The Modification of the Extraocular Muscle Insertion and Change of Slanting Degrees after a Slanted Recession

1. Minwook Chang
2. Seung Hyun Kim

Department of Ophthalmology, Korea University College of Medicine, Seoul, Korea

Purpose: To evaluate the change of slanting degree after slanted superior rectus muscle recession using a rabbit model.

Methods: A prospective, controlled study was performed in 10 eyes of 5 rabbits with anatomically normal eyes. These eyes were divided into two groups according to the amount of slanted recession. In right eyes, slanted superior recti(SR) muscle recession was performed with 6mm of nasal margin and 2mm of temporal margin (4mm slanting group), and in fellow eyes, slanted SR muscle recession was performed with 6mm and 4mm, respectively (2mm slanting group). We measured both margins of superior recti from insertion and calculated the amount of anterior creeping movement of both margins at at 30, 60, and 90 postoperative days, and also compared the change of slanting degree of the SR muscle between the two groups.

Results: Slanting degrees showed a gradual decrease in all rabbit eyes. In the 4mm slanting group, each margin of anterior movement was 2.4.mm and 0.9 mm and slanting degrees decreased in 50~75%. In the 2mm slanting group, the margins of anterior movement were 2.9mm and 1.8mm, respectively, and slanting degrees decreased in 25~50%. The amount of slanting degree showed a greater decrease in group A than in group B (p= 0.045).

Conclusion: Both margins of SR in slanted recession showed anterior movement at postoperative 3 month; therefore, the effectiveness of slanted recession might be decreased postoperatively.