One- Versus Two-Muscle Surgery for Presumed Unilateral Fourth Nerve Palsy Associated With Moderate Angle...

Area of Science:

• Ophthalmology
• Strabismus Surgery
• Pediatric Ophthalmology

Background:

• Unilateral fourth nerve palsy can cause moderate hyperdeviations.
• Surgical correction aims to restore binocular alignment and eliminate diplopia.
• The choice between one-muscle and two-muscle surgery for these deviations is debated.

Purpose of the Study:

• To compare the efficacy of one-muscle versus two-muscle surgery for moderate hyperdeviations (14-25 PD) in presumed unilateral fourth nerve palsy.
• To evaluate motor and diplopia success rates at 6 weeks and 1 year postoperatively.

Main Methods:

• Retrospective chart review of 73 patients (aged 5-86 years) with moderate hyperdeviation.
• Patients underwent either one-muscle or two-muscle surgery.
• Success defined by motor alignment (0-4 PD undercorrection) and absence of diplopia.

Main Results:

• Motor success rates were similar at 6 weeks (64% vs 67%) and 1 year (47% vs 55%) between one-muscle and two-muscle surgery.
• One-muscle surgery had more undercorrections (36% vs 16%) at 6 weeks.
• Two-muscle surgery had more overcorrections (0% vs 18%) at 6 weeks.
• Diplopia success was similar at 6 weeks (73% vs 60%) and 1 year (45% vs 59%).

Conclusions:

• One-muscle and two-muscle surgery demonstrate comparable motor outcomes for moderate hyperdeviations in presumed unilateral fourth nerve palsy.
• Diplopia success rates were similar, attributed to fewer symptomatic overcorrections with one-muscle surgery and fewer undercorrections with two-muscle surgery.
• No clear advantage of two-muscle surgery was identified for motor outcomes in this patient group.