[Marcus Gunn Phenomenon: differential diagnosis of palpebral ptoses in children].

OBJECTIVE: The aim of this paper is to review existing literature on the subject and to report on and discuss a case of Marcus Gunn Phenomenon. DESCRIPTION: A five year-old female, otherwise a healthy patient, while still a few months old, was seen by a pediatrician who detected a disorder of the right eye, initially believed to be strabismus, at a follow-up childcare consultation. Several ophthalmologists failed to establish a precise diagnosis. After a pediatric ophthalmologist had examined the child at four years of age, a diagnosis of Marcus Gunn Phenomenon, otherwise known as jaw-winking phenomenon, was confirmed. Apart from this anomaly, physical, ophthalmological, and neurological examinations were normal. Since ptosis was mild and no association with strabismus, amblyopia or other conditions was established, no surgical procedures were necessary. COMMENTS: This report is an alert to pediatricians regarding the presence of this largely unknown phenomenon, making it possible for pediatricians to identify the phenomenon, refer the patient to an ophthalmologist, and establish differential diagnosis from other, more severe forms of ptosis, requiring more aggressive treatment.