Eye Movements, Strabismus, Amblyopia, and Neuro-Ophthalmology Directional Asymmetries in Human Smooth Pursuit Eye Movements

Citation: Ke SR, Lam J, Pai DK, Spering M. Directional asymmetries in human smooth pursuit eye movements. Invest Ophthalmol Vis Sci. 2013;54:4409–4421. DOI:10.1167/iovs.12-11369 PURPOSE. Humans make smooth pursuit eye movements to bring the image of a moving object onto the fovea. Although pursuit accuracy is critical to prevent motion blur, the eye often falls behind the target. Previous studies suggest that pursuit accuracy differs between motion directions. Here, we systematically assess asymmetries in smooth pursuit. METHODS. In experiment 1, binocular eye movements were recorded while observers (n 1⁄4 20) tracked a small spot of light moving along one of four cardinal or diagonal axes across a featureless background. We analyzed pursuit latency, acceleration, peak velocity, gain, and catch-up saccade latency, number, and amplitude. In experiment 2 (n 1⁄4 22), we examined the effects of spatial location and constrained stimulus motion within the upper or lower visual field.