Risk Factors And Surgical Outcomes Of Strabismus Reoperation (RSOR)

Risk Factors And Surgical Outcomes Of Strabismus Reoperation: A Clinical Study

Horizontal strabismus, commonly known as inward or outward deviation of the eyes, is a frequent eye condition that may require surgical correction. Although the first surgery is often successful, some patients develop residual or recurrent eye misalignment and require a second operation (reoperation).

This study aims to identify the clinical and surgical factors that may increase the risk of undercorrection, overcorrection, or recurrence after the first surgery. It also evaluates the outcomes and success rate of repeat surgery in patients with horizontal strabismus.

Patients undergoing reoperation will receive a complete ophthalmological examination before surgery. The surgical plan will be individualized based on previous surgical history and current eye findings. All procedures will be performed under general anesthesia by the same surgeon. Participants will be followed for three months after surgery to assess eye alignment, movement, and possible complications.

The results of this study may help improve surgical planning and predict which patients are at higher risk of requiring additional surgery in the future.

Study Overview

• Status: Not yet recruiting
• Conditions: Strabismus; Exotropia; Esotropia
• Intervention / Treatment: Procedure: Horizontal Strabismus Reoperation

Detailed Description

Horizontal strabismus, including esotropia and exotropia, represents the most common form of ocular misalignment requiring surgical intervention. Despite advances in surgical techniques, a proportion of patients experience residual deviation, overcorrection, or recurrence after primary surgery, necessitating reoperation. Reoperation presents unique surgical challenges due to altered anatomy, scar tissue formation, possible muscle slippage, and variability in postoperative healing response.

Reported reoperation rates vary across studies and clinical settings, with multiple patient-related and surgical factors implicated in surgical failure. These factors may include age at primary surgery, magnitude of deviation, amblyopia, number of operated muscles, surgical technique, and time interval between surgeries. However, data regarding predictive risk factors and standardized outcome evaluation in reoperated horizontal strabismus remain limited in the local setting.

This prospective interventional study will be conducted at Assiut University Hospital. It will include patients undergoing repeat surgery for correction of horizontal strabismus. Patients with vertical deviations, paralytic or restrictive strabismus, neurological or syndromic associations, or incomplete previous surgical data will be excluded.

Preoperative assessment will include measurement of visual acuity, cycloplegic refraction, anterior and posterior segment examination, evaluation of ocular motility in nine diagnostic positions of gaze, and measurement of angle of deviation using prism and alternate cover test or Krimsky test when appropriate. Documentation of conjunctival scarring and previous surgical details will be performed.

The surgical approach will be individualized according to preoperative findings and prior operative records. Exploration of previously operated muscles will be performed when clinically indicated. Intraoperative forced duction testing will assess muscle tightness. All surgeries will be conducted under general anesthesia by the same surgeon to reduce inter-operator variability.

Participants will be followed postoperatively at 1 day, 1 week, 1 month, and 3 months. Surgical success will be defined as postoperative alignment within ±10 prism diopters of orthotropia at final follow-up. Secondary outcomes include stability of alignment and postoperative complications such as limitation of ocular motility or conjunctival scarring.

Statistical analysis will evaluate associations between demographic and clinical variables and surgical outcomes using multivariate regression to identify independent risk factors for reoperation outcomes.

The findings of this study aim to improve risk stratification, optimize surgical planning, and enhance long-term outcomes in patients undergoing horizontal strabismus reoperation.

• Study Type: Interventional
• Enrollment (Estimated): 62
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Rehab Safwat Hamza; Phone Number: 01112603390; Email: Rehabsafwat347@gmail.com

Study Locations

• Egypt
  • Asyut, Egypt
    • Assiut University
    • Contact: Assiut University; Phone Number: 08822080150; Email: vp_grad@aun.edu.eg

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Patients diagnosed with horizontal strabismus (esotropia or exotropia).

  • Patients undergoing repeat surgery for correction of residual, recurrent, undercorrected, or overcorrected horizontal strabismus.
  • Availability of sufficient medical records documenting previous strabismus surgery.
  • Ability to attend scheduled postoperative follow-up visits.
  • Written informed consent obtained from the patient or legal guardian.

Exclusion Criteria:

• Combined vertical and horizontal strabismus.

  • Paralytic strabismus.
  • Restrictive strabismus.
  • Strabismus associated with neurological or syndromic conditions.
  • Patients with incomplete or insufficient documentation of previous surgical procedures.
  • Patients unwilling or unable to complete follow-up.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Horizontal Strabismus Reoperation; All enrolled participants undergo repeat surgery for correction of horizontal strabismus (esotropia or exotropia). The surgical approach is individualized based on preoperative clinical evaluation and prior operative records. Exploration of previously operated muscles is performed when indicated, particularly in cases of limited ocular motility or suspected scarring. Otherwise, surgery is performed on unoperated horizontal rectus muscles when appropriate. Intraoperative forced duction testing is conducted to assess muscle tightness, and scar tissue release is performed if necessary. All procedures are performed under general anesthesia by the same surgeon. Participants are followed postoperatively to evaluate alignment, ocular motility, and surgical outcomes.

Procedure: Horizontal Strabismus Reoperation; Horizontal strabismus reoperation is performed to correct residual or recurrent esotropia or exotropia following previous strabismus surgery. The surgical plan is individualized based on preoperative assessment and prior operative records. Previously operated muscles are explored when limited ocular motility, scarring, or suspected muscle slippage is present. In other cases, surgery may be performed on unoperated horizontal rectus muscles when appropriate. Intraoperative forced duction testing is conducted to assess muscle tightness, and scar tissue is released when indicated. All procedures are performed under general anesthesia by the same surgeon. Postoperative alignment and ocular motility are evaluated during follow-up visits.; Other Names: Strabismus Reoperation; Repeat Strabismus Surgery; Horizontal Rectus Muscle Reoperation

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Rate Of Surgical Success After Horizontal Strabismus Reoperation	Percentage of participants achieving postoperative ocular alignment within ±10 prism diopters of orthotropia measured using the Prism and Alternate Cover Test at distance fixation.	3 months postoperative

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Preoperative Angle Of Deviation	Angle of ocular deviation measured in prism diopters using the Prism and Alternate Cover Test at distance fixation before surgery.	Baseline (preoperative)
Age At Primary Strabismus Surgery	Age of the participant at the time of initial strabismus surgery obtained from medical records.	Baseline
Presence Of Amblyopia	Presence of amblyopia determined by best corrected visual acuity assessment during preoperative evaluation.	Baseline
Number Of Extraocular Muscles Operated During Reoperation	Number of horizontal rectus muscles surgically operated during the reoperation procedure.	Intraoperative

Collaborators and Investigators

• Sponsor: Assiut University

Publications and helpful links

General Publications

• Rajavi Z, Gozin M, Sabbaghi H, et al. Reoperation in horizontal strabismus and its related risk factors. Med Hypothesis Discov Innov Ophthalmol. 2018;7(2):73-82.
• Heo H, Park H, Kim J, Lee S. Effect of age on reoperation rate in children undergoing exotropia surgery. Acta Ophthalmol. 2021;101(3):e412-e416.
• Yetkin AA. Factors affecting surgical success rates in pediatric horizontal strabismus surgery: deviation angle and amblyopia. Cureus. 2024;16(5):e12345.
• Akbari MR. Preoperative factors associated with multiple strabismus surgeries: a large retrospective database study. Optom Vis Sci. 2026;103(1):45-52.
• Olitsky SE, Coats DK. Complications of strabismus surgery: incidence and risk factors. Middle East Afr J Ophthalmol. 2015;22(3):320-332.
• Niu R, Zhang J, Chen X, Li Y, Wang L. Comprehensive analysis of strabismus reoperations: clinical insights and recurrence after primary correction. BMC Ophthalmol. 2024;24:446. doi:10.1186/s12886-024-03712-2.
• Samplaski MK. Editorial Commentary. Urol Pract. 2019 Jan;6(1):44. doi: 10.1097/01.UPJ.0000552857.40544.a1. Epub 2018 Dec 27. No abstract available.

Study record dates

Study Major Dates

• Study Start (Estimated): March 1, 2026
• Primary Completion (Estimated): May 1, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: February 24, 2026
• First Submitted That Met QC Criteria: February 27, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): March 9, 2026
• Last Update Submitted That Met QC Criteria: March 6, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: Ocular alignment; Horizontal strabismus; Strabismus reoperation; Recurrent strabismus; Prism diopters; Paediatric strabismus surgery; Orthotropia; Ocular motility
• Additional Relevant MeSH Terms: Nervous System Diseases; Eye Diseases; Cranial Nerve Diseases; Ocular Motility Disorders; Exotropia; Strabismus; Esotropia
• Other Study ID Numbers: AUH-STRAB-REOP-2026

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No