A young boy undergoes an operation to remove his cataract in a hospital in India. Credit: Fabienne Fossez / Alamy Stock Photo
Surgery done at various stages of adolescence can aid sight recovery in children born with dense bilateral cataracts1.
The operation alters the brain’s specific visual pathways, allowing patients to discriminate between pictures and recognize faces.
The sensitive period for visual development closes around 5 to 7 years, so the conventional wisdom has been that surgery during adolescence can only offer limited benefits for congenital cataracts.
To investigate this, scientists followed 19 cataract patients aged 7 to 16 who received surgery. They found that surgery improved early parts of the visual system. The majority of this improvement occurred in the first few days after surgery.
The team, which included a researcher at the Indian Institute of Technology in New Delhi, found that the patients were able to distinguish pictures of faces from non-face stimuli. Patients who had operations at a younger age experienced greater improvements in performance.
The researchers linked behavioural improvements in visual perception to underlying neuroanatomical changes, such as the plasticity of white matter – made of nerve fibres such as axons – in the two late visual pathways of the brain.
The researchers say these observed structural changes were stable and resulted from mechanisms such as the remodelling of myelin, which wraps around the axons, and the growth of synapses, each of which is a connection between two neurons.
