CLINICAL SCIENCES The Effect of Anterior Transposition of the Inferior Oblique Muscle on the Palpebral Fissure Burton J. Kushner, MD Background: Anterior transposition of the inferior ob- Results: The narrowing of the palpebral fissure after lique muscle is a popular treatment for dissociated ver- surgery (mean±SD) was −0.14±0.6 mm in the 16 pa- tical divergence. It seems that this surgical procedure may tients in the control group, −1.2±0.9 mm in the 14 pa- alter the palpebral fissure. tient in the insertion study group, and −2.1±0.5 mm in the 6 patients in the 2-mm study group. The differences Objectives: To investigate the alteration of the palpe- were statistically significant between the control and bral fissure with inferior oblique muscle anterior the insertion study groups (P=.001, t test) and between transposition when it is performed as the sole opera- the control and the 2-mm study groups (P,.001, t test). tive procedure and to report the cases of patients who One of the 16 control patients and 10 of the 14 insertion developed noticeable upper eyelid retraction after infe- study patients showed bulging of the lower eyelid on rior oblique muscle anterior transposition preceded by upgaze after surgery. This difference was statistically large superior rectus muscle recessions. significant (P<.001, Fisher exact test). In addition, 3 pa- tients were seen who developed marked upper eyelid Methods: The change in the height of the palpebral fis- retraction when anterior transposition of the inferior sure surgery was evaluated from photographs by 2 masked oblique muscles followed previous large superior rectus observers in 3 groups of patients. The control group un- muscle recessions. derwent inferior oblique muscle recession without trans- position. The second group (or the insertion study group) Conclusions: Anterior transposition of the inferior ob- underwent transposition of the inferior oblique muscle lique muscle causes significant narrowing of the palpe- that was level with the inferior rectus muscle insertion. bral fissure as a sole procedure. When preceded by large The third group (or the 2-mm study group) had the in- superior rectus muscle recessions, it can cause upper eye- ferior oblique muscle placed 2 mm anterior to the infe- lid retraction. rior rectus muscle insertion. Also, the insertion study and the control groups were evaluated after surgery for bulg- ing and elevation of the lower eyelid on upgaze. Arch Ophthalmol. 2000;118:1542-1546 NTERIOR transposition of tor.3,6 This anti-elevating force seems help- the inferior oblique muscle ful in controlling DVD. Subsequently, is a popular treatment op- others have recommended transposing the tion for correcting disso- inferior oblique muscle even further an- ciated vertical divergence teriorly, positioning it as much as 2 to 4 (DVD) associated with inferior oblique mm anterior to the insertion of the infe- A 1-6 2 muscle overaction. This procedure, rior rectus muscle. Although anterior popularized by Elliott and Nankin,1 is transposition of the inferior oblique muscle based on theoretical work by Scott.7 He seems effective for treating DVD associ- suggested that transposing the inferior ob- ated with inferior oblique muscle overac- lique muscle anteriorly and placing it at tion, several adverse outcomes have been the temporal corner of the inferior rectus reported. Particularly when performed uni- muscle insertion would increase the ef- laterally, this procedure can create a limi- fect of a recession. Subsequently, it was tation of elevation of the operated on eye From the Department of theorized that anterior transposition of the and may cause hypotropia in the primary 6,8,9 Ophthalmology and Visual inferior oblique muscle creates a vector for position. When performed bilaterally Sciences, University of depression, because it places the new in- and particularly if the posterolateral fi- Wisconsin, Madison. sertion of the muscle anterior to the equa- bers of the inferior oblique muscle are (REPRINTED) ARCH OPHTHALMOL / VOL 118, NOV 2000 WWW.ARCHOPHTHALMOL.COM 1542 ©2000 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/01/2021 SUBJECTS AND METHODS photographs were taken in an identical manner approxi- mately 3 months after surgery (range, 2.5-4.5 months). At surgery the corneal horizontal diameter was measured to The study contains a prospective aspect and a retrospective use as a conversion factor for the magnification in the pho- aspect. The prospective arm consists of consecutive pa- tographic slides, which were reproduced as 436-in prints. tients in whom I performed anterior transposition of the in- Photographs were graded by measuring the distance be- ferior oblique muscle to treat DVD associated with inferior tween the upper and lower eyelid margin at the point that oblique muscle overaction, in whom the inferior oblique bisected the light reflex on the cornea. Two different ex- muscle was the only muscle operated on in the fixing eye at aminers graded each photograph and were masked to the the time of the surgical procedure that was evaluated in this patients’ identity, clinical history, and whether the photo- article. If patients had freely alternating fixation, they were graph was taken before or after surgery. In addition, to as- only included if anterior transposition of the inferior ob- sess reproducibility of the measurement technique, 10 se- lique muscle was the sole surgical procedure in each eye. lected photographs were graded by each of the 2 examiners Anterior transposition of the inferior oblique muscle was at 2 different grading sessions, several months apart. The carried out in a manner similar to that described by Elliott difference between the height of the palpebral fissure be- and Nankin,1 except that in all cases the anterior end of the fore and after surgery for each patient, determined by the muscle was bunched and sutured level with the inferior 2 examiners, was averaged and used for data analysis. The rectus muscle insertion. The 2 scleral tunnels were ap- mean difference of the palpebral fissure after surgery in proximately 1 to 2 mm apart horizontally. Hence, these pa- the 2 groups was compared (unpaired 2-tailed t test). In tients are referred to as the “insertion study group.” The each case, only the data from the habitually fixing eye control group consisted of consecutive patients meeting were used for data analysis. Photographs were cropped so the same criteria as the insertion study group, with the ex- the examiner could not see the fellow eye and hence not ception that the inferior oblique muscle was recessed determine if there was a manifest strabismus present, be- (without anterior transposition) between 10 and 12 mm in cause the presence of a manifest strabismus might be sug- the standard manner. For the control group, the inferior gestive that a given photograph was taken before surgery. oblique muscle was also bunched and sutured either 3 mm A second aspect of the study was to assess the defor- posterior and 2 mm temporal to the temporal end of the in- mity of the lower eyelid that may occur on upgaze after an- ferior rectus muscle insertion, or 4 mm posterior and 0.5 terior transposition of the inferior oblique muscle. Because mm temporal to the temporal end of the inferior rectus the diagnosis of this finding is subjective and does not lend muscle insertion for either approximately a 10-mm or itself well to quantitative analysis, this issue was addressed 12-mm recession, respectively, based on data by Apt and in the following manner: Ten consecutive patients in the Call.11 Preoperative photographs were taken with the ha- insertion study group and 10 consecutive control patients bitually fixing eye looking at the center of the camera lens with approximately 34 magnification. Postoperative Continued on next page spread out laterally at the time of resuturing to the sclera, rior rectus muscle recessions. It is known that inferior a restriction of elevation in abduction associated with a rectus muscle restriction or marked superior rectus muscle Y or V pattern can result.10 This complication mimics re- weakness can cause retraction of the upper eyelid on at- sidual contralateral inferior oblique muscle overaction tempted upgaze owing to fixation duress to the levator because, on sidegaze the adducting eye excessively el- palpebrae superioris muscle. In theory, the anti- evates on attempted upgaze due to fixation duress. This elevating effect of anterior transposition of the inferior set of findings has been named the “anti-elevation syn- oblique muscle, when combined with recession of the su- drome.”10 perior rectus muscle, might also be an iatrogenic cause I have the impression that anterior transposition of for upper eyelid retraction. the inferior oblique muscle causes substantial narrow- ing of the palpebral fissure, which can be cosmetically RESULTS noticeable, particularly in patients treated unilaterally. I also believe it results in a characteristic deformity of the This study consists of 36 patients, of whom 14 under- appearance of the lower eyelid on upgaze. This mani- went anterior transposition of the inferior oblique muscle fests as an abnormal elevation of the lower eyelid asso- level with inferior rectus muscle insertion (insertion study ciated with a noticeable bulging of the central aspect of group), 16 underwent standard inferior oblique muscle the lower eyelid on upgaze. To my knowledge, the ef- recession without anterior transposition (control group), fect of the anterior transposition on the palpebral fis- and 6 patients in whom the inferior oblique muscle was sure has not been studied rigorously. The purpose of this placed 2 mm anterior to the inferior rectus muscle in- study is to investigate the alteration of the palpebral fis- sertion (2-mm study group). In addition, there were the sure with inferior oblique muscle anterior transposition previously mentioned 3 patients, who manifested upper when it is performed as the sole operative procedure.