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Available on 2026-07-02
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A distinctive feature of individuals who confuse red and green is that blue and yellow appear remarkably vivid to them compared to red and green.
The screening for color vision deficiencies using the Ishihara Test Book—38 plates—is based on this characteristic.
- Plate number 1 is the introductory plate, and everyone can read the number 12, even people with color blindness. This is followed by 6 groups of 4 consecutive plates.
- Plates 2 through 5 therefore exploit the same color confusion. Normally, numbers different from those perceived by people with normal color vision are visible in cases of red-green dichromacy.
- Plates 6 through 9 are of the same difficulty level and explore a confusion between red and green that is very similar to that tested in the previous group but with a different background.
- Plates 10 through 13 are based on blue-green–orange confusion. Individuals with the condition perceive nothing.
- Plates 14 through 17 are very similar to plates 6 through 9 but have a slightly different background. Furthermore, as in the previous series, color-blind subjects perceive nothing.
- Plates 18 through 21 are constructed differently. Unlike the previous ones, individuals with normal color vision or achromats perceive nothing, while dichromats can perceive or distinguish the numbers.
- Plates 22 through 25 are crucial because their purpose is to identify whether an individual has protanopia or deuteranopia.
Plates 1 through 25 of the Ishihara Test Album—38 plates—must be identified within a maximum of 3 seconds. If the subject does not recognize the numbers, plates 26 through 28 are used, on which the subject must trace the winding line between the two Xs with a brush in 10 seconds or less.
It is not always necessary to use the entire series of plates. For example, plates 22, 23, 24, and 25 may not be presented to the subject if the purpose of the test is simply to identify subjects with normal color vision by distinguishing them from those with color vision deficiency.
In simple screening cases, it may even be sufficient to present only 6 plates from the Ishihara Test Album—38 plates. If the subject hesitates while viewing these 6 plates, they should undergo the complete examination. Furthermore, the order of the plates may be varied if it appears that the subject is feigning the condition.
Checked by OPHTAZON
3
Year of mfg.
-
Available
Checked by OPHTAZON
3
Year of mfg.
-
Available
New equipment
5
Year of mfg.
2026
Available
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