Three-Muscle Surgery for Large- and Medium-Angle Intermittent Exotropia.

Area of Science:

• Ophthalmology
• Strabismus Surgery
• Pediatric Eye Care

Background:

• Intermittent exotropia (IXT) is a common strabismus condition.
• Surgical correction is often necessary for medium- to large-angle deviations (20-45 PD).
• Comparing surgical approaches is crucial for optimizing patient outcomes.

Purpose of the Study:

• To compare the success rate and dose-response ratio of three-muscle versus two-muscle surgery for IXT.
• To evaluate surgical outcomes for intermittent exotropia with deviations ranging from 20 to 45 prism diopters (PD).

Main Methods:

• Retrospective review of medical records for patients with IXT (20-45 PD).
• Comparison between bilateral lateral rectus recession (two-muscle) and bilateral lateral rectus recession with unilateral medial rectus resection (three-muscle) groups.
• Assessment of preoperative and postoperative deviations, successful motor outcomes (≤10 PD), and dose-response ratio.

Main Results:

• The three-muscle group achieved higher successful motor outcomes (84.6%) compared to the two-muscle group (70.5%).
• The three-muscle group demonstrated a significantly higher mean dose-response ratio (2.72 PD/mm vs. 1.82 PD/mm).
• Overcorrection rates were comparable between the two surgical approaches.

Conclusions:

• Three-muscle surgery is an effective primary treatment for intermittent exotropia (20-45 PD).
• This approach yields excellent outcomes and a favorable dose-response ratio.
• The risk of overcorrection is low with the three-muscle surgical technique.