Quantifying Sensory Eye Dominance in the Normal Visual System: A New Technique and Insights into Variation across Traditional Tests

Abstract

PURPOSE.Although eye dominance assessment is used to assist clinical decision-making, current understanding is limited by inconsistencies across the range of available tests. A new psychophysical test of sensory eye dominance has been developed that objectively measures the relative contribution of each eye to a fused suprathreshold binocular percept. METHODS. Six standard tests and the newly developed test were used to measure motor and sensory dominance in a group of 44 binocularly normal individuals (mean age, 29.5 Ϯ 9.10 years). The new test required observers to perform a motion coherence task under dichoptic viewing conditions, wherein a population of moving, luminance-defined signal (coherently moving) and noise (randomly moving) dots were presented separately to each eye. The observers judged the motion direction of the signal dots. Motion coherence thresholds were measured by varying the ratio of signal-to-noise dots, in a staircase procedure. RESULTS. The new dichoptic motion coherence threshold test revealed a clear bimodal distribution of sensory eye dominance strength, wherein the majority of the participants (61%) showed weak dominance, but a significant minority (39%) showed strong dominance. Subsequent analysis revealed that the strong-dominance group showed greater consistency across the range of traditional eye dominance tests used. CONCLUSIONS. This new quantitative dichoptic motion coherence threshold technique suggests that there are two separate sensory eye dominance strength distributions among observers with normal binocular vision: weak and strong eye dominance. This finding may provide a basis for clinical decision-making by indicating whether eye dominance is likely to be an important consideration in a particular patient. (Invest Ophthalmol Vis Sci. 2010;51:6875-6881)

A comparison of tests for quantifying sensory eye dominance

“…Rather than directly asking observers to make a judgement about contrast similarity (as required for e.g. the Sbisa bar), 85 psychometric assessment tends to rely on forced-choice methods (for a study that linked traditional clinical methods of SED to a common psychophysical measure see Li, Lam et al 2010). Pairing robust psychophysical judgements with carefully-designed stimuli allows assessment of the relative contribution of each eye to visual processing in different stages of the cortical hierarchy.…”

“…Reported position allows one to determine the interocular 95 contrast difference that supports equal contribution from each eye, and it is this contrast difference that quantifies "binocular balance". Another test embeds contrast manipulation within a global processing task (Mansouri, Thompson et al 2008, Li, Lam et al 2010, Black, Thompson et al 2011, Hamm, Chen et al 2017. In motion coherence paradigms (Li, Lam et al 2010), the observers are required to discriminate the direction of a pattern of 100 moving dots, comprised of signal-dots (moving in one direction) and noise-dots (moving in random directions).…”

Balanced Eyes See Stereopsis More Quickly, but Not More Finely

“…Neither method directly measures the relative sensitivity of the visual part of the brain to visual signals from the two eyes. 23,24 In the current study, we measured ocular sensory dominance and quantified it with the ocular dominance index for each subject, and subsequently identified the dominant eye. The aim of this study is to provide a quantitative assessment of …”

The Measurement and Treatment of Suppression in Amblyopia

“…The contrast offset at which neither eye has a performance advantage is a measure of the "balance point" and is a direct measure of suppression. This technique has been validated psychophysically both in control 13,14 and patient 6,9,11 populations.…”