A continuation of the study of the clinical stereo field test

Abstract

This is an extension of a previous study to develop a simple stereoscope test to determine the extent of the stereofield [maximum parallactic angle]. An additional test card was developed along with an additional instructional set to determine the effects of instructed fixations on the phenomenal extent of the stereofield. Using a Brewster stereoscope at a shaft setting of 1.25 diopters [or 80 em], 61 volunteer subjects viewed the 4 test cards with each of the four different instructional sets. Significant differences were found in the magnitude of the stereofield with various instructions. The magnitude of the stereofield was compared to accommodative and convergence index scores, which were calculated from the data on the subjects 21 point eye examination, by a computer program developed by Professor Harold Haynes. Little relationship was found between the magnitudes of the Ai and Ci scores and the stereofield