Surgical Dosing for Correction of Consecutive Exotropia

Purpose: As surgical tables have not previously been available for consecutive exotropia, this study aimed to determine optimal surgical dosing for medial rectus (MR) advancement in this condition. Design: Comparative interventional case series. Methods: Data were reviewed for 46 patients with consecutive exotropia who underwent MR advancement with or without lateral rectus (LR) recession. Result: A total of 46 patients were included with 35±20 (standard deviation) years average age. Mean preoperative exotropia was 26±12∆ at distance and 33±19∆ at near. Thirty-six patients underwent unilateral or bilateral MR advancement (MRa group), and 10 underwent MR advancement combined with LR recession (MRa+LRc group). For MRa, mean MR advancement was 5.0±1.4mm. At the last follow-up visit, exotropia was reduced from 27±12∆ to 7±11∆ at distance. For MRa+LRc, mean MR advancement was 6.2±2.0mm, and the mean total surgical dose, including LR recession was 14.6±4.7mm. Overall, distance exotropia at last follow-up was surgically reduced from 40±19∆ to 9±14∆. Exodrift from initial to final follow-up was 6.5∆ for MRa and 7.5∆ for MRa+LRc. To achieve full correction, the required MR advancement was recalculated based on the surgical dose–response regression, suggesting that each MR advancement should be increased by 2mm more than Parks' general surgical recommendation for MR resection treating exotropia. Conclusion: Advancement of the MR must be augmented for correction of consecutive exotropia, but is effective and affords opportunity to explore the MR muscle.