By the age of 3 to 4 months, an infant’s eyes should be able to focus on small objects, and the eyes should be straight and well-aligned. A 6-month-old infant should be able to focus on objects both near and far.
Strabismus usually appears in infants and young children, and most often by the time a child is 3 years old. However, older children and even adults can develop strabismus. The sudden appearance of strabismus, especially with double vision, in an older child or adult could indicate a more serious neurologic disorder. If this happens, call your ophthalmologist immediately.
A condition called pseudostrabismus (false strabismus) can make it appear that a baby has crossed eyes when in fact the eyes are aiming in the same direction. Pseudostrabismus can be caused by extra skin covering the inner corners of the eyes and/or a flat nasal bridge.