GB597062A - An improved instrument for use in retinoscopy - Google Patents

Abstract

597,062. Sight-testing instruments. PHILLIPS, R. A. July 31, 1945, No. 19692. [Class 97 (i)] An instrument for use in retinoscopy consists of a frame mounting a plane semi-transparent reflector, whereby the patient's eye placed before the mirror may be focused on the image of an object formed by reflection in the mirror, the line of vision between the patient and the observer passing through the mirror, and a convex lens which serves to bring the light from the patient's eye to a focus at the observer's eye is provided between the mirror and the observer in the line of vision. Correcting lenses may also be placed in the line of vision either on the observer's side or the patient's side of the mirror. As shown in Fig. 1, the instrument is mounted on a stand 2, a lamp 3 projecting light through a sighting chart 5 on to a mirror 6, conveniently placed in a dark room to reflect the light on to a metallised mirror 7, which co-operates with a semi-transparent mirror 8, in the form of a parallel-sided glass plate or a narrow angle prism, so that a patient A looking through an aperture in the stand views an image of the chart 5. The observer B employs a retinoscope 1 to examine each eye in turn, correcting lenses being placed in the line of vision A-B and a convex lens, bringing the light to a focus on the observer's retina, is mounted in a holder 9 which is slidable along a bar 10 supported as at 11. The correcting lenses may be mounted in the line of vision on either side of the mirror 8 in a frame containing a slidably mounted lens holder held in position on the frame by spring means. The mirror 8 may be wider than the spacing between the patient's eyes and movable across the optical axis to block one of the eyes from the observer's view by one of the silvered portions at each end of the mirror. In another embodiment, light from the lamp may pass through collimating lenses on to the transparent mirror. The instrument may be monocular or binocular. Specification 449,830 is referred to.