Internally illuminated optometrists test chart

Catalogue Number: 3406
Internally illuminated optometrists test chart
Category: Equipment
Sub-Category: Visual Acuity, Contrast sensitivity tests
Year Of Publication/Manufacture: c 1930
Time Period: 1900 to 1939
Place Of Publication/Manufacture: Sydney/Melbourne, Australia
Publisher/Manufacturer: Optical Products Ltd
Description Of Item: Internally illuminated optometrists' test chart, comprising a wooden light box, 510 W x 770 H x 175 D, painted black with a hinged front panel behind which are 4 separate light boxes fitted with incandescent lamps. The hinged panel has four white translucent plastic panel that locate in front of the light boxes when the hinged front is closed. Three of the light diffusing panels have Snellen letters for the measurement of visual acuity: the largest one has Snellen letter sizes 6/60, 6/30 and 6/21 and two small ones have smaller Snellen letters of size 6/15, 6/12 and 6/9 on one panel and 6/4.5, 6/3 and 6/6 on the other. Below is a large translucent panel bearing an astigmatic fan and a rotating block and V chart for precise determination of the axis and optical power of astigmatism. On the top of the box is a fifth light box and translucent panel bearing two identical letter sets. This is a duochrome test with red and green colour filters behind the diffusing panel. There is a light just above the astigmatism panel for use as a fixation light or a light source for the Maddox rod test. A switch box is affixed to the left side so each light box can be illuminated independently. On the right hand side of the box is a plate bearing the name of the manufacturer 'OPTICAL PRODUCTS SYDNEY & MELBOURNE'.
Historical Significance: This vision test chart is a typical example those commonly used by Australian optometrists from 1930 to 1950. Test charts of this kind were replaced with very similar internally-illuminated test charts but of more sophisticated construction. Catalogue No. 1507 is an example of this later form of the test chart. Internally-illuminated test charts were later replaced by projectors and then by computer controlled video screen. Optical Products, the manufacturer of this item, was a well known wholesale optical supplier with offices and laboratories in both Melbourne and Sydney for a good part of the 20th century. It went into liquidation in August 2013 and deregistered October 2014 See MiVision of that date)
How Acquired: Donated by Optometry Australia(NSW/ACT)
Date Acquired: Aug 2017
Condition: Good
Location: Archive room. West wall.

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