Development of Dynamic Contrast Sensitivity Chart.

Abstract

Dynamic visual acuity (DVA) is a complex visual function that requires the observer to detect a moving target, to visually acquire it by eye movements, and to resolve critical details contained in it, in a relatively brief time exposure. Dynamic contrast sensitivity (DCS) functions are determined over a range of angular velocities to complement the traditional contrast sensitivity (CS) functions (obtained with stationary targets). A new chart is constructed to assess DCS by chosen 5×5 grid and Sloan letters (D, H, N, U, V, R, Z, S, K, O, C). Letters are constructed at a constant visual acuity of six lines having the contrast varied at each interval of the line. Each line has six letters and each line subtends different contrast (0.20 logCS-1.70 logCS). The chart has a motor of 45 revolutions per minute (rpm) and 30 rpm and measured among the normal population of the age group of 17 to 30. Results shows that CS declines once the target stimulus is in motion. There was a statistically significant difference (p < 0.05) between the stimulus speeds of 30 rpm and 45 rpm. Dynamic contrast sensitivity values increased for lower target velocity indicating that as speed of the target stimulus increases, CS decreases. This study concludes that the DCS decreases as the velocity increases. Consequently, incorporating the DCS chart into comprehensive eye examinations provides a holistic understanding of an individual's visual function.