Catalogue Number: 2053
Sub-Category: Equipment, other clinical
Designer/inventor: BIESSELS W J
Year Of Publication/Manufacture: c 1968
Time Period: 1940 to 1999
Place Of Publication/Manufacture: West Germany
Publisher/Manufacturer: Carl Zeiss
Description Of Item: An accessory for a refractor (phoropter) for making simultaneous comparisons in subjective refraction. It is an image spliting device that produces monocular diplopia so that + and - 0.25 DS views can be compared side by side in one mode. In the other mode it acts as a cross cylinder test but with simultaneous comparisons of the two images rather than successive. Packed in a black boxed embossed 'CARL ZEISS Made in West Germany'. Box: 8.8 x 8.8 x 5.2cm. US Pat No 3240548.
Historical Significance: This test is described by its inventor W J Biessels of the Hague Holland in a paper in the Optician 1957 Jun 7; 133: 533-536, 541 and J Amer Optom Assoc 1968; 38: 473-476. In the latter paper it is described as planned for production by Carl Zeiss in 1967. A paper by EJ Daniels in the Optician 1968; 156: 83-85 shows a picture of the then newly released Zeiss instrument.
How Acquired: Donated by Ian Douglas
Date Acquired: 03.04.2012
Location: Archive room. West wall. Unit 6 Drawer 4