Age-related cataracts are often linked with several other conditions. In a recent study, Nemet et. al. found that there is an association between cataracts and the incidence of cardiovascular disease (CVD). 12,894 patients, ages 50 and older, were examined. Each patient was matched by age and gender with two controls who did not undergo cataract surgery. Information regarding the prevalence of various CVD or CV risk factors in each subject was extracted, including carotid artery disease (CAD), diabetes, peripheral vascular disease (PVD), systemic arterial hypertension, chronic renal failure (CRF), ischaemic heart disease (IHD), congestive heart failure (CHF), smoking, alcohol abuse, and hyperlipidaemia.
[caption id="attachment_1861" align="alignright" width="200"] Dr. Krawitz examining a patient with cataracts during his medical mission in Myanmar[/caption]
The findings show that CVD and CV risk factors have a higher occurrence rate in patients undergoing cataract surgery compared to the controls. Statistically significant results were obtained for all CVD and CV risk factors except for alcohol abuse. CAD was the most common CVD associated with cataracts. Since the carotid artery supplies blood to the eye, damage to the artery can cause cataracts by reducing ocular circulation. Strong associations of diabetes and smoking with cataracts were also found. Both of these CV risk factors are thought to induce cataracts via oxidative damage of the proteins of the ocular lens. Glycosylation of tissue proteins associated with diabetes may also cause the observed association. Prior evidence additionally suggests that there may be an inflammatory process involved, for elevated levels of CRP and interleukin-6 have been linked with diabetes and cataractogenesis.
One important caveat to this experiment lies with the fact that the controls were designated as those who did not experience cataract removal. It is possible that some of the controls possessed cataracts but chose not to undergo surgery for a variety of reasons. Hence, the prevalence of cataracts may have been underestimated, hindering the strength of the results. Nevertheless, it certainly appears that there is a positive association between cataracts and cardiovascular disease. However, definitive identification of the biological mechanisms behind this association requires further research.
Brian Krawitz
Staff Writer