Abstract
Purpose: :
Investigate the ability of orbital ultrasound to detect slipped extraocular muscle location and function.
Methods: :
Patients who present with a history of strabismus surgery and clinical evidence of slipped horizontal rectus muscles undergo orbital ultrasonography to evaluate the muscle cross-sectional area. Differences between lateral gazes (percentage) are analyzed and compared.
Results: :
A consecutive series of nine patients have been identified with slipped EOM. Data revealed muscle belly cross-sectional thickness change with contraction (range -2.7 to +34.3%). Six of these patients have undergone muscle surgery. One patient was lost to follow up. The preoperative ultrasound measurements of the remaining five patients correlated with the functionality and postoperative outcome following muscle re-insertion. In other words, those muscles that had lost function over time had little or no change (range -2.7 to + 6.6%) in cross-sectional thickness and had subsequent undercorrection in postoperative alignment measurements. Those muscles that had hypertrophied had more drastic changes (range +22.5 to +34.3%) and had subsequent postoperative overcorrection. Three patients are awaiting surgery and postoperative measurements.
Conclusions: :
This study supports the use of dynamic orbital ultrasonography to guide the treatment and surgical planning of slipped EOM. Evaluation of this function preoperatively may allow fewer surgeries without the added complication of worsening scar tissue, thus leading to optimized outcomes for each patient.
Keywords: strabismus: diagnosis and detection • extraocular muscles: structure • strabismus: treatment