Simple eye scan opens window to multiple sclerosis

October 15, 2007

A five-minute eye exam might prove to be an inexpensive and effective way to gauge and track the debilitating neurological disease multiple sclerosis, potentially complementing costly magnetic resonance imaging to detect brain shrinkage - a characteristic of the disease’s progression.

A Johns Hopkins-based study of a group of 40 multiple sclerosis (MS) patients used a process called optical coherence tomography (OCT) to scan the layers of nerve fibers of the retina in the back of the eye, which become the optic nerve. The process, which uses a desktop machine similar to a slit-lamp, is simple and painless. The retinal nerve fiber layer is the one part of the brain where nerve cells are not covered with the fat and protein sheathing called myelin, making this assessment specific for nerve damage as opposed to brain MRI changes, which reflect an array of different types of tissue processes in the brain.

Results of the scans were calibrated using accepted norms for retinal fiber thickness and then compared to an MRI of each of the patient’s brains - also calibrated using accepted norms. Experimenters found a correlation coefficient of 0.46, after accounting for age differences. Correlation coefficients represent how closely two variables are related -- in this case MRI of the brain and OCT scans. Correlation coefficients range from -1 (a perfect opposing correlation) through 0 (no correlation) to +1 (a perfect positive correlation). In a subset of patients with relapsing remitting MS, the most common form of the disease, the correlation coefficient jumped to 0.69, suggesting an even stronger association between the retinal measurement and brain atrophy.

“This is an encouraging result,” says Johns Hopkins neurologist Peter Calabresi, M.D., lead author of the study, which appears in the October 2007 issue of Neurology. “MRI is an imperfect tool that measures the result of many types of tissue loss rather than specifically nerve damage itself. With OCT we can see exactly how healthy these nerves are, potentially in advance of other symptoms.”

In addition, says Calabresi, OCT scans take roughly one-tenth as long and cost one-tenth as much as the MRI, which means they are faster and cheaper to use in studies that track the effectiveness of new treatments for MS.

Approximately 400,000 people in the United States have MS, marked by an abnormal immune system that attacks and kills a person’s own brain cells. As these neurons die, the volume of the brain decreases. MRI of the brain, which can measure total volume, has long been the primary tool used to monitor MS. But MRI, aside from being expensive and uncomfortable, is often misleading since brain inflammation - also a symptom of the disease - can skew brain volume readings. Also, the brain begins shrinking relatively late in the progression of the disease, so MRI isn’t as good at detecting the disease in its early stages when treatments are most effective. OCT scans look directly at the thickness, and therefore health, of the optic nerve, which is affected early on in the disease, often before the patient suffers permanent brain damage.

Calabresi added that many of the disabilities suffered by MS patients - numbness, tingling, visual impairment, fatigue, weakness and bladder function disturbance - are the result of nerve cell degeneration, so a test that specifically measures nerve cell health is potentially the clearest picture of the status of the disease.

He cautions that optic nerve damage can point to a number of diseases and is not a unique diagnostic tool for MS. However, he says, it certainly sends up a flag suggesting that MS might be present. And since optic nerve damage is one of the first recognizable symptoms of MS, doctors have a chance to identify the disease potentially before the patient suffers the physical limitations generally associated with its advanced stages.

“Treatments for MS cannot reverse the damage but they can arrest it, so the earlier we get someone on medication the quicker we can stop the disease from causing more harm,” says Calabresi. This tool may be useful as an outcome measure in MS clinical trials to assess the efficacy of neuroprotective drugs.

In the study, researchers recruited 40 patients from the Johns Hopkins MS clinic. Twenty had relapsing remitting MS, 15 had secondary progressive MS, and five had primary progressive MS. Researchers also recruited 15 healthy control patients free from ophthalmological or neurological disease as a comparison group.

Calabresi says his next step will be to look at changes in the fiber layer thickness in 100 patients over a period of three years.

Source: Johns Hopkins Medical Institutions

Explore further: New method that leads to the formation of specialized tissue cells for disease treatment

Related Stories

New method that leads to the formation of specialized tissue cells for disease treatment

July 19, 2017
A new method that leads to the formation of specialized tissue cells could improve the understanding of neurodegenerative diseases, inflammatory diseases and cancer.

The brain and the gut talk to each other—how fixing one could help the other

July 17, 2017
It's widely recognised that emotions can directly affect stomach function. As early as 1915, influential physiologist Walter Cannon noted that stomach functions are changed in animals when frightened. The same is true for ...

Study identifies new target to preserve nerve function

July 14, 2017
Scientists in the Vollum Institute at OHSU have identified an enzyme that plays a crucial role in the degeneration of axons, the threadlike portions of a nerve cell that transmit signals within the nervous system. Axon loss ...

Researcher discusses neurological underpinnings of pain

July 18, 2017
Pain—feared, misunderstood and even poeticized in works of art and literature—has long captivated the scientific imagination of Clifford Woolf since his days as a medical student in South Africa.

Newly discovered gene variants link innate immunity and Alzheimer's disease

July 17, 2017
Three new gene variants, found in a genome wide association study of Alzheimer's disease (AD), point to the brain's immune cells in the onset of the disorder. These genes encode three proteins that are found in microglia, ...

Agent clears toxic proteins and improves cognition in neurodegeneration models

July 16, 2017
Researchers have found cell receptors abnormally overexpressed in post-mortem brains of those with Parkinson's and Alzheimer's diseases, and that they can be inhibited in animal models to clear toxic protein buildup, reduce ...

Recommended for you

Want to win at sports? Take a cue from these mighty mice

July 20, 2017
As student athletes hit training fields this summer to gain the competitive edge, a new study shows how the experiences of a tiny mouse can put them on the path to winning.

Engineered liver tissue expands after transplant

July 19, 2017
Many diseases, including cirrhosis and hepatitis, can lead to liver failure. More than 17,000 Americans suffering from these diseases are now waiting for liver transplants, but significantly fewer livers are available.

Lunatic Fringe gene plays key role in the renewable brain

July 19, 2017
The discovery that the brain can generate new cells - about 700 new neurons each day - has triggered investigations to uncover how this process is regulated. Researchers at Baylor College of Medicine and Jan and Dan Duncan ...

'Smart' robot technology could give stroke rehab a boost

July 19, 2017
Scientists say they have developed a "smart" robotic harness that might make it easier for people to learn to walk again after a stroke or spinal cord injury.

New animal models for hepatitis C could pave the way for a vaccine

July 19, 2017
They say that an ounce of prevention is worth a pound of cure. In the case of hepatitis C—a disease that affects nearly 71 million people worldwide, causing cirrhosis and liver cancer if left untreated—it might be worth ...

Omega-3 fatty acids fight inflammation via cannabinoids

July 18, 2017
Chemical compounds called cannabinoids are found in marijuana and also are produced naturally in the body from omega-3 fatty acids. A well-known cannabinoid in marijuana, tetrahydrocannabinol, is responsible for some of its ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.