"The eye is the window into the brain and by measuring how healthy the eye is, we can determine how healthy the rest of the brain is," says Peter A. Calabresi, M.D., a professor of neurology at the Johns Hopkins University School of Medicine, and leader of the studies described in recent issues of The Lancet Neurology and the Archives of Neurology. "Eye scans are not that expensive, are really safe, and are widely used in ophthalmology, and now that we have evidence of their predictive value in MS, we think they are ready for prime time. We should be using this new quantitative tool to learn more about disease progression, including nerve damage and brain atrophy."
Calabresi and his colleagues used optical coherence tomography (OCT) to scan nerves deep in the back of the eye, applying special software they co-developed that is capable of assessing previously immeasurable layers of the light-sensitive retinal tissue. The scan uses no harmful radiation and is one-tenth the cost of an MRI. The software will soon be widely available commercially. In the Lancet paper, Calabresi and his team reported measuring thickness or swelling of the inner nuclear layer of the retina in 164 patients with MS and 60 healthy controls, following changes in these tissues over four years. At the same time, they also used brain MRI to measure inflammation spots directly, and performed clinical tests to determine disability levels.
The more inflammation and swelling the researchers found in the retinas of the MS patients, the more inflammation showed up in their brain MRIs. The correlation, they said, affirmed the value of the retinal scans as a stand-alone surrogate for brain damage. Having such information so easily available could allow physicians to accurately tell how far the disease has progressed, and to better advise patients about how they should proceed with their care.
The researchers also found microcystic macular edema in the central part of the retinas of 10 of the MS patients, tiny pockets of fluid typically found in older, usually diabetic people. While Calabresi cautions that eye scans do not as yet have primary diagnostic value for MS, he says finding a cyst like this on the eye of a young, healthy person might be reason to have her evaluated for the disorder.