To investigate the dose response according to tendon width of the medial rectus in patients with recurrent exotropia who underwent unilateral medial rectus resection.
Patients with basic recurrent exotropia after bilateral lateral rectus recession were included. All patients underwent unilateral medial rectus resection according to the preoperative angle of deviation. Under general anesthesia, the tendon width of the medial rectus in the operated eye was measured. The patients were divided into 2 groups (narrow and wide) according to the median value of the tendon width of the medial rectus. The angle of deviation at postoperative day 1 was measured. The dose response was calculated based on the amount of correction and resection.
This study included 38 patients. Age and preoperative angle of deviation were 11.0 ± 3.0 years (range, 6 – 19 years) and 21.3 ± 3.2 prism diopters (PD; range, 15 – 25 PD), respectively. Tendon width of the medial rectus was 7.6 ± 0.7 mm (range, 6.0 - 8.5 mm) and the median value of tendon width was 7.5 mm. The dose response was 4.6 ± 0.8 PD/mm (range, 2.4 - 5.6 PD/mm). The dose response was significantly greater in the wide than in the narrow tendon width group (p < 0.001). Tendon width of the medial rectus was significantly correlated with age, the preoperative angle of deviation and surgical dose response (all, p < 0.05).
The tendon width of the medial rectus could be a predictor for estimating the surgical dose response when considering unilateral medial rectus resection in patients with the moderate angle of recurrent exotropia.