Worth test
The Worth test (also: Four-light test according to Worth ) is an examination method with a medium degree of dissociation , which is used in strabology for the qualitative examination of simultaneous viewing and fusion and thus provides information about latent or manifest strabismus deviations. It is suitable for performing at a distance and near.
execution
During the examination, the test person is presented with red-green glasses or a simple red-green filter in order to separate the visual impressions of the right and left eyes by color. He then looks at four diamond-shaped lights at a distance of five meters. The upper light is red, the two middle lights on the right and left are green. The lower light is white. Due to the provided color filters, only the white light is visible with both eyes, depending on the dominance in a mixed color or alternating red and green. The upper red light, however, is eliminated by the green color filter, the two green lights by the red color filter.
evaluation
A subject with normal eyesight or harmoniously abnormal retinal correspondence will now be able to see four lights in the above arrangement. Double vision ( diplopia ) occurs in people with an unstable fusion, but who still have simultaneous vision , and they recognize five lights - red above, green in the middle right and left, and red next to green below. They are more or less distinctly shifted from one another in the horizontal and / or vertical plane. If the subject's binocular vision is so disturbed that there is no simultaneous vision and the visual impression of one eye is suppressed, he only perceives the lower light either together with the upper red or the two middle green ones on the right and left.
See also
literature
- Herbert Kaufmann (Ed.): Strabismus. With the collaboration of Wilfried de Decker et al. Enke, Stuttgart 1986, ISBN 3-432-95391-7 .
