Development of pattern vision following early and extended blindness.
Visual plasticity peaks during early critical periods of normal visual development. Studies in animals and humans provide converging evidence that gains in visual function are minimal and deficits are most severe when visual deprivation persists beyond the critical period. Here we demonstrate visual development in a unique sample of patients who experienced extended early-onset blindness (beginning before 1 y of age and lasting 8-17 y) before removal of bilateral cataracts. These patients show surprising improvements in contrast sensitivity, an assay of basic spatial vision. We find that contrast sensitivity development is independent of the age of sight onset and that individual rates of improvement can exceed those exhibited by normally developing infants. These results reveal that the visual system can retain considerable plasticity, even after early blindness that extends beyond critical periods.
Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139.
Amy
A
Kalia
Luis Andres
LA
Lesmes
Michael
M
Dorr
Tapan
T
Gandhi
Garga
G
Chatterjee
Suma
S
Ganesh
Peter J
PJ
Bex
Pawan
P
Sinha
D001766:Blindness / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D015350:Contrast Sensitivity / Q000502:physiology*; D003430:Cross-Sectional Studies; D006306:Health Surveys; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D013997:Time Factors; D014785:Vision, Ocular / Q000502:physiology*
brain plasticity; childhood blindness; sensitive periods; sight restoration; visual impairment