[Lawtan]

Umm...isn't a time component required - the restoration of a blind man (naturally blind, not burned) has taken 6 months -> a year for his brain to start seeing colors and make out blurry shapes. That was after a few months of surgery...
So, unless it is a purely magical matter, it would take time for Dante's brain to adjust to having sight.
At least...according to an article I read.