Rate of deterioration in accommodative esotropia correlated to the AC/A relationship

Abstract

We analyzed the claim that accommodative esotropia tends to deteriorate with greater frequency if the accommodation convergence relationship (AC/A) is high. Records of 119 patients whose eyes were aligned with spectacles alone were studied. Their AC/A relationships were graded according to the difference between the distance and near measurements: normal included 0 to 9 prism diopters (delta) difference; grade 1 ranged from 10 to 19 delta difference; grade 2 from 20 to 29 delta difference; and in grade 3 the difference was 30 delta or greater. Deterioration is characterized by a nonaccommodative component of esotropia greater than 10 delta at distance becoming superimposed on the initial accommodative esotropia. Deterioration occurred in 7.7% of patients with a normal AC/A, 25% with grade 1 high AC/A, 44% with grade 2 high AC/A, and 52% with grade 3 high AC/A. Hypotheses were investigated using chi square, t-test, analysis of variance (ANOVA), and log linear analyses. Distributional differences were highly significant by chi square test (p = 0.001) with a rejection of the null hypothesis of no difference between the groups at the alpha = 0.05 level. An alternate analysis of average AC/A ratio in the deteriorated versus nondeteriorated patients was equally statistically significant by the t-test. Hypermetropia was significantly higher in the normal AC/A group. Multi-factor comparisons showed that time-to-deterioration, treatment delay, age of onset, and amblyopia were factors that did not relate significantly to the incidence of deterioration.