Reduction of ocular muscle power by splitting of the rectus muscle I: biomechanics

Inferior Rectus Muscle Y-Split for Thyroid-Related Vertical Strabismus

Incomitant hypotropia in thyroid eye disease can be difficult to manage, especially in the presence of orthotropia with fusion in down gaze and reading position. Recessing the affected ipsilateral inferior rectus muscle may result in an undesirable downgaze diplopia secondary to a hypertropia in downgaze. Various surgical techniques have been described to manage this potential complication including asymmetric recession of both inferior rectus muscles, posterior myoscleropexy operation, and the Scott recess/resect procedure of the contralateral inferior rectus. In 2004, Hoerantner et al. introduced the y-split recession of the medial rectus muscle for near esotropic deviations. The anterior portion of muscle is split and secured in a y-shaped configuration, which reduces the muscle lever arm and helps minimize incomitance and muscle slippage. Unlike the traditional Cüppers Faden, a y-split recession results in torque reduction in all gaze positions. In addition, a y-split recession does not involve scleral passes posteriorly reducing the risk of globe perforation. We report a patient with incomitant strabismus secondary to thyroid eye disease who underwent a combination of traditional recession and y-splitting recession of the contralateral inferior rectus muscle, resulting in good functional alignment in primary gaze and in the reading position.

Inferior rectus muscle Y splitting procedure for near-distance hypotropia disparity: an alternative to the Faden procedure

A young male patient with unilateral pathological myopia complained of selective hypotropia for distance with exophoria. Due to large globe, a notable amount of inferior scleral show was evident. In this scenario, extensive dissection along inferior rectus muscle to perform a Faden procedure would have worsened the inferior scleral show. Thus, as an alternative, the anterior procedure, that is, "inferior rectus muscle Y-splitting procedure with 4-mm recession" was undertaken. At the end of 3 months follow up, the troublesome selective hypotropia for distance disappeared significantly with very little changes along the lower lid position. Therefore, in presence of specific anatomical limitations, the inferior rectus muscle Y splitting procedure can be considered in lieu of Faden procedure for near-distance hypotropia disparity.

Modified Y- split and recession of medial rectus muscles in convergence excess esotropia

PURPOSE

The convergence excess esotropia (CEET) is defined when near esotropia is greater than the distance by at least 10 PD while the eye is corrected with the full cycloplegic refraction. The purpose of this study is to evaluate the effect of a modified technique of Y- split recession of the medial rectus muscles on CEET.

METHODS

This was a retrospective study on patients diagnosed with CEET. The surgery included longitudinally dividing the medial rectus muscles into two equal halves and re-attaching them in a recessed and one-tendon width apart position. Success was defined as a residual distance and near esotropia of less than 10 PD and a distance-near disparity of less than 5 PD.

RESULTS

Fourteen patients, including 8 (57.1%) females, were enrolled with a mean age of 7.1 ± 2.9 years. The mean follow-up period was 28.6 ± 12.1 months. The mean preoperative distance and near esotropia was 31 ± 10 and 45 ± 11.3 PD respectively that decreased to 2.4 ± 3 and 3.6 ± 3.8 PD at the final visit (p < 0.001). The Mean distance-near disparity of esotropia was 14 ± 4.5 PD before the operation that decreased to 1.3 ± 1.8 PD at the final visit (p < 0.001). The motor success rate was 78.6%, bifocal glasses were no more required in 92.9% of patients, and stereopsis improved in 35.7% of patients after the surgery.

CONCLUSION

Bilateral modified Y- split and recession of the medial rectus muscle is an effective technique for the treatment of CEET with persistent outcomes in the long-term follow-up.

Different Surgical Approaches for Treatment of Dissociated Vertical Deviation (DVD)

Introduction

DVD is a rare, poorly understood eye motility disorder of unknown etiology. In socially unacceptable deviation, surgical treatment is an option. We present patients operated with three different surgical methods.

Aim

To evaluate and compare different surgical approaches for treatment of dissociated vertical deviation (DVD).

Methods

Total amount of 20 patients with DVD of ≥ 20 PD are operated with three different techniques on superior rectus (SR) muscle: Group I with preoperative angle of 20-30 PD was operated with 8 mm recession of SR, Group II with preoperative angle of ≥ 30 PD undergo 3 mm recession with posterior fixation on SR and Group III with preoperative angle of ≥ 30 PD undergo-splitting of SR muscle. Surgeries for associated horizontal deviations were performed before surgery for DVD. Follow up was three years.

Results

In all cases amount of DVD deviation was significantly reduced. No binocularity was gained. Although hyperdeviation of affected eye was reduced in all patients, we didn't eliminate deviation completely. Despite smaller preoperative angle, residual angle was bigger (6-12 PD) in the patients in group I where only recession of SR was performed, compared to Group II and III where postoperative angle was 4-8 PD in both groups.

Conclusion

There are no recommended guidelines for the surgical treatment of DVD and treatment is based more on the surgeon's experience than evidence based data. In our experience recession of the SR should be method of choice in the cases of smaller deviation. SR recession combined with posterior fixation suture and Y-splitting seems to be a safe and effective method for surgical treatment of unilateral DVD with bigger deviation angles. Y splitting with less surgical complications and increasing effect with time can be a good alternative to posterior fixation surgery.

Adhesion after Y-split procedure can affect its mechanism for treating overshoots in Duane's syndrome

PURPOSE

To investigate the extent of adhesion and changes in the Y configuration after the Y-split procedure, compared with the posterior fixation suture.

METHODS

Twelve New Zealand white rabbits were included in the study. The 10-mm Y-split procedure was performed in the superior rectus muscle (SR) of one eye, and the 10-mm posterior fixation suture was made in the SR of the other eye. Six weeks after surgery, the Y arm lengths and lengths of adherence to the sclera were measured. If the adhesion involved the whole Y arm, the distance between the original SR insertion and most proximal part of the adhered SR was measured. In the eyes with posterior fixation suture, the distance between the SR insertion and most proximal part of the adhered SR was evaluated.

RESULTS

The average nasal and temporal Y arm lengths were 6.37 ± 0.65 and 6.54 ± 0.63 mm, respectively, a significant decrease from those measured immediately after surgery (P = 0.002 and 0.002, respectively). Adhesions involved the entire Y arms in 11 of 12 SRs (91.7%), with an average adhesion length of 7.01 ± 1.04 mm. In SRs with posterior fixation sutures, the average adhesion was 9.18 ± 0.62 mm from the insertion, which was only 2.17 mm posterior to proximal portion of adhesion in Y-split SR (P < 0.001).

CONCLUSIONS

Healing process reduces the Y arm length. Adhesion may involve the entire Y arm and could weaken or alter the therapeutic mechanism after the Y-split procedure.

Comparative Study of Y-Split Recession versus Faden Technique for Management of Infantile Esotropia in Egyptians

Purpose

This study compares the results of Y-split recession versus de Decker's (modified Cüppers) Faden techniques of medial rectus (MR) muscles for the management of essential infantile esotropia (IET).

Patients and Methods

Fifty patients had IET divided into Group A who underwent Y-split recession of MR muscles and Group B who underwent de Decker's Faden technique of MR muscles. All patients had complete ophthalmic examination done including deviation angle measurement and met the inclusion criteria of the study. Operations were performed using general anesthesia. Patients were followed up at day 1, week 1, and months 1, 3, and 6 after operation.

Results

The mean age distribution for group A was 21.56 months (SD 12.55) and for group B was 21.4 months (SD 12.35), and the mean postoperative follow-up interval was 6 months for both groups. The preoperative maximum angle of deviation in both groups ranged from 15 to 40 degrees, while the minimum angle of deviation ranged from 10 to 20 degrees. Immediately postoperatively both groups showed 88% of patients with satisfactory results (within 10 degrees of orthotropia). Group A showed two patients (8%) with ET and one patient (4%) with exotropia (XT). For group B, it showed one patient (4%) with ET and two patients (8%) with XT. Three patients in each group underwent a second intervention. All patients remained within the satisfactory range.

Conclusion

The results of this study suggest that both techniques show comparable results for the correction of IET.

Y-splitting with recession of lateral rectus versus lateral rectus recession in correcting upshoot in Duane retraction syndrome

PURPOSE:

To report the surgical effect in upshoot of Duane retraction syndrome (DRS) with corecession of horizontal rectus muscles with or without Y-splitting.

PATIENTS AND METHODS:

A retrospective chart review of six patients of DRS received muscle surgeries for upshoot in adducted position was performed.

RESULTS:

From 1994 to 2010, six Duane patients received muscle surgeries for upshoots of lesion eye in adduction. Their age of receiving surgery ranged from 5 to 41 years. Four of the patients were male, and five had their left eye involved. Three underwent recession of ipsilateral medial and lateral rectus (LR) muscles, and the other three also received Y-splitting of LR muscle when recession. One of the patients that received Y-splitting showed mild hypertropia at down gaze postoperatively, and another one had little improvement of exotropia at the primary position. All patients showed improvement of their upshoots and lid fissure narrowing in adduction as well as face turn.

CONCLUSION:

Postoperative improvements in abnormal head posture and upshoots were achieved with corecession of horizontal muscles with or without Y-splitting. Although Y-splitting of the LR muscle is an effective surgery, it might cause undesired complications.

Y-Split Recession of the Medial Rectus Muscle as a Secondary and/or Unilateral Procedure in the Treatment of Esotropia with Distance/Near Disparity

Introduction

In esotropia with larger angles > near than at distance, splitting of the medial rectus muscle has been suggested as a treatment option. Previous reports of bilateral medial rectus Y-splitting as a first intervention showed a reduction of the distance/near disparity with fewer side effects compared to posterior fixation surgery. We address whether a medial rectus Y-splitting as a secondary and/or a unilateral procedure also reduce distance/near disparity.

Materials and Methods

We retrospectively reviewed the charts of four patients undergoing Y-split recession as a second and/or unilateral surgery. Main outcomes were distance/near disparity and squint angles.

Results and Discussion

Three of the four patients had undergone unilateral Y-splitting of the medial rectus as a secondary surgery, three as a unilateral procedure. Mean distance/near disparity was reduced from 17 PD preoperatively to zero at the final follow-up (FU). Preoperative angles ranged from 45 PD to 66 PD at near and from 25 PD to 55 PD at distance. At the final FU, these angles ranged from 0 PD to 20 PD at near and at distance. Mean FU was 42 months (range: 12–60 months).

Conclusion

Y-split recession as a secondary and/or unilateral surgery for distance/near esotropia can reduce distance/near disparity with good long-term results. Residual esotropia can be corrected by adding resection of the lateral rectus muscle.

[Conservative and surgical treatment of convergence excess]

Convergence excess is a common finding especially in pediatric strabismus. A detailed diagnostic approach has to start after full correction of any hyperopia measured in cycloplegia. It includes measurements of manifest and latent deviation at near and distance fixation, near deviation after relaxation of accommodation with addition of +3 dpt, assessment of binocular function with and without +3 dpt as well as the accommodation range. This diagnostic approach is important for the classification into three types of convergence excess, which require different therapeutic approaches: 1) hypo-accommodative convergence excess is treated with permanent bifocal glasses, 2) norm-accommodative patients should be treated with bifocals which can be weaned over years, especially in patients with good stereopsis and 3) non-accommodative convergence excess and patients with large distance deviations need a surgical approach. The most effective operations include those which reduce the muscle torque, e. g. bimedial Faden operations or Y‑splitting of the medial rectus muscles.

Y-Split Recession vs Isolated Recession of the Lateral Rectus Muscle in the Treatment of Vertical Shooting in Exotropic Duane Retraction Syndrome

Purpose

To compare the results of 2 surgical procedures in the management of vertical shooting in exotropic Duane retraction syndrome (XT-DRS).

Methods

This was a prospective, interventional study of consecutive patients with XT-DRS with vertical shooting on adduction operated on from August 2012 to January 2015. A total of 25 patients were identified and were divided into 2 groups: the Y-split (Y) group, which included 12 patients, who underwent Y-splitting with recession of the lateral rectus muscle (LR); and the isolated recession (R) group, which included 13 patients, who underwent isolated LR recession. Surgical outcomes in both groups were compared in terms of improvements in vertical shoots, ocular deviation, and face turn.

Results

Upshoot, downshoot, XT, and face turn showed significant postoperative improvement in both groups (p<0.001). When comparing the groups, the difference in the average correction of the upshoot and downshoot was statistically significant ( p = 0.0004 and 0.0174, respectively) in benefit of the Y-group. One case of horizontal overcorrection (consecutive esotropia) with another case of horizontal undercorrection (persistent XT) were reported postoperatively in the Y-group.

Conclusions

In our series, both procedures achieved comparable results in the correction of XT and face turn. The combined Y-split recession procedure attained a more significant improvement of upshoot and downshoot but with higher incidence of postoperative complications.

Comparative study of Y-split recession versus bilateral medial rectus recession for surgical management of infantile esotropia

Aim

This prospective study compares the results of bilateral medial rectus recession versus (vs) Y-split recession of medial recti techniques for surgical management of essential infantile esotropia.

Patients and methods

Thirty patients were included in this study and had preoperative infantile esotropia with large angles (ie, >30 prism diopters [PD]). Patients were divided into Group A, which underwent bilateral medial rectus (BMR) recession and Group B, which underwent bilateral Y-split recession of medial recti muscles. All patients were subjected to complete ophthalmologic examination and met the criteria for inclusion in this study. The degrees of BMR recessions performed ranged from 6.0–7.5 mm. All operations were performed under general anesthesia. Follow-up visits were conducted at 1 and 2 weeks, and 1, 3, and 6 months postoperatively. Rates of reoperation for residual esotropia and consecutive exotropia were determined.

Results

The patients’ preoperative angles of deviation ranged from 30–80 PD. Group A consumed 57% less operative time than Group B. Immediately postoperatively, the Y-splitting technique showed satisfactory results (ie, orthotropic or residual angles ≤15 PD) in 73% of patients vs 67% only for the BMR recession patients. By the end of six months of follow up; 13% of the BMR technique patients vs 27% of the Y-splitting technique patients showed negative change of PD but without reoperation.

Conclusion

Our results suggest that, although the Y-splitting technique is more difficult and time consuming, both procedures are effective and have shown comparable results for the correction of horizontal deviation ≤70 PD.

Isolated lateral rectus recession with Y splitting versus anchoring of the lateral rectus muscle in patients with exotropic Duane syndrome

PURPOSE

To compare the outcome of two surgical procedures used to treat up- and downshoots in Duane retraction syndrome associated with exotropia.

METHODS

The medical records of patients with exotropic Duane retraction syndrome seen at a single tertiary care facility from 2009 to 2012 were retrospectively reviewed. Patients were divided into two groups, one comprising patients treated with Y splitting and recession of the lateral rectus muscle; the other, patients treated with anchoring of the lateral rectus muscle to the lateral palpebral ligament. Surgical outcomes were compared in terms of deviation, head turn, up- and downshoot, and duration of surgery.

RESULTS

A total of 15 patients were included, 7 treated by Y splitting and recession and 8 by anchoring of the lateral rectus muscle. Both groups were comparable in terms of age, sex, laterality, best-corrected visual acuity, mean deviation in primary position, and preoperative head turn to the affected side. Torticollis decreased from 27.9° ± 6.4° to 2.6° ± 4.4° in the Y-split group and from 22.5° ± 5.9° to 1.6° ± 3.1° in the anchoring group (P < 0.001 [95% CI]). Exotropia decreased from 26.4(Δ) ± 5.6(Δ) to 2.28(Δ) ± 4.07(Δ) in the Y-split group and 26.9(Δ) ± 5.3(Δ) to 1.5(Δ) ± 6.88(Δ) in the anchoring group (P < 0.001 [95% CI]). The up- and downshoots decreased markedly in the both groups (P = 0.7 for upshoots and P = 1 for downshoots). The mean operating time was 15.3 ± 2.0 minutes for Y splitting plus recession and was 8.3 ± 1.8 minutes for anchoring.

CONCLUSIONS

In our patient cohort, the two procedures yielded comparable results in terms of the correction of the horizontal position deviation, head posture, and up- and downshoots.

Stability of Y-splitting procedure combined with hang-back recession of the rectus muscle in rabbit eyes

BACKGROUND

The Y-splitting procedure has been used both to treat up-shoots and down-shoots in Duane syndrome, and as a substitute for posterior fixation suture. The Y-split is often performed in conjunction with a hang-back recession when a large amount of recession or an adjustable suture is necessary. Herein, we evaluated the stability of Y-splitting hang-back recession in the rectus muscle.

METHODS

Under general anesthesia, a 5-mm hang-back recession of the superior rectus muscle (SR) with Y-splitting was performed in ten eyes from ten rabbits (hang-back group). A conventional recession was performed in the SR of the fellow eye (control group). Six weeks after the procedure, the distance between the original insertion and the recessed SR (recession amount) and the width between the nasal and temporal halves of the SR were measured. These values were compared to the measurements taken at the time of surgery.

RESULTS

The hang-back group had a significantly larger forward displacement than the control group (P < 0.001 for both the nasal and temporal halves). The width change between the nasal and temporal halves was also significantly larger in the hang-back group (4.94 ± 1.32 mm) than in the control group (1.14 ± 0.60 mm, P < 0.001). Additionally, the Y-configuration appeared to be more collapsed in the hang-back group than in the control group.

CONCLUSION

Y-splitting of the rectus muscle may be unstable when it is combined with a hang-back recession. Surgeons should consider this possibility when performing Y-splitting procedures.

A comparison of two different techniques for oculomotor torque reduction

PURPOSE

To compare the results of two different surgical techniques: 'Cüppers technique', in which the torque of oculomotor rectus muscles is reduced by suturing the muscle to the globe in the posterior half of the globe; and 'Y-split recessions', in which the muscle torque is reduced by Y-splitting the rectus muscles, and reattaching the two halves at an angle to each other.

METHODS

We carried out a retrospective analysis of the outcome of surgery on 100 patients with infantile esotropia.

RESULTS

Both techniques show a sufficient reduction of strabismus angle variability, and minimal and maximal strabismus angle.

CONCLUSIONS

Both techniques achieve satisfactory results. In addition, the Y-split technique allows for accurate control of the muscle torque and requires no access to the posterior half of the eye, which can facilitate the surgical approach. For a reduction in muscle torque, the Y-split recession is a good alternative to the established Cüppers technique.

Reduction of ocular muscle torque by splitting of the rectus muscle II: technique and results

AIM

To present the results of a new technique that the authors have developed to weaken the extraocular muscles. The biomechanics of this technique, which is termed "Y-split recession," are given in the companion paper.

METHODS

A retrospective study, testing the effects of a new surgical technique on strabismus, nystagmus, and visual acuity. 228 patients (aged 6.8 (SD 6.0) years) with variable angle strabismus and nystagmus were treated by splitting and detaching two rectus muscles, and re-attaching the two halves at an angle of about 65 degrees to each other. Subjects were examined with the usual orthoptic tests immediately after the operation, and up to 96 months later.

RESULTS

The operation reduced the strabismus, eliminated or weakened the nystagmus in primary position, and improved binocular vision and the development of visual acuity. Only minor side effects were observed.

CONCLUSIONS

The Y-split recession can be used to reduce the torque for extraocular rectus muscles, and provides an alternative to "Cuppers Fadenoperation," recession, and similar procedures.