An eyesight testing apparatus examines associated heterophoria of the eyes of a subject. The apparatus includes an image generation device having a display unit for generating test patterns for display to the eyes. An optical assembly is arranged on that side of the display unit facing the eyes. This assembly separates light supplied by a first group of selected zones of the display unit from light supplied to a beam path by a second group of selected zones of the display unit. The left eye only receives the light from the first group. The light from the second group only passes to the right eye. The optical assembly includes a prism matrix having a multiplicity of prism portions extending in the vertical direction and each having a lens-shaped region with a convex surface facing the display unit.
