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
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
Colour vision was severely impaired (0/15 on Ishihara pseudoisochromatic plates) and funduscopy revealed bilateral profound optic atrophy (Fig.
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. A pass on this test indicates normal colour vision and satisfies the requirements of both standards.
(26) Colour vision is initially assessed using the Ishihara pseudoisochromatic plates. A candidate who wishes to work on the deck but fails the Ishihara test can have their colour vision reassessed with Holmes Wright B Lantern.
The improvement of performance on pseudoisochromatic plates with a monocular coloured filter:
c) Improves performance on pseudoisochromatic plates
(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).