Patent References 3669530 Shunt for providing a direct electrical connection Automatic refraction apparatus and method Patent #: 4105302 InventorsAssigneeApplicationNo. 05/838178 filed on 09/30/1977US Classes:351/237, Including target image projection351/241, Astigmatism type351/243IlluminatedExaminersPrimary: Corbin, John K.Assistant: Bovernick, Rodney B. Attorney, Agent or FirmInternational ClassA61B 3/13 (20060101)AbstractA compact ophthalmic instrument for refraction of patient's eyes is obtained by substantial folding of the optical system. The optical system is folded in one location using a reflection means that moves to vary the location of a target image being viewed by a patient for identifying the spherical power of a corrective lens, if any, required by the patient. A second folded portion of the optical system contains a cylinder means for cylindrically varying the target image. | |