Dvorine Technical
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The following paragraphs are excerpted from the Procedures for Testing
Color Vision Document ADA 113680 issued by the National Research Council.
Committee on Vision Assembly of Behavioral and Social Sciences published by the
National Academy Press, Washington D.C. 1981. This document is available
form the U.S. Department of Commerce, National Technical Information Service
5285 Port Royal Rd Springfield VA, 22161 Phone 703-487-4600. Comments added this
date are in parenthesis ().
Dvorine Pseudoisochromatic Plates 1963
23 plates
General Description:
The Dvorine Pseudoisochromatic Plate test
is designed to screen red-green defective color vision and to differentiate
between protan and deutan defects. The test consists of single- and double-digit
numerals (15 plates) and paths to be traced with a soft-tipped paintbrush (8
plates). The latter plates are intended for use with illiterates. Instructions
for administration and scoring with a sample scoring sheet are provided. Printed
scoring sheets may be purchased separately.
Of the 15 numeral plates, plate 1 is a
demonstration plate. A double-digit numeral composed of colored circles of
various sizes appears against a background of different-colored circles. Colors
are chosen so that all observers with visual acuity better than 20/200 can read
the plate. If an observer fails to read this plate the test should be
discontinued. The remaining 14 plates are based on Pseudoisochromatic principles
and are of the vanishing type. Twelve of these plates are screening plates
(plates 2 to 5 and 8 to 15); two are diagnostic plates (plates 6 and 7).
Administration:
The observer must read the numeral on the
pate within 5 seconds. The pates are held 75cm, perpendicular to the line of
sight, under daylight illumination. The pages are awkward to turn. The plates
are not numbered, but the numerical sequence is given on the record sheet. The
plate sequence can be changed and the examiner should number the plates in the
original sequence. Test time two minutes per eye.
Scoring:
Scoring instructions accompany the test.
For the numerals, an incorrect response to two or fewer plates is considered
normal due to legibility confusion. An incorrect response to three or more
plates indicates defective color vision. For the purpose of civil aviation, five
or more incorrect responses result in failure of the test. There are three
plates for differentiation of protans and deutans. A classification of severity
is based on the number of plates missed; 0 to 2 is normal, 3 or 4 indicates mild
color defect, 5 to 11 indicates moderate color defect, 12 to 14 indicates severe
color defect.
Maintenance:
No information is provided in the manual.
The Dvorine, like other test plates, should be kept closed and dust-free when
not in use.
Calibration:
Lakowski (1966) presented
spectrophotometric analysis for sample plates. No calibration is required by the
user. Standard illuminant C or an approximation must be used.
Reliability:
We found no test-retest data in the course
of our research.
Validity:
A number of authors have presented data
from which co-efficients of agreement, 'k,' may be calculated.
Author Test of 'k'
Sloan and Habel (1956) Screening .95
Belcher et al (1958) Screening (3 errors)
.97
Frey (1962) Screening .95
Frey (1963) Qualitative diagnosis .88
In general, screening validity is very
high ('k'= 0.95 to 1.00), and the test will detect at least 95% of color
defective observers. Qualitative classification is good according to Frey
(1963). The value of 'k' is reduced primarily by those color defective observers
who are unclassified; the conditional 'k' is 0.97. Peters (1956) and Dvorine
(1963) suggested that qualitative classification be defined by the total error
score. We have found no evaluation of this suggestion that would allow
calculation of a statistical of agreement. Other authors have compared the
Dvorine to other color vision tests (Peters, 1954; Pickford and Lakowski, 1960;
Stern and Lewis, 1972).
Other Remarks:
The Dvorine test is useful for rapid
screening of red-green defects. The test provides differential diagnosis for
protan and deutan defects and classifies three levels of severity. No Tritan
plates are provided. A number of pates may be mis-read die to legibility
confusion. Included is a color-naming test of medium and low-saturation colors.
The test is widely used in the United States and is recognized by U.S. civil and
military licensing authorities.
Dvorine Pseudoisochromatic Plates
Color Vision Test Index
Richmond
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