Statins Linked With Development of Cataracts
August 13, 2012 (Waterloo, Ontario) — Statin users are more than 50% likelier to develop age-related cataracts, according to the results of a new study [1]. And type 2 diabetics who use statins are at even greater risk of cataracts, report investigators.
"The bioplausibility of these results lies in the fact that the crystalline lens membrane requires high cholesterol for proper epithelial cell development and lens transparency," write Dr Carolyn Machan (University of Waterloo, ON) and colleagues in the August 2012 issue of Optometry and Vision Science. "Increased cataract formation has been seen in both animals and humans with hereditary cholesterol deficiency, and the risk exists that statins can inhibit cholesterol biosynthesis in the human lens."
Asked to comment on the paper for heartwire, Dr Richard Karas (Tufts University School of Medicine, Boston, MA), called the findings "an interesting observation [that] isn't alarmist." There is, he says, a "suggestion" here that statins may increase the risk of cataracts, but this visual problem eventually afflicts everyone of a certain age anyhow, he says, adding that further study of this association will be required.
Waterloo Eye Study Includes Almost 6500 Patients
The analysis included 6397 patients with and without diabetes. As the researchers note, diabetes is a risk factor for the development of cataracts, leading the group to analyze the prevalence of cataracts among patients with diabetes taking statins (n=452) and the prevalence among those taking statins but without diabetes (n=5884). The mean age of patients with diabetes was 14 years older than those without diabetes and included a slightly higher proportion of female subjects. The prevalence of statin use in patients 38 years of age and older was 56% for those with type 2 diabetes and 16% for those without diabetes.
In the study, known as the Waterloo Eye Study, diabetes was associated with an 86% higher risk of developing cataracts (odds ratio [OR] 1.86; 95% CI 1.34–2.59) across the lifespan after researchers controlled for multiple variables, including age, female sex, smoking, and blood pressure. A diagnosis of diabetes was also associated with an increased risk of different subtypes of cataracts: an 84% greater risk of nuclear sclerosis, a 38% higher risk of cortical cataract, and a 52% rise in posterior subcapsular cataract
Statin use was also associated with a significantly increased risk of developing age-related cataracts (OR 1.57; 95% CI 1.15-2.13) and some subtypes, including a 48% higher risk of nuclear sclerosis and a 48% rise in posterior subcapsular cataract but no increased risk of cortical cataract.
In an analysis of cataract prevalence among patients with and without diabetes taking statins, Machan and colleagues found that the prevalence of cataract increased at a faster rate in patients with diabetes who used statins. "Similar prevalence levels were seen in patients with diabetes who did not use statins and in patients without diabetes who did use statins," according to the researchers. "The prevalence of cataract increased at the slowest rate in patients without diabetes who did not use statins."
An Awareness of a Potential Issue, But Not an Issue
Speaking with heartwire, Karas said that without belittling the development of cataracts, which he added are a "life-altering event," MI, stroke, and diabetes are nevertheless significantly more damaging to health and quality of life. He noted that when statins first emerged on the market, there were some initial concerns that the cholesterol-lowering medications might cause cataract, leading some physicians to recommend that patients get eye examinations before undergoing treatment.
"Then, as often happens, when the larger databases were looked at, the concerns about cataract abated," said Karas. "When I say that, we've seen studies saying that statins cause Alzheimer's disease, osteoporosis, and cancer, among other things, and each of these when they get looked at in totality do not seem to be true." In addition, he said the present study doesn't provide any information about the dose of statin therapy used in patients or how long they were taking the drugs. Such data are necessary to get a better sense of the potential relationship between statin therapy and the development of cataracts.
Karas also noted that the researchers used a very sensitive definition for cataract, an important distinction because many of these identified cataracts might not cause any symptoms. In fact, he noted that by 70 years of age, all of the patient population, including those with and without diabetes, had developed cataracts, but not all of these were clinically relevant, because 100% of people reaching that age did not undergo cataract surgery.
"It's a nice paper, an interesting observation, and it isn't alarmist in that it doesn't make a blanket recommendation that we should start providing screening for all patients undergoing statin therapy," said Karas. "I think it raises the issue where additional study in perhaps an even larger patient population might be warranted. Also, it raises awareness of the potential for an issue, but on its own this study doesn't confirm that cataracts are an issue."
References
- Machan CM, Hrynchak PK, Irving EL. Age-related cataract is associated with type diabetes and statin use. Optom Vis Sci 2012; 89:1165-1171. Abstract
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