Relation between Visual Acuity and Slope of Psychometric Function in Young Adults

Mita et al. (2010) devised a technique of comparing a visual acuity (VA) change in an individual with more accurate VA than conventional VA tests by significant difference examined logarithmic (Log) VA ± standard deviation (SD). Using this technique, in this study, we examined a relation between VA and the slope of the psychometric function in normal young subjects. Six occlusion foil conditions were employed (1.0, 0.8, 0.6, 0.4, 0.1 and without the foil) under a full refractive correction. Ten normal young adults (22.8 years old on average) who have no ophthalmologic disease except ametropia participated in the measurement. The experiment was carried out with the constant method, a series of ten Landolt rings were used and each ring was presented 20 times randomly in a measurement. A 5.6-inch type of liquid crystal display driven by a computer, which has 1,280×800 pixels spatial resolution, was used to present the stimulus. In the normal young adults, the slope of the psychometric function did not change as the VA change systematically, and there was almost no correlation between them (r = −0.103).