Effects of dominant and nondominant eyes in binocular rivalry.
OBJECTIVE
To investigate the relation between sighting and sensory eye dominance and attempt to quantitatively examine eye dominance using a balance technique based on binocular rivalry.


METHODS
The durations of exclusive visibility of the dominant and nondominant eye target in binocular rivalry were measured in 14 subjects. The dominant eye was determined by using the hole-in-card test (sighting dominance). In study 1, contrast of the target in one eye was fixed at 100% and contrast of the target in the other eye was varied from 100% to 80% to 60% to 40% to 20%, when using rectangular gratings of 1, 2, and 4 cycles per degree (cpd) at 2 degrees, 4 degrees , and 8 degrees in size. In study 2, contrast of the target in the nondominant eye was fixed at 100% and contrast of the target in the dominant eye was varied from 100% to 80% to 60% to 40% to 20%, when using a rectangular grating of 2 cpd at 4 degrees in size.


RESULTS
In study 1, the total duration of exclusive visibilities of the dominant eye target; that is, the target seen by the eye that had sighting dominance was longer compared with that of the nondominant eye target. When using rectangular gratings of 4 cpd, mean total duration of exclusive visibility of the dominant eye target was statistically longer than that of the nondominant eye target (p < 0.05). In study 2, reversals (in which duration of exclusive visibility of the nondominant eye becomes longer than the dominant eye when the contrast of the dominant eye target is decreased) were observed for all contrasts except for 100%.


CONCLUSIONS
The dominant sighting eye identified by the hole-in-card test coincided with the dominant eye as determined by binocular rivalry. The contrast at which reversal occurs indicates the balance point of dominance and seems to be a useful quantitative indicator of eye dominance to clinical applications.
Handa
Tomoya
T
Department of Ophthalmology, Doctor's Program of Medical Science, Kitasato University Graduate School, Kitasato, Sagamihara, Japan. tomoya.handa@nifty.com
Mukuno
Kazuo
K
Uozato
Hiroshi
H
Niida
Takahiro
T
Shoji
Nobuyuki
N
Shimizu
Kimiya
K
D000328:Adult; D023882:Dominance, Ocular / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D015348:Vision, Binocular / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology*