Congenital Colour Vision Deficiency Research Articles

Quantitative Scoring Methods for D15 Panel Tests in the Diagnosis of Congenital Color Vision Deficiencies

Farnsworth's standard D15 and L'Anthony's desaturated D15 panel tests were administered to 99 congenital red-green color defective subjects. The results were analyzed in three ways: (1) by summing the color differences between adjacent caps according to Bowman, (2) by averaging color difference vectors (CDV) according to Vingrys and King-Smith, and (3) by visually inspecting and counting the crossings. The Bowman measure was highly correlated with one of the CDV measures but provides less information regarding a cap arrangement. The desaturated D15 test can be expected to misclassify 5% of dichromats by type (protan/deutan) compared to a type misclassification rate of less than 0.1% for the D15 panel test. The correct diagnostic rates for type were 45% for the standard D15 test and 58% for the desaturated D15 test. However, the improvement in correct diagnostic rate for the latter test was accompanied by an increase in the misdiagnostic rate from 2 to 10%. The main value of the desaturated D15 test in congenital color vision diagnosis would seem to be in providing classification of those subjects who pass the standard D15 test. Quantitative scoring of the tests provides a good estimate of severity of defect. Visual inspection provides a similar diagnostic rate to CDV analysis, but has a lower type misdiagnostic rate at the desaturated D15 test and is more likely to be correct when the two methods disagree. We suggest that quantitative scoring techniques are of limited benefit for the clinical diagnosis of congenital color vision defects but that they are of use in clinical trials or for the monitoring of changes in color vision over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the standard and Adams desaturated D‐15 tests with congenital colour vision deficiencies

The Adams desaturated D-15 was designed to be administered to patients with acquired colour vision defects by simply reducing the chroma of the Munsell colours by 2 for each cap in the test. In this study, the performance of the Adams desat D-15 in the assessment of congenital colour vision deficiencies is evaluated. The standard D-15 and Adams desat D-15 tests were administered to 75 congenital red-green colour deficient subjects who had been diagnosed on the basis of their performance on the Nagel anomaloscope Mark 1. The results were analysed in terms of the directions, extent and specificity of errors and compared with the diagnosis on the Nagel anomaloscope. Of the 13 colour-deficient subjects who made no errors on the standard D-15, 1 failed the Adams desat D-15 and 2 made single crossings. No colour-deficient subject who failed the standard D-15 made anything less than a simple inversion of adjacent caps on the Adams desat D-15. The Adams desat D-15 did not perform as well as the standard D-15 in identification of the type of defect in dichromats. On the basis of these data, it is predicted that about 5% of dichromats will be mis-classified by the Adams desat D-15 whilst under 0.1% will be mis-classified by the standard D-15. However, with the anomalous trichomats, more crossings were made on the Adams desat D-15, particularly by the milder anomals, and a diagnosis was possible in more cases. Where a diagnosis was possible, it was also correct more often with the Adams desat D-15.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the standard and Adams desaturated D-15 tests with congenital colour vision deficiencies

Comparison of the standard and Adams desaturated D-15 tests with congenital colour vision deficiencies

Huematic--an automated scorer for the Farnsworth-Munsell 100 hue test.

A cheap, portable automated scorer for the Farnsworth-Munsell (FM) 100 hue test has been developed. It consists of a light pen, a series of omni-directional bar-codes attached to the reverse of the FM 100 hue caps and a small micro-computer. The print-out includes patient details, a linear histogram of the partial errors by cap position, indication of the peak error positions for congenital colour vision deficiencies and appropriate statistical analysis of the total error score. All the results are available within four minutes of completing the testing procedure.

Color-vision mechanisms of the extrafoveal retina

Wavelength discrimination, spectral sensitivity as well as color-matching performance were measured at the fovea and at different eccentricities in the peripheral retina. The results show that the underlying mechanisms of color vision in the normal peripheral retina are different from those of the classic forms of congenital color blindness. On the other hand, a close correspondence was found between color-vision characteristics obtained in the extrafoveal retina and in patients with acquired color-vision defects due to diseases of the optic nerve, suggesting that the loss of color discrimination with eccentricity and during progression of these diseases has a common underlying basis.

Congenital color blindness.

The term "color blind" is encountered frequently in areas pertaining to health, commerce, art, and entertainment, but in these cases it is generally not appropriate. Complete color blindness or achromasy is rare, but weakness or absence of discrimination to certain colors can be found in at least 8% of the male population. The most useful description of these color defects is in terms of hue and saturation, thresholds of which can be plotted as polar coordinates on a circular diagram. Plotting color thresholds with the chromagraph reveals more clearly than other clinical systems the true nature of color defects, as well as some inconsistencies in the traditional terminology and test methods. Fifty strongly color-defective subjects were tested by five different methods and the results compared. Normal values are also indicated.

Evidence for reduced colour vision in carriers of congenital colour vision deficiencies (author's transl)

The ability to recognize small spots of coloured light in parafoveal regions of the retina was investigated in women heterozygous for protanopia (2 subjects), deuteranopia (2 subjects), or deuteranomaly (1 subject) and in 3 normal subjects. The homozygous colour normals had excellent discrimination up to 8 degrees excentricity, whereas in heterozygous carriers of congenital colour vision deficiencies the ability to differentiate colours varied from point to point within the retina. The results may be explained by assuming the existence of alternating patches of trichromatic and dichromatic cell populations with the retina of the heterozygous carriers.

The cone degenerations.

The cone degenerations.

Blue-blindness in the normal fovea.

An area at the center of the human fovea, subtending a visual angle of only 7–8 min and hence hardly larger than the fixation area, is blue-blind in the sense of almost or entirely lacking blue-sensitive cones. This is a matter of foveal topography, not size of field, for in fields of this size elsewhere in the fovea or in the parafovea, blue-sensitive cones are well represented. The blue-cone system falls in sensitivity from the border of the photopic zone—the functionally all-cone area—to a minimum, usually to extinction, at its center. Other features of foveal topography oppose this trend: the density of cones rises and the macular pigmentation thins out toward the center of the fovea. Also the red- and green-cone systems display the opposite gradient; their sensitivities decline regularly from the center toward the borders of the fovea and beyond.Tritanopia, though the rarest form of congenital color-blindness, is thus a regular feature of the center of the normal fovea. The existence of two neutral points in this condition, in the yellow and violet, has its basis in the observation that the luminosity curves of the red- and green-sensitive cones, drawn so as to cross in the yellow, cross again or fuse in the violet region. It is suggested that the blue-blindness of the fixation area is a final step in the general withdrawal of image vision from the short wavelengths of the spectrum, for which the chromatic aberration of the eye is greatest. The blue-blindness of the fixation area, taken together with the red-green blindness of more-or-less concentric zones of the near periphery, and the total colorblindness of the far periphery, raises the possibility that various zones of the normal retina display all the major forms of colorblindness. Trichromic vision is normal only in the broad, central annulus of the retina, which alone is ordinarily tested. Some instances of defective color vision may be similarly localized. The problems of both normal and defective color vision involve not only the presence or absence of certain visual pigments and types of cone, but their spatial distributions on the retinal surface, and their neural connections.

PHOTOPIC FLICKER ERG IN CASES OF CONGENITAL NIGHT BLINDNESS AND TOTAL COLOR BLINDNESS.

The photopic flicker ERG in response to intense intermittent light of fixed brief duration has been investigated in normal subjects and those with some specific congenital deficiencies of the retina.

John Dalton, F.R.S., D.C.L., LL.D., Captain Joseph Huddart, F.R.S., and the Harris family; historical notes on congenital colour blindness.

John Dalton, F.R.S., D.C.L., LL.D., Captain Joseph Huddart, F.R.S., and the Harris family; historical notes on congenital colour blindness.

The Colour Sensation of Congenital Total Colour Blindness

The Colour Sensation of Congenital Total Colour Blindness

Total congenital color-blindness

Total congenital color-blindness

A Case of Congenital Total Color-Blindness

A Case of Congenital Total Color-Blindness

Case of Congenital Unilateral Color-Blindness

Case of Congenital Unilateral Color-Blindness

Incurability of Congenital Color-Blindness

Incurability of Congenital Color-Blindness