Age-Related Eye Disease Study Examines Macular Degeneration Risk Related To Cataract Surgery
February 9, 2009
Adapted from the American Academy of Ophthalmology
Age-related macular degeneration (AMD) and cataract are leading causes of visual impairment in the United States. Both are related to aging, and they share other risk factors, but it has been unclear whether a direct causal link might be involved. Several large epidemiological studies had raised concern that cataract surgery might accelerate AMD progress and threaten vision. To address this concern, Emily Y. Chew, M.D., of the National Eye Institute, and colleagues analyzed data for a cohort of participants in the Age-Related Eye Disease Study (AREDS). This cohort is the only large prospective study in which the severity of AMD was documented before and after cataract surgery and which included more than five years of in-depth participant follow-up.
AMD causes changes in the retina, the light-sensitive tissue that focuses images at the back of the eye, and severe AMD leads to loss of central vision. Cataract is cloudiness or opacity in the eye's lens that interferes with the clear focus of images on the retina.
AREDS researchers concluded there was little evidence that cataract surgery had a negative effect on progression to advanced AMD. "These data may provide some reassurance to patients with AMD who are considering cataract surgery," Dr. Chew said.
Several factors may explain the divergent conclusions reached by AREDS and the earlier studies. The most likely cause would be that earlier studies had unintended biases or confounding variables. Also, techniques of cataract surgery and lens replacement have changed over time, and AREDS participant surgeries were performed more recently than those tracked in the combined-population studies. A significant number of subjects in earlier studies did not have lens replacement after cataract extraction, while AREDS participants were likely to have had ultraviolet-B light blocking lenses inserted, which may have protected their maculae and decreased AMD risk.
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