If your newborn's eyes frequently cross or of if they are not moving in the same direction after a few months, then the muscles in his eyes may be unbalanced (strabismus). This should be aggressively treated with patching, glasses and or surgery. If not treated, strabismus can lead to one of your child's eyes becoming much weaker (amblyopia) than the other, causing permanent vision problems.
Another condition in which in your child's eyes appear to cross is called pseudo-strabismus. In this condition, your child's eyes line up perfectly, but appear to cross because of a broad nasal bridge. Your doctor and easily test for pseudo-strabismus. No treatment is necessary and your child will outgrow the appearance of crossing as he gets older.