Neonatal enucleation during a critical period reduces the precision of cortico-cortical projections in visual cortex

► Normal visual cortico-cortical projections show a degree of convergence/divergence. ► We studied whether enucleation changes convergence/divergence in callosal projections. ► Enucleation at birth induces a significant increase in convergence/divergence. ► Enucleation at postnatal day 7 has no significant effect on convergence/divergence. ► Retinal input during first week specifies precision of cortico-cortical projections.