Comparison between adjustable and non-adjustable hang-back muscle recession for concomitant exotropia.

We compared the results of strabismus surgery using adjustable and non-adjustable hang-back muscle recessions in 38 patients having concomitant exotropia. The two groups were matched for age of the patient, type of concomitant exotropia, amount of deviation, and type and amount of muscle surgery. At 6 months follow-up, 18 of the 19 patients (95%) in the adjustable hang-back recession group and 17 of the 19 patients (90%) in the non-adjustable hang-back recession group had ocular alignment within 10 prism diopters (PD) of orthophoria. At the most recent follow-up (mean 3.4 years), 12 of the 13 patients (92%) in adjustable hang-back recession group and 12 of the 14 patients (86%) in non-adjustable hang-back recession group had ocular alignment within 10 PD of orthophoria. There was no statistically significant difference in success rates between the two groups at 6 months postoperatively and at the most recent follow-up. This preliminary study suggests that non-adjustable hang-back muscle recession can be considered for routine concomitant exotropia.