Editor,—George et al 1recently undertook a review of 23 cases of Horner’s syndrome presenting in the first year of life. They remind us of the difficulty in differentiating between congenital and acquired Horner’s syndrome in this age group. In their introduction they state that, in both congenital and acquired cases, “heterochromia may appear to be progressive as the child develops normal pigmentation in the fellow iris”. Iris heterochromia would therefore appear to be of little value in distinguishing between congenital and acquired cases, the latter …