A Peculiar Disease with Peculiar Eye Movements

A 15 year old schoolboy was referred for follow-up of a chronic neurologic disease. His gestation and birth seemed normal, but he failed to thrive. Hepatosplenomegaly and diarrhea were prominent symptoms early on, but his disorder eluded diagnosis until he was 5 years old. By that time he was the smallest kid in the class at school and he remains so. Currently he is in special education, but seems only mildly retarded. His visual acuity is 20/20 in each eye with the near card, fields are full to confrontation, and his optic discs appear normal, as do his retinas. His pupils are equal and react briskly to light, but his eyes are divergent and seem to move independently. He has great difficulty moving the left eye upward or medial ward. When he tries to look to the right, the right eye turns downward.