Is surgical intervention on one or two extraocular (eye) muscles beneficial for a patient with poorly controlled intermittent exotropia that has worsened over 2 years, initially presenting with diplopia?

Surgical Intervention for Poorly Controlled Intermittent Exotropia

Both unilateral two-muscle surgery (lateral rectus recession and medial rectus resection) and bilateral lateral rectus recession are equally effective for treating poorly controlled intermittent exotropia with diplopia that has worsened over 2 years. 1

Surgical Decision Making Algorithm

1. Initial Assessment:

   • Evaluate the pattern of deviation:
     • If distance deviation exceeds near deviation: Consider bilateral surgery
     • If near deviation exceeds distance deviation: Consider unilateral surgery
     • If poor vision in one eye: Prefer unilateral surgery on the affected eye
     • If A or V pattern with oblique overaction: Prefer bilateral surgery

2. Surgical Options:

   • Option 1: Bilateral lateral rectus muscle recession
   • Option 2: Unilateral lateral rectus recession with medial rectus resection (recess-resect)
   • Option 3: Single muscle surgery (for small-angle exotropia only)

Evidence Supporting Surgical Intervention

A large clinical trial of 197 children with basic-type intermittent exotropia showed no significant difference in outcomes between bilateral lateral rectus recession and unilateral recess-resect procedures at both 6 months and 3 years post-surgery 1. This finding is supported by recent meta-analyses.

Key outcomes from the clinical trial:

• Reoperation rates by 3 years: 10% for bilateral recession vs. 5% for unilateral recess-resect
• Approximately 80% of patients show good alignment at 6 months post-surgery
• Long-term results tend to be less favorable with recurrence common over time

Special Considerations

Pattern Deviations

• For A or V pattern exotropia with oblique overaction:
  • Upshift of both lateral rectus muscles improves V pattern
  • Downshift improves A pattern
  • Small vertical deviations typically don't require vertical muscle surgery

Potential Complications

• Consecutive esotropia: May occur immediately after surgery causing diplopia
  • Often temporary but can persist
  • Management: Temporary membrane prisms (gradually reduced in power)
  • If persistent: Additional surgery may be required
• Risk of amblyopia: Higher in young children with constant or poorly controlled exotropia
• Loss of stereoacuity: Particularly with postoperative consecutive esotropia 2

Follow-up Protocol

• Initial follow-up within 1 week post-surgery
• Subsequent follow-ups at 1 month, 3 months, and 6 months
• Long-term follow-up every 6-12 months to monitor for recurrence 2
• Monitor for:
  • Alignment stability
  • Visual acuity
  • Binocularity
  • Need for prism adjustment

Alternative Approaches

While surgery is the preferred definitive treatment for poorly controlled intermittent exotropia with worsening symptoms 3, some non-surgical approaches may be considered:

• Temporary prism therapy: Can alleviate diplopia while determining if spontaneous improvement will occur 2
• Part-time alternate occlusion: May improve control and decrease exotropia size in some patients 4
• Overminus spectacles with prism: May temporarily improve control while wearing them 5

However, for a patient with poorly controlled intermittent exotropia that has worsened over 2 years with intermittent diplopia, surgical intervention offers the best chance for long-term improvement in ocular alignment and binocular function.