Medial transposition of the split lateral rectus muscle used as a primary procedure for treatment of complete third nerve palsy.

Purpose: This case series aims to study the effect of medial transposition of the split lateral rectus (MTSLR) muscle used as a primary procedure for surgical management of complete third nerve palsy. Methods: A retrospective review of all cases with complete third nerve palsy which underwent surgical intervention in a tertiary care center from 2019 to 2023 was undertaken, and only cases underwent isolated MTSLR as a primary procedure were included. Data collection included age, etiology, laterality, follow-up, preoperative and postoperative deviation, and postoperative complications. Results: A total of 12 patients (14 eyes) were identified, and mean follow-up after surgery was 15.4 months (range; 7-37 months). Mean age at time of surgery was 34.5 years (range; 2-65 years). Right eye was involved in 5 patients, left eye in 5 patients, while two cases were bilateral. Surgical success (within 10PD of orthotropia) was achieved in all patients. Mean primary gaze exotropia (XT) improved from 96.2PD before surgery (range; 60-130 PD) to 1.8PD after surgery (range; 6PD ET to 8PD XT) (p ˂ .0001). Mean primary position Hypotropia, which was present in 5 cases only, improved from 4.2PD (range 5-14PD) to 0.7PD (range 0-4PD). Abduction significantly declined from a mean of 0 to -3.9 postoperatively, with no significant improvement of limited adduction. No postoperative complications have been encountered, apart from transient postoperative horizontal diplopia in one patient which resolved spontaneously. Conclusion: MTSLR muscle attains long term acceptable aesthetic results and functional alignment when used as a primary procedure for treatment of complete oculomotor nerve palsy, with low rate of postoperative complications.