The Association between Different Ocular Dominance and Fixation Preferences in Adolescents with Intermittent Exotropia

Objective: To investigate the association between different ocular dominance and fixation preferences in adolescents with intermittent exotropia (IXT). Methods: In this case serial study, a total of 43 patients with IXT from Aier Institute of Optometry and Vision Science from July to December 2018 participated. With full refractive error correction, the hole-in-the-card test was used to identify sighting dominance, the near point of convergence test was used to determine motor dominance, and a continuous flash technique based on a Gabor patch was used to determine ocular sensory dominance. The preferred eye for fixation was determined by Mayo's office control scale when observing a target at long distance. The degree of agreement between the dominant eye and the preferred eye for fixation was quantified with Kappa statistics. And the association between the above-mentioned concordance and ocular dominance index (ODI) was analyzed by logistic regression. Results: For a total of 43 patients with IXT, sighting dominance, motor dominance, and sensory dominance showed moderate agreement with fixation preference (the Kappa values were 0.46, 0.43, and 0.68, respectively, P<0.001). When there was a clear sensory dominance, the agreement between the sensory dominant eye and the preferred fixation eye was fairly high (Kappa values was 0.86, P<0.001), while the agreements of the other two kinds of ocular dominance and fixation preference were still moderate (the Kappa values were 0.57 and 0.44, respectively, P<0.01). Logistic regression showed that the probability for the preferred fixation eye to agree with the sensory dominant eye increased with the value of ODI (B=0.53, OR=1.70, P<0.001), the greater the ODI value, the higher the probability for agreement between the sensory dominant eye and the preferred fixation eye. Conclusion: For IXT adolescents, there is a consistent relationship between ocular dominance and fixation preference. The results of sensory ocular dominance are more closely related to the preferred eye for fixation, especially when there is a clear sensory dominance, which is more reliable than a sighting dominance test or motor dominance test. Key words: intermittent exotropia; ocular dominance; fixation preference; adolescents