Тadalafil эм болон нүдний глаукомын эрсдэлийн хамаарлыг судалжээ

Some myths refuse to die, especially when they mix sex and shame.

For generations, young people were warned that sexual activity could make them blind. Science has long dismissed the claim.

But a new study has brought the old myth back in an unexpected form.

This time, sex is not under suspicion. A pill is.

Tadalafil, best known by the brand name Cialis, is widely used to treat erectile dysfunction, or difficulty getting or maintaining an erection. It is also prescribed regularly for urinary problems associated with an enlarged prostate.

Now, a large study has linked long-term tadalafil use to an increased risk of glaucoma, a group of eye diseases where optic nerve damage causes vision loss.

The reassurance: The study does not show that sex harms the eyes or that occasional tadalafil use causes blindness.

The study focused on men over 40 who regularly took tadalafil for urinary symptoms, such as frequent or urgent urination or a weak stream.

Researchers used the TriNetX Analytics Network, a platform containing anonymized health records from across 21 countries. Its scale let them search for an uncommon pattern beyond a single hospital.

They identified 36,927 men aged 40 or older who had no previous glaucoma diagnosis and had been prescribed regular tadalafil for at least 3 months. They were compared with 36,927 matched men who had used no drug from the same family.

The groups were matched for factors that could influence glaucoma risk, including age, smoking, health conditions, and other medications. Their health records covered up to five years.

Over five years, glaucoma appeared in roughly four of every 100 tadalafil users, compared with about three of every 100 non-users. The precise rates of diagnosis in each group were 3.93 percent and 3.16 percent, respectively, over the five-year period.

Researchers described that difference as a 22 percent increase in relative risk. It sounds dramatic, but the gap between the two groups was less than one percentage point: equivalent to about 77 additional diagnoses for every 10,000 men.

Most men in both groups did not develop glaucoma.

The same pattern appeared in related outcomes. Tadalafil users were about one-third more likely to develop abnormally high eye pressure or primary open-angle glaucoma, or begin glaucoma treatment.

No significant increase was found for low-tension glaucoma or primary angle-closure glaucoma.

Glaucoma can develop without obvious early symptoms. The damage to the optic nerve interrupts the flow of visual information to the brain. Lost vision usually cannot be restored, making early detection important.

So how could a medication used for erections and urinary problems affect the eyes?

Tadalafil belongs to a family of medications called phosphodiesterase type 5 inhibitors, or PDE5 inhibitors. Sildenafil, better known as Viagra, belongs to the same group.

These medications prolong a chemical signal that relaxes smooth muscles and widens blood vessels. This can increase blood flow to the penis while relaxing muscles around the prostate and bladder.

But the system does not operate only below the belt.

PDE5 is also present in the retina, ocular blood vessels, the area producing the eye’s internal fluid, and the optic nerve head.

One possibility is that tadalafil widens blood vessels in the eye and temporarily increases production of aqueous humor, the clear fluid filling the front of the eye. If this fluid accumulates faster than it drains, pressure can rise.

Repeated pressure changes during years of daily treatment could potentially damage the optic nerve in susceptible people. To detect such changes, researchers are developing ‘smart’ contact lenses that release glaucoma medication as required, but human trials are still needed.

The biology is complicated. The same chemical pathway may also help fluid drain from the eye, potentially lowering its pressure. Tadalafil could therefore create opposing effects, and researchers do not know which matters most over time.

The study was observational, so although it found an association between long-term tadalafil use and glaucoma, it cannot prove that tadalafil caused the additional glaucoma cases.

Diagnoses came from medical codes, and the database lacked direct measurements of eye pressure, visual fields, or optic nerve changes.

Researchers could not confirm every dose or calculate total tadalafil exposure. Regular users might also visit doctors more often, making glaucoma more likely to be detected.

The findings are not a reason to stop taking prescribed tadalafil. Patients should not discontinue medication without speaking to their doctor.

Instead, regular users, particularly those with glaucoma, elevated eye pressure, severe short-sightedness, or a family history of glaucoma, may wish to discuss eye monitoring with a healthcare professional.

The old warning that sex leads to blindness remains firmly in the realm of myth.

Related: Newly Developed Smart Contact Lens Could Treat The Second Leading Global Cause of Blindness

The modern scientific message is subtler: What happens in the bedroom is not the concern. But a medication taken regularly might be a reason to keep a slightly closer eye on your eyes.

The study was published in the British Journal of Ophthalmology.