Abstract: A laser interference instrument for determination of the visual acuity of the human eye includes an interference optical system for producing an interference light pattern mounted on a slit lamp microscope disposed on an instrument support that is finely adjustable horizontally and in height. The interference optical system includes a laser light source and a rotatable turntable carrying a plurality of plane parallel plates or wedge plates which may be selectively moved into the light path of the laser light source to produce different interference patterns to be projected onto the human eye and which are then observable through the slit lamp microscope.