Catalogue Number: 1645
Friedmann visual field analyser Mark I
Sub-Category: Perimeter, visual field analyser
Designer/inventor: FRIEDMANN A I
Year Of Publication/Manufacture: c 1970
Time Period: 1940 to 1999
Place Of Publication/Manufacture: England
Publisher/Manufacturer: Clement Clarke International Ltd
Description Of Item: An instrument for testing central visual fields using static perimetry. Blue-green metal construction: a light source bowl mounted on a base provides illumination on the internal surface of a flat black screen with 47 holes providing the test stimuli. An internal mask operated by a sliding knob on the top of the bowl sets the choice of 15 configurations of test stimuli. A vertical slide, also on the top of the bowl introduces filters to vary stimulus colour. Controls on the back face of the bowl vary stimulus intensity and there is a red 'firing' button to activate the stimulus presentations. A chin and forehead rest also mounted on the base has provision for inserting corrective lenses and a light source to illuminate the external face of the stimulus screen. Power cord and response button on an electrical lead. Makers Plate inscribed 'Clement Clark International Ltd Serial No 2128 Cat No 650 Made in England' Plastic box fixed on the base contains spare globes and fuses. Its lid lists Patents in several countries.
Historical Significance: Perimetry has a long history but was revolutionised by the introduction of automated static perimetry in the 1980s. The Friedmann VFA is a precursor to automated static perimetry. Von Graefe is credited with introducing perimetry in 1855 when he published "Examination of the Visual Functions in Amblyopic Affections." He used a crude tangent screen for his investigations. It was not until 1869 that the arc perimeter was devised by Aubert and Forster. Danish ophthalmologist Jannik Bjerrum (1851-1920), advanced the idea of testing central fields using a tangent screen in the closing years of the 19th C. Goldmann and Traquair (1875-1954) standarised measurement of visual fields by better instruments (the Goldmann Perimeter) and standardised targets (in the Goldmann perimeter in 1945 and Traquair targets for central field testing). Automated static perimetry began with the automation of the Goldmann bowl in 1980 followed by the development of instruments such as the Octopus and Humphrey visual field analysers that used projection stimili in the bowl. Friedman devised this instrument in 1966[Friedmann AI. Serial analysis of changes in visual field defects employing a newinstrument to determine the activity of diseases involving the visual pathway.Ophthalmologica 1966; 152: 1-12]. Mark II was produced in 1979 and it had 99 stimuli and was more automated. Friedmann is a British ophthalmologist. His 1966 paper on this instrument gives his address as the Royal College of Surgeons and the Royal Eye Hospital London. He was research active between 1955 and 1989.
How Acquired: Donated by Ian Douglas, member of the College
Date Acquired: 2007
Condition: Very good
Location: Archive office. East wall shelves unit 1