Pupillometer made by adapting a trial frame

Catalogue Number: 2892
Pupillometer made by adapting a trial frame
Category: Equipment
Sub-Category: PD ruler, pupillometer
Year Of Publication/Manufacture: 1920 to 1940
Time Period: 1900 to 1939
Place Of Publication/Manufacture: Germany
Description Of Item: Trial frame, 108 x 50 mm, adapted for use as a pupillometer to measure the distance between the centre of the pupils of the two eyes. Base metal construction. Two circular eye rims from which the usual semicircular cells for holding trial lenses appear to have been removed and a vertical wire added, presumably for the purpose of alignment with the centres of the pupils. Both eye rims have white plastic cylindrical lens axis scales. The separation of the eye rims is adjustable by two independently operating screws with a horizontal scale in mm for reading the uniocular pupillary distance in mm for each eye. There is an nose rest adjustable for both height and vertex distance. Curl sides adjustable for length with scales to measure side length. Marked D.R.G.M on back of the horizontal eye separation scale
Historical Significance: This is an elaborate trial frame with some novel mechanical features. The mark D.R.G.M signifies the design was registered with the Deutsches Reiches Gebrauchs Musterschutz under German law to protect the product. Its adaptation as a pupillometer signifies the importance early optometrists placed on fitting spectacle frames and locating the optical centres correctly.
How Acquired: Donated by Estate of William Cooper, via Peter Lewis
Date Acquired: May 2016
Condition: Good except for light corrosion on front rims and nose rest
Location: Archive office. East wall shelves unit 3. Drawer 10

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