Cardell Optometer for domicillary eye sight testing
 Catalogue Number: 2915 Cardell Optometer for domicillary eye sight testing Category: Equipment Sub-Category: Optometer Designer/inventor: J D Magor Cardell Year Of Publication/Manufacture: After 1934 Time Period: 1940 to 1999 Place Of Publication/Manufacture: London Publisher/Manufacturer: Rayner Optical Ltd Description Of Item: An instrument for subjectively determining refracting errors, black metal tube with a lens at one end and a frosted glass plate at the other on the inside surface of which is engraved a target comprised of two blocks of black lines oriented at right angles to each other and an arrow between the two blocks. The target end can be rotated by the observer to find the orientation of the targets at which one block is clearest and the other block least distinct. An external scale measures the angle of rotation. An arm with chromed metal cheek rest positions the observer, Historical Significance: This instrument is basically a collimator designed to be used with a trial frame and lenses. It was devised by J D M Cardell in 1934 as an easily portable instrument for domicillary testing of vision. See J Roy Soc Med 1934; 27: 303 -305. The cap is interchangeable with target caps for astigmatism and Snellen visual acuity, but this example only has the asigmatism cap, the others presumably being lost. The cheek rest ensures there is space for the patient to be wearing a trial frame and for the examiner to be able to rotate a Jackson cross cylinder to determine the power and axis of astimatism How Acquired: Donated by Estate of William Cooper, via Peter Lewis Date Acquired: Apr 2016 Condition: Good except some black enamel has flaked off at the scale end Location: Archive room. West wall. Unit 4 Drawer 5 |