Millions of people take medicines every day to lower high blood pressure.
These treatments are important because uncontrolled blood pressure can damage blood vessels and greatly increase the risk of heart attacks, strokes, kidney disease and other serious health problems.
One common group of blood pressure medicines is known as calcium channel blockers, or CCBs. Drugs in this family include amlodipine and several other widely prescribed medicines, and they have been used safely for many years.
However, research from the United Kingdom has raised questions about whether these medicines could be connected with glaucoma. Glaucoma is a group of eye diseases that damage the optic nerve, which carries information from the eye to the brain.
The condition is a major cause of permanent blindness worldwide. Vision that has already been lost to glaucoma usually cannot be restored, making early diagnosis especially important.
Glaucoma can be difficult to notice because it often develops slowly. In its early stages, a person may have no pain and no obvious change in eyesight, while damage to the optic nerve is already taking place.
Pressure inside the eye is one of the best-known risk factors for glaucoma, although people can develop the disease even when their eye pressure is within the normal range. Age, family history and some health conditions can also increase risk.
In the study, researchers led by Dr. Alan Kastner of Moorfields Eye Hospital and University College London examined information from more than 427,000 people in the UK Biobank. More than 33,000 participants reported using calcium channel blockers.
The researchers compared medicine use with glaucoma diagnoses and measurements of the eye. They also adjusted their analysis for factors that might affect the results, including age, smoking, lifestyle and other medical conditions.
People taking calcium channel blockers had higher odds of having glaucoma than people who were not taking these medicines. The same pattern was not found for several other major groups of blood pressure drugs.
The researchers also found signs of structural changes in the eyes of people taking calcium channel blockers. Interestingly, the association did not appear to be explained by higher pressure inside the eye.
That finding is important because it raises the possibility that calcium channel blockers could be connected with glaucoma through a process that does not involve increased eye pressure. Scientists do not yet know what that process might be.
The study was published in JAMA Ophthalmology in 2023. Because it was an observational study, however, it cannot prove that calcium channel blockers directly cause glaucoma.
There may be other differences between people who take these medicines and those who do not that could help explain the results. Researchers therefore say more studies are needed to confirm the association and understand whether the medicines themselves affect the optic nerve.
People taking calcium channel blockers should not stop their medicine because of these findings. Suddenly changing blood pressure treatment without medical advice can be dangerous, and the proven benefits of controlling high blood pressure remain very important.
Instead, people who are concerned can discuss the study with their doctor. A doctor can consider their blood pressure, heart health, other medicines and personal risk factors before deciding whether any change in treatment is appropriate.
Regular eye examinations may also be useful, particularly for older adults and people with a family history of glaucoma. Eye specialists can often detect early changes before a person notices vision loss, allowing treatment to begin sooner.
The researchers disclosed financial relationships that some authors had with pharmaceutical and medical companies, as is routinely required in scientific publications. The findings now provide another reason to study how long-term use of common blood pressure medicines may affect eye health.
For now, the research should be viewed as an important warning sign rather than proof of harm. Calcium channel blockers remain valuable medicines, but continued research may help doctors identify which patients need closer eye monitoring while receiving them.
If you care about high blood pressure, please read studies that early time-restricted eating could help improve blood pressure, and natural coconut sugar could help reduce blood pressure and artery stiffness.
For more health information, please see recent studies about How to eat your way to healthy blood pressure and results showing that Modified traditional Chinese cuisine can lower blood pressure.
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