Retinal Thinning After Optic Neuritis May Help Predict Relapse Recovery
Subclinical nerve cell damage can remain after recovery from initial relapse
After a relapse involving optic neuritis, or inflammation in the nerves connecting the eyes and brain, measurements of retinal thinning may predict the likelihood of full recovery from future relapses in people with multiple sclerosis (MS), a study suggests.
The measurement could identify subclinical nerve cell damage that remains in patients who appear to have symptomatically recovered from a relapse, according to researchers. More extensive nerve cell damage in the retina may determine which patients are more likely not to recover fully from relapses in the future.
The study, “Retinal Layer Thinning After Optic Neuritis is Associated With Future Relapse Remission in Relapsing Multiple Sclerosis,” was published in Neurology.
In relapsing forms of MS, recovery from early disease relapses is often used to determine a person’s prognosis for recovery from future relapses. In other words, patients who completely recover from early relapses are more likely to do so in the future, and have better long-term outcomes.
However, patients who fully recover from relapses may retain some nerve damage. In early relapses, this damage may not be extensive enough to cause overt symptoms, but as more relapses occur and nerve damage accumulates, the likelihood of patients experiencing persisting symptoms (or incomplete relapse recovery) increases.
While nerve damage is difficult to track in the brain and spinal cord, there is an easy and reliable way to measure the nerve damage that results from optic neuritis, even when patients appear to have clinically recovered from their vision problems.
This is done with optical coherence tomography, a noninvasive technique used to image layers of the retina — the back part of the eye that contains the cells that sense light and the nerve cells that transmit signals to the brain. Research has suggested thinning of certain layers of the retina serves as a biomarker of nerve damage in MS and may be able to predict disability worsening.
In the new study, a team of researchers from the Medical University of Vienna, in Austria, wanted to understand whether retinal thinning after an optic neuritis episode could be used predict the degree of recovery from subsequent relapses not involving the optic nerve.
To do so, they examined data from 167 adults with MS who had experienced an acute optic neuritis episode, and at least one subsequent non-optic-neuritis relapse. Participants had been included in the Vienna MS database; 71.3% of them were women and the mean age was 36.5 years.
Retinal thinning measurements were taken before the optic neuritis episode (baseline), within one week after the episode (acute), and 3–6 months after (follow-up).
The team focused on two retinal layers, namely the peripapillary retinal nerve fiber layer (RNFL) and the macular ganglion-cell-and-innerplexiform-layer (GCIPL), whose thinning is linked to neuronal damage in the brain and spinal cord.
What were the results of the retinal thinning study?
Results indicated that patients who recovered from the initial optic neuritis episode experienced significantly less thinning in their retinal layers — indicating less extensive nerve damage — between baseline and follow-up.
Over a mean of 1.8 years after the initial optic neuritis episode, patients experienced a total of 250 additional relapses not involving the optic nerve. Of them, 99 relapses across 61 patients had an incomplete remission, meaning that patients experienced increases in disability, as measured by the Expanded Disability Status Scale six months after the relapse.
Incomplete recovery in these subsequent relapses was significantly associated with a greater thinning in the retinal layers after the optic neuritis episode. More GCIPL thinning from acute to follow-up measurements also was associated with incomplete recovery.
These relationships remained true for the 87 people who experienced complete recovery after their initial optic neuritis relapse, which further highlights the value of using retinal thinning measurements over evaluating only clinical symptoms, the team noted.
Other known predictors, including older age, severe relapse, and proportion of incomplete recoveries from prior relapses were also associated with incomplete recovery. Use of highly effective DMTs, on the other hand, was linked to a lower likelihood of incomplete recovery.
The findings overall show that retinal thinning provides “prognostic value for determining the likelihood of incomplete recovery from future relapses outside the visual system,” the researchers wrote, noting that the greater observed impact of GCIPL thinning relative to RNFL is in line with previous studies.
“We should strive to obtain a baseline [optical coherence tomography] scan in every MS patient at the earliest possible time, ideally at initial diagnosis or first consultation, providing not only the opportunity for stratification of future risk of disease progression but also a reliable baseline scan in case of a future ON [optic neuritis] episode,” the researchers wrote.
“Reliable biomarkers detecting subclinical processes are paramount for both determining the necessary level of efficacy and enabling early adaption of treatment,” the team concluded.