An Investigation Of Vergence Minification Effects On Measures Of Spatial Vision.

Abstract: Under horizontal prismatic viewing conditions, the literature on macropsia/micropsia would predict altered size perceptions in normal subjects. Little
data exists, however, as to the range of prism powers over which these effects occur.
Moreover, it is undetermined whether these effects are constant and/or predictable across stimulus sizes and for all subjects. We set out to study the effects of a range of base in and out prisms on the apparent sizes of single vertical line (bar) and spatial gratings in a contrast sensitivity test setting at a 3 meters distance. The results suggest that 1. Minification may not be linear with prism-induced vergence in any given patient. 2. The amount of minification for a given amount of disparity vergence stimulus varies among subjects.