The Ratio of Accommodative-Convergence to Accommodation in Patients with Nonrefractive Accommodative Esotropia

ABSTRACT

PURPOSE: To measure the ratio of accommodative-convergence to accommodation (AC/A ratio) in patients with nonrefractive accommodative esotropia in comparison to refractive accommodative esotropia and normal groups. METHODS: A total of 43 subjects were divided into 3 groups the nonrefractive accommodative esotropia group (group 1), the refractive accommodative esotropia group (group 2) and the normal group (group 3). Age, sex, age of onset, and refractive errors were recorded. The deviation angle was measured near and at distance by using a prism cover test. The AC/A ratio was calculated using a gradient method. RESULTS: Refractive errors were 2.3 +/- 1.7 D (OD) and 2.4 +/- 2.1 D (OS) in group 1, 4.8 +/- 0.9 D (OD) and 4.6 +/- 1.1 D (OS) in group 2, and -0.3 +/- 1.5 D (OD) and -0.5 +/- 1.5 D (OS) in group 3. Group 2 had higher mean refractive errors than groups 1 and 3, while the difference in refractive error between group 1 and group 3 was not statistically significant. The AC/A ratio was 5.5 in group 1, 2.1 in group 2 and 2.2 in group 3; there was no significant difference between groups 2 and 3, while group 1 had a significantly higher AC/A ratio than both of these groups. CONCLUSIONS: AC/A ratio in patients with nonrefractive accommodative esotropia is higher than that of refractive accommodative esotropia or normal children. It could be used for bifocal lens as non-surgical treatment.