Optical test chart for testing binocular reading ability

Abstract

Abstract An optical test chart for testing binocular vision. The chart has three lines of text, with the middle line printed or marked in letters or characters which have no polarizing effect. The line above this middle line is marked in letters or characters which have the effect of polarizing light reflected from them, in a plane of polarization in one direction, while the line below the middle line is similarly marked with letters or characters having the effect of polarizing reflected light but with the plane of polarization in a different direction at a substantial angle, preferably a right angle, to the direction of polarization caused by the upper line. The person whose vision is being tested views the test chart through polarizing spectacles, the spectacle in front of one eye having a plane of polarization corresponding to that of the upper line of text on the chart, and the spectacle in front of the other eye having a plane of polarization corresponding to that of the lower line of the text. If the person being tested perceives all three lines of the text with equal contrast, he has normal binocular vision or reading ability. If he perceives a difference in contrast between the different lines on the chart, or if he is unable to read either the top or bottom line, his binocular reading ability is impaired, and the kind of impairment can be determined by determining what he is able to read. Preferably a series of such test charts with the text in letters of different size are mounted displaceably on a lectern or easel, so that the chart sheets may be selectively turned to test the subject with lettering of different size, to determine the minimum size which the subject can read, thus establishing his visual acuity as well as his binocular reading ability.

Inventors

• 👤 Heinz Gottlob
• 👤 Horst Falk

Bibliographic Details