The effect of an inferior oblique muscle weakening procedure on surgical alignment in children and adolescents with exotropia

Abstract

Objective To compare the outcomes of surgery for exotropia and surgery for exotropia combined with an inferior oblique muscle weakening procedure in children and adolescents. Methods In a retrospective study, 179 cases of the children underwent conventional horizontal muscle surgery for exotropia from August 2009 to September 2011 were included. All children were divided into two groups based on whether or not they underwent an inferior oblique weakening procedure: group A included 48 patients who underwent surgery for exotropia combined with an inferior oblique weakening procedure, and group B included 131 patients who were only treated with surgery for exotropia. The success rates of alignment, overcorrection, and under-correction were compared between the 2 groups at postoperative days 1 to 3 and then at the final follow-up (a minimum of 6 months) . Enumeration data were analyzed with a χ2 test, measurement data were analyzed with an independent samples t test. Results At postoperative days 1 to 3, the success rates of alignment were 73% and 72%, the over-correction rates were 23% and 21%, and the under-correction rates were 4% and 6% in groups A and B, respectively (χ2=0.276, P>0.05). At the final follow-up, the success rates of alignment were 62% and 69%, the over-correction rates were 6% and 5%, and the under- correction rates were 31% and 26% in groups A and B, respectively (χ2=0.807, P>0.05). There was no significant difference in surgical outcomes between groups A and B at postoperative days 1 to 3 and at the final follow-up. Conclusion The inferior oblique muscle weakening procedure might have no significant effect on surgical alignment in children with exotropia. Eye surgeons may not need to change the conventional parameters of muscle strabismus surgery for horizontal exodeviations when inferior oblique muscle weakening procedures are simultaneously performed. Key words: Strabismus surgery; Exotropia; Children and adolescents; Therapy outcome