The maximum motor fusion test: a parameter for surgery for acquired esotropia

Area of Science:

• Ophthalmology
• Strabismus Surgery
• Binocular Vision

Background:

• Acquired esotropia (ET) often requires long-term optical correction (glasses or bifocals) post-surgery.
• Current surgical techniques aim to correct deviations but may not always minimize the need for continuous optical wear.
• Developing surgical parameters that reduce reliance on postoperative correction is a key goal in strabismus management.

Purpose of the Study:

• To evaluate if maximum motor fusional capacity, measured by prism bar, can optimize bilateral medial rectus recession in acquired esotropia.
• To determine if this approach can reduce the incidence of early overcorrection or late consecutive exotropia (XT).
• To assess the potential for decreasing the need for postoperative glasses or bifocals.

Main Methods:

• Patients were categorized into three groups based on esotropia (ET) severity, AC/A ratio, and prior surgery history.
• Bilateral medial rectus recessions were performed using a dose-response table, with maximum motor fusional capacity as the primary input parameter.
• Category III patients underwent re-recessions based on distance fusional amplitude.

Main Results:

• In Category I (high ET), 80% of patients achieved independence from glasses post-surgery, with a 10% reoperation rate for residual ET/XT.
• In Category II (low ET with high AC/A), 98% of patients avoided bifocals, with a 9% reoperation rate for XT.
• In Category III (recurrent ET), all patients avoided bifocals, with a 20% reoperation rate for XT.

Conclusions:

• Maximum motor fusional capacity is a valuable parameter for designing strabismus surgery to reduce postoperative optical appliance dependence.
• This surgical strategy effectively manages acquired esotropia across different patient categories.
• Optimizing surgical planning based on fusional capacity can lead to improved functional vision and reduced long-term patient burden.