A task to assess dynamic visual acuity and a valuation of the stability of its measurements.

Abstract

Despite the importance of dynamic visual acuity evaluation (DVA), there is hardly any specific measuring instrument that would be consistent and reliable in its evaluation and, at the same time, that would be of easy use. It is also been stated the lack of an evaluation paradigm sensible to the factors previously related to DVA. This was the aim of the proposed task of DVA evaluation, defined as the ability to discriminate details in conditions of relative movement between the subject and the stimulus. With this objective in mind two psychophysics studies were developed. The first one showed that there are three factors modulating DVA: speed, contrast and trajectory of the moving stimulus, with a significant interaction between the two first. In the second study the correlation between DVA, showed by the subjects in three different times, with at least one week (t1 and t2) and two weeks (t2 and t3) was investigated. The correlations oscillated between 0,78-0,92, for a speed of 0.50 m/seg (14,1º/seg.) and between 0,72-0,85 for a speed of 0.05 m/seg (1,4º/seg.). Finally, comparing the average DVA measurements of the three moments no significant differences were found. We conclude that our task constitutes an objective tool of easy application, both experimentally and clinically, and of proved usefulness to evaluate DVA.