Measurements for horizontal extraocular muscle surgery from the suture site: Outcome and influencing factors

Abstract

Background. Measurement of recession in strabismus surgery is performed either from the limbus or from the muscle insertion. These measurement methods may result in inaccuracies that may influence the outcome of the procedure. We prospectively evaluated the outcome of recessions measured from the extraocular muscle suture site to its insertion in an incidence cohort. Methods. Thirty-six consecutive surgical procedures for infantile esotropia and 23 for constant exotropia were performed in which measurements were performed from the suture site. A successful surgery for esotropia was defined as an orthophoria of up to +10 prism dioptres of deviation for non-accommodative targets at a distance of 20 feet, measured by cover and prism test. A successful surgery for exotropia was defined as a residual deviation between -10 and +10 prism dioptres. The statistical significance of the outcome influencing factors was assessed by chi-square test. Results. Six weeks following surgery, 28 procedures (78%) for infantile and non-accommodative esotropia and 19 procedures (83%) for exotropia were successful. At the end of the follow-up period (mean 13.7 months ± 9.4 for esotropia and 11.6 months ± 12.8 for exotropia), the success rate was 77% for esotropia and 75% for exotropia. Prematurity and mental retardation in esotropia, exotropia with pre-operative deviations larger than -45 prism dioptres and amblyopia in exotropia were related to unfavourable outcome (p < 0.05). Conclusions. Measurement for muscle recession can be performed from the suture site. The outcome is comparable to the outcome when measurements are performed from the limbus or the insertion, probably due to the incidence cohort. Refinement of the technique and defining other factors influencing the outcome of strabismus surgery may improve the outcome.