Medial rectus re-advancement: more bang for your buck?

Introduction: Although there are guidance tables in the literature on surgical dosage for primary medial rectus resection-lateral rectus recession surgery, there is a lack of consensus on the surgical gains in medial rectus re-advancement (MRR) for the management of consecutive exotropia. We compared the surgical outcomes of primary medial rectus resection-lateral recession (RR) surgery, to MRR in patients with consecutive exotropia. Methods: Retrospective, electronic note review of consecutive patients undergoing primary RR surgery for basic exotropia (RR group), convergence insufficiency-type exotropia, and divergence excess, and consecutive patients undergoing MRR with or without lateral rectus recession (MRR group) for consecutive exotropia in a teaching university hospital. Results: There were 84 patients in the RR group and 27 patients in the MRR group. The median age in the RR group was 25.50 years (range 4-79) and 45 years (18-87) in the MRR group (p = .002). Median follow-up was 7 months (3-43) in the RR group and 1 month (1-12) in the MRR group. Post-operatively, there was a median exotropia reduction of 27.00 prism diopters (PD) (range +5, -65; p < .0001) for near, and 27.00 PD (+10, -51; p < .0001) for distance in the RR group. In the MRR group, the median exotropia reduction was 34.50 PD (2, -67; p < .0001) for near and 33.00 PD (1, -67; p < .0001) for distance. There was a greater reduction in the exotropia in the MRR group compared to the RR group for distance (p = .047), but this did not meet statistical significance for near (p = 0.10). The median dose-effect relationship (PD/millimeter) was higher in the MRR group both for near deviation (2.90 vs 2.15, p = .0073) and for distance deviation (2.91 vs 2.15, =0.0041). Conclusion: Based on our study cohort, medial rectus re-advancement appears to have a greater dose-effect in reducing the distance angle of deviation for both near and distance compared to primary recess-resect surgery. Further prospective longitudinal studies would shed further light on the dose-effect relationship over time.