Worth 4 dot test

The Worth - test (also: Four lights test according Worth) is an investigational procedure mean degree of dissociation, which is in the squint medicine ( Strabismus ) for the qualitative examination of simultaneous vision and fusion used and thus indicates latent or manifest squint deviations. It is suitable for implementation in both distance and near.

Implementation

In the investigation the respondent with a red-green glasses or a simple red-green filter is kept to color separate the visual impressions of the right and left eye. He then considered at a distance of five meters, four diamond- shaped arrangement lights. The upper light is red, the middle two lights right and left each green. The lower light is white. Thanks to the pre -preserved color filters the white light is only visible with both eyes, depending on dominance in a mixed color or red and green alternately. The upper red light is, however, eliminated by the green color filter, the two green light through the red color filter.

Evaluation

One subject with normal vision or harmonious abnormal retinal correspondence is now able to recognize four lights in the above arrangement. In people with unstable fusion, but nevertheless present simultaneous vision contact double vision (diplopia ), and they recognize five lights - red at the top, in the middle of the right and left green and red on the bottom next to green. They are moved in the horizontal and / or vertical plane more or less pronounced mutually. If the binocular vision of the subject as far as disturbed that no simultaneous vision is present and the visual impression of an eye is suppressed, he takes only the lower light true either together with the upper red or the two middle green right and left.