Eye Changes Found in Alzheimer's Patients

Researchers have found that amyloid-beta (A-beta), the protein that forms plaques in the brains of Alzheimer's patients, can also be detected in the lens of the eye. This finding, which may lead to an early diagnostic test for Alzheimer's, was reported in the April 12, 2003, issue of The Lancet.

While A-beta was identified in the lenses of elderly individuals with and without Alzheimer's disease, an unusual pattern of amyloid deposits was found only in the lenses of Alzheimer's patients. Researchers examined samples of brain tissue and lenses taken from nine people who had died from Alzheimer's and from eight controls who died from other neurodegenerative disorders. They also tested samples of aqueous humor taken from healthy volunteer patients having cataracts removed. A distinctive pattern of deposits was found in the outer, peripheral portion of only the lenses from Alzheimer's patients. The researchers noted that people with Down syndrome, who develop Alzheimer's at an early age, are also prone to early-onset cataracts.

"One of the most exciting aspects of this finding is the fact that these deposits are associated with a type of cataract seen rarely in the general population,” said Leo T. Chylack, Jr., M.D., director of the Center for Ophthalmic Research at the Brigham and Women's Hospital (BWH, Boston, MA, USA) and one of the principal investigators. "These cataracts do not block vision and can only be seen when the pupil is dilated widely. If the association of these deposits with Alzheimer's holds up in future studies, it would be very simple to develop a noninvasive test of disease progression.”




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