men taking tadalafil should undergo regular eye examinations and follow-up care with an ophthalmologist.