Human Gaze Following Response Is Affected by Visual Acuity

The present study investigated how gaze following eye movements are affected by stimulus contrast and spatial frequency and by aberrations in central visual acuity due to refractive errors. We measured 30 healthy subjects with a range of visual acuities but without any refractive correction. Visual acuity was tested using a Landolt-C chart. Subjects were divided into three groups with low, intermediate, or good visual acuity. Gaze following responses (GFR) to moving Gabor patches were recorded by video-oculography. In each trial, the subjects were presented with a single Gabor patch with a specific spatial frequency and luminance contrast that moved sinusoidally in the horizontal plane. We observed that GFR gain decreased with increasing spatial frequency and decreasing contrast and was correlated with visual acuity. GFR gain was lower and decreased more for subjects with lower visual acuity; this was especially so for lower stimulus contrasts that are not tested in standard acuity tests. The largest differences between the groups were observed at spatial frequencies around 4 cpd and at contrasts up to 10%. Aberrations in central visual acuity due to refractive errors affect the GFR response depending on the contrast and spatial frequency of the moving stimulus. Measuring this effect may contribute to a better estimate of changes in visual function as a result of aging, disease, or treatments meant to improve vision.