Three pigments in normal and anomalous color vision.
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Color Perception↗
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Homogeneity of large-field color matches in congenital red-green color deficients.
Rayleigh matches obtained from red-green color deficients with conventional methods show large individual differences within diagnostic categories. Similar matches obtained from the same observers with a large-field substitution method show much less variability and suggest that the differences observed among simple anomals, extreme anomals, and dichromats with conventional methods are probably not solely due to the visual pigments contained in the cones. A theory that attributes these differences to the relative number of abnormal cones present in the observer's retina is described.
Color Perception↗
Early-stage abnormality of foveal pi mechanisms in a patient with retinitis pigmentosa.
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Adult↗
Field sensitivity of the short-wavelength-sensitive mechanism in the protanope's parafoveal retina.
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Adult↗
Analysis of Rayleigh match data with psychometric functions.
Color matches have been used for a variety of purposes, yet the psychometric properties of color-matching data have not been thoroughly investigated. A method is given for generating psychometric functions for the two ends of the color-matching range by use of a perceptual dimension for stimulus magnitude based on ratios of cone quantal catches. The analysis was applied to Rayleigh match data gathered from 250 naïve observers with an automated protocol. Slopes of the psychometric functions were significantly shallower for anomalous trichromats than for normal trichromats, consistent with the assumption that stimulus magnitude is based on ratios of cone quantal catches. These results indicate that the tester's criterion for response consistency can strongly affect Rayleigh match widths. The analysis may also be useful for other perceptual tasks, such as contrast matching and spatial alignment.
Adolescent↗
Color matches in diseased eyes with good acuity: detection of deficits in cone optical density and in chromatic discrimination.
Reduced foveal cone optical density in diseased eyes with normal acuity can affect color matches. Using field diameters of 1 degree, 2 degrees, 4 degrees, and 8 degrees, we measured mean color-match midpoints and match widths in patients who had good acuity and who exhibited three categories of eye disease: hereditary macular degeneration (n = 12), retinitis pigmentosa (n = 19), and glaucoma (n = 18). Results were compared with those for normal observers of comparable ages. Mean color-match midpoints were abnormal only for the population with hereditary macular degeneration, indicating a reduction in cone optical density in the central 4 degrees. Mean color-match widths were enlarged for both hereditary macular degeneration and retinitis pigmentosa, a result consistent with a reduction in the number of foveal cones.
Adult↗
Eigenvector interpretation of the Farnsworth-Munsell 100-hue test.
We measured the reflectance spectra for the 85 color caps of the Farnsworth-Munsell 100-hue test. Eigenvectors and eigenvalues of a correlation matrix of cone responses were computed, with the cone responses being determined from the 85 test caps, arranged in order (according to color) by means of a linear model. It is shown that the Farnsworth-Munsell 100-hue test can be simulated by use of eigenvectors of the cone responses. The eigenvectors can be interpreted as nonopponent signal and opponent color signals. The normal observer can determine the color of a cap by using two opponent color signals. For color-blind persons (dichromats) one or the other opponent signal is defective, and errors can occur during the test. The simulation results also suggest that eigenvectors can be used to predict results of arrangement tests similar to the Farnsworth-Munsell 100-hue test.
Color Perception↗
Traffic signal color recognition is a problem for both protan and deutan color-vision deficients.
We investigated the effect of color-vision deficiency on reaction times and accuracy of identification of traffic light signals. Participants were 20 color-normal and 49 color-deficient males, the latter divided into subgroups of different severity and type. Participants performed a tracking task. At random intervals, stimuli simulating standard traffic light signals were presented against a white background at 5 degrees to right or left. Participants identified stimulus color (red/yellow/green) by pressing an appropriate response button. Mean response times for color normals were 525, 410, and 450 ms for red, yellow, and green lights, respectively. For color deficients, response times to red lights increased with increase in severity of color deficiency, with deutans performing worse than protans of similar severity: response times of deuteranopes and protanopes were 53% and 35% longer than those of color normals. A similar pattern occurred for yellow lights, with deuteranopes and protanopes having increased response times of 85% and 53%, respectively. For green lights, response times of all groups were similar. Error rates showed patterns similar to those of response times. Contrary to previous studies, deutans performed much worse than protans of similar severity. Actual or potential applications of this research include traffic signal design and driver licensing.
Accidents, Traffic↗
[Chromatic sense: types of defects and clinical evaluation tests].
Evaluation of the chromatic sense has a great value in ophthalmic practice, both for diagnosis of the congenital defects (daltonism), as well as for diagnosis and follow-up of acquired defects. Many clinical tests are available to be used for this purpose. However it is necessary to know the details and sensitivity of each test, since there are many variations in the results, depending on the searched condition, if congenital or acquired pathologies. Our goal is to review the types of defects of the chromatic sense and provide information about the main current available tests and their best purpose. We further emphasize the importance of standard illumination procedure in the application of the tests.
Color Perception↗
Abnormal color vision and reliable self-monitoring of blood glucose.
Color vision was assessed in 103 insulin-dependent diabetic patients using the Farnsworth-Münsell 100-Hue Test. All showed color vision impairment. Thirty-four had true dyschromatopsia while 22 suffered from tritanopia or other axial defects. We evaluated how accurately diabetic patients could monitor their own blood glucose by asking them to read a series of 30 precalibrated BM Test Glycemic Strips (Chemstrip, Boehringer, Mannheim, West Germany) without a meter. Patients with axial defects performed least well regardless of 100-Hue scores. Reading accuracy of patients with no axial defects was strongly correlated to 100-Hue scores, although patients having dyschromatopsia were consistently hesitant about their readings. Our results suggest that self-monitoring of blood glucose without a meter is indicated only after color vision has been examined by the 100-Hue Test. Self-monitoring should be voided with patients suffering from axial defects or having unsatisfactory 100-Hue scores.
Adult↗
Spectral sensitivity in primates: a comparative study.
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Adult↗
Exchange threshold colorimeter and analytical anomaloscope of class I and class II subjects and colour defectives.
The spectral absorption curve of 'red' cones erytholabe and the 'green' cones chlorolabe are examined by these techniques. Evidence is elicited for a fourth photopic response peaking at approximately 570 nm.
Color Perception↗
Changes in perceived color with intermittent illumination.
Using 24 observers with normal color vision, perceived shifts in hue were determined for a yellow-red, green, and blue-green at intermittencies of 5, 10, and 20 cps. The hue shift for yellow-red was consistent with the hue shift exhibited by a deuteranomalous observer while the hue shift for green and blue-green was consistent with that exhibited by a protanomalous observer.
Color Perception↗
Bishnupur achromats and their relatives (an exploratory study with six colour vision tests).
Thirteen subjects from the 'Sankhabaniks' of Bishnupur and two new similar cases were given six colour vision tests. All had photophobia, fixation nystagmus, low visual acuity and marked, though not complete, loss of colour sense. Forty other males and 24 females related to the defectives were also tested with at least five of the tests, for comparison. The tests were Ishihara, HRR test, Sloan's Achromatopsia test, the Dichotomous (D 15) test, Hundred Hue test and the Pickford-Nicolson Anomaloscope. The present research confirmed the provisional conclusion of Bose et al. (1968) that the achromatopsia in Bishnupur is an autosomal recessive character. That women relatives of the achromats showed greater average error scores with the Dichotomous test, the Hundred Hue test and the Sloan's test than male relatives, suggests that the defect is more readily manifested in males, and that the female relatives would include a number of genetic defectives with incomplete manifestation due to sex control. The defectives were clearly distinguished from the relatives as a group.
Adult↗
Color spaces of color-normal and color-abnormal observers reconstructed from response times and dissimilarity ratings.
With multidimensional scaling analysis, color spaces were reconstructed from reaction times (RTs) required to make same-different judgements of pairs of 15 equiluminant colors and from dissimilarity ratings between them. In addition to normal trichromats, observers with red-green color deficiency were tested. Two main purposes were served by this study: (1) to compare spatial representations of colors derived from discriminative RTs with those derived from dissimilarity measures and (2) to examine whether the task may selectively affect the dimension reflecting, in color-abnormal spaces, the deficient red-green mechanism. Contradicting our hypothesis of lower dimensionality of RT spaces, as compared with rating spaces, no consistent differences in solution dimensionality were found. However, configurations derived from the two measures diverged. The rating procedure yielded the most logical results for recovering color space. The RT configuration revealed contraction in the tritanopic direction, indicating longer color processing when the short-wavelength mechanism is involved, and in addition, for color-abnormal observers, clustering in the protanopic and deuteranopic directions, indicating even longer processing by the deficient red-green mechanism. This finding implies that RTs are suitable for detecting temporal differences in color processing but, for that very same reason, rather ill-suited for reconstructing color spaces.
Adult↗
Color vision in diabetic school children.
The color vision of 64 diabetic school children was studied. Acquired color vision defects due to diabetes could not be found in any of the children. Two of the children had a congenital red-green color vision defect. In the examination, three different pseudoisochromatic plate tests (Isihara, Standard Pseudoisochromatic Plates part 2, and Lanthony Tritan Album) were used as well as the Nagel anomaloscope and three different cap arrangement tests (Panel D 15, Lanthony Desaturated Panel, and Farnsworth-Munsell 100 hue). The plate tests and the anomaloscope examination were fast, reliable, and well accepted by the children. The cap arrangement tests took more time, and many of the children neither liked nor properly performed these tests. Twelve color dependent glucose strip tests for diabetes care at home were also studied. A few of the youngest school children made mistakes in interpreting the colors of these strips, although their color vision was normal.
Adolescent↗
[Individual variations in color vision and its molecular biology].
Individual variations in normal color vision and congenital red-green color vision defects in Japanese males were investigated using both psychophysics and molecular biology techniques. 1. Normal color vision. We studied 72 Japanese males who were diagnosed as having normal color vision using the Ishihara plates test and Nagel model I anomaloscope. The structure of the gene arrays of the X-linked L- and M-pigment genes was determined using quantitative PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism). We found the following variations of the number of M-pigment genes: 27 (38%) of these men had only one M-pigment gene, 29 (40%) had two, 13 (18%) had three and 3 (4%) had four. Two common polymorphisms were found at amino acid residue 180 of both L- and M-opsin, of the total 56 (78%) were Ser and the other 16 (23%) were Ala in the L-pigment and of the total 65 (90%) were Ala and the other 7 (10%) were Ser in the M-pigment. The Rayleigh match midpoints fell within the normal range, however there were two fairly distinct groups with consistent differences in each group. The mean values of the proportion of red in a mixture of red and green were 0.564 +/- 0.026 (mean +/- standard deviation). Correlation was found only between the Rayleigh match midpoint and the polymorphism at residue 180 of L-pigment. In order to estimate the variations of L/M cone ratio in the retinae the spectral sensitivities using heterochromatic flicker method were measured. Using the hypothesis that the luminosity function is proportional to the sum of L- and M-cone spectral sensitivity (k L (lambda) + M (lambda)), the constant k values were obtained. The k values for the subjects with Ser180 and Ala180 L-pigment were 1.89 +/- 1.44 and 1.85 +/- 1.02 respectively. Furthermore, in order to study the variation of information processing system, the spectral sensitivities for 1 degree, 200-ms test flash on a white background were measured. Using the hypothesis that the spectral sensitivity is proportional to the difference of L- and M-cone spectral sensitivity (L (lambda) - k' M (lambda)), the k' values were obtained. The k' values for the subjects with Ser180 and Ala180 L-pigment were 1.38 +/- 0.06 and 1.49 +/- 0.07 respectively. As a result, it was suggested that there are individual variations in both the L/M cone ratio and the color opponent system. 2. Congenital red-green color vision deficiencies. We studied the structure of the gene arrays of the X-linked L- and M-pigment genes and investigated the relationship between genotype and phenotype in 21 Japanese males comprising 4 protanopia, 6 protanomaly, 7 deuteranopia and 4 deuteranomaly. All of the protan subjects had 5' L-M fusion gene with/without the M gene. All of the deutan subjects had a normal L gene with/without 5' M-L fusion gene. Genotype agreed with phenotype in 8 of 10 protan subjects and 10 of 11 deutan subjects. Two of them were diagnosed as abnormal trichromatism in spite of having only one gene. One of them was diagnosed as dichromatism in spite of having two genes that encoded spectrally different pigments. As a result, it was felt that the diagnosis of dichromacy and abnormal trichromacy with an anomaloscope has limitations.
Asian People↗