Novel Inferior Oblique Muscle Y Splitting Procedure to Minimize the Anti-Elevation Syndrome: A Pilot Study

Area of Science:

• Ophthalmology
• Strabismus Surgery
• Oculomotor Muscle Procedures

Background:

• Anti-elevation syndrome is a common complication following strabismus surgery.
• Inferior oblique muscle overaction can cause primary gaze hypertropia and excyclotorsion.
• Existing surgical techniques may not fully mitigate anti-elevation effects.

Purpose of the Study:

• To describe a novel Y-splitting procedure for the inferior oblique muscle.
• To assess the efficacy of this Y-splitting technique in mitigating anti-elevation syndrome.
• To correct primary gaze hypertropia and excyclotorsion in patients with inferior oblique muscle overaction.

Main Methods:

• A pilot, prospective interventional study was conducted on 14 patients with unilateral 3+ or greater inferior oblique muscle overaction.
• A Y-splitting procedure of the inferior oblique muscle was performed, combined with routine horizontal muscle surgery.
• Surgical outcomes were evaluated at baseline and 6 months post-intervention, assessing hypertropia, excyclotorsion, and inferior oblique muscle overaction.

Main Results:

• The Y-splitting procedure significantly reduced mean hypertropia from 18.42 PD to 1.57 PD (p = 0.005) and excyclotorsion from 14.14 degrees to 3.85 degrees (p < 0.05).
• Mean inferior oblique muscle overaction decreased from +3.21 to +0.28.
• Three patients experienced residual/variable anti-elevation effects; however, no adverse events or additional surgeries were required.

Conclusions:

• The novel "Y splitting" procedure for the inferior oblique muscle is a viable surgical option.
• This technique effectively corrects primary gaze hypertropia and excyclotorsion.
• The Y-splitting approach appears to mitigate the anti-elevation effect compared to traditional methods.