How do i know my 3 months old son is blind?

See a doctor.: An ophthalmologist is able to roughly check the vision of an infant. But more importantly there can be very serious and even life threatening reasons why an infant can't see. This needs further investigation. I would suggest as soon as possible with a pediatric ophthalmologist. Frequently found in larger cities or university settings.

Cues: Does he ever look at you, even briefly ? Can he follow a light or brightly colored toy you bring into view ? Does he smile at you if you hold him and smile at him ? Will he stick his tongue out to mimic you doing the same thing ? These are things pediatricians do during their regular visits to check an infants vision. Talk with your doc if concerned.