선천 하직근 결손 1예

A Case of Congenital Absence of the Inferior Rectus Muscle

Purpose: To report a patient with isolated congenital absence of the right inferior rectus muscle. To our knowledge, this is the first case reported in Korea. Methods: A 6-year-old girl presented with an anomalous head posture of 15° head tilt. She had 45? right hypertropia, 15? A-pattern exotropia and a marked underaction of the right inferior rectus. At the time of the surgery, forced duction test of the right eye showed no limitation and the inferior rectus muscle was found to be absent. Inferior transposition of the horizontal rectus muscles was more approximated to each other than that described in the classic Knapp operation. This was carried out while the right medial rectus muscle was simultaneously resected 2mm for correction of the exotropia. Results: There was significant improvement in infraduction at 6 months postoperative with only a residual 6? exotropia in primary position. Conclusions: Absence of the inferior rectus showed hypertropia with A pattern exotropia. It did not bring about contracture of the superior rectus muscle or amblyopia. The outcome of the modified Knapp procedure was satisfactory.