Researchers from the Netherlands Institute for Neuroscience have discovered an underlying cause for why people with albinism have poor eyesight, and it’s called pendular nystagmus – the spontaneous back-and-forth movement of the eye.
Pendular nystagmus resembles the eye movements people make when looking outside while riding a moving train: the eyes automatically move along with the moving landscape, then spring back to the resting position.
Nerve cells in the nucleus of the optic tract selectively respond to this movement and become active. In healthy individuals, this activity leads to the tightening of the eye muscles to stabilise the image. However, researchers have demonstrated in mice with albinism that the cells in this brain area are no longer selective for the direction of image movement. As a result, the image cannot stabilise, leading to the condition of pendular nystagmus.
They said this phenomenon not only makes seeing difficult but also hinders social eye contact. Treatment sometimes involves medications or surgery on the eye muscles, but these methods have unpleasant side effects and are not fully effective.
Currently, surgery of this brain area is not possible, but the research provides hope that in the future, pendular nystagmus can be reduced by manipulating activity in this brain region. Possible approaches to be considered are deep brain stimulation of the area, surgery or even gene therapy.
Reference
1. Montijn, J.s., Riguccini, V., Levelt, C.N., Heimel J.A., Impaired Direction Selectivity in the Nucleus of the Optic Tract of Albino Mice. Investigative Opthalmology & Visual Science, 2023; 64 (11): 9 DOI: 10.1167/iovs.64.11.9