To diagnose binocular vision, to determine the leading and trailing eyes, a red-green or polarizing filter is used in conjunction with a sign projector. Diagnostics is carried out on the appropriate tests of the projector itself.

The four-point color test, available in the sign projector, facilitates the diagnosis process and the correct diagnosis.

A specific projector test makes it possible to diagnose binocular vision by separating fields with a polarizing filter. In the presence of binocular vision, the patient sees a volumetric object through a polarizing filter.

The image of the stereoscopic test of the sign projector is projected onto its own screen, which has this effect.