Two emerging research projects peer into the eyes to look for early indicators of difficult-to-diagnose neurological diseases.
Researchers at the Center for Ophthalmic Research at Brigham and Womens Hospital, in Boston, have developed tests that may detect Alzheimers disease. The tests quantitatively measure amyloid beta protein in the eye.
Researchers know that a build-up of amyloid beta protein in the brain is a hallmark of the disease. The researchers found that the lens of the eye, like the brain, produces its own amyloid beta protein.
The process thats going on in the brain is also going on in the eye, says Lee Goldstein, M.D., Ph.D., who is directing the research. The idea is to use [the eye] as a window to whats going on in the brain and to pick up the pathology before it is manifested.
The researchers also discovered that the amyloid beta proteins in the lens produce a very unusual cataract, which forms in a different place in the eye than common cataracts.
There is currently no definitive diagnostic test for Alzheimers. Without a way to truly diagnose the disease, there is no way to tell, for instance, if a new drug really works. To that end, Dr. Goldstein and colleagues developed two complementary tests:
Quasielastic light scattering. This test, given first, employs low-power infrared laser light to noninvasively detect protein particles in the specific part of the lens where the unusual cataracts form.
Fluorescence ligand scanning. This second test would be applied to those who screen positively for the proteins in order to confirm an Alzheimers diagnosis. The investigators apply special fluorescing eye drops that have image-enhancing molecules that bind to the amyloid beta molecules and light them up if any amyloid beta molecules are present.
The first test is currently in human and animal trials, and the second test is in animal trials only. These findings were presented in mid-October at the annual Optical Society of America meeting.
In Australia, an arm of the Blue Mountains Eye Study adds to the growing research that retinal changes in the eye can help to predict stroke. The results held true even after researchers took into account traditional risk factors for stroke, such as smoking and high blood pressure.
Specifically, people with retinopathy are 70% more likely to suffer a stroke than people without.1 This association is even stronger in subjects without severe hypertension or in those with two or more retinal microvascular signs.
The researchers analyzed retinal photos of 3,654 participants age 49 years and older. During the seven-year follow-up, researchers tallied 24 cases of non-fatal stroke and 11 cases of transient ischemic attack. Also, 859 subjects died, including 97 from cerebrovascular causes.
Stroke events were more frequent in participants who had retinopathy (5.7%), with moderate/severe arteriovenous nicking (4.2%), or with focal arteriolar narrowing (7.2%) compared with those without any of these signs (1.9%).
More research needs to be done to confirm these results, but its exciting to think that this fairly simple procedure could help us predict whether someone will be more likely to have a stroke several years later, says Paul Mitchell, M.D., Ph.D., of the University of Sydney, in Australia.
1. Mitchell P, Wang JJ, Wong TY, et al. Retinal microvascular signs and risk of stroke and stroke mortality. Neurology 2005 Oct 11;65(7):1005-9.
