The temporal stability of visual cortical processing in humans depends on early experience.

Proper timing is essential for effective neural processing. Yet, how early postnatal vision shapes the temporal stability of human visual cortical processing remains unknown. Here, using electroencephalography, we examined cortical timing properties in individuals who were born pattern-vision blind due to congenital cataracts, but surgically recovered sight. Although sight-recovery individuals exhibited an attenuated cortical oscillatory phase coherence (i.e., higher temporal variability) during visual processing, their cortical oscillatory strength was unimpaired. Moreover, phase coherence information, but not activation strength, allowed classification of sight-recovery individuals from control individuals. Finally, exchanging phase information between sight-recovery and control individuals indicated oscillatory timing impairments as the source of group differences in higher-order visual cortical processing. Neural timing impairments were specific to reversed congenital blindness, that is, they were not observed in individuals with reversed developmental (late-onset) cataracts. These results suggest that the development of intricately temporally orchestrated visual cortical processing in humans requires early visual experience.NEW & NOTEWORTHY In rare individuals who were born with pattern-vision blindness but later recovered sight, we report a markedly higher temporal variability of oscillatory brain activity during visual processing, which could not be attributed to impaired oscillatory strength. Thus, precisely timed visual processing in the human brain crucially depends on early visual experience. Imprecise timing, cascading through the visual cortical hierarchy, might be a major source of the remaining visual impairments in individuals with reversed congenital blindness.