Eye testing device

Details Eye testing device Eye testing device

1978-01-03

1980-07-15

Corbin, John K.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Folding

351 3Z, A61B 302

Patent

active

042125200

ABSTRACT:
The eye testing device for testing visual acuity includes a light-colored, opaque front chart having a plurality of cut-out openings in the shape of letters, numerals, or similar characters and a black box located behind the chart for absorbing ambient light transmitted through the cut-out openings and thereby providing a 100% contrast for the indicia or characters defined by the cut-out openings. In one embodiment, the device includes a plurality of panels or cards which vary in color intensity, e.g., from white to pitch black. Individual panels can be moved adjacent the back side of the chart to vary the degree of contrast perceived at the cut-out openings.

REFERENCES:
patent: 800521 (1905-09-01), Watson
patent: 931188 (1909-08-01), Ellis
patent: 2231743 (1941-02-01), Young et al.
patent: 2817913 (1957-12-01), Meyer
patent: 3469904 (1969-09-01), Allen
Luckiesh, Test Charts Representing a Variety of Visual Tasks, Mar. 1944, American Journ. of Ophth.

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