Reduction in Rectus Muscle Recession Depending on the Distance Between Rectus Muscle Suture Placement and Scleral Insertion in Rabbit Eyes.

PURPOSE: To quantitatively determine how a large tendon remnant reduces the effect of the rectus muscle recession procedure with respect to the distance between the placement of the muscle suture and the scleral insertion. METHODS: Thirty-six eyes from 18 rabbits were randomly divided into four groups according to the distance between the superior rectus muscle suture placement and the scleral insertion (1, 2, 3, and 4 mm). The superior rectus muscle was sutured at the previously listed distances from the insertion. Each superior rectus muscle was reattached using a scleral pass at a site 4 mm posterior to its original insertion. The amount of recession was measured as the distance between the most anterior aspect of the reattached muscle and the original insertion site. RESULTS: The mean amount of recession was 4.07 ± 0.25 mm in the 1-mm group and 2.76 ± 0.55 mm in the 4-mm group at postoperative week 4. There were significant differences in the amount of recession between the four groups. Linear regression analyses revealed a significant relationship between the distance of the muscle suture placement from the scleral insertion and the amount of recession (r(2) = 0.521). The superior rectus muscle was estimated to be reattached 0.437 mm anterior to the desired location for every 1 mm that the muscle suture was placed posterior to the scleral insertion. CONCLUSIONS: The potential error that depends on the distance between the muscle suture placement and the scleral insertion should be considered to reduce undercorrection and ensure a good surgical outcome.