November 2008

 

OPHTHALMOLOGY NEWS

 

Universal risk factors


by Matt Young EyeWorld Contributing Editor

 

 
An IOL is being implanted. A new study suggests some cardiovascular risk factors also are risk factors for both cataract and AMD Source: Jorge L. Alio, M.D.

There are risk factors for cataract. And there are risk factors for age-related macular degeneration (AMD). But are there risk factors for both cataract and AMD? A new study suggests that there are, and that these risk factors are cardiovascular-related as well. “Cardiovascular risk factors like elevated high-sensitivity CRP or increased IMT [intima-media thickness] of the carotid arteries were found to be associated with comorbid cataract and AMD,” wrote Dalia Zaliuniene, M.D., department of ophthalmology, Kaunas University of Medicine, Kaunas, Lithuania, in the May-June 2008 issue of the European Journal of Ophthalmology.

The common links

Dr. Zaliuniene analyzed 47 patients with both early or intermediate AMD and cataract (group 1), 35 with cataract only (group 2), and 49 with early or intermediate AMD only (group 3). Patient tests included carotid ultrasound, ischemia-induced brachial artery reactivity test, and ankle-brachial index (ABI) along with analysis of other cardiovascular risk factors. “Increased levels (more than 1.23 mg/L) of high-sensitivity C-reactive protein (hsCRP) and IMT (more than 0.97 mm) increased prevalence odds for AMD and cataract 3.1 and 3.9 times, respectively,” Dr. Zaliuniene reported. Dr. Zaliuniene noted that intimal thickening of the common carotid artery, bifurcation, and internal carotid artery were significantly greater in group 1 than in group 2 and group 3 patients. However, other potential risk factors were not significant. Carotid plaques did not differ significantly among the groups, for instance. There were no differences in endothelial function and ABI. “The studied groups did not differ in mean endothelium dependent vasodilation after ischemia induced by the pressure in a sphygmomanometer cuff and in endothelium-independent vasodilation after sublingual administration of nitroglycerin,” Dr. Zaliuniene reported. Finally, Dr. Zaliuniene noted, “In binary logistic regression model that included age, gender, smoking, body mass index, total cholesterol, LDL cholesterol, DTL cholesterol, triglyceride, glucose level, white blood cell count, systolic blood pressure, hsCRP, and IMT, only hsCRP level and IMT showed significant associations with coexistent AMD and cataract group.”

Just being male, apparently, also was enough to be a common risk factor for cataract and AMD. “Patients with AMD and cataract more often were male, were cigarette smokers, and had more thickened intima-media in the carotid arteries than patients with only one disorder: cataract or AMD,” Dr. Zaliuniene reported. Factors other than being male, however, such as elevated hsCRP levels and increased IMT of the carotid artery, revealed more interesting conclusions about cataract and AMD risk factors. “These findings confirm importance of atherosclerotic process, cigarette smoking, and inflammation in development of comorbid cataract and AMD,” Dr. Zaliuniene concluded.

Those factors contrast markedly with risk factors for patients that only had AMD. “Patients with only AMD were younger, were more often female (therefore, with lower stature), and more often had parents with stroke because of greater prevalence of arterial hypertension in them (the latter finding was determined only in comparison with comorbid patients). Multi-variate analysis did not confirm association between these factors and AMD only,” Dr. Zaliuniene noted. Considering that Dr. Zaliuniene noted that most studies have analyzed risk factors for AMD and cataract separately, this study adds an important new dimension to research: which risk factors are common for both diseases. This is particularly important as both diseases are commonly found in older eyes. “They are two of the most important causes of decreased vision in the majority of developed countries, including Lithuania” Dr. Zaliuniene noted. “Certain types of cataract and AMD might occur together more frequently as cataract and AMD share one or more common risk factors.”

Mark Packer, M.D., clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., said that it makes sense that there would be common risk factors for AMD and cataract. “Sick people get sicker I suppose,” Dr. Packer said. He explained that C-reactive protein (CRP) relates to the inflammatory process, and intima-media thickness (IMT) is “part and parcel of cardiovascular disease.

Already, he said, there have been studies demonstrating ties between AMD and high blood pressure and cigarette smoking. Now it’s interesting that some ties extend to cataract, he said. “We know that all parts of the eye are nourished by blood flow,” Dr. Packer said. So clearly blood flow changes would have some impact on the eye. The bottom line is that apparently, there are some risk factors of cardiovascular disease that also are risk factors of cataract and AMD.

Editors’ note: Dr. Zaliuniene has no financial interests related to this study. Dr. Packer has no financial interests related to his comments.

Contact information:

Packer: 541-687-2110, mpacker@finemd.com
Zaliuniene: r.zaliunas@gmail.com

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