Abstract
P 064
A simple plate test of blue and yellow colour contrast thresholds to examine retinopathies
Hermann Krastel1, Renate Wolber2, Christian Kahlert3
1Neckargemünd, 2CEO Farb-Design, Torso-Verlag, Wertheim, 3Universitäts-Augenklinik Heidelberg
Objective
Colour perception is the visual system’s highest achievement. Weakening of blue and yellow perception early indicates retinopathies, and opticopathies if spatial organization is affected. Although there are a few blue pseudoisochromatic plates in clinical application, arrangement tests are usually preferred. Our test for contrast thresholds of blue and yellow is aimed at an easy and speedy examination by plates.
Methods
Plate design is based on a pseudo-chaotic pattern of small circular elements of varying diameters. The Pfluger illiterate “E” serves as optotype, to which the observer is made familiar by an introductory black and white specimen. Thereafter, yellow “E”s are presented in a neutral light grey environment of similar texture, and blue “E”s in a dark one. On 5 yellow and 5 blue plates optotypes are stepwise reduced in contrast. Initially the plate of highest contrast is shown. Subsequently the plate of lowest perceptible contrast is sought.
Illumination comes from white fluorescent tubes with continuous spectral emission and a correlated colour temperature of about 6500o K. Typical luminance of the yellow plates amounts to 150 cd/m2, luminance of the blue plates to 15 cd/m2.
Standard distance of observation is 40 cm. In defining additional distances of observation the test’s significance may be expanded to measuring chromatic acuity. The exam is done monocularly. The test is performed within two through three minutes.
Results
First results display a deterioration of blue as well as of yellow recognized colour contrast in early diabetic retinopathy (prior to any ophthalmoscopic fundus findings) in comparison to the normal observer. Congress participants may try a demo test version on the poster.
Conclusions
Examination of blue and yellow colour contrast thresholds by means of the new plate test exhibits pathology in early diabetic retinopathy which precedes ophthalmoscopic findings. Handling of the test is quick and straight-forward.
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