What is the recommended treatment for poorly controlled intermittent exotropia (intermittent outward deviation of the eye) with worsening symptoms and intermittent diplopia (double vision) over a 2-year period?

Management of Poorly Controlled Intermittent Exotropia with Worsening Symptoms

For poorly controlled intermittent exotropia that has been worsening over 2 years with intermittent diplopia, surgical intervention with either bilateral lateral rectus muscle recessions or unilateral lateral rectus recession with medial rectus resection is the recommended treatment approach. 1

Initial Non-Surgical Management Options

Before proceeding to surgery, several non-surgical approaches may be considered:

1. Refractive Error Correction

   • Prescribe corrective lenses for any clinically significant refractive error
   • For myopes: Full correction or slight overcorrection may help control exotropia
   • For hyperopes: Undercorrection is preferred as reducing accommodative convergence can worsen exotropia 1

2. Stimulating Accommodative Convergence

   • Consider increasing myopic correction in myopes
   • Consider reducing hyperopic correction in hyperopes
   • Consider prescribing myopic correction in ametropes 1
   • Note: Some patients, particularly older patients, may not tolerate this approach due to visual discomfort

3. Patching Therapy

   • Part-time patching (2-6 hours daily) may improve fusional control
   • Can be applied to the preferred eye or alternated between eyes
   • Most effective in the 3-10 year age group 1
   • May slightly lower probability of deterioration, though deterioration is uncommon regardless

4. Convergence Exercises

   • Particularly useful for patients with convergence insufficiency type of exotropia
   • Near point of convergence exercises on accommodative targets
   • Convergence exercises with base-out prism 1
   • Recent evidence shows vision therapy/orthoptics can improve control of intermittent exotropia compared to observation alone 2

Surgical Intervention

Given the progressive worsening over 2 years with intermittent diplopia, surgical intervention is indicated for this case. The American Academy of Ophthalmology guidelines support this approach for persistent exotropia with symptoms 1, 3.

Surgical Options:

1. Bilateral Lateral Rectus Muscle Recessions

   • Based on the distance deviation measurement
   • Approximately 80% of patients have good alignment 6 months postoperatively 1

2. Unilateral Lateral Rectus Recession with Medial Rectus Resection (Recess-Resect)

   • A large clinical trial showed no significant difference in outcomes between this approach and bilateral lateral rectus recession 1
   • Slightly lower reoperation rate at 3 years (5% vs 10% for bilateral recession) 1

Important Considerations:

• Measurements with best optical correction should be repeated at near and distance
• Pattern of deviation (A or V pattern) should be assessed
• Any vertical component should be evaluated 3
• The alternate cover test should be used to quantify the total deviation for surgical planning 1

Post-Surgical Management

• Follow-up within 1 week, then at 1 month, 3 months, and 6 months 3
• Long-term follow-up every 6-12 months to monitor for recurrence 3
• Temporary esotropia may occur immediately after surgery, often causing diplopia
  • This is usually temporary and may increase likelihood of satisfactory long-term alignment
  • If persistent for several weeks, temporary membrane prisms can help 1

Potential Complications

• Risk of consecutive esotropia after surgery, which could cause persistent diplopia 3
• Possibility of amblyopia development if the deviation is not addressed promptly 3
• Loss of stereoacuity if binocular vision is not restored 3
• Recurrence of exotropia over time (common) 1

Adjunctive Post-Surgical Therapy

Recent evidence suggests that post-surgical eye exercises using physiotherapy modalities (twice weekly for three months) can significantly improve exotropia control for both near and far targets 4, which may help maintain surgical outcomes.

Prognosis

While approximately 80% of patients have good alignment 6 months postoperatively after bilateral lateral rectus muscle recession, long-term results are less favorable, and recurrence is common over time 1. However, properly designed strabismus surgery may provide sustainable control of alignment and symptomatic relief in selected patients 5.