Visual acuity threshold as a function of size of the blind spot

Abstract

In our previous research it was found that the perceived apparent movement between two points across the blind spot was faster than that between two points located above the blind spot, when distance between two points was kept constant. Furthermore, a high correlation between perceived movement and the size of blind spot was obtained (r = 0.87 with p = 0.05). Thus, a larger blind spot contributed to the perception of faster apparent movement when the distance between two spots remained constant. The present research examines the effects of size of blind spot on visual acuity threshold. Eight graduate students whose size of blind spots differed from each other served as subjects. A homemade perimeter presented Vernier acuity stimuli. A 2 × 2 factorial analysis was used. The first two factors in the analysis were vertical height and horizontal width of the blind spot; the second two factors were two points across the blind spot and upper retinal two points which were 2 cm above the blind spot. The acuity thresholds were measured by the method of limits. A high correlation between visual acuity threshold and the size of blind spot was obtained (r = 0.67 with p = 0.05) with the horizontal width. However, the visual acuity threshold was not significantly influenced by the vertical height of the blind spot.