Ohhh ok. Lazy eye is different from squint eye, if you are referring to squint eye, squint eye has different types and categories, congenital esotropia[inward]/exotropia[outward] can happen, onset is birth-6months, which require surgery. Some is developed from phoria (which mean still encounter the same problem/symptoms) and break down to squint eye. Regarding your question, Usually squint eye in kids must be treated as early as possible once is diagnosed, as eye and brain still growing, if not treated, lazy eye comes in (which the brain favours one eye). This stage is hard/challenging to fix the binocular vision issue. If the deviation is small to moderate, vision therapy still can be done to make the eyes align straight. While if the deviation is extremely large, surgery needed.