Evaluation of Stereoacuity and Binocular Functions in Patients with Anisometropic Amblyopia Through Titmus, TNO, and Synoptophore

INTRODUCTION: The aim of the study was to evaluate the effect of amblyopia on binocular functions in patients with anisometropic amblyopia.
METHODS: This prospective study was conducted on 45 patients with anisometropic amblyopia. The difference between the best-corrected visual acuities of the two eyes (DVA) for the depth of amblyopia, the spherical equivalent difference between two eyes (D-SE) and root-mean-square spherical equivalent (RMS-SE) for the degree of anisometropia, the Titmus and the TNO tests for the stereoacuity and synoptophore for the fusion capabilities was used.
RESULTS: The mean age was 21.44±7.45 years. Twenty-three patients had moderate-severe amblyopia and 22 had mild amblyopia. There was a correlation between D-SE and TNO and RMS-SE and TNO in the mild group; DVA and Titmus, DVA and TNO, and RMS-SE and Titmus in the moderate-severe group; DVA and RMS-SE, DVA and Titmus, DVA and TNO, and D-SE and TNO in all patients without grouping. The stereoacuity levels were subnormal and decreased in relation to the depth of amblyopia. About 31.1% of patients with the Titmus and 17.8% with the TNO had good stereoacuity. None of the patients could reach the best threshold value with the TNO test. Three patients were able to achieve the best threshold value with the Titmus. All patients had first-degree fusion. About 95% of mild amblyopia and 75% of moderate-severe amblyopia had second and third-degree fusion.
DISCUSSION AND CONCLUSION: This study shows a relationship between the depth of amblyopia and the stereoacuity levels and the amount of anisometropia. The RMS-SE as an anisometropia index and the Titmus or the TNO test as a stereoacuity test may be used to predict the depth of amblyopia in patients with anisometropic amblyopia.