Contrast Sensitivity and Ocular Microtremor: A Model Study of Gravity Effects on Visual Perception

Abstract: An assessment was made of visual contrast sensitivity and tremor micromovements of the eyes under conditions of “dry” immersion (DI), which simulates the physiological effects of weightlessness in the human body. Visual contrast sensitivity and ocular microtremor were evaluated in 10 human subjects (mean age 30.8 ± 4.6 years) during dry immersion (DI) as a model of the physiological effects of microgravity. Contrast sensitivity was assessed by visocontrastmetry upon presentation of Gabor patches with spatial frequencies of 0.4, 1.0, 3.0, 6.0, and 10.0 cycles per degree (cpd). The amplitude and frequency of ocular microtremor were measured using a high-frequency optical tweezer. Measurements were performed a day prior to DI; on DI days 1, 3, 5, and 7; and on the next day after DI completion. Contrast sensitivity was found to be altered within both low and high spatial frequencies; ocular microtremor amplitudes changed within a wide range. At this point in time, the findings are a step forward in searching for a method to objectively assess the function of the central nervous system in a changed environment. © 2023, Pleiades Publishing, Inc.