Evaluation of The Techniques in Correcting Large-Angle Exotropia

Exotropia Clinical Trial

Official title:

Evaluation of The Techniques of Lateral Rectus Muscle Combined Recession With Hang Back and Combined Recession With Z-Tenotomy in Correcting Large-Angle Exotropia

Clinical Trial Details — Status: Not yet recruiting

Administrative data

• NCT number: NCT06084442
• Other study ID #: Large-Angle Exotropia
• Status: Not yet recruiting
• Phase: N/A
• Start date: October 2023
• Est. completion date: April 2024

Study information

• Verified date: October 2023
• Source: Tanta University
• Contact: Basma Gamal Mohamed Ahmed Sayed Ahmed, Msc
• Phone: +20 1017954454
• Email: basmagamal9090[@]yahoo.com
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

The aim of this study is to evaluate the techniques of combined lateral rectus muscle recession with hang back and combined lateral rectus muscle recession with z-tenotomy in correcting large-angle exotropia.

Description:

Strabismus was defined as any heterotropia at near or distance fixation, or both, on cover testing. Micro strabismus was known as a deviation of fewer than 10 prism diopters (PD). Different studies have defined large angle deviation as 35 Δ , 40 Δ, 50 Δ and 60 Δ.

Studies revealed that during the first decade of life, exotropia is most prevalent with intermittent exotropia and convergence insufficiency are the most frequent. Exotropic deviations include exophoria, infantile exotropia, intermittent exotropia, sensory exotropia and consecutive exotropia.

Large-angle constant exotropia has a negative impact on the patients and surgical treatment of exodeviations improves the patient's psychosocial functioning. Hence, many surgical techniques have been described for management of exotropia, including bilateral lateral rectus recessions or recess/resect procedures. Botulinum toxin injection combined with recession-resection procedures was used as another surgical technique.

As a fact large-angle exotropia usually requires greater amounts of surgery, often a surgery on a greater number of extraocular muscles. Hence, 3 or 4 horizontal muscle surgery was performed for correcting large angle exotropia. Single-staged three horizontal muscles surgery for large angle intermittent exotropia has been more successful.

Recently, medial rectus muscle surgery as bilateral medial rectus resection for primary large-angle exotropia has been used with successful results. A successful outcome of surgery was defined as deviation within 10 prism diopters for both distance and near.

Moreover, hang-back loop suspension surgical technique can be performed for lateral rectus (LR) muscle recession. This technique can offer potential advantages over the conventional rectus muscle recession, including better exposure of the site of scleral sutures, lower risk of scleral perforation , shorter procedure duration and lower postoperative induced astigmatism.

On the other hand, the hang-back recession has some limitations as a potential unpredictability in surgical outcomes.Although previous reports suggest that the hang-back technique for LR recession for exotropia results in poorer surgical success and may require a different surgical dosage, another study proved that the hang-back surgical technique was as effective as conventional LR recession surgery for children with exotropia.

Furthermore, many studies were performed on Z-tenotomy technique as an alternative procedure for muscle weakening. This technique was applied for superior oblique muscle in cases with mild to moderate over depression in adduction with success rate 90%. An Other study has revealed that z-tenotomy up to 50% progressively reduces extraocular tendon force transmission, but Z-tenotomy of ≥50% is biomechanically equivalent in vitro to complete tenotomy.

In the past it was thought that muscle recessions with the muscle placed behind the anatomical equator of the globe would cause limitation of ocular rotation. Postoperative abduction limitation is one of the main problems in large recession and/or resection for primary and recurrent exotropia with large angle. It is generally thought that keeping the lateral rectus recession to no more than 8 mm prevents this complication. However, several studies revealed that large amounts of recession can be done without causing significant ocular movement limitation.

Recruitment information / eligibility

• Status: Not yet recruiting
• Enrollment: 50
• Est. completion date: April 2024
• Est. primary completion date: March 2024
• Accepts healthy volunteers: No
• Gender: All
• Age group: N/A and older

Eligibility

Inclusion Criteria:

• Patients suffering from large angle exotropia; defined, in this study, as an angle of deviation = 40 prism diopters (PD).

Exclusion Criteria:

1. Patients suffering from exotropia with angle < 40 prism diopters (PD).

2. Patient with paralytic strabismus.

3. Patient with restrictive strabismus.

4. Patient with combined vertical and horizontal deviation.

5. Patients with previous strabismus surgery.

6. Patients who had previously been administered botulinum toxin A.

7. Patient refusal.

Related Conditions & MeSH terms

• Exotropia

Intervention

Procedure:
• Evaluation of The Techniques of Lateral Rectus Muscle Combined Recession with Hang Back and Combined Recession with Z-Tenotomy in Correcting Large-Angle Exotropia
Patients will be divided into 2 groups: Group (A): Patients will undergo combined LR recession 7mm and hang back technique. Group (B): Patients will undergo combined LR recession 7mm and Z-tenotomy technique.

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
Tanta University

References & Publications (6)

Betts C, Olitsky S. Corneal astigmatic effects of conventional recession vs suspension recession ("hang-back") strabismus surgery: a pilot study. Binocul Vis Strabismus Q. 2006;21(4):211-3. — View Citation

Chen JH, Morrison DG, Donahue SP. Three and Four Horizontal Muscle Surgery for Large Angle Exotropia. J Pediatr Ophthalmol Strabismus. 2015 Sep-Oct;52(5):305-10. doi: 10.3928/01913913-20150609-02. Epub 2015 Jun 15. — View Citation

Chung AK, Rehman SU, Bradbury JA. Comparison of modified anchored "hang-back technique (HBT)" with conventional HBT in bimedial rectus recession. J AAPOS. 2005 Jun;9(3):234-9. doi: 10.1016/j.jaapos.2005.02.011. — View Citation

Livir-Rallatos G, Gunton KB, Calhoun JH. Surgical results in large-angle exotropia. J AAPOS. 2002 Apr;6(2):77-80. doi: 10.1067/mpa.2002.122059. — View Citation

Orlin A, Mills M, Ying GS, Liu C. A comparison of hang-back with conventional recession surgery for exotropia. J AAPOS. 2007 Dec;11(6):597-600. doi: 10.1016/j.jaapos.2007.06.001. Epub 2007 Oct 24. — View Citation

Shin A, Yoo L, Demer JL. Biomechanics of superior oblique Z-tenotomy. J AAPOS. 2013 Dec;17(6):612-7. doi: 10.1016/j.jaapos.2013.09.004. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	sucessful alignment	Successful motor alignment will be defined as orthotropia or = 10 ? Exotropia or Esotropia at 6 m distance with spectacle correction worn at 6 months. Successful sensory alignment will be by achievement of fusion and moderate or good stereoacuity postoperatively.	Follow up period of 6 month from the time of initial surgery. All patients will be examined at one week, one month, 3 month and 6 months.