With this study the investigator wants measure the individual cyclofusion competence from healthy subjects and patients suffering from Strabismus with a only binocularly visible threedimensional Landolt-C stimulus. For this the participant has to look at a 3-D monitor with shutter glasses. The participant is sitting in 2 meter distance in front of the monitor. On the monitor appears the Landolt-C stimulus as a dynamic Random-Dot Stimulus. As long as the participant can fuse the stimulus he will be able to see the Landolt C-ring threedimensional. The participant is then ask to tell in which direction the notch of the Landolt-C ring points out. Once a critical degree of cyclotorsion is reached the participant will no longer be able to see the Landolt C ring and the individual cyclofusion competence is reached.

Inclusion Criteria:

• Visual acuity >0,4; Stereopsis

Exclusion Criteria:

• Visual acuity <0,4; no Stereopsis