LOW SPATIAL FREQUENCY SUPPRESSION DURING VERTICAL SACCADIC EYE MOVEMENTS

Purpose Contrast sensitivity reduction to low spatial frequency stimuli has previously been found to occur around the time of onset of both horizontal saccadic and vergence eye movements. In this study we aim to examine whether similar reductions in contrast sensitivity occur during vertical saccadic eye movements. Methods Contrast sensitivity during vertical saccadic eye movements were measured in six young optically corrected adults (Mean age (±SD) was 25.5 ± 7.5 years). We used vertical sinusoidal grating of 0.5c/deg as a test stimuli. Two computer generated white fixation crosses (4 deg above and below the horizontal) were used to initiate the vertical saccades. Infrared video eye tracker (EyeLink I) was used to record binocular eye movements. The test stimulus was presented at various time lags across the saccadic response range. Detection thresholds measured during the vertical saccade (single interval yes/no procedure and method of constant stimuli) was compared to static thresholds. Results Average onset latencies and velocities for vertical saccades in all experimental conditions did not differ significantly among subjects (mean latency = 166 ± 2.7ms, mean velocity = 194 ± 63deg/sec). A statistically significant reduction in contrast sensitivity was found in all subjects (mean reduction 0.24 ± 0.05, p< 0.05) around the onset (-50 to +100 ms) of the fixation change when compared to static condition values. Conclusion Reduced contrast sensitivity to low spatial frequency information was found around the onset of vertical saccadic eye movements. The magnitude and timing of the reduction is similar to previous values found during horizontal saccadic and vergence eye movements. Meeting abstract presented at VSS 2015