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Prisoptometer - Dr Culbertson's Prisoptometer

From the Collection of The Cyril Kett Optometry Museum Australian College of Optometry Corner Keppel & Cardigan Streets Carlton Victoria

Description
This instrument is an optometer, that is, a device to measure the refractive error of an eye. It is made of cast iron, steel, brass and glass. It contains a prism which could be rotated, and was used to view a disc or an object circle. The prism caused monocular doubling of the object circle and the separation of the two images varied as the prism rotated, depending on the astigmatism present. The axis of the astigmatism was indicated by the prisoptometer and trial lenses were used to determine the the magnitude of the spherical and cylindrical refractive error
Size
L:55cm x W:21cm
Object Registration
4003
Keywords
optometry, prisoptometer, optometer, astigmatism, refractive error, refraction, culbertson
Historical information
How widely the prisoptometer was used is unclear but the Standard Optical Company later patented a new model, The Standard Prisoptometer, on June 21, 1904. Edward Jackson's crossed cylinder technique of determining astigmatism was first detailed in the Transactions of the American Ophthalmological Society (1887)4:595-598. The convenience of Jackson's crossed cylinder lenses over the prisoptometer in weight, cost, portability and reliability meant that they were soon almost universally adopted.
When Made
1886 (estimated); late 19th century
Made By
Geneva Optical Company (Maker)
Significance
This is a rare item as few are known world wide.
Inscriptions & Markings
Imprinted:"DR CULBERTSON'S PRISOPTOMETER/ GENEVA OPTICAL COMPANY MAKERS, GENEVA, N.Y./ PATENTED SEPT, 21, 1886". Stamped "853" on eyepiece and lens mounting.
Last updated
3 Mar 2017 at 10:09AM