To report the clinical outcomes of a new modification to muscle belly union surgery in heavy eye syndrome.

Muscle belly union was performed in patients with large-angle esotropia and characteristic findings of heavy eye syndrome on orbital imaging. After isolation of superior and lateral rectus muscle and passing a single armed suture in each muscle belly, approximation was achieved via tying of both arms of separate sutures together. Medial rectus (MR) was also recessed considering the results of the intraoperative force duction test.

Surgery was conducted in 24 eyes of 16 patients. The mean preoperative esotropia was 93.71 ± 23.1 prism diopters (PD), which improved significantly after the operation (final esotropia: 11.53 ± 15.59 PD, P value = 0.001). Six patients also exhibited mild hypotropia preoperatively (9.33 ± 6.88 PD), which resolved completely after surgery in all cases. Evaluation of preoperative abduction limitation (minus 3.1 ± 1.83) showed a significant improvement postoperatively (minus 0.95 ± 0.68, P value = 0.000). Additionally, mild limitation of adduction (minus 1) was seen in nine patients due to large MR recession. However, none of the patients reported postoperative diplopia.

Our new approach in muscle belly union surgery resulted in favorable outcomes compared with previous studies. It seems that the two-suture technique presented in this study yields more convenient approximation of muscle bellies and acts as a safety suture upon spontaneous loosening of the first applied suture.