C O L O U R     V I S I O N    T E S T I N G Early diagnosis of colour vision abnormality can save a child lots of frustration, and help ease school work. The Ishihara test is part of a comprehensive eye exam. Children should have their first eye exam starting at age three, and yearly thereafter. Colour problems are much more common in males. Please keep in mind that computer monitors will vary widely in color representation, brightness and contrast and so these images should not be considered diagnostic. They will, however, give a good idea of how the colour testing works.

ISHIHARA PSEUDO-ISOCHROMATIC PLATES

Plate #1Both the colour normal and those with all sorts of colour vision deficiencies read it as 12. Plate #2The colour normal reads this as 8. Red-green deficient people see a 3. Plate #3The colour normal reads this as 6. Red-green deficient people see a 5. Plate #4The colour normal reads this as 29. Red-green deficient people see a 70. Plate #5The colour normal reads this as 57. Red-green deficient people see a 35. Plate #6The colour normal reads this as 5. Red-green deficient people see a 2. Plate #7The colour normal reads this as 3. Red-green deficient people see a 5. Plate #8The colour normal reads this as 15. Red-green deficient people see a 17. Plate #9The colour normal reads this as 74. Red-green deficient people see a 21. Plate #10The colour normal reads this as 2. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #11The colour normal reads this as 6. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #12The colour normal reads this as 97. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #13The colour normal reads this as 45. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #14The colour normal reads this as 5. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #15The colour normal reads this as 7. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #16The colour normal reads this as 16. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #17The colour normal reads this as 73. Most with colour vision deficiencies are unable to read this or read it incorrectly. Plate #18The normal sees no numeral. Most with red-green deficiencies read this 5. Plate #19The normal sees no numeral. Most with red-green deficiencies read this 2. Plate #20The normal sees no numeral. Most with red-green deficiencies read this 45. Plate #21The normal sees no numeral. Most with red-green deficiencies read this 73.

The following children, who are color deficient, illustrate how the condition can cause problems at school. 1. John is working in his reading workbook. The directions to one  item say to draw a line to the red ball. The other ball is brown. Both colors look alike to John, so he guesses. The teacher reminds him not to be careless. 2. A teacher is writing vocabulary words on a green chalk board with yellow chalk in mid-afternoon. There is a glare on the board from unshaded windows. Peter is sitting so that the glare diminishes the figure-ground contrast. The teacher wonders why he is copying from a neighbor's paper. 3. Tommy ordinarily seems to enjoy reading aloud. Today, however, he doesn't volunteer and balks when the teacher calls on him to read. The poem in the reader is printed in blue on a purple background. 4. Susan, a bright and articulate youngster, was asked to go to the front of the class and read from the blue green book on the teachers' desk.  She went to the front of  the class and  just stood there looking at the pile of different colored books. Not knowing which one to pickup, she started to cry. 5. T.J. was very out going in pre-school & kindergarten. He loved to wave his arms and volunteer to answer questions the teacher asked. The only time he did not volunteer answers was when it came to learning or identifying his colors. A lot of the colors looked the same to him. They just had different names. 6. The kindergarten teacher notices the kids during art class teasing Jimmy.  The other kids think it is funny that Jimmy's stick people have green faces. 7. The kids at school told the teacher Jeff was cheating during kick ball.  They said he would break the rules by kicking the ball when it was out of bounds. They accusingly stated the boundary lines on the green grass were clearly marked with orange chalk. Jeff, rather than admitting he could not see the boundary line, simply quit playing with the other kids during recess. This series of plates is designed to provide a test which gives a quick and accurate assessment of colour vision deficiency of congenital origin. This is the commonest form of colour vision disturbances. Most cases of congenital colour vision deficiency are characterized by a red-green deficiency which may be of two types: first, a protan type which may be absolute (protanopia) or partial (protanomalia), and secondly a deutan type which may be absolute (deutanopia), or partial (deuteranomalia). In protanopia, blue-green colour appears as grey. In deuteranopia, green appears as grey. Consequently, one of the peculiarities of of red-green deficiencies is that blue and yellow colours appear to be remarkably clear compared with red and green colours. This is the basis of the Ishihara plate series. There is also a very rare group of persons who suffer from total colour blindness and show a complete failure to discriminate any colour variations, usually with an associated impairment of central vision with photophobia and nystagmus. For more on this see the personal account of vision scientist and achromat Knut Nordby. ANALYSIS An assessment of the readings of plates 1 to 21 determines the normality or defectiveness of colour vision. If 17 or more plates are read normally, the colour vision is regarded as normal. If only 13 or less than 13 plates are read normal, the colour vision is regared as deficient. It is rare to find a person whose recording of normal answers is between 14 - 16 plates. Such a result requires the use of other colour vision tests.