Long-term outcome and predictor variables in the treatment of acquired esotropia with botulinum toxin.

PURPOSE To determine the long-term results of botulinum therapy in acquired esotropia and to identify predictors of a satisfactory outcome. METHODS Sixty-eight children (age range, 8-64 months) with acquired esotropia were enrolled in a prospective study. Botulinum toxin A was injected in the two medial recti. Motor and sensory statuses were evaluated at 1 and 2 weeks; 3, 6, and 12 months; and every year after the last injection. Univariate and multivariate logistic regression analyses were performed to relate motor and sensory outcome to variables recorded as potential predictors. RESULTS After an average follow-up of 4.8 years since the last injection, motor success was obtained in 36 children with one injection (52.9%), increasing to 48 (70.6%) and 60 (88.2%) children after two and three injections, respectively. Forty-eight (70.6%) patients had at least peripheral fusion (category 1 binocularity) and 32 (47.1%) had stereoacuity of at least 400 seconds of arc (category 2 binocularity). Higher hypermetropia, less severe amblyopia, and a smaller angle of esotropia were the best predictors of motor success. Minimal amblyopia and favorable motor alignment were associated with better binocularity outcome. CONCLUSIONS Botulinum is an effective long-term treatment of acquired esotropia. It is especially useful in children with high hypermetropia, minimal amblyopia, and small esotropic deviation.