Apparatus for measuring and recording refractive errors of a patient{3 s eye

Claim 1

Apparatus for recording the refractive error measurements of a patient''s eye, said apparatus comprising a light source, an array of target elements illuminated by said light source, first optical means including lens means for directing light rays from each of said target elements toward a predetermined eyeexamination position of said apparatus one of said target elements serving as a reference target element for an emmetropic eye, said lens means having such a focal length and being so positioned as to have its focal plane coincident with said reference target element, each of said target elements being so differently located in the object field of and adjacent the optical axis of said lens means and so differently axially spaced from said lens means as to enable said lens means in conjunction with the lens of the patient''s eye to tend to form images of said target elements at a plurality of different image planes in close proximity to the plane of the retina of said eye, whereby when any other target element is in focus upon the retina of the eye, the distance separating said other target element from said reference target element will be a function of the refractive error of the patient''s eye, each of said target elements being located a predetermined known axial distance from an adjacent target element of said array, film means for receiving and recording light rays reflected from said retina, second optical means including lens means for directing said retina-reflected light rays toward said film means, and image field-flattener means having an exit surface disposed in contacting relation with said film means, and having a plurality of entrance surfaces disposed at such different optical distances respectively from said eye-examination position as to be in conjugate relation to said image planes at said eye position.