Visual restoration may never be complete in long-term blindness

Surgery cannot completely undo the brain rewiring caused by long-term blindness, finds a study.

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.

"We had the opportunity to study the rare case of a woman with very low vision since birth and whose vision was suddenly restored in adulthood following the implantation of a 'Boston Keratoprosthesis' in her right eye," explained lead researcher Giulia Dormal from the University of Montreal.

On the one hand, the findings reveal 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, we discovered that several months after the surgery, the visual cortex had not regained full normal functioning," Dormal noted.

The visual cortex is the part of the brain that processes information from our eyes.

The researchers worked with the patient, a 50-year-old Quebec woman in Canada.

The study suggests 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.

"The recovery observed in the visual cortex is not total," Dormal added.

"The findings open the door to the use of functional magnetic resonance imaging before surgery as a prognostic tool for visual outcome and pave the way for the development of adapted rehabilitation programs following visual restoration," the authors concluded.

The study was published in the Journal of Neurophysiology.