Abstract: A method and apparatus are disclosed for controlling the refractive state of the eye. The image of a visual target is continuously positioned close to, but offset from, the retinal plane of the eye to be controlled. The offset is in such a direction from the retina that as the eye attempts to focus on the image, the refractive state of the eye will change toward the desired goal. To increase the effectiveness of the method and apparatus, the position of the image is continually varied along the optical axis.

Abstract: Apparatus and method is disclosed for measuring refractive properties such as spherical power, cylindrical power, cylindrical axis, etc., which are potentially present in a sphero-cylindrical optical system. Relative movement is effected between an incident light beam and the optical system under test so as to cause the incident beam to effectively move about a pre-defined first locus in the plane of the optical system thereby producing a refracted light beam which moves correspondingly about a second locus in a subsequent plane parallel to the plane of the optical system.