3. Cheung JC, Summers CG, Young TL. Myopia predicts better outcome in persistent hyperplastic primary vitreous. J Pediatr Ophthalmol Strabismus 1997;34:170 –176. Limitation of Opposing Ductions Following Augmented Horizontal Rectus Muscle Transposition Mohamed A.W. Hussein, MD, and David K. Coats, MD PURPOSE: To report the effect on ductions in opposing gaze following augmented horizontal rectus muscle trans- position to treat cyclovertical muscle palsies. METHODS: Record review of 5 patients who underwent augmented horizontal rectus muscle transposition for treatment of vertical gaze misalignment secondary to cyclovertical muscle palsy. RESULTS: Ductions in the direction of the palsied muscle improved in all patients. Four patients (80%) developed significant limitation of vertical gaze in the direction opposite that of the palsied muscle. CONCLUSION: Augmented transposition surgery for ver- tical muscle palsy can produce considerable limitation of ductions in the direction opposite to that of the paralyzed muscle. (Am J Ophthalmol 2003;136:947–949. © 2003 by Elsevier Inc. All rights reserved.) A MONG THE SURGICAL PROCEDURES AVAILABLE TO treat paralytic strabismus, transposition muscle proce- dures are most efficient when complete rectus muscle paralysis is present. Successful use of augmented transposition procedures in the management of vertical misalignment secondary to vertical muscle paralysis has been reported. 1 Reported benefits have included improved primary gaze alignment with modest improvement of eye rotation in the field of action of the paralyzed vertical rectus muscle. The effect of this procedure on ductions in the direction opposite that of the paralyzed vertical muscle has not been reported. Our purpose is to report the effect of augmented transposition of horizontal rectus muscles on opposing ductions when done for treatment of cyclovertical muscle palsy. We reviewed the records of five patients (Patients 1– 4 have been reported previously 1,2 ) who underwent partial or total horizontal rectus muscle transposition augmented with posterior fixation suture for treatment of vertical gaze misalignment due to cyclovertical muscle palsy. The pre- operative and postoperative ocular motility status of each patient is tabulated (Table 1). Mean follow-up was 16 months (5–24 months). All patients had excellent vertical alignment in the primary position after the transposition surgery with improvement of ductions in the field of action of the palsied muscle. One (Patient 4) required additional surgery for concurrent horizontal and residual vertical strabismus. Four (80%) of the patients developed consid- erable limitation of ductions in the direction opposite that of the palsied muscle following the transposition surgery with an average duction limitation of -2.5 (Figure 1; Table 1). Patient 1, who did not develop limitation of opposing ductions, had previously undergone lateral rectus muscle recession in both eyes for management of intermit- tent exotropia. Managing a severe palsy of elevation or depression represents a challenging problem. The major goals of surgery are to improve alignment in the primary position, create a maximum field of single binocular vision, and, if possible, to improve rotation of the eye in the direction of the paralyzed muscle. Transposition of part or all of the rectus muscles invariably results in some mechanical re- striction to full rotation of the globe in the opposite direction 3 by altering the force vectors of the transposed vertical muscles. Elongating the path of the transposed muscle induces passive elastic force, increasing the tone of the transposed muscles. Contraction of the muscles con- cerned with movement of the eyes in the opposite direc- tion to that of the paralyzed muscle hence will always face an increased opposing tone. Posterior fixation suture aug- mentation enhances the tone of transposed muscles by providing additional stretching, contributing to duction limitation on attempted opposite gaze. Limitation of duc- tions in the opposite direction to that of the transposed muscles following vertical muscle transposition to treat horizontal muscle palsies has not been a problem. 4 The explanation by Clark and associates 5 of horizontal trans- lation of the globe in the direction of horizontal eye movement may help to explain the absence of opposing duction limitation following vertical rectus transposition for horizontal rectus palsy. Although translocation follow- ing horizontal rectus muscle transposition has not been studied, it may be more limited and thus could help explain opposing duction limitation following surgery. Whether subtle weakness of the inferior rectus in Patient 2 or the superior rectus in Patient 4 contributed to postoperative duction limitation is not clear, but it is possible. It is also unclear why one patient did not develop limitation of opposing ductions. Perhaps transposition of the previously recessed lateral muscles produced fewer unwanted restrictive forces than transposition of previ- ously unoperated muscles. Accepted for publication April 29, 2003. From the Cullen Eye Institute, Department of Ophthalmology (M.A.W.H., D.K.C.), and the Department of Pediatrics (D.K.C.), Baylor College of Medicine, Texas Children’s Hospital, Houston, Texas. This study supported in part by an unrestricted grant from Research to Prevent Blindness, Inc., New York, NY. Inquiries to David K. Coats, MD, Baylor College of Medicine, Texas Children’s Hospital, 6621 Fannin MC CC 640.00, Houston, Texas 77030; fax: (713) 796-8110; e-mail: dcoats@bcm.tmc.edu BRIEF REPORTS VOL. 136,NO. 5 947