[Random dot stereograms and the limits of their detectability].

The influence of contrast reduction combined with aniseikonia on disparities in the TNO test was investigated with monocular induced refractive errors by spherical convex and concave lenses. Single contrast reduction was produced by Bangerter foils. Unilateral near vision of 0.1-0.2 is compatible with a positive TNO test. The average tolerance limit of the TNO test was 6% when produced by monocular induced refractive error. Otherwise, pure aniseikonia values of 5% to 9% produced by overall-size lenses are compatible with the TNO test.