BOSTON — There is a clear subset of pediatric patients with demyelinating disease who have substantial damage to the nerve layer in the retina but nevertheless have no vision loss, a new study shows.
"Understanding how this subset of patients recover functionally after optic nerve damage could lead to great insight into best acute treatment options and a better understanding of brain plasticity and neural networking," lead author Samuel Hughes, BS, UT Southwestern Medical Center, Dallas, Texas, concluded.
"We need to analyze other variables in these children, including age, sex, time to acute treatment, and type of treatment to see if we can shed light on how this is occurring."
He presented their findings here at MS Boston 2014, the 2014 Joint Americas and European Committees for Treatment and Research in Multiple Sclerosis (ACTRIMS/ECTRIMS) meeting.
"This is a really crazy cohort of kids that no one has identified before who can see normally but from looking at their retina they should be blind," Hughes said.
"Maybe there is some kind of mechanism that children have but adults don't to compensate for the loss of nerve fibres in the retina," he speculated. "We need to understand better what it is about these children that helps them recover functionality. Something could be happening in the visual cortex of the brain causing it to rewire."
He added that this could have implications for understanding neural networking and finding treatments for the adult population with demyelinating disease. "If we could pinpoint what is happening in the brains of these children we may be able to figure out some functional stimulation to enhance that process."
Cochair of the session at which the study was presented, Patrick Vermersch, MD, PhD, Centre Hospitalier Régional Universitaire de Lille, France, called this an "interesting observation. It certainly appears that the optic nerve in some children is more resilient than in adults. We need to learn why this is the case," he told Medscape Medical News.
As background, Hughes noted that in adults visual acuity (especially low contrast) correlates to retinal nerve fiber layer thinning as measured by optical coherence tomography (OCT), and a threshold of 75 microns predicts persistent visual dysfunction. But these measures have not been well established in children.
For the current study, OCT data and corresponding visual acuities were obtained from a total of 378 eyes of children with demyelinating disease, including multiple sclerosis, acute disseminated encephalomyelitis, or idiopathic optic neuritis.
Results showed that while there was a relationship between the thickness of the retinal nerve layer and visual acuity in most patients, a small subset of 9 eyes had a very thin retinal nerve layer (55 to 59 microns) but the patients had normal high and low visual acuity.
Hughes noted that it is important to validate the normative data in the pediatric population.
"OCT is well validated in adults. It is a ubiquitous tool for understanding optic nerve damage and is starting to be used as a proxy for disease progression. It is being used in the pediatric population but our data begs the question that we may need different parameters in children."
MS Boston 2014: 2014 Joint Americas and European Committees for Treatment and Research in Multiple Sclerosis (ACTRIMS/ECTRIMS) Meeting. Abstract Y12.4 Presented September 10, 2014.
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Cite this: Some Children See Well Despite Severe Optic Nerve Damage - Medscape - Sep 11, 2014.