Our son was diagnosed with congenital OMA at 3 months. He shakes his head to correct his eye positions, though much less frequently nowadays and most often when he's tired or agitated. He is now almost 4 years old and has recently had his regular 6-monthly check-up. His vision is very good and his score on 3-dimensional tests was above average. In other words his sight isn't affected by his OMA.
He was later than average at walking (19 months), but he above average height and weight for his age.
He is also late at learning to speak, but he is learning 2 languages. We are an English family living in Italy and our son goes to an Italian nursery where he hears only Italian. All his friends are Italian as are TV and radio. At home though we speak English most of the time, which probably accounts (in part, at least) for the lateness.
In all other respects he seems to be a happy, healthy little boy.