[The Goldmann Memorial Lecture--historical and current aspects of stereopsis]

According to Goldmann stereopsis is the highest performance of binocular recognition. A historical review shows that binocular stereopsis was explained only in 1838 by Wheatstone, whereas the monocular clues for stereopsis e.g. size, position and covering of the objects, light and shadow, perspective of the air, parallax and linear perspective were known long ago. The denomination depth perception is ambiguous: "depth" is the opposite of "height". Stereopsis means natural recognition of distance and objects in space, stereoscopy means recognition by the aide of an instrument. Natural and dichoptic stereopsis and the influences of vertical structures, of pupillary distance and of astigmatism are discussed. Examination of stereopsis is discussed, among others the two pencil test, the stereo-modification Bagolini-glasses, the combination of the plano-cylinders of W. R. Hess with random dots without glasses, the disk stereopsis etc. Goldmann's theory of binocular vision helps to understand different forms of strabismus, e.g. the statistical interplay of fixation and fusion for microtropia, the fixation mechanism for the congenital strabismus syndrome, the use of binocular stereopsis only for near explains intermittent divergence.