[Experiences in the measurements of correspondence using dark red glass and according to image after Cüppers (author's transl)].

The measurement of correspondence using a dark red glass in front of the fixating eye and a foveal after image in the deviating eye according to Cüppers is really an efficient clinical method. In spite of the fact that we are dealing with a dissociating test this method offers these advantages: 1. The objective angle is well known at any time. 2. This method allows a sufficient discrimination in the range of 15 min. of arc. 3. There is a permanent retinal stimulation contrary to the method utilizing after-flash images.--General objections to dissociating tests, for example that given by Goldman, are only limited value, because of the fact that patients with disturbed functions must be differentiated easily from normal persons. Sources of error system mainly from inconcentrated fixation. There is a great demand for attention on the part of the patient. Using this method we have been able to show the 17 cases examined up to now a paradoxical anomaly, demonstrated by a larger subjective angle than the objective angle. Besides that we could prove that lability of correspondence, characteristic for an anomaly, and its alteration depending on which method was used. A paradoxical anomaly was also obtained with other methods such as Hering's after images alone, after image plus real object + Haidinger brushes (synoptophor). From five examples the conditions are presented under which this phenomenon was observed up to the present. The reason of paradoxical anomaly may be seen in the loss of specific ability of cortical cells to localize exactly, especially those cells which are stimulated by foveal area, so that subjective localisation becomes very inexact.