To Cross Their Eyes.
Infants normally seem to cross their eyes until about three months of age.
If they are still crossing their eyes by three to six months of age this is abnormal and they should be seen by an opthalmologist for an assessment. The question asked is an important one because half of all children with strabismus may develop amblyopia and approximately one third of all children with amblyopia will also have strabismus. It is thought that amblyopia is uncorrectable after about six or seven years of age, so as long as they are diagnosed before this time the prognosis for normal vision is excellent. Sjostrand J. and Abrahamsson M., Prevention of Amblyopia and The Concept of Cure.