Surgery to restore eyesight cannot entirely undo the brain rewiring caused by long term blindness, reveals a new study.
Recent scientific advances have meant that eyesight can be partially restored to those who previously would have been blind for life.
However, scientists at the University of Montreal and the University of Trento have discovered that the rewiring of the senses that occurs in the brains of the long-term blind means that visual restoration may never be complete.
Scientists know that in cases of untreatable blindness, the occipital cortex that is the posterior part of the brain that is normally devoted to vision becomes responsive to sound and touch in order to compensate for the loss of vision.
Giulia Dormal said that on one hand, the findings revealed that the visual cortex maintains a certain degree of plasticity that is the capacity to change as a function of experience, in an adult person with low vision since early life.
On the other, they discovered that several months after the surgery, the visual cortex had not regained full normal functioning, he further added.
The study suggested that eye surgery can lead to a positive outcome even when performed in adulthood after a life-time of profound blindness. There is however an important caveat.
Giulia Dormal said that the recovery observed in the visual cortex, which was highlighted by a decrease in auditory-driven responses and by an increase in both visually-driven responses and grey matter density with time, was not total.
Indeed, auditory-driven responses were still evidenced in certain regions of the visual cortex even 7 months after surgery, and these responses overlapped with visually-driven responses. This overlap may be the reason some aspects of vision, despite having improved with time, still remained below normal range 7 months after surgery, Dormal further added.