Essential infantile esotropia: postoperative motor outcomes and inferential analysis of strabismus surgery

BACKGROUND The aim of this retrospective study is a long-term evaluation of postoperative motor outcomes and the inferential analysis of strabismus surgery in infant eyes with essential infantile esotropia. METHODS 576 patients were compatible with the criteria: confirmed EIE diagnosis, angle ≥ 30 pD, absence of associated ocular anomalies, onset by 6 months of age, absence of hyperopia > 3 Diopters, operation before age 4. Preoperative deviation classes (30-40 pD, 41-59 pD, ≥ 60 pD) were established, different types of surgery were performed. Follow-up was conducted for 5 years after surgery. Longitudinal data were analyzed using general linear mixed models stratified according to the class of pre-operative deviation. A random intercept and a random slope with time (in months) was assumed with an unstructured within subject correlation structure for repeated measurements. RESULTS In patients with preoperative angle ≤ 40 pD, a significant interaction effect for intervention by time (F5,155.9 = 3.56, p = 0.004) and a significant intervention effect (F5,226.1 = 6.41, p < 0.001) on residual deviation were observed; only the intervention 5 showed a residual deviation inside the limits of a partial success. In Class 41-59, a significant interaction effect for intervention by time (F4,166.7 = 5.16, p = 0.001), intervention (F4,178.1 = 2.48, p = 0.046) and time (F1,174.6 = 9.99, p = 0.002) on residual deviation were observed; intervention 7 had the highest degree of stability showing an outcome within the range of a partial success. In Class ≥ 60 pD no significant effect for intervention (F4,213.9 = 0.74, p = 0.567), time (F1,169.5 = 0.33, p = 0.569) or intervention by time (F4,160.9 = 1.08, p = 0.368) on residual deviation was observed; intervention 3,6 and 7 resulted in a residual deviation within the range of a partial success. CONCLUSIONS We suggest, where possible, a two-horizontal muscles approach in small angle EIE, while a multiple muscles surgery in large angle EIE.