Millions of men rely on tadalafil—sold as Cialis—to manage erectile dysfunction or urinary symptoms from an enlarged prostate. Now a large study suggests the drug may come with a higher risk of glaucoma, a leading cause of irreversible blindness.
Glaucoma affects about 2 percent of men over age 50 and is a leading cause of blindness worldwide.
The study, published in the British Journal of Ophthalmology, analyzed anonymized medical records from nearly 74,000 men age 40 and older, using a multinational health records database. Half the men had been prescribed tadalafil or similar drugs for up to five years to treat urinary symptoms from an enlarged prostate; the other half had not. Researchers matched the two groups by age, ethnicity, health conditions, and other medication use to keep the comparison fair.
Compared with men who weren’t taking tadalafil, those who were had a 22 percent higher risk of developing glaucoma, a 32 percent higher risk of developing high eye pressure (ocular hypertension), and a 33 percent higher risk of starting treatment for glaucoma.
Why This Matters
Glaucoma is not a single disease but a group of conditions that gradually damage the optic nerve, the cable that carries visual information from the eye to the brain.
The condition usually has no early symptoms. By the time someone notices vision changes, some damage may already be permanent. That’s why doctors emphasize regular screening over waiting for warning signs.
High pressure inside the eye is a well-known risk factor, but it’s not the whole story.
“The exact mechanism of glaucoma isn’t always known,” Christina Herald, a glaucoma-certified optometrist in Fall River, Massachusetts, who was not involved in the study, told The Epoch Times. Some forms can develop even when eye pressure looks normal.
How Might Tadalafil Affect the Eyes?
Tadalafil belongs to a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil (Viagra) and vardenafil (Levitra). These drugs relax and widen blood vessels, which is exactly what makes them effective for erectile dysfunction and for easing urinary blockage tied to an enlarged prostate.
However, blood vessels in the eye are part of the same system these drugs act on. Dr. Bing Chiu, an ophthalmologist and cataract surgeon in Langhorne, Pennsylvania, who was not involved in the study, told The Epoch Times that the vessel-relaxing effect could theoretically affect pressure inside the eyes, as well as blood flow to the optic nerve.
Previous research has found that by systemically lowering blood pressure while simultaneously raising internal eye pressure, tadalafil may compromise blood flow directly to the optic nerve head, the point where the optic nerve leaves the eye, making the nerve highly susceptible to damage and cell death.
More research is needed, Chiu cautioned. “Ultimately, these mechanisms remain theoretical possibilities, and further prospective research is needed to determine if any of these proposed pathways are truly driving the clinical outcomes seen in the study.”
This isn’t the first time PDE5 inhibitors have been linked to eye problems. Prior research has tied them to rare optic nerve disorders and issues affecting the macula, the part of the retina responsible for sharp central vision. However, a link to glaucoma specifically had remained unclear until now.
Dr. Andrew Lee, chair of ophthalmology at Houston Methodist Hospital, who was not involved in the study, told The Epoch Times that these findings do not mean men should abruptly stop necessary medications.
Instead, he recommends seeking a baseline comprehensive eye examination with an optometrist or ophthalmologist that includes checking eye pressure and evaluating the optic nerve, especially if the patient has risk factors such as a family history of glaucoma, severe nearsightedness, or ocular hypertension.
What Men Taking Tadalafil Should Do
The researchers stressed that their findings are not a reason to stop taking tadalafil. Instead, they argue for closer eye monitoring for men on long-term tadalafil therapy.
“The most important thing anyone can do for their eye health is a yearly comprehensive eye exam,” Herald said. That exam typically includes a review of current medications, an eye pressure check, and an inspection of the optic nerve, the same nerve glaucoma damages.
Chiu recommended that men also make sure their eye doctor, primary care physician, and urologist are in communication with each other and support their cardiovascular health more broadly, since cardiovascular health is connected to blood flow throughout the body, including the eyes.
“Those over age 50, with high nearsightedness, or with a family history of glaucoma should be especially proactive.”