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Daniela M. Bonci, Maureen Neitz, Jay Neitz, Mirella Gualtieri, Mirella T. Barboni, Thiago L. Costa, Luiz Carlos L. Silveira, Dora F. Ventura; Color vision of female carriers and color vision deficiency subjects evaluated with the Cambridge Colour Test. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6401.
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To evaluate the color vision of subjects with congenital color vision loss and female carriers of a deutan color defect we performed the Cambridge Colour Test (CCT - Cambridge Research Systems Ltd.) in a group from São Paulo, Brazil.
We evaluated 19 control (5 men and 14 women) and 15 daltonic (14 men and 1 woman) subjects. Color discrimination thresholds were measured using the CCT along the protan (P), deutan (D) and tritan (T) axes, as well an ellipse around CIE 1976 coordinates u’=0.1977 v’=0.4689. Thresholds were expressed in u'v'*103 units of vector length within the CIE 1976 chromaticity diagram. A genetic screen using real time quantitative polymerase chain reaction was used to estimate the relative number of L and M cone opsin genes.
L and M genes estimated for control group subjects were consistent with a trichromatic color vision. However three females were carriers of a deutan defect (more than one L gene in the X chromosome sequence). The average color discrimination thresholds of the control group were 36 ± 11, 36 ± 13 and 54 ± 19 u'v'*103 for the P, D and T axes respectively. The discrimination ellipses had a mean area of 580 ± 279, 602 ± 255 and 2676 ± 1863 (u'v'*103)2 for the ellipses 1, 2 and 3, respectively. No statistical difference (p>0.05) was found between female carriers and control group for the P, D and T color thresholds and discrimination ellipses. L and M gene estimation for the daltonic group characterized 5 protan subjects, 9 deutan subjects and 1 subject whose dichromatic phenotype was caused by a polymorphism (C203R) in the M opsin gene. In the daltonic group the mean color discrimination threshold for the P, D and T axes was, respectively, 536 ± 120, 242 ± 67 and 54 ± 9 u'v'*103 for the protan group, and 285 ± 101, 797 ± 274 and 72 ± 27 u'v'*103 for the deutan group. Comparing these results with those obtained in the control group, there was a very large difference in the protan and deutan thresholds between the groups (p<0.05) unlike the tritan threshold which remained similar to the control group (p>0.05).
There was no color vision loss in female carriers of protan defect when evaluated with the Cambridge Colour Test.
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