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MRI brain scans have been used to calibrate and corroborate the results of a new eye-scanning technique that can diagnose multiple sclerosis in a few minutes. The technique, optical coherence tomography (OCT), scans the layers of nerve fibres in the retina to reveal nerve damage associated with the disease. The quick test will ultimately complement more detailed MRI studies of the brain should nerve damage be found. Neurologist Peter Calabresi of Johns Hopkins University and his colleagues studied forty patients with multiple sclerosis using a desktop machine similar to a slit-lamp to carry out the simple and painless OCT tests. By focusing on retinal nerve fibres, which have no myelin sheath, they could make a specific assessment of the patients' status without turning to a brain MRI scan, which would reveal an array of different types of tissue processes in the brain. The team calibrated their OCT results with accepted norms for retinal fibre thickness and then compared to an MRI of each of the patients' brains. In a subset of patients with relapsing-remitting MS, the most common form of the disease, the correlation coefficient between OCT and MRI results was as high as 0.69, suggesting a strong association between the retinal measurements and brain shrinkage, or atrophy, associated with MS. "This is an encouraging result," says Calabresi, "With OCT we can see exactly how healthy these nerves are, potentially in advance of other symptoms." The test makes it possible to focus solely on nerve damage, which is not possible with MRI. Calabresi adds that OCT scans take just a few minutes rather than an hour or two and so provide results at less cost and more quickly in tracking the effectiveness of new treatments for MS. Calabresi adds 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, however, that optic nerve damage can point to a number of diseases and is not a unique diagnostic tool for MS. Related links:
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Calabresi, quick eye check for nerve damage in multiple sclerosis |
