[Fixation disparity in peripheral and central binocular vision under conditions of prismatic heterophoria (author's transl)].

A critical review of the literature shows that there are controversal interpretations of thephenomenon fixation disparity. The former findings of Ogle and coworkers are ascertained byinvertigator to close the central gap in the fusional patter. Formerly the gap was essentialdue to polarisation techiques. 1. Without central gap fixation disparity decreases, but remainssignificantly different from zero. 2. Diminution or closing of the gap leads to more preciseresults, since the position of the eyes is better controlled. 3. Straining the binocular vision with high prism power cortical tolerances increase when fusion was aided by central stimuli. Fixation disparity could be extended up to 20' (minutes of are) which is three times the well accepted size of the Panum area.