Evaluating Online Measures of Contrast Sensitivity and Visual Acuity

Good visual acuity (VA) and contrast sensitivity (CS) are essential for many behaviours (from reading to driving), and tests of visual function have become crucial for many purposes. Clinicians and researchers administer the clinically validated versions of these tests under carefully controlled lighting conditions. However, the rapid expansion of online testing highlights the great utility of having these tests available in digital format. We conducted two experiments to determine whether accurate and reliable online testing of VA and CS is possible. Firstly, participants completed both the Online and Clinical measures of CS and VA in one session and the Online measures in a separate session. Secondly, we artificially degraded vision (using 0.4 logMAR Bangerter filters) in three different visual conditions (full vision, monocular blur and binocular blur) and again compared the Online and clinical tests. The results showed that the Online tests of CS and VA provided a reasonable estimation of CS and VA with little to no bias compared to their clinical equivalent. However, the Online tests were affected by increased noise compared to the clinical tests. The Online tests were sensitive to changing levels of visual blur and were robust to poorly calibrated visual displays. We conclude that our Online measures provide a valid, reliable and robust option for the mass testing of CS and VA.