Correlation between hand preference and distance of focusing points of two eyes in the horizontal plane.

Relationships among hand preference, ocular dominance, and the degree of ocular shifting were studied in 78 right-handed and 16 left-handed subjects. Ocular dominance was assessed with the Miles test. The shifting degree of eye was assessed using a modified Miles test. The shifting distance of the right-eye was marginally greater, although significant, in the left-handers as compared to the right-handers. The shifting distance of the left-eye was greater in the right-handers than in the left-handers. The distance of focusing points of two eyes in the horizontal plane was greater in the right-handers than in the left-handers. In the total sample, there was a significant negative Pearson correlation between hand-preference and the shifting distance of the right-eye, and there was a positive correlation between hand-preference and the shifting distance of the left-eye. In addition, there was a significant positive correlation between hand preference and the distance of focusing points of two eyes. These results suggest that hand preference may be related to the degree of ocular asymmetry.