The blood pressure drugs known as beta blockers and ACE inhibitors may increase the risk of cataract formation and the need for surgery to restore vision, Australian researchers reported in the British Journal of Ophthalmology. Some experts argue that it is high blood pressure itself that causes the increased risk, but studies targeted at verifying that contention have produced mixed results.
Cataracts are a clouding of the lens of the eye that obscured vision. Clear eyesight can generally be restored by surgery to remove the cataract and replace it with a clear plastic lens. Cataract-related problems are present in 42% of Americans between ages 42 and 64 and in 91% of those older than 75.
Beta blockers, which typically have a name ending in "-olol," like propranolol and metoprolol, are given orally to reduce high blood pressure and applied to the eye in a liquid to treat glaucoma. Angiotensin-converting enzyme (ACE) inhibitors, which typically have a name ending in "-pril," like captopril, are given orally to reduce blood pressure.
Dr. Paul Mitchell of the Center for Vision Research at Westmead Hospital in Sydney and his colleagues studied the eye health of 3,654 patients over age 49, following them for five to 10 years. When they controlled for other factors that increase the risk of cataracts, such as smoking and steroid use, they found that beta blockers, either given orally or applied to the eye, increased the risk of cataracts by 45% and the risk of cataract surgery by 61%. ACE inhibitors increased the risk of surgery by 54%.
No association was found with other blood pressure drugs, such as diuretics.
Experts cautioned against drawing any firm conclusions from such a limited study and urged patients to continue taking drugs as prescribed by their physicians. Cataracts are a readily treatable problem, but the strokes and heart attacks that result from high blood pressure are not. Glaucoma is also difficult to treat, and the benefit of beta blockers is greater than the potential risks.
-- Thomas H. Maugh II