A binocular multiplexing device for a single-channel ophthalmological instrument for objective measurement of at least one vision parameter of a subject, the ophthalmological instrument including elements for generating a single light beam, elements for collecting a measurement beam by reflecting and/or refracting the light beam against the subject's eye and a sensor associated with the single measurement channel. The binocular multiplexing device includes optical separation first elements for receiving an image beam originating from a stimulus target and separating the image beam into a right and left ocular stimulation beam; optical switching elements for switching the single light beam selectively onto a right or left monocular light beam's optical path to form, after reflection and/or refraction by the eye in question, a right, respectively left, ocular measurement beam, and optical combination elements for superimposing the right, respectively left, ocular stimulation beam, and the right, respectively left, monocular light beam.