pseudoisochromatic plates

plates, pseudoisochromatic 

Charts for testing colour vision on which are printed dots of various colours, brightness, saturation and sizes, arranged so that the dots of similar colour form a figure (a letter, a numeral, a geometrical shape or winding path) among a background of dots of another colour. The colours of the figure and the background correspond to the confusion colours of the various types of anomalous colour vision. A dichromat or an anomalous trichromat has difficulty in perceiving the pattern because it is distinguishable from the background only by its difference in hue. There are many different sets of such plates, some using figures (circles, crosses or triangles) such as the AO, HRR plates, or numbers or lines such as those of Ishihara (Fig. P13) and Dvorine, or five spots such as the City University colour vision test, or the Lanthony tritan album, which consists of a square matrix of grey dots in which one corner on each plate contains blue-purple dots of different saturation and the subject has to identify the corner. See confusion colours; defective colour vision; Macbeth lamp; Farnsworth test; City University colour vision test.
Fig. P13 One of the Ishihara pseudoisochromatic platesenlarge picture
Fig. P13 One of the Ishihara pseudoisochromatic plates
References in periodicals archive ?
The test includes several pseudoisochromatic plates, each composed of a pattern of differently shaded dots.
In both instances, colour vision is initially assessed using the Ishihara pseudoisochromatic plates.
The improvement of performance on pseudoisochromatic plates with a monocular coloured filter:
c) Improves performance on pseudoisochromatic plates
67-69) The studies that have looked at the effectiveness of this lens agree that it improves performance of colour deficient subjects on pseudoisochromatic plate tests.
13) The design of the Ishihara pseudoisochromatic plates is based on the plates of Stilling.
Hardy-Rand-Rittler pseudoisochromatic plates The original edition of the Hardy-Rand-Rittler (HRR) pseudoisochromatic plates (American Optical HRR) is no longer available.
The design of the display used in the Cambridge Colour Vision test is based on the pseudoisochromatic plates of Stilling or Ishihara, but the test uses a Landolt C as the target (Figure 7).