Method and apparatus for measuring contrast sensitivity

Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Subjective type

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351239, A61B 302

Patent

active

045264520

ABSTRACT:
A method is provided for testing the ability of a subject to visually perceive contrast between adjacent fields of different luminance. The subject is presented with a series of visual test patterns, each one of which includes at least two fields of differing luminance resulting in a contrast edge at the interface between the fields. The subject's ability to perceive the edge between the fields is monitored. A series of different test patterns are presented electronically to the subject on a computer-controlled screen which includes one field of constant or fixed luminance and one field of variable luminance. The luminance level of the variable field may be predetermined and varied by the computer in one protocol or controlled by the subject using a subject operated control device as an alternative protocol. In the first protocol, the computer will present on the screen a series of test patterns of different edge width and different contrast and the subject is asked to indicate whether he is able to see an edge. In the second protocol, the computer will present a series of test patterns of different edge widths and the subject is asked to adjust the luminance of the variable field to a point where the transition edge between the two fields is eliminated. In each protocol, the amount of contrast necessary for the subject to perceive an "edge" is measured. The subject's responses in either case are monitored and compared against a control.
In an alternative embodiment, the test patterns may be presented on a screen using a projection device.

REFERENCES:
patent: 3969020 (1976-07-01), Lynn et al.
patent: 4293200 (1981-10-01), Dobson et al.
patent: 4384768 (1983-05-01), Guzman
patent: 4405920 (1983-09-01), Weisstein

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