Vision following extended congenital blindness

Animal studies suggest that visual deprivation early in the lifespan can have profound consequences, causing functional blindness for the remainder of the animal’s life. However, very little human data exist on this issue. Given enough time for recovery, can a person who has suffered several years of congenital blindness gain visual skills? Addressing this question is difficult since instances of sight acquisition late in life are extremely rare. We recently had an unusual opportunity to work with an individual in India whose case-history sheds light on this question. SRD was born blind, and remained so until the age of 12 years. She then underwent surgery for the removal of dense congenital cataracts. We evaluated her performance on an extensive battery of visual tasks 20 years after her surgery. We found that although SRD's acuity is compromised, she is highly proficient on mid/high-level visual tasks. These results suggest that the human brain retains an impressive capacity for visual learning well into late childhood. They have implications for our conceptions of cortical plasticity, and argue for treating congenital blindness even in older children