A group of investigators from Johns Hopkins studied 40 multiple sclerosis (MS) patients with optical coherence tomography (OCT) of the eye (see flashbacks below about the technology), and found that this technique offers a potentially new, cost-effective way to diagnose and monitor the progression of the disease:
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.
Press release: SIMPLE EYE SCAN OPENS WINDOW TO MULTIPLE SCLEROSIS …
Flashbacks: FDA Approves Optical Coherence Tomography (OCT) ; Optical Coherence Tomography System by Imalux; Optical Coherence Tomography: Positive Results in Clinical Study Reported.
