Visual acuity tester

Details Visual acuity tester Visual acuity tester

1975-09-03

1976-11-16

Dixon, Harold A.

Optics: eye examining, vision testing and correcting

Spectacles and eyeglasses

Folding

351 13, 351 30, A61B 314

Patent

active

039920879

ABSTRACT:
A device for objectively determining visual acuity includes a viewing screen on which a moving spot of light of diminishing intensity is projected. Infrared eye tracking sensors scan the eyes of the subject and generate a voltage analog signal of the eyes' position. The position signal is compared with a signal representing the position of the moving spot, and the difference is fed to a threshold detector circuit. As the spot becomes too dim to be seen by the subject, the eyes fail to track the spot, and the difference between the two signals surpasses the threshold of the detector circuit. The brightness of the spot when last tracked successfully, which correlates with standard visual acuity measurements, is then displayed as the visual acuity of the subject.

REFERENCES:
patent: 3473868 (1969-10-01), Young et al.
patent: 3679295 (1972-07-01), Newman
patent: 3827789 (1974-08-01), Molner

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