Major Articles Comparison of augmented superior rectus transposition with medial rectus recession for surgical management of esotropic Duane retraction syndrome Shailja Tibrewal, MS,a Virender Sachdeva, MS, DNB,b Mohammed Hasnat Ali, MBA,c and Ramesh Kekunnaya, MD, FRCSd BACKGROUND
Medial rectus recession (MRc) and vertical rectus transpositions are procedures used to treat esotropic Duane retraction syndrome. Recently superior rectus transposition (SRT) combined with MRc has also been shown to improve primary alignment and abduction. The purpose of this study is to compare the results of augmented (ie, with scleral fixation) SRT with or without MRc with either unilateral or bilateral MRc for treatment of esotropic Duane syndrome.
METHODS
The medical records of patients who underwent surgery for esotropic Duane syndrome between May 2007 and February 2013 were retrospectively reviewed. Success was defined as alignment within 8D of orthotropia and abnormal head posture of \5 . There were 8 patients in the SRT group (6 of whom had additional ipsilateral MRc) and 13 in the MRc group (6 unilateral and 7 bilateral). In the SRT group, the mean preoperative deviation was 20D of esotropia; the mean postoperative deviation, 3D. In the MRc group, the mean preoperative deviation was 24D of esotropia; the mean postoperative deviation, 4D. The success rate was 87% in the SRT group; 77%, in MRc group (P 5 0.98). Mean abduction limitation improved from 3.6 to 2.4 units in the SRT group and from 3.6 to 3.3 units in the MRc group (P 5 0.003). Induced vertical deviation or subjective torsion was not seen. Three patients in each group developed adduction limitation postoperatively.
RESULTS
CONCLUSIONS
Although both the procedures successfully correct esotropia in Duane syndrome, SRT with or without MRc has the additional advantage of improving abduction. ( J AAPOS 2015;19:199-205)
D
uane retraction syndrome is a complex strabismus characterized by limitation of abduction and/or adduction associated with globe retraction and corresponding lid fissure changes. It is a
Author affiliations: aDepartment of Pediatric Ophthalmology and Strabismus, Dr. Shroff’s Charity Eye Hospital, Daryaganj, New Delhi, India; bNimmagada Prasad Children’s Eye Care Centre, GMRV Campus, L V Prasad Eye Institute, Visakhapatnam, Andhra Pradesh, India; cCenter for Clinical Epidemiology and Bio-statistics (CCEB), KAR Campus, L V Prasad Eye Institute, Hyderabad, Andhra Pradesh, India; dJasti V Ramanamma Children’s Eye Care Centre, KAR Campus, L V Prasad Eye Institute, Hyderabad Presented as a poster at the 40th Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, Palm Springs, California, April 2-6, 2014. Submitted July 29, 2014. Revision accepted February 1, 2015. Correspondence: Ramesh Kekunnaya, MD, FRCS, Head, Jasti V Ramanamma Children’s Eye Care Centre, Consultant, Pediatric Ophthalmology, Strabismus and Neuroophthalmology Services, L V Prasad Eye Institute, Kallam Anji Reddy Campus, L V Prasad Marg, Banjara Hills, Hyderabad – 500034 India (email: [email protected], drrk123@ gmail.com). Copyright Ó 2015 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2015.02.006
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congenital abnormality now considered to be part of the broad category of congenital cranial dysinnervation disorders. Huber classified Duane syndrome into three types based on electromyographic findings.1 Type 1 is characterized by limited abduction and co-contraction of both the horizontal rectus muscles during attempted adduction. Various studies have shown that type 1 Duane syndrome with esotropia in primary position is by far the most common type.2-5 Unilateral or bilateral medial rectus recession (MRc) is performed to correct primary position esotropia in these patients.6-11 It effectively corrects the deviation and abnormal head posture; there may also be a small improvement in abduction in 28%-30% of patients.12-14 To improve abduction effectively, vertical rectus transposition to the lateral rectus muscle has been suggested and performed by various authors.15-17 However, it may be associated with consecutive vertical deviations in 13%-30% of cases.18 Also there is an increased risk of anterior segment ischemia following vertical rectus transposition, especially when it is combined with MRc.19
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In 2006 Johnston proposed a novel technique of transposing the superior rectus muscle alone to the lateral rectus muscle (Johnston SC, et al. IOVS 2006;47:e-abstract 2475). Recently Mehendale and colleagues20 combined augmented superior rectus transposition (SRT) with MRc in 10 patients with esotropic Duane syndrome. The procedure resulted in good postoperative alignment as well as improved abduction without inducing vertical deviations or significant torsion. The purpose of the present study was to compare the results of augmented SRT with or without MRc with unilateral or bilateral MRc alone for treatment of esotropic Duane syndrome.
Patients and Methods The medical records of unilateral esotropic Duane syndrome patients who underwent surgery between May 2007 and February 2013 at the L V Prasad Eye Institute, Hyderabad, with either augmented superior rectus transposition with or without medial rectus recession (SRT group) or unilateral or bilateral medial rectus recession alone (MRc group) were retrospectively reviewed. The former procedure was adopted by the senior author (KR) in 2011 as a change in practice pattern. Prior to that, unilateral or bilateral medial rectus recessions were being performed. Even though the mechanism by which ipsilateral and contralateral medial rectus recession act are quite different—that is, ipsilateral recession improves alignment only and contralateral recession creates fixation duress as well—both procedures aim to achieve improvement in ocular alignment and improve head posture. This study was approved by the Institutional Review Board of the Hyderabad Eye Research Group and adhered to the tenets of Declaration of Helsinki. The review included all patients with unilateral type 1 esotropic DRS who had undergone surgery for correction of esotropia and/ or abnormal head posture. Those who had undergone subsequent reoperations were included, but only the results of the first surgery were analyzed. Patients who had preoperative up- or downshoot in adduction were included. Patients who underwent a Y-split procedure or ipsilateral lateral rectus recession for associated overshoots or globe retraction were excluded. SRT was not performed in patients with preexisting vertical deviation (.4D) in primary position to avoid unpredictable results. To maintain comparability, patients with vertical deviation were excluded from the MRc group as well. A minimum postoperative follow-up of 4 months was required for inclusion. The superior rectus transposition with augmentation suture was performed via the fornix approach in all patients in the SRT group as described elsewhere.20 The superior rectus muscle was secured using double armed 6-0 polyglactin 910 suture. Its attachments to the levator palpebrae superioris and the superior oblique tendon were carefully dissected. After disinsertion, the superior rectus muscle was attached adjacent to the superior border of the lateral rectus muscle along the spiral of Tillaux. Thereafter an augmentation suture (5-0 polyester Dacron) was passed 8 mm behind the lateral rectus insertion incorporating one-fourth thickness of each of the superior and lateral rectus muscles and the underlying sclera. The choice of fornix or limbal incision was based on surgeon
Volume 19 Number 3 / June 2015 preference and not laterality of the surgery in the MRc group. The amount of surgery was based on amount of the deviation in primary position and surgeon’s experience. Data were collected regarding change in the amount of esotropia, correction of abnormal head posture, and improvement in abduction. Limitation of ductions (abduction and adduction) was measured on a scale from 0 to 4, with 0 indicating no limitation and 4 failure of the eye to cross the midline. Head turn was measured with a goniometer as the amount of turn (in degrees) that the patient maintained while reading a vision chart at 3 meters centered in front of him/her. In preschool children the head turn was measured while an interesting target was shown at a distant door post approximately 3 meters away. Globe retraction, that is, narrowing of palpebral fissure height (measured at the center of the palpebral fissure width) in adduction compared to the fellow eye in abduction, was graded according to the following scale: 0, no narrowing; 1, \25%; 2, 25% to \50%; 3, 50% to \75%; 4, $75%. Overshoot (with the involved eye in adducted position a straight line parallel to the intermedial canthal line is drawn from pupillary center of the fellow eye) was graded as follows: 0, line bisects the pupil of involved eye; 1, line lies between pupillary center and pupillary margin (including margin); 2, line lies between pupillary margin and limbus; 3, line lies at limbus or over sclera; 4, cornea disappearing below the lid. Success was arbitrarily defined as postoperative primary position deviation within 8D of orthotropia and anomalous head posture \5 . Statistical analysis was performed using the R software version 2.14.1 (R Foundation for Statistical Computing; http://www. R-project.org). The Shapiro Wilk test was used to study the distribution of the data. The Mann-Whitney test with continuity correction and Welch two sample t test were used to compare the distribution of preoperative parameters, such as age, deviation, abnormal head posture, abduction limitation, globe retraction, and duration of follow-up. The two-sample proportion test and t test were used to compare success rates and postoperative abduction difference respectively between groups.
Results The SRT group comprised 8 patients (3 males); the MRc group, 13 (6 males). Mean age at the time of surgery was 12 years (range, 5.4-23.6 years) in the SRT group; 13 years (range, 1.6-33.6 years), in the MRc group. The groups were comparable in terms of age distribution, preoperative deviation, abnormal head posture, abduction limitation, globe retraction, and duration of follow-up. Table 1 shows the distribution of the baseline demographic and clinical characteristics. In the MRc group, 6 patients (46%) underwent unilateral recession and 7 (54%) underwent bilateral asymmetrical recessions. The average amount of medial rectus recession performed was 5 mm/eye (range, 3.5–7 mm) and 7.7mm per patient. In the SRT group 6 patients underwent the additional ipsilateral MRc, with the average amount of recession being 5 mm/eye (range, 3.5–6 mm). The other 2 patients underwent SRT alone.
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Table 1. Distribution of the baseline demographic and clinical characteristics in patients undergoing SRT with or without MRc and MRc alone Parameter Preoperative esotropia, PD, mean (range) Preoperative head posture, degrees Preoperative abduction limitation Follow up (months) Globe retraction (grade)
SRT MRc group 20.4 (8 to 45) 13.5 (8-20) 3.6 ( 2 to 4) 20.6 (7.4-33.7) 1.3 (1-2)
MRc group a
24.2 (10-45) 17.8 (5-30) 3.6 ( 2 to 4) 24.2 (4.6-58.4) 1.4 (0-4)
P value 0.49 0.42 0.70 0.64 0.96
MRc, medial rectus recession; PD, prism diopter; SRT, superior rectus transposition. a Unilateral cases, mean 5 19 PD (range, 10-30); bilateral cases, mean 5 28 (range, 25-45).
FIG 1. Box plot showing the postoperative change in esodeviation in the patients who underwent superior rectus transposition with or without medial rectus recession (SRT group) versus those underwent unilateral or bilateral medial rectus recession alone (MRc group).
Mean preoperative deviation decreased from 20D (range, 8 -45D) and 24D (range, 10D-45D) of esotropia to 3D (range, 6D exotropia to 6D esotropia) and 4D of esotropia (range 0 – 20) in the SRT and MRc group, respectively (Figure 1). The average reduction in esotropia/mm of medial rectus recession was 4.1D/mm (range, 2.3-6.7) when SRT was combined with MRc as compared to 2.6D/mm (range, 1.2-4.2) with MRc alone. Figure 2 shows an arrow plot depicting the change in primary position esotropia among the individual patients of the study. The abnormal head posture decreased from a mean of 14 (range, 8 to 20 ) to 2 (range, 0 -7 ) in the SRT group. Similarly, in the MRc group the AHP decreased from 18 degrees (range, 5 -30 ) to 3 (range, 0 -20 ). None of the patients in either group had reversal of the head posture following surgery. The success rate was comparable between groups being 87% (95% CI, 64%-110%) in the SRT group and 77% (95% CI, 54%-100%) in MRc group (P 5 0.98). One patient had a residual head posture of 7 in the SRT MRc group which did not require further intervention. In the MRc group there were three patients with residual esotropia of 9D, 14D, and 20D and residual head turn of D
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5 , 20 , and 10 , respectively. The patient with 9D residual esotropia was satisfied with the alignment and the patient with 20D residual esodeviation was lost to follow up. The patient with residual esotropia of 14D had 20D of esotropia initially had undergone 5 mm of ipsilateral medial rectus recession. For the residual esotropia SRT was performed 11 months after the first surgery. His deviation decreased to 6D esotropia, face turn decreased to 7 and abduction improved from 4 to 2 following SRT. Consecutive exodeviation of small amount was observed in one patient in SRT group (6D exotropia, with no limitation in adduction). The abduction limitation improved by an average of 1.2 units, from 3.6 units (range, 2 to 4) preoperatively to 2.4 (range, 2 to 3) postoperatively in the SRT group, compared to an average of 0.3 units, from 3.6 units (range, 2 to 4) to 3.3 units (range, 1 to 4) in the MRc group (P # 0.003), as shown in Figure 3. Overall 87.5 % patients in the SRT group showed at least 1 unit improvement in abduction, whereas only 23.1% of patients in the MRc group showed 1 unit of abduction improvement. The ocular motility photographs of patients who underwent SRT with or without MRc and MRc alone are provided in Figure 4: a significantly greater amount of improvement in abduction can be seen in the former. In 2 patients augmented SRT was the sole procedure. The first had a right-sided Duane syndrome with preoperative deviation of 14D and a right head turn of 20 . Following SRT the deviation reduced to 8D of esotropia and the head posture decreased to 7 of right head turn. The second patient, also with a right-sided Duane syndrome had a small esodeviation of 8D and right face turn of 10 . Postoperatively, the deviation recorded was 6D exotropia with no abnormal head posture. Average abduction improvement in these 2 patients was 1.5 units and there was no adduction limitation seen postoperatively. No new vertical deviations were seen in any patient following augmented SRT. One patient had a small ( 0.5) limitation of elevation at 3 weeks’ follow-up, which improved completely by 19 months. Preoperatively globe retraction of grade 1 was seen in 6 patients and grade 2 in 2 SRT group patients. Postoperatively globe retraction reduced in 2 patients and remained unchanged in 6. In the MRc group, 4 patients had significant lid fissure narrowing (grade 2 or more) preoperatively; the rest had grade 1 globe retraction. Postoperatively lid fissure changes remained unchanged in 5 patients but reduced in the
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FIG 3. A mean plot showing the reduction in the abduction deficit in the SRT group as compared to that in the MRc group.
affected eye. Although this procedure achieved orthotropia in primary position, there was a large exotropia in adduction. This particular patient had very severe globe retraction (grade 4) at presentation.
Discussion
FIG 2. A, Arrow plot showing change in primary position esotropia among the patients in the SRT group (patients 7 and 8 underwent SRT alone). B, Arrow plot showing change in primary position esotropia among patients in the MRc gorup. The vertical dashed line marks the upper limit of success criteria (8D of esotropia).
remaining. None of the patients in either group had significant overshoot preoperatively. One patient in the SRT group and 2 in the MRc group had minimal (grade 1) overshoot, which did not change following either surgery. None of the patients who underwent SRT complained of torsional diplopia. Postoperatively indirect ophthalmoscopy was performed in 6 of 8 patients in SRT group; none showed any objective torsion. Postoperative limitation of adduction (range, 0.5 to 3) was observed in 3 of 8 patients (37.5%) in the SRT group and 3 of 13 (23%) in the MRc group. The adduction limitation in the SRT group was 0.5, 0.5, and 2 in the 3 patients. The adduction limitation in the 3 patients in the MRc group was 0.5, 1, and 3. The patient who developed a limitation of 3 had undergone 6 mm of MRc in the
The goal of surgery in patients with Duane syndrome is to reduce or eliminate anomalous head posture, achieve good alignment in primary position, and increase the range of binocular single vision. Results of surgery in Duane syndrome may sometimes be unsatisfactory because of complex mechanisms involving innervational abnormalities, co-contraction, and muscle contracture. Classically, medial rectus recession has been described, which improves alignment and head posture in majority of patients.6-8 However MRc alone may lead to only a small improvement in abduction and there may be risk of postoperative adduction limitation21 and/or decrease in convergence, especially when large recessions are performed bilaterally. Vertical rectus transposition to the lateral rectus muscle for improvement of abduction in Duane syndrome patients has been studied by various authors.15-17 Foster22 suggested that vertical rectus transposition alone may achieve good results when augmented with posterior fixation sutures. However, subsequent MRc or botulinum toxin injection may be required in some patients, especially when the medial rectus muscle is found to be tight during intraoperative forced duction testing.17 The average amount of improvement in abduction limitation after transposition procedure as reported in various studies is shown in Table 2. The present study showed that SRT with or without MRc was similar to MRc alone in terms of correction of abnormal head posture and alignment. Recently Yang
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FIG 4. A, Pre- (above) and postoperative (below) clinical photographs of a patient who underwent SRT with ipsilateral medial rectus recession. B, Pre- (above) and postoperative (below) clinical photographs of a patient who underwent bilateral asymmetrical MRc.
and collegues14 reported similar results in comparing SRT with or without MRc and unilateral or bilateral MRc. The surgical technique followed by these authors differed from ours. They performed adjustable medial rectus recession, whereas we prefer fixed sutures. They observed torsional changes in 1 patient where a scleral pass had been taken for augmentation of SRT. We used scleral pass in all our patients; however, none of our patients reported torsional diplopia. The results of the present study are also comparable to those of Mehendale and colleagues,20 where 10 patients with esotropic Duane syndrome and 7 with lateral rectus palsy were treated with SRT with or without augmentation and MRc. None of the patients with Duane syndrome in their study developed vertical deviation, but 2 with chronic lateral rectus palsy did develop hypotropia (mean, 10D). Also 1 patient had subjective torsion following SRT for either Duane syndrome or lateral rectus palsy. New vertical deviation or limitation of elevation was not seen in any of our patients, and none complained of torsional diplopia. In the current study, augmented transposition of the superior rectus muscle improved abduction in 87.5% patients with esotropic Duane syndrome. The degree of improvement in abduction was comparable to that achieved with both vertical rectus transposition and SRT as seen in related studies (Table 2). Compared to vertical rectus transpostion, SRT is unlikely to increase the risk of ante-
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rior segment ischemia. However, most patients undergoing SRT also required ipsilateral MRc to achieve good alignment. Based on our experience in the initial 4-5 cases, we found that SRT alone was effective in correcting up to 15D of esotropia. Beyond this, additional MRc was necessary. It should be borne in mind that the response to surgery in Duane syndrome also depends on tightness of the medial rectus muscle, the amount of misinnervation of the lateral rectus muscle, and patient age. In our study, bilateral surgery (medial rectus recessions) was required in patients with .25D of esotropia. Addition of SRT to ipsilateral MRc obviated the need for contralateral eye surgery and was effective in correcting up to 45D of esotropia with unilateral surgery. Similar to our study, previous studies report around 28% to 30% of improvement in abduction in patients undergoing unilateral or bilateral medial rectus recessions.12-14 Barbe and colleauges8 documented improved abduction (range, 0.5-2 units) in 69% of cases with unilateral Duane syndrome undergoing unilateral or bilateral MRc. However, an equal number of patients in their study developed an adduction limitation of 1-3 units. The average MRc/eye performed in their patients was 5.8 mm, with 16 of 22 patients undergoing $6 mm of recession in the affected eye. Pressman and colleagues6 reported similar results. Thus increasing the amount of MRc may improve abduction further, but at the cost of decreased adduction.
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Table 2. Improvement in abduction following vertical rectus transposition as reported in various studies Mean abduction limitation Study Molarte 199015 Foster 199722 Velez 200117 Velez 200117 Britt 200323
Sterk 200424 Britt 200516 Yazdian 201025 Mehendale 201220 Yang 201414
Present study
Type of VRT
N
Pre-op
Post-op
Non augmented VRT Augmented VRT Augmented VRT Nonaugmented VRT Augmented partial VRT following prior nontransposition surgery Nonaugmented VRT with MRc VRT augmentation in bilateral Duane syndrome Augmented VRT Augmented SRT with MRc Augmented SRT MRc
13 5 32 22 5
3.8 4 3.9 0.2 3.7 0.4 3.8
2.3 3.4 2.9 0.6 2.7 0.7 3.1
36
4.7 8.2 dega
20.6 8.6 dega
11
3.75
2.68
Augmented SRT 1 MRc SRT alone
38 10 19
6 2
4.00 0.23 4 —
2.11 0.48 2 —
3.66 3.5
2.58 2
Average improvement in abduction, units 1.5 0.6 1 1 0.7
15.9 8.1 dega 1 1.89 2 79% of patients showed $1 unit improvement in abductionb 1.08 1.5
MRc, medial rectus recession; SRT, superior rectus transposition; VRT, vertical rectus transposition. a Abduction measured in degrees on the arms of synaptophore. b Abduction improvement as percentage of patients showing improvement of $1 unit.
There is an increased chance of developing postoperative adduction limitation with SRT, as occurred in 37% of patients in our SRT group (95% CI, 3.5%-70.5%), compared to 23% in the MRc group (95% CI, 0.12%45.88%). It has also been suggested that patients with exotropia in adduction may be predisposed to develop consecutive exotropia after transposition surgery in Duane syndrome.26 The above observation of adduction limitation in the initial 3 cases made us reduce the MRc dosage in patients undergoing SRT. Hence we suggest that the maximum recession of the ipsilateral medial rectus muscle should be limited to 5–5.5 mm in combination with SRT. The present study is limited by its retrospective design. Although the groups were comparable in terms of preoperative deviation, head posture, and abduction limitation, certain parameters that could have been important pertaining to surgical success (eg, forced duction testing, alignment in lateral gazes) were not compared between groups. Multiple surgeons were involved in the MRc group; a single surgeon, in the SRT group. Binocular visual fields were not compared in most patients. In view of the fact that a higher number of patients had a postoperative adduction limitation in the SRT group versus the MRc group, we cannot conclude from our data whether a greater improvement in abduction led to improvement in binocular visual fields. Finally, pre- and postoperative torsion was not measured in all patients. Despite these limitations, the current study suggests that, although both SRT MRc and MRc alone are comparable in terms of improvement in primary position devi-
ation and abnormal head posture, the former leads to greater improvement in abduction. References 1. Huber A. Electrophysiology of the retraction syndromes. Br J Ophthalmol 1974;58:293-300. 2. O’Malley ER, Helveston EM, Ellis FD. Duane’s retraction syndrome—plus. J Pediatr Ophthalmol Strabismus 1982;19:161-5. 3. Raab EL. Clinical features of Duane’s syndrome. J Pediatr Ophthalmol Strabismus 1986;23:64-8. 4. Ro A, Gummeson B, Orton RB, Cadera W. Duane’s retraction syndrome: southwestern Ontario experience. Can J Ophthalmol 1989; 24:200-203. 5. Kekunnaya R, Gupta A, Sachdeva V, et al. Duane retraction syndrome: series of 441 cases. J Pediatr Ophthalmol Strabismus 2012; 49:164-9. 6. Pressman SH, Scott WE. Surgical treatment of Duane’s syndrome. Ophthalmology 1986;93:29-38. 7. Kraft SP. A surgical approach for Duane syndrome. J Pediatr Ophthalmol Strabismus 1988;25:119-30. 8. Barbe ME, Scott WE, Kutschke PJ. A simplified approach to the treatment of Duane’s syndrome. Br J Ophthalmol 2004;88:131-8. 9. Kubota N, Takahasi H, Hayashi T, Sakaue T, Maruo T. Outcome of surgery in 124 cases of Duane’s retraction syndrome (DRS) treated by intraoperatively graduated recession of the medial rectus for esotropic DRS, and of the lateral rectus for exotropic DRS. Binocul Vis Strabismus Q 2001;16:15-22. 10. Farvardin M, Rad AH, Ashrafzadeh A. Results of bilateral medial rectus muscle recession in unilateral esotropic Duane syndrome. J AAPOS 2009;13:339-42. 11. Dotan G, Klein A, Ela-Dalman N, Shulman S, Stolovitch C. The efficacy of asymmetric bilateral medial rectus muscle recession surgery in unilateral, esotropic, type 1 Duane syndrome. J AAPOS 2012;16: 543-7.
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Volume 19 Number 3 / June 2015 12. Kaban TJ, Smith K, Day C, Orton R, Kraft S, Cadera W. Single medial rectus recession in unilateral Duane syndrome type I. Am Orthoptic J 1995;45:108-14. 13. Merino P, Merino M, G omez De Lia~ no P, Blanco N. Horizontal rectus surgery in Duane syndrome. Eur J Ophthalmol 2011;22:125-30. 14. Yang S, MacKinnon S, Dagi LR, Hunter DG. Superior rectus transposition vs medial rectus recession for treatment of esotropic Duane syndrome. JAMA Ophthalmol 2014;132:669-75. 15. Molarte AB, Rosenbaum AL. Vertical rectus muscle transposition surgery for Duane’s syndrome. J Pediatr Ophthalmol Strabismus 1986;27:171-7. 16. Britt MT, Velez FG, Velez G, Rosenbaum AL. Vertical rectus muscle transposition for bilateral Duane syndrome. J AAPOS 2005;9:416-21. 17. Velez FG, Foster RS, Rosenbaum AL. Vertical rectus muscle augmented transposition in Duane syndrome. J AAPOS 2001;5: 105-13. 18. Ruth AL, Velez FG, Rosenbaum AL. Management of vertical deviations after vertical rectus transposition surgery. J AAPOS 2009;13: 16-19. 19. Murdock TJ, Kushner BJ. Anterior segment ischemia after surgery on 2 vertical rectus muscles augmented with lateral fixation sutures. J AAPOS 2001;5:323-4.
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20. Mehendale RA, Dagi LR, Wu C, Ledoux D, Johnston S, Hunter DG. Superior rectus transposition and medial rectus recession for Duane syndrome and sixth nerve palsy. Arch Ophthalmol 2012;130:195-201. 21. Shiratori A, Kameyama C, Sibasaki K. Adduction deficiency following a large medial rectus recession in Duane’s retraction syndrome type 1. J Pediatr Ophthalmol Strabismus 1999;36:98-100. 22. Foster RS. Vertical muscle transposition augmented with lateral fixation. J AAPOS 1997;1:20. 23. Britt M, Velez F, Thacker N, Alcorn D, Foster RS, Rosenbaum AL. Partial rectus muscle augmented transpositions in abduction deficiencies. J AAPOS 2003;7:325-32. 24. Sterk CC, van Hulst-Ginjaar SP, Swart-van den Berg M. Improvement of horizontal excursion and abduction by vertical muscle transposition in patients with Duane’s retraction syndrome type I. J Pediatr Ophthalmol Strabismus 2004;41:204-8. 25. Yazdian Z, Rajabi MT, Ali Yazdian M, Rajabi MB, Akbari MR. Vertical rectus muscle transposition for correcting abduction deficiency in Duane’s syndrome type 1 and sixth nerve palsy. J Pediatr Ophthalmol Strabismus 2010;47:96-100. 26. Velez FG, Laursen JK, Pineles SL. Risk factors for consecutive exotropia after vertical rectus transposition for esotropic Duane retraction syndrome. J AAPOS 2011;15:326-30.
Medial rectus recession (MRc) and vertical rectus transpositions are procedures used to treat esotropic Duane retraction syndrome. Recently superior rectus transposition (SRT) combined with MRc has also been shown to improve primary alignment and abduction. The purpose of this study is to compare the results of augmented (ie, with scleral fixation) SRT with or without MRc with either unilateral or bilateral MRc for treatment of esotropic Duane syndrome.
METHODS
The medical records of patients who underwent surgery for esotropic Duane syndrome between May 2007 and February 2013 were retrospectively reviewed. Success was defined as alignment within 8D of orthotropia and abnormal head posture of \5 . There were 8 patients in the SRT group (6 of whom had additional ipsilateral MRc) and 13 in the MRc group (6 unilateral and 7 bilateral). In the SRT group, the mean preoperative deviation was 20D of esotropia; the mean postoperative deviation, 3D. In the MRc group, the mean preoperative deviation was 24D of esotropia; the mean postoperative deviation, 4D. The success rate was 87% in the SRT group; 77%, in MRc group (P 5 0.98). Mean abduction limitation improved from 3.6 to 2.4 units in the SRT group and from 3.6 to 3.3 units in the MRc group (P 5 0.003). Induced vertical deviation or subjective torsion was not seen. Three patients in each group developed adduction limitation postoperatively.
RESULTS
CONCLUSIONS
Although both the procedures successfully correct esotropia in Duane syndrome, SRT with or without MRc has the additional advantage of improving abduction. ( J AAPOS 2015;19:199-205)
D
uane retraction syndrome is a complex strabismus characterized by limitation of abduction and/or adduction associated with globe retraction and corresponding lid fissure changes. It is a
Author affiliations: aDepartment of Pediatric Ophthalmology and Strabismus, Dr. Shroff’s Charity Eye Hospital, Daryaganj, New Delhi, India; bNimmagada Prasad Children’s Eye Care Centre, GMRV Campus, L V Prasad Eye Institute, Visakhapatnam, Andhra Pradesh, India; cCenter for Clinical Epidemiology and Bio-statistics (CCEB), KAR Campus, L V Prasad Eye Institute, Hyderabad, Andhra Pradesh, India; dJasti V Ramanamma Children’s Eye Care Centre, KAR Campus, L V Prasad Eye Institute, Hyderabad Presented as a poster at the 40th Annual Meeting of the American Association for Pediatric Ophthalmology and Strabismus, Palm Springs, California, April 2-6, 2014. Submitted July 29, 2014. Revision accepted February 1, 2015. Correspondence: Ramesh Kekunnaya, MD, FRCS, Head, Jasti V Ramanamma Children’s Eye Care Centre, Consultant, Pediatric Ophthalmology, Strabismus and Neuroophthalmology Services, L V Prasad Eye Institute, Kallam Anji Reddy Campus, L V Prasad Marg, Banjara Hills, Hyderabad – 500034 India (email: [email protected], drrk123@ gmail.com). Copyright Ó 2015 by the American Association for Pediatric Ophthalmology and Strabismus. 1091-8531/$36.00 http://dx.doi.org/10.1016/j.jaapos.2015.02.006
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congenital abnormality now considered to be part of the broad category of congenital cranial dysinnervation disorders. Huber classified Duane syndrome into three types based on electromyographic findings.1 Type 1 is characterized by limited abduction and co-contraction of both the horizontal rectus muscles during attempted adduction. Various studies have shown that type 1 Duane syndrome with esotropia in primary position is by far the most common type.2-5 Unilateral or bilateral medial rectus recession (MRc) is performed to correct primary position esotropia in these patients.6-11 It effectively corrects the deviation and abnormal head posture; there may also be a small improvement in abduction in 28%-30% of patients.12-14 To improve abduction effectively, vertical rectus transposition to the lateral rectus muscle has been suggested and performed by various authors.15-17 However, it may be associated with consecutive vertical deviations in 13%-30% of cases.18 Also there is an increased risk of anterior segment ischemia following vertical rectus transposition, especially when it is combined with MRc.19
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In 2006 Johnston proposed a novel technique of transposing the superior rectus muscle alone to the lateral rectus muscle (Johnston SC, et al. IOVS 2006;47:e-abstract 2475). Recently Mehendale and colleagues20 combined augmented superior rectus transposition (SRT) with MRc in 10 patients with esotropic Duane syndrome. The procedure resulted in good postoperative alignment as well as improved abduction without inducing vertical deviations or significant torsion. The purpose of the present study was to compare the results of augmented SRT with or without MRc with unilateral or bilateral MRc alone for treatment of esotropic Duane syndrome.
Patients and Methods The medical records of unilateral esotropic Duane syndrome patients who underwent surgery between May 2007 and February 2013 at the L V Prasad Eye Institute, Hyderabad, with either augmented superior rectus transposition with or without medial rectus recession (SRT group) or unilateral or bilateral medial rectus recession alone (MRc group) were retrospectively reviewed. The former procedure was adopted by the senior author (KR) in 2011 as a change in practice pattern. Prior to that, unilateral or bilateral medial rectus recessions were being performed. Even though the mechanism by which ipsilateral and contralateral medial rectus recession act are quite different—that is, ipsilateral recession improves alignment only and contralateral recession creates fixation duress as well—both procedures aim to achieve improvement in ocular alignment and improve head posture. This study was approved by the Institutional Review Board of the Hyderabad Eye Research Group and adhered to the tenets of Declaration of Helsinki. The review included all patients with unilateral type 1 esotropic DRS who had undergone surgery for correction of esotropia and/ or abnormal head posture. Those who had undergone subsequent reoperations were included, but only the results of the first surgery were analyzed. Patients who had preoperative up- or downshoot in adduction were included. Patients who underwent a Y-split procedure or ipsilateral lateral rectus recession for associated overshoots or globe retraction were excluded. SRT was not performed in patients with preexisting vertical deviation (.4D) in primary position to avoid unpredictable results. To maintain comparability, patients with vertical deviation were excluded from the MRc group as well. A minimum postoperative follow-up of 4 months was required for inclusion. The superior rectus transposition with augmentation suture was performed via the fornix approach in all patients in the SRT group as described elsewhere.20 The superior rectus muscle was secured using double armed 6-0 polyglactin 910 suture. Its attachments to the levator palpebrae superioris and the superior oblique tendon were carefully dissected. After disinsertion, the superior rectus muscle was attached adjacent to the superior border of the lateral rectus muscle along the spiral of Tillaux. Thereafter an augmentation suture (5-0 polyester Dacron) was passed 8 mm behind the lateral rectus insertion incorporating one-fourth thickness of each of the superior and lateral rectus muscles and the underlying sclera. The choice of fornix or limbal incision was based on surgeon
Volume 19 Number 3 / June 2015 preference and not laterality of the surgery in the MRc group. The amount of surgery was based on amount of the deviation in primary position and surgeon’s experience. Data were collected regarding change in the amount of esotropia, correction of abnormal head posture, and improvement in abduction. Limitation of ductions (abduction and adduction) was measured on a scale from 0 to 4, with 0 indicating no limitation and 4 failure of the eye to cross the midline. Head turn was measured with a goniometer as the amount of turn (in degrees) that the patient maintained while reading a vision chart at 3 meters centered in front of him/her. In preschool children the head turn was measured while an interesting target was shown at a distant door post approximately 3 meters away. Globe retraction, that is, narrowing of palpebral fissure height (measured at the center of the palpebral fissure width) in adduction compared to the fellow eye in abduction, was graded according to the following scale: 0, no narrowing; 1, \25%; 2, 25% to \50%; 3, 50% to \75%; 4, $75%. Overshoot (with the involved eye in adducted position a straight line parallel to the intermedial canthal line is drawn from pupillary center of the fellow eye) was graded as follows: 0, line bisects the pupil of involved eye; 1, line lies between pupillary center and pupillary margin (including margin); 2, line lies between pupillary margin and limbus; 3, line lies at limbus or over sclera; 4, cornea disappearing below the lid. Success was arbitrarily defined as postoperative primary position deviation within 8D of orthotropia and anomalous head posture \5 . Statistical analysis was performed using the R software version 2.14.1 (R Foundation for Statistical Computing; http://www. R-project.org). The Shapiro Wilk test was used to study the distribution of the data. The Mann-Whitney test with continuity correction and Welch two sample t test were used to compare the distribution of preoperative parameters, such as age, deviation, abnormal head posture, abduction limitation, globe retraction, and duration of follow-up. The two-sample proportion test and t test were used to compare success rates and postoperative abduction difference respectively between groups.
Results The SRT group comprised 8 patients (3 males); the MRc group, 13 (6 males). Mean age at the time of surgery was 12 years (range, 5.4-23.6 years) in the SRT group; 13 years (range, 1.6-33.6 years), in the MRc group. The groups were comparable in terms of age distribution, preoperative deviation, abnormal head posture, abduction limitation, globe retraction, and duration of follow-up. Table 1 shows the distribution of the baseline demographic and clinical characteristics. In the MRc group, 6 patients (46%) underwent unilateral recession and 7 (54%) underwent bilateral asymmetrical recessions. The average amount of medial rectus recession performed was 5 mm/eye (range, 3.5–7 mm) and 7.7mm per patient. In the SRT group 6 patients underwent the additional ipsilateral MRc, with the average amount of recession being 5 mm/eye (range, 3.5–6 mm). The other 2 patients underwent SRT alone.
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Table 1. Distribution of the baseline demographic and clinical characteristics in patients undergoing SRT with or without MRc and MRc alone Parameter Preoperative esotropia, PD, mean (range) Preoperative head posture, degrees Preoperative abduction limitation Follow up (months) Globe retraction (grade)
SRT MRc group 20.4 (8 to 45) 13.5 (8-20) 3.6 ( 2 to 4) 20.6 (7.4-33.7) 1.3 (1-2)
MRc group a
24.2 (10-45) 17.8 (5-30) 3.6 ( 2 to 4) 24.2 (4.6-58.4) 1.4 (0-4)
P value 0.49 0.42 0.70 0.64 0.96
MRc, medial rectus recession; PD, prism diopter; SRT, superior rectus transposition. a Unilateral cases, mean 5 19 PD (range, 10-30); bilateral cases, mean 5 28 (range, 25-45).
FIG 1. Box plot showing the postoperative change in esodeviation in the patients who underwent superior rectus transposition with or without medial rectus recession (SRT group) versus those underwent unilateral or bilateral medial rectus recession alone (MRc group).
Mean preoperative deviation decreased from 20D (range, 8 -45D) and 24D (range, 10D-45D) of esotropia to 3D (range, 6D exotropia to 6D esotropia) and 4D of esotropia (range 0 – 20) in the SRT and MRc group, respectively (Figure 1). The average reduction in esotropia/mm of medial rectus recession was 4.1D/mm (range, 2.3-6.7) when SRT was combined with MRc as compared to 2.6D/mm (range, 1.2-4.2) with MRc alone. Figure 2 shows an arrow plot depicting the change in primary position esotropia among the individual patients of the study. The abnormal head posture decreased from a mean of 14 (range, 8 to 20 ) to 2 (range, 0 -7 ) in the SRT group. Similarly, in the MRc group the AHP decreased from 18 degrees (range, 5 -30 ) to 3 (range, 0 -20 ). None of the patients in either group had reversal of the head posture following surgery. The success rate was comparable between groups being 87% (95% CI, 64%-110%) in the SRT group and 77% (95% CI, 54%-100%) in MRc group (P 5 0.98). One patient had a residual head posture of 7 in the SRT MRc group which did not require further intervention. In the MRc group there were three patients with residual esotropia of 9D, 14D, and 20D and residual head turn of D
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5 , 20 , and 10 , respectively. The patient with 9D residual esotropia was satisfied with the alignment and the patient with 20D residual esodeviation was lost to follow up. The patient with residual esotropia of 14D had 20D of esotropia initially had undergone 5 mm of ipsilateral medial rectus recession. For the residual esotropia SRT was performed 11 months after the first surgery. His deviation decreased to 6D esotropia, face turn decreased to 7 and abduction improved from 4 to 2 following SRT. Consecutive exodeviation of small amount was observed in one patient in SRT group (6D exotropia, with no limitation in adduction). The abduction limitation improved by an average of 1.2 units, from 3.6 units (range, 2 to 4) preoperatively to 2.4 (range, 2 to 3) postoperatively in the SRT group, compared to an average of 0.3 units, from 3.6 units (range, 2 to 4) to 3.3 units (range, 1 to 4) in the MRc group (P # 0.003), as shown in Figure 3. Overall 87.5 % patients in the SRT group showed at least 1 unit improvement in abduction, whereas only 23.1% of patients in the MRc group showed 1 unit of abduction improvement. The ocular motility photographs of patients who underwent SRT with or without MRc and MRc alone are provided in Figure 4: a significantly greater amount of improvement in abduction can be seen in the former. In 2 patients augmented SRT was the sole procedure. The first had a right-sided Duane syndrome with preoperative deviation of 14D and a right head turn of 20 . Following SRT the deviation reduced to 8D of esotropia and the head posture decreased to 7 of right head turn. The second patient, also with a right-sided Duane syndrome had a small esodeviation of 8D and right face turn of 10 . Postoperatively, the deviation recorded was 6D exotropia with no abnormal head posture. Average abduction improvement in these 2 patients was 1.5 units and there was no adduction limitation seen postoperatively. No new vertical deviations were seen in any patient following augmented SRT. One patient had a small ( 0.5) limitation of elevation at 3 weeks’ follow-up, which improved completely by 19 months. Preoperatively globe retraction of grade 1 was seen in 6 patients and grade 2 in 2 SRT group patients. Postoperatively globe retraction reduced in 2 patients and remained unchanged in 6. In the MRc group, 4 patients had significant lid fissure narrowing (grade 2 or more) preoperatively; the rest had grade 1 globe retraction. Postoperatively lid fissure changes remained unchanged in 5 patients but reduced in the
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FIG 3. A mean plot showing the reduction in the abduction deficit in the SRT group as compared to that in the MRc group.
affected eye. Although this procedure achieved orthotropia in primary position, there was a large exotropia in adduction. This particular patient had very severe globe retraction (grade 4) at presentation.
Discussion
FIG 2. A, Arrow plot showing change in primary position esotropia among the patients in the SRT group (patients 7 and 8 underwent SRT alone). B, Arrow plot showing change in primary position esotropia among patients in the MRc gorup. The vertical dashed line marks the upper limit of success criteria (8D of esotropia).
remaining. None of the patients in either group had significant overshoot preoperatively. One patient in the SRT group and 2 in the MRc group had minimal (grade 1) overshoot, which did not change following either surgery. None of the patients who underwent SRT complained of torsional diplopia. Postoperatively indirect ophthalmoscopy was performed in 6 of 8 patients in SRT group; none showed any objective torsion. Postoperative limitation of adduction (range, 0.5 to 3) was observed in 3 of 8 patients (37.5%) in the SRT group and 3 of 13 (23%) in the MRc group. The adduction limitation in the SRT group was 0.5, 0.5, and 2 in the 3 patients. The adduction limitation in the 3 patients in the MRc group was 0.5, 1, and 3. The patient who developed a limitation of 3 had undergone 6 mm of MRc in the
The goal of surgery in patients with Duane syndrome is to reduce or eliminate anomalous head posture, achieve good alignment in primary position, and increase the range of binocular single vision. Results of surgery in Duane syndrome may sometimes be unsatisfactory because of complex mechanisms involving innervational abnormalities, co-contraction, and muscle contracture. Classically, medial rectus recession has been described, which improves alignment and head posture in majority of patients.6-8 However MRc alone may lead to only a small improvement in abduction and there may be risk of postoperative adduction limitation21 and/or decrease in convergence, especially when large recessions are performed bilaterally. Vertical rectus transposition to the lateral rectus muscle for improvement of abduction in Duane syndrome patients has been studied by various authors.15-17 Foster22 suggested that vertical rectus transposition alone may achieve good results when augmented with posterior fixation sutures. However, subsequent MRc or botulinum toxin injection may be required in some patients, especially when the medial rectus muscle is found to be tight during intraoperative forced duction testing.17 The average amount of improvement in abduction limitation after transposition procedure as reported in various studies is shown in Table 2. The present study showed that SRT with or without MRc was similar to MRc alone in terms of correction of abnormal head posture and alignment. Recently Yang
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FIG 4. A, Pre- (above) and postoperative (below) clinical photographs of a patient who underwent SRT with ipsilateral medial rectus recession. B, Pre- (above) and postoperative (below) clinical photographs of a patient who underwent bilateral asymmetrical MRc.
and collegues14 reported similar results in comparing SRT with or without MRc and unilateral or bilateral MRc. The surgical technique followed by these authors differed from ours. They performed adjustable medial rectus recession, whereas we prefer fixed sutures. They observed torsional changes in 1 patient where a scleral pass had been taken for augmentation of SRT. We used scleral pass in all our patients; however, none of our patients reported torsional diplopia. The results of the present study are also comparable to those of Mehendale and colleagues,20 where 10 patients with esotropic Duane syndrome and 7 with lateral rectus palsy were treated with SRT with or without augmentation and MRc. None of the patients with Duane syndrome in their study developed vertical deviation, but 2 with chronic lateral rectus palsy did develop hypotropia (mean, 10D). Also 1 patient had subjective torsion following SRT for either Duane syndrome or lateral rectus palsy. New vertical deviation or limitation of elevation was not seen in any of our patients, and none complained of torsional diplopia. In the current study, augmented transposition of the superior rectus muscle improved abduction in 87.5% patients with esotropic Duane syndrome. The degree of improvement in abduction was comparable to that achieved with both vertical rectus transposition and SRT as seen in related studies (Table 2). Compared to vertical rectus transpostion, SRT is unlikely to increase the risk of ante-
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rior segment ischemia. However, most patients undergoing SRT also required ipsilateral MRc to achieve good alignment. Based on our experience in the initial 4-5 cases, we found that SRT alone was effective in correcting up to 15D of esotropia. Beyond this, additional MRc was necessary. It should be borne in mind that the response to surgery in Duane syndrome also depends on tightness of the medial rectus muscle, the amount of misinnervation of the lateral rectus muscle, and patient age. In our study, bilateral surgery (medial rectus recessions) was required in patients with .25D of esotropia. Addition of SRT to ipsilateral MRc obviated the need for contralateral eye surgery and was effective in correcting up to 45D of esotropia with unilateral surgery. Similar to our study, previous studies report around 28% to 30% of improvement in abduction in patients undergoing unilateral or bilateral medial rectus recessions.12-14 Barbe and colleauges8 documented improved abduction (range, 0.5-2 units) in 69% of cases with unilateral Duane syndrome undergoing unilateral or bilateral MRc. However, an equal number of patients in their study developed an adduction limitation of 1-3 units. The average MRc/eye performed in their patients was 5.8 mm, with 16 of 22 patients undergoing $6 mm of recession in the affected eye. Pressman and colleagues6 reported similar results. Thus increasing the amount of MRc may improve abduction further, but at the cost of decreased adduction.
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Table 2. Improvement in abduction following vertical rectus transposition as reported in various studies Mean abduction limitation Study Molarte 199015 Foster 199722 Velez 200117 Velez 200117 Britt 200323
Sterk 200424 Britt 200516 Yazdian 201025 Mehendale 201220 Yang 201414
Present study
Type of VRT
N
Pre-op
Post-op
Non augmented VRT Augmented VRT Augmented VRT Nonaugmented VRT Augmented partial VRT following prior nontransposition surgery Nonaugmented VRT with MRc VRT augmentation in bilateral Duane syndrome Augmented VRT Augmented SRT with MRc Augmented SRT MRc
13 5 32 22 5
3.8 4 3.9 0.2 3.7 0.4 3.8
2.3 3.4 2.9 0.6 2.7 0.7 3.1
36
4.7 8.2 dega
20.6 8.6 dega
11
3.75
2.68
Augmented SRT 1 MRc SRT alone
38 10 19
6 2
4.00 0.23 4 —
2.11 0.48 2 —
3.66 3.5
2.58 2
Average improvement in abduction, units 1.5 0.6 1 1 0.7
15.9 8.1 dega 1 1.89 2 79% of patients showed $1 unit improvement in abductionb 1.08 1.5
MRc, medial rectus recession; SRT, superior rectus transposition; VRT, vertical rectus transposition. a Abduction measured in degrees on the arms of synaptophore. b Abduction improvement as percentage of patients showing improvement of $1 unit.
There is an increased chance of developing postoperative adduction limitation with SRT, as occurred in 37% of patients in our SRT group (95% CI, 3.5%-70.5%), compared to 23% in the MRc group (95% CI, 0.12%45.88%). It has also been suggested that patients with exotropia in adduction may be predisposed to develop consecutive exotropia after transposition surgery in Duane syndrome.26 The above observation of adduction limitation in the initial 3 cases made us reduce the MRc dosage in patients undergoing SRT. Hence we suggest that the maximum recession of the ipsilateral medial rectus muscle should be limited to 5–5.5 mm in combination with SRT. The present study is limited by its retrospective design. Although the groups were comparable in terms of preoperative deviation, head posture, and abduction limitation, certain parameters that could have been important pertaining to surgical success (eg, forced duction testing, alignment in lateral gazes) were not compared between groups. Multiple surgeons were involved in the MRc group; a single surgeon, in the SRT group. Binocular visual fields were not compared in most patients. In view of the fact that a higher number of patients had a postoperative adduction limitation in the SRT group versus the MRc group, we cannot conclude from our data whether a greater improvement in abduction led to improvement in binocular visual fields. Finally, pre- and postoperative torsion was not measured in all patients. Despite these limitations, the current study suggests that, although both SRT MRc and MRc alone are comparable in terms of improvement in primary position devi-
ation and abnormal head posture, the former leads to greater improvement in abduction. References 1. Huber A. Electrophysiology of the retraction syndromes. Br J Ophthalmol 1974;58:293-300. 2. O’Malley ER, Helveston EM, Ellis FD. Duane’s retraction syndrome—plus. J Pediatr Ophthalmol Strabismus 1982;19:161-5. 3. Raab EL. Clinical features of Duane’s syndrome. J Pediatr Ophthalmol Strabismus 1986;23:64-8. 4. Ro A, Gummeson B, Orton RB, Cadera W. Duane’s retraction syndrome: southwestern Ontario experience. Can J Ophthalmol 1989; 24:200-203. 5. Kekunnaya R, Gupta A, Sachdeva V, et al. Duane retraction syndrome: series of 441 cases. J Pediatr Ophthalmol Strabismus 2012; 49:164-9. 6. Pressman SH, Scott WE. Surgical treatment of Duane’s syndrome. Ophthalmology 1986;93:29-38. 7. Kraft SP. A surgical approach for Duane syndrome. J Pediatr Ophthalmol Strabismus 1988;25:119-30. 8. Barbe ME, Scott WE, Kutschke PJ. A simplified approach to the treatment of Duane’s syndrome. Br J Ophthalmol 2004;88:131-8. 9. Kubota N, Takahasi H, Hayashi T, Sakaue T, Maruo T. Outcome of surgery in 124 cases of Duane’s retraction syndrome (DRS) treated by intraoperatively graduated recession of the medial rectus for esotropic DRS, and of the lateral rectus for exotropic DRS. Binocul Vis Strabismus Q 2001;16:15-22. 10. Farvardin M, Rad AH, Ashrafzadeh A. Results of bilateral medial rectus muscle recession in unilateral esotropic Duane syndrome. J AAPOS 2009;13:339-42. 11. Dotan G, Klein A, Ela-Dalman N, Shulman S, Stolovitch C. The efficacy of asymmetric bilateral medial rectus muscle recession surgery in unilateral, esotropic, type 1 Duane syndrome. J AAPOS 2012;16: 543-7.
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Volume 19 Number 3 / June 2015 12. Kaban TJ, Smith K, Day C, Orton R, Kraft S, Cadera W. Single medial rectus recession in unilateral Duane syndrome type I. Am Orthoptic J 1995;45:108-14. 13. Merino P, Merino M, G omez De Lia~ no P, Blanco N. Horizontal rectus surgery in Duane syndrome. Eur J Ophthalmol 2011;22:125-30. 14. Yang S, MacKinnon S, Dagi LR, Hunter DG. Superior rectus transposition vs medial rectus recession for treatment of esotropic Duane syndrome. JAMA Ophthalmol 2014;132:669-75. 15. Molarte AB, Rosenbaum AL. Vertical rectus muscle transposition surgery for Duane’s syndrome. J Pediatr Ophthalmol Strabismus 1986;27:171-7. 16. Britt MT, Velez FG, Velez G, Rosenbaum AL. Vertical rectus muscle transposition for bilateral Duane syndrome. J AAPOS 2005;9:416-21. 17. Velez FG, Foster RS, Rosenbaum AL. Vertical rectus muscle augmented transposition in Duane syndrome. J AAPOS 2001;5: 105-13. 18. Ruth AL, Velez FG, Rosenbaum AL. Management of vertical deviations after vertical rectus transposition surgery. J AAPOS 2009;13: 16-19. 19. Murdock TJ, Kushner BJ. Anterior segment ischemia after surgery on 2 vertical rectus muscles augmented with lateral fixation sutures. J AAPOS 2001;5:323-4.
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20. Mehendale RA, Dagi LR, Wu C, Ledoux D, Johnston S, Hunter DG. Superior rectus transposition and medial rectus recession for Duane syndrome and sixth nerve palsy. Arch Ophthalmol 2012;130:195-201. 21. Shiratori A, Kameyama C, Sibasaki K. Adduction deficiency following a large medial rectus recession in Duane’s retraction syndrome type 1. J Pediatr Ophthalmol Strabismus 1999;36:98-100. 22. Foster RS. Vertical muscle transposition augmented with lateral fixation. J AAPOS 1997;1:20. 23. Britt M, Velez F, Thacker N, Alcorn D, Foster RS, Rosenbaum AL. Partial rectus muscle augmented transpositions in abduction deficiencies. J AAPOS 2003;7:325-32. 24. Sterk CC, van Hulst-Ginjaar SP, Swart-van den Berg M. Improvement of horizontal excursion and abduction by vertical muscle transposition in patients with Duane’s retraction syndrome type I. J Pediatr Ophthalmol Strabismus 2004;41:204-8. 25. Yazdian Z, Rajabi MT, Ali Yazdian M, Rajabi MB, Akbari MR. Vertical rectus muscle transposition for correcting abduction deficiency in Duane’s syndrome type 1 and sixth nerve palsy. J Pediatr Ophthalmol Strabismus 2010;47:96-100. 26. Velez FG, Laursen JK, Pineles SL. Risk factors for consecutive exotropia after vertical rectus transposition for esotropic Duane retraction syndrome. J AAPOS 2011;15:326-30.
