Postoperative Muscle Migration Through Stretched Scar Formation After Superior Rectus Muscle Nonscleral Sutured Resection in Rabbit Eyes.

PURPOSE: To determine whether suturing to the residual muscle stump induces postoperative muscle migration after superior rectus muscle (SRM) resection in rabbit eyes.

METHODS

Twenty-four eyes in 12 rabbits were randomly divided into two groups. Each group underwent a 3-mm SRM resection. The muscle stump was not removed in one randomly assigned eye in each rabbit and the resected muscle was sutured to the residual muscle stump (residual muscle stump group). In the other eye, the muscle stump was completely removed and the resected muscle was sutured to the original insertion site (control group). At postoperative weeks 1, 2, and 4, the distances between the most anterior aspect of the reattached muscle and the corneal limbus were measured. Histopathologic differences at the new attachment sites were assessed between the two groups at postoperative week 4.

RESULTS

The mean distance between the corneal limbus and SRM was 2.97 ± 1.00 mm in the residual muscle stump group and 1.99 ± 0.40 mm in the control group at postoperative week 2 (P = .026) and 3.14 ± 0.78 mm in the residual muscle stump group and 1.81 ± 0.44 mm in the control group at postoperative week 4 (P = .002). Connective tissue, fibrosis, and myofibroblast proliferation in the front of the SRM were identified based on histopathologic findings.

CONCLUSIONS

Postoperative loosening associated with a stretched scar frequently occurred in cases with suturing to the residual muscle during rectus muscle resection and could result from fibrosis and connective tissue proliferation in front of the rectus muscle. [J Pediatr Ophthalmol Strabismus. 2019;56(4):254-260.].