Internally illuminated optometrists test chart

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'.