The Comparison of Binocular Function of Basic and Simulated Divergence Excess Type in Intermittent Exotropia

ABSTRACT

PURPOSE: The purpose of this study was to evaluate and compare the binocular function in patients with basic and simulated divergence excess types of intermittent exotropia [X(T)]. METHODS: Seventy-seven patients, 46 basic type and 31 simulated divergence excess type, were studied by Worth 4-dot test (W4D), Polarized 4-dot test (P4D), Titmus test, and distance stereoacuity test using Mentor B-VAT(R)II videoacuity tester. RESULTS: Near W4D, distant W4D and distant P4D were fused in 71.7%, 8.6% and 52.2% in basic type and in 100%, 25.8% and 87.1% in simulated divergence excess type, respectively. The fusion rate in simulated divergence excess type was significantly higher, than in basic type (P=0.001, 0.04, 0.001). However, the difference in near P4D between the two types was not significant (P=0.24). In distance stereoacuity test, basic type showed 272 seconds and simulated divergence excess type showed 177 seconds, showing a significant difference (P=0.02). There was no significant difference in near stereoacuity between the two types (P=0.08). CONCLUSIONS: The study demonstrated a difference in binocular function in patients with basic and simulated divergence excess types of X(T). A better binocular function was observed in the latter group.