Retinal damage a marker of MS severity

It is essential to assess the severity of multiple sclerosis (MS) in order to choose appropriate therapeutic measures, but this cannot be reliably done using existing methods. Researchers at the Medical University of Vienna have now shown that the retina can be used as a prognostic marker, with retinal layer thinning as a result of an MS relapse predicting the severity of future relapses and, hence, the likelihood of disability.

Multiple sclerosis is a chronic inflammatory autoimmune disease that leads to the loss of axons and neurons throughout the entire nervous system. Although this damage often goes unnoticed by patients at first, its extent determines the prognosis for the severity of the disease. Since predictions about the course of the disease are important in MS for selecting the appropriate treatment, medical research has long been searching for reliable prognostic tools.

The Vienna researchers studied 167 MS patients over a period of more than three years, hypothesising that retinal damage due to relapse reflects the extent of damage in the brain. The researchers measure retinal layer thickness using optical coherence tomography (OCT) — an imaging technique that uses infrared light to produce high-resolution three-dimensional images of very thin layers of tissue in the micrometre range. It is already used as a tool for diagnosing eye diseases such as glaucoma and for evaluating disease progression. “The technique for predicting the course of MS is therefore already available to us,” said Gabriel Bsteh, first author of the study.

As the scientific analyses confirmed, the loss of approximately 5 µm of retinal layer thickness after optic neuritis equates to a doubling of the risk of permanent disability after the next relapse. The results of the study, published in the journal Neurology, suggest that more aggressive treatment is indicated where there is significant retinal layer thinning than would be the case for a smaller degree of thinning. This is true even if the patient has no disability or only slight disability at the time of measurement.

“As we discovered in the course of our clinical trial, measurements should be taken at initial diagnosis, directly when optic neuritis occurs in relapsing MS and six months thereafter,” Bsteh said.

“In retinal layer thickness, we have found a new biomarker that represents a window to the brain, as it were,” Bsteh concluded. If the results are confirmed in larger follow-up studies, the technique could also be applied in routine clinical practice.

Image credit: iStock.com/bombuscreative

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