Optical coherence tomography (OCT) can identify multiple sclerosis (MS) earlier in the course of the disease than other detection methods, and OCT could also be used to track the progression of MS, according to a small cohort study in the October 16 issue of Neurology.

In the study, researchers at Johns Hopkins Multiple Sclerosis Center used OCT to scan the retinal nerve fiber layer (RNFL) of 40 patients with MS. They found a strong association between RNFL loss and brain atrophy.

This study is promising because the earlier that MS is diagnosed, the sooner treatment can begin and the more damage can be prevented. But, as yet, no single test confirms the diagnosis.

MS affects the optic nerve in 55% to 60% of cases, and optic neuritis is the initial presentation in 20% of the patients, says Han Cheng, O.D., Ph.D., researcher at the Multiple Sclerosis Eye Center for Analysis, Research and Education (MS Eye CARE) at the College of Optometry of the University of Houston. Compelling evidence indicates that axonal loss and degeneration starts early in the disease process and is ultimately responsible for disability in MS.

Magnetic resonance imaging, spinal tap, and other tests for MS are not as easily or as inexpensively performed as measuring the RNFL, which the OCT quantifies easily.

The use of OCT can contribute to early diagnosis of MS and to timely implementation of medication to forestall the progression of the disease, says Laura J. Frishman, Ph.D., director of research at the MS Eye CARE center. While OCT is definitely a useful tool, it cannot replace a comprehensive eye exam. Optic nerve diseases other than optic neuritisincluding glaucoma, ischemic optic neuropathy, compressive lesions and traumacan also cause RNFL loss.

So, MS suspects must also be seen by a neurologist to rule out other conditions, Dr. Frishman says.