Fast facts:
- Congenital cataracts are the leading cause of treatable blindness in children worldwide. In nations where the surgery is widely available, surgery occurs during infancy and there is a good prognosis for the recovery of visual function.
- It is widely accepted that the window for surgical intervention for congenital cataracts closes by the time a child reaches the ages of six to eight years old, as that is a critical period for visual brain development. Restoration of the visual input later in life is generally thought to have limited benefit because the brain will lack sufficient plasticity to adapt to and utilize input from the eyes.
A team of NYU Abu Dhabi researchers, led by Bas Rokers, director of the NYUAD Neuroimaging Center, studied the changes in the brain that can lead to visual skills improvements. The investigators teamed up with Project Prakash, a combined humanitarian and scientific effort to restore sight in curably blind children from rural parts of India. They discovered that improvements in visual functions are linked to changes in white matter pathways, which connect neurons in different brain regions.
They studied many pathways, but only those involved in high-order visual functions, such as face recognition, were directly linked to the visual improvement. Moreover, researchers saw that the patient’s amount of change in late visual pathways, specifically the posterior callosum forceps, predicted the amount of behavioral improvement. This is a new result that identifies the location of brain changes responsible for behavioral improvement.
In the paper titled White Matter Plasticity Following Cataract Surgery in Congenitally Blind Patients published in the journal Proceedings of the National Academy of Sciences of the United States of America (PNAS), the researchers also confirm that cataract surgery has a greater impact on visual function and brain plasticity if received at younger age, but recovery is still possible even if the eye surgery is received later in adolescence.
The results suggest that sufficient plasticity remains in adolescence beyond the critical period for visual development, allowing patients to partially overcome abnormal visual development and help localize the sites of neural change underlying recovery in blind teenagers. There is therefore a window of time wider than previously thought, during which sight-recovery surgeries can be useful to improve visual perception by altering structural brain plasticity. The team’s research shed light on the definition of the sites of neural change related to sight-recovery, which can guide the development of treatments that attempt to induce neural plasticity through behavioral and surgical interventions.
