Evaluation of superior oblique weakening procedures

Asymmetric superior oblique split Z-tendon lengthening for face turn in bilateral asymmetric superior oblique overaction and exotropia

INTRODUCTION

The aim was to evaluate the effectiveness of the procedure of the superior oblique split Z-tendon lengthening to collapse A pattern and treat face turn in a cohort of patients with both incomitant intermittent exotropia and a vertical deviation associated with a bilateral asymmetric superior oblique overaction.

METHODS

We retrospectively reviewed the clinical records of patients with facial turn associated with intermittent exotropia and bilateral asymmetric superior oblique overaction, who underwent superior oblique muscle split tendon lengthening and concurrent horizontal surgery between 2009 and 2017.

RESULTS

A total of eight patients met the inclusion criteria. The preoperative average face turn was 26.8° (range, 20°-5°), and it significantly improved to 5.4° (range, 2°-8°) (p < 0.05). All the patients showed an improvement in the face turn with neutralization of the vertical deviation. The vertical deviation in the right gaze for the patient with a right turn and the left gaze in patients with left turn improved significantly (values of p < 0.05).

CONCLUSION

The superior oblique split Z-tendon lengthening was an effective procedure to collapse the A pattern and the treatment of the face turn in a cohort of patients with both incomitant intermittent exotropia and a vertical deviation associated with a bilateral asymmetric superior oblique muscle overaction with less complications, and less varying results.

Effects of Bilateral Superior Oblique "Hang-Back" Recession in Treatment of A-pattern Strabismus with Superior Oblique Overaction

PURPOSE

To investigate the efficacy and safety of bilateral hang-back recession of superior oblique (SO) muscles in the treatment of A-pattern strabismus with superior oblique overaction (SOOA).

METHODS

Thirty-one (31) patients (62 eyes) with A-pattern horizontal deviation and SOOA underwent hang-back recession of SO and retrospective analysis of the surgical amount of hang-back recession of SO, preoperative and postoperative A-pattern, ocular motility, and corrected objective torsion. Patients were evaluated before and 6 to 9 months after surgery.

RESULTS

The average A-pattern horizontal deviation was 27.58 ± 11.47 prism diopters (PD) before surgery and 3.48 ± 3.70 PD after surgery (n=31, P<0.05). The mean corrected A-pattern was horizontal deviation 24.10 ± 10.32 PD. The average scale of SOOA on a scale of +1 to +4 was +3.05 ± 0.80 before surgery and +0.42 ± 0.50 after surgery in 62 eyes (P<0.05). The mean corrected objective torsion was 4.91° ± 4.53°. The surgical amount of SO hang-back recession ranged from 4 to 10 mm (mean: 7.62 ± 1.18 mm), which was related to the preoperative A-pattern and corrected A-pattern. There were no surgical complications.

CONCLUSIONS

SO hang-back recession is a safe and efficient option for A-pattern caused by SOOA.

Bilateral posterior tenectomy of the superior oblique muscle for the treatment of A-pattern strabismus

PURPOSE

To evaluate the efficacy of bilateral posterior superior oblique tenectomy for the treatment of A-pattern strabismus due to superior oblique overaction regardless of the magnitude of the pattern.

METHODS

The medical records of patients with A-pattern esotropia or exotropia in the presence of superior oblique overaction who underwent combined horizontal muscle surgery along with bilateral superior oblique posterior 7/8 tenectomy from 2003 to 2013 were retrospectively reviewed. Patients with at least 3 months' follow-up were included.

RESULTS

A total of 73 patients were included. Of these, 46 had esotropia; 27, exotropia. The preoperative A-pattern deviation for the study population was 19.6(Δ) ± 11.4(Δ) (range, 10-60), with a final postoperative patten collapse of 18.2 ± 3.6. Superior oblique overaction was 2.3 ± 0.7 preoperatively and 0.3 ± 0.7 postoperatively. Overall, 87.7% of patients had a successful collapse of their pattern to <10(Δ) following the initial bilateral superior oblique posterior tenectomy, with an additional 4.1% following a second procedure. Of patients with a pattern deviation of <25(Δ), 87.9% had successful collapse of the pattern following 1 surgery, and 86.7% of patients who had a pattern of ≥25(Δ) had successful collapse. Postoperatively, 7 patients demonstrated mild inferior oblique overaction. No surgical complications were noted.

CONCLUSIONS

A uniform dose of bilateral posterior 7/8 tenectomy surgery successfully collapses A-pattern deviations of all magnitudes.

Effect of 10-mm superior oblique posterior tenectomy combined with frenulum dissection in A-pattern with superior oblique overaction

PURPOSE

To evaluate the effect of 10-mm tenectomy of the posterior fibers of the superior oblique (SO) tendon combined with dissection of the frenulum for correction of A-pattern deviation and vertical deviation with SO overaction.

DESIGN

Retrospective, interventional case series.

METHODS

Seventy-five patients with A-pattern strabismus associated with SO overaction who underwent surgery between March 1, 2004 and August 31, 2007. Retrospective analysis of A-pattern strabismus patients with SO overaction who underwent unilateral or bilateral 10-mm SO posterior tenectomy combined with frenulum dissection and who underwent at least 12 months of follow-up.

RESULTS

The mean preoperative amount of A-pattern for all patients was 21.20 +/- 7.25 prism diopters (PD), with a mean postoperative collapse of 17.63 +/- 5.33 PD (range, 10 to 30 PD), which was statistically significant (P = .001). After surgery, the mean A-pattern correction was 22.12 +/- 6.30 PD in the group that underwent bilateral posterior tenectomy and 13.33 +/- 5.20 PD in the group that underwent unilateral posterior tenectomy. The mean degree of preoperative vertical deviation in the group that underwent unilateral posterior tenectomy was 11.50 +/- 3.96 PD, and the mean correction was 9.21 +/- 4.22 PD (P = .01). There were no surgical complications, except in 5 patients, who manifested mild inferior oblique overaction.

CONCLUSIONS

We believe that 10-mm SO posterior tenectomy combined with frenulum dissection effectively collapses A-pattern deviation of less than 25 PD with mild to moderate SO overaction and reduces associated vertical deviation of 10 PD.

Z-tenotomy of the superior oblique tendon and horizontal rectus muscle surgery for A-pattern horizontal strabismus

PURPOSE

Few studies have investigated combined surgeries for horizontal deviation and A pattern caused by superior oblique overaction (SOOA). This study presents our experience with combined surgery and examines the effect of the type of strabismus and prior surgery on outcome.

METHODS

The medical records of patients who underwent combined surgery for horizontal deviation occurring with A-pattern misalignment from 2000 through 2004 were reviewed. The procedure consisted of horizontal extraocular muscle recession or resection with superior oblique Z-tenotomy. The criteria for surgical success were horizontal deviation at primary gaze of </=10(Delta), A pattern of </=8(Delta), and SOOA of </=1.0.

RESULTS

The study group included 28 patients with a mean age of 13.4 years. Thirteen (46.4%) had A-pattern esotropia; 15 (53.6%) had A-pattern exotropia. Fifteen (50%) had undergone previous surgery. The success rate for the whole group was 60.7%. There was no statistically significant difference in success rate between patients with esotropia (53.8%) or exotropia (66.7%) (p = 0.48) or between patients in whom the combined procedure was the primary (71.4%) or secondary (50.0%) treatment (p = 0.246). Measurements of horizontal strabismus remained stable throughout follow-up in the esotropia group but were unpredictable in the exotropia group.

CONCLUSIONS

The success rate of combined horizontal deviation/A-pattern surgery is unaffected by type of horizontal deviation or prior surgery.

Super oblique tendon elongation with fascia lata

PURPOSE

Superior oblique lengthening with a silicone retinal band is used to treat superior oblique overaction (SOOA); however, secondary infection, implant extrusion, orbital cellulitis, and adhesion may occur. We present a method of superior oblique tendon elongation in which autogenous fascia lata is used to decrease the likelihood of these complications.

METHODS

Six patients (5 female, 1 male) aged 7-22 years (mean, 17 years) with 40-85(Delta) exotropia and SOOA (range, +2 to +4; mean, +3.5) underwent bilateral superior oblique lengthening with insertion of fascia lata. In the last 2 cases, the values of elongation were augmented by 2 mm. Fascia lata was harvested through a linear incision on the lateral aspect of the patient's thigh.

RESULTS

Postoperatively, correction of A-pattern exotropia to within 10(Delta) was achieved in 66% of the cases as well as correction of SOOA to within +1 in 58% of the cases, with a follow-up of 9 months. All patients with +2 to +3 SOOA (3 cases) were fully corrected, whereas those with +4 SOOA (9 eyes) had residual overaction of +1 to +3. In the 4 eyes with augmented elongation, residual SOOA was between 0 and +2. No patient developed superior oblique palsy.

CONCLUSIONS

Autogenous fascia lata may be used as an alternative to a silicone band for superior oblique lengthening. Our results were comparable with published results for the silicone band, with a lower rate of overcorrection. The improved biocompatibility makes it likely that autogenous fascia lata will have a lower complication rate than with a silicone band.

Effect of posterior tenectomy of the superior oblique on objective and subjective torsion in cases of superior oblique overaction

PURPOSE

To evaluate the effect of posterior tenectomy of the superior oblique on the correction of A-pattern, superior oblique overaction and the changes in torsion that occur in such cases.

PATIENTS AND METHODS

This prospective study included 15 consecutive cases of bilateral superior oblique overaction with an A-pattern of more than 20 PD, a difference of deviation between 25 degrees up-gaze and 35 degrees downgaze, and superior oblique overaction of 2+ to 3+ on a scale of 0 to 4+. Deviation was measured in the primary position, 25 degrees upgaze, and 35 degrees downgaze using the prism bar cover test, and torsion was measured using a synoptophore, the double Maddox rod test, and fundus photographs. Measurements were obtained preoperatively and postoperatively at 1 week, 1 month, and 3 months. All case-patients underwent a standard temporal route posterior tenectomy of the superior oblique by a single surgeon.

RESULTS

Mean age was 11.2 +/- 4.2 years with 14 cases of A-pattern exotropia. Mean superior oblique overaction was 2.60 +/- 0.50 in the right eye and 2.26 +/- 0.45 in the left eye, which decreased postoperatively to 2.20 +/- 0.56 and 1.80 +/- 0.41, respectively. The index of surgical effect was 0.84 in the right eye and 0.79 in the left eye. Postoperatively, mean correction of the A-pattern was 17.53 +/- 5.82 PD (index of surgical effect, 0.7). Subjective measurement of torsion was more consistent with the synoptophore compared with the double Maddox rod test. Objective measurement of torsion (fundus photography) was higher compared with subjective measurement. Postoperatively, there was insignificant change in the amount of torsion in upgaze and primary position.

CONCLUSION

Posterior tenectomy of the superior oblique results in significant and controlled weakening of the superior oblique and collapse of the A-pattern with a clinically insignificant change in the amount of torsion.