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 be absolute (protanapia) or partial (protanomalia), and secondly, a deutan type which may be absolute (deuteranopia) or partial (deuteranomalia).
• In protanopia, the visible range of the spectrum is shorter at the red end and compared with that of the normal, and that part of the spectrum which appears to the normal as blue-green, appears to those with protanopia as grey. • In deuteranopia, that part of the spectrum which appears to the normal as green, appears as grey, and the visible range of the spectrum is divided by this zone into two areas, each of which appears to be of one system of colour.
In the congenital colour vision deficiencies, although very rare, there is total colour blindness which may be typical or atypical. The subject who suffers from typical total blindness shows a complete failure to discriminate any colour variations, usually with an associated impairment of central vision with photophobia and nystagmus.
How to use the test
The plates are designed to be appreciated correctly in a room which is lit adeguately by daylight. The introduction of the direct sunlight or the use of electric light may produce some discrepancy in the results because of an alteration in the appearance of shades of colour. When it is convenient only to use electric light, it should be adjusted as far as possible to resemble the effect of natural daylight.
The plates are held 75 cm from the subject and titled so taht the plane of the paper is at right angle to the line of vision. The correct position of each plates is indicated by the number which is printed on the back of the plate.
The numerals which are seen on plates 1-17 are stated, and each answer shoul be given without more than three seconds delay. If the subject is unable to read numerals, plates 18-24 are used and the winding lines between the two x's are traced with the brush. Each tracing should be completed within ten seconds.
It is not necessary in all cases to use the whole series of plates. Plates 16 and 17 may be omitted if the test is designed merely to separate the colour defectives from those with normal colour appreciation. It may be necessary to vary the order of the plates if it is suspected that there is a deliberate deception on the part of the subject.
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 be absolute (protanapia) or partial (protanomalia), and secondly, a deutan type which may be absolute (deuteranopia) or partial (deuteranomalia).
• In protanopia, the visible range of the spectrum is shorter at the red end and compared with that of the normal, and that part of the spectrum which appears to the normal as blue-green, appears to those with protanopia as grey. • In deuteranopia, that part of the spectrum which appears to the normal as green, appears as grey, and the visible range of the spectrum is divided by this zone into two areas, each of which appears to be of one system of colour.
In the congenital colour vision deficiencies, although very rare, there is total colour blindness which may be typical or atypical. The subject who suffers from typical total blindness shows a complete failure to discriminate any colour variations, usually with an associated impairment of central vision with photophobia and nystagmus.
How to use the test
The plates are designed to be appreciated correctly in a room which is lit adeguately by daylight. The introduction of the direct sunlight or the use of electric light may produce some discrepancy in the results because of an alteration in the appearance of shades of colour. When it is convenient only to use electric light, it should be adjusted as far as possible to resemble the effect of natural daylight.
The plates are held 75 cm from the subject and titled so taht the plane of the paper is at right angle to the line of vision. The correct position of each plates is indicated by the number which is printed on the back of the plate.
The numerals which are seen on plates 1-17 are stated, and each answer shoul be given without more than three seconds delay. If the subject is unable to read numerals, plates 18-24 are used and the winding lines between the two x's are traced with the brush. Each tracing should be completed within ten seconds.
It is not necessary in all cases to use the whole series of plates. Plates 16 and 17 may be omitted if the test is designed merely to separate the colour defectives from those with normal colour appreciation. It may be necessary to vary the order of the plates if it is suspected that there is a deliberate deception on the part of the subject.
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