Neurology Central

Amblyopia results in physical changes to myelin

Alterations in brain connections in individuals with amblyopia, more commonly referred to as ‘lazy eye’, have been identified by a team of researchers at the University of Wisconsin-Madison (WI, USA). The research, which was published in Vision Research recently, could influence future treatments for the common disorder.

Through the use of diffusion-weighted imaging, the study group were able to map three sets of pathways already known to be involved in the transfer of visual information from the eyes to the brain.

Analysis indicated that water was able to diffuse more easily down the brain’s visual pathways in individuals with amblyopia than in those without the disorder. “What we think may be happening in amblyopia is that the conductive sheath around neurons becomes thinner,” Bas Rokers (University of Wisconsin-Madison) explained.

The team believe that as the brain develops it also develops a preference for the dominant eye’s input due to its heightened ability to focus. Consequently the connections to the weaker eye are altered over time, ultimately resulting in physical changes to the neuronal pathways.

“Most often in amblyopia patients, one eye is better at focusing,” added Rokers. “The brain prefers the information from that eye, and pushes down the signal coming from the other, ‘lazy’ eye. In a way, it’s better to think of the better eye as a bully, rather than the poorer eye as lazy.”

The understanding of the structural effects of amblyopia may be key in improving treatments for not just amblyopia but also other similar vision disorders, potentially including the development of therapeutic video games or virtual reality headsets. It may also help in developing treatments for adults with the disorder, as emphasized Rokers: “You don’t see any adults walking around with patched eyes, because adults’ brains are less plastic, less trainable, and we think the patch approach doesn’t have any effect late in life. But that belief is changing, and this diffusion-weighted imaging approach will help us understand whether, and how much, brain training treatments work.”

Source: University of Wisconsin-Madison press release: