To investigate whether ocular sensory dominance (OSD) changes with viewing distance.

Sixty subjects were enrolled in this perspective study. OSD was quantified by a computer-based psychophysics technique that involved the dichoptic presentation of a Mondrian noise and a Gabor patch. The threshold to detect the Gabor patch in the presence of a decreasing contrast of the Mondrian stimulus and increasing contrast of the Gabor stimulus was recorded as the ocular sensory index (OSI). OSI was measured at two different viewing distances, one for near at 60 cm and the other for far at 6 m. A t-test was used to compare the 50 OSI values collected from each eye, and the t-value was used as a subject′s ocular dominance index (ODI).

Qualitative analysis revealed that in 31(52%) subjects, the dominant eyes remained the same for both far and near conditions. In 3(5%) subjects, the dominant eyes switched at far and near distances. In the remaining subjects (26, 43%), ocular dominance was unclear at either far or near. Quantitative analysis showed that the mean ODI changed from-1.88 ± 2.71 at far to-0.72 ± 2.95 at near, which indicated that ocular dominance tended to be more balanced at the near distance (P<0.01). Moving from far to near, in the majority of the subjects (45, 75%), sensory dominance shifted to the original weaker eye, and in only 15(25%) subjects did dominance drift further towards the original stronger eye. The mean amplitude shifting towards the weaker eye (2.66± 0.32) was significantly larger than the amplitude shifting towards the stronger eye (1.04 ± 0.25, P< 0.01).

Compared to viewing at far, the sensory dominance measured at near tends to shift to the original weaker eye, and leads to a more balanced binocular sensory dominance.

Visual perception; Dominance, ocular; Viewing distance