What is common in infancy
It is common for a baby's eyes to turn in or out too much at moments in the early months. In most cases they become steady and straight as the child grows older. If, however, the eyes turn in or out all the time or much of the time, even in the first months, or if they are not steady by 3 months, an eye doctor should be consulted.
Many times parents think their baby's eyes are crossed when they are really straight. This is because the skin area between the eyes is relatively wider in a baby than in an older person; so the amount of white of the eye showing on the inner side of the iris is much smaller than the white on the outer side (toward the ear).
Another reason babies' eyes sometimes appear crossed is that when they are looking at something in their hands they have to converge (cross) the eyes a lot to focus on it, because the arm is too short. If you think your baby's eyes may be crossed, you can check the image of a light as it is reflected in the baby's pupils. If the image of the light is always located symmetrically on the baby's pupils, its unlikely that the eyes are crossed.
Parents often ask whether it is safe to hang toys over the crib,since the baby sometimes is cross-eyed looking at them. Don't hang a toy right ontop of a baby's nose, but it's perfectly all right to hang it at arm's reach.
Carrefully watch the signs
The main reason why it is important for infants' eyes to be examined promptly, when there is a question about whether they are straight,is because a crossed eye will gradually become nonseeing if efforts are not begun early to make the child use it. When the two eyes do not coordinate and converge on an object, each eye will be seeing a somewhat different scene.
The children will be "seeing double". This is confusing and uncomfortable for them. So automatically the babies learn to ignore and supress the vision of the eye. They gradually make the eye blind - not in the sense of a physical change - it's a psychological process. If this goes on too long, it will become impossible to ever bring back the vision in the eye. This has been called "lazy eye". The doctor may prescribe glasses to further encourage the coordinated use of the two eyes. Then comes the decision whether there should be an operation, in addition.
Its not uncommon in a newborn baby for the lid of one eye to droop a little lower than the other or for one eye to look smaller. In most cases, these differences become less and less noticeable as the baby grows older. The baby's eyes should be examined, to be sure that they are straight.Text source: Dr. Spock's Baby and Child Care -Beanjamin Spock and Michael Rothenberg