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The Titmus Pediatric Color Perception Test was compared to three other standard tests of color vision (Ishihara, Dvorine, Farnsworth D-15) with a population of adults. It is concluded that the results of the Titmus test are consistent with those of the other tests if certain specific scoring methods, described in the text, are used.
The color-matching functions of individual tritanopes differ significantly from those predicted with the assumption that the two cone pigments of the tritanope are those which underlie the matches of the standard observer. The differences cannot be explained completely by the abnormal luminosity curve of the standard observer nor by abnormalities in transmissivity of the eye media. Individual tritanopes differ significantly in their color matches in ways not entirely accounted for by eye media differences. The results are consistent with the view that there are a variety of different long- and medium-wave-sensitive cone visual pigments among different tritanopes.
The vision status of 77 deaf children from Beverly School for the Deaf, Beverly, Massachusetts, was investigated in 6 general areas: visual acuity, refractive status, binocularity, color vision, pathology, and visual perceptual motor function. The significant results of this study that were different from the previously investigated work were in the areas of myopia and visual perceptual motor function. Myopia of only moderate to low degree was found in about 5.8% of the total poulation, which is significantly below the mean percentage found in a normal population. Almost 50% of the children showed deficiencies in and 1 or more of the 3 perceptual motor areas investiaged, i.e., visual memory, spatial organization, and Gesell copy forms.
The genetic polymorphism of human color vision is examined within the framework of a photopigment replacement model. An analysis of the X-linked recessive dichromacies and anomalous trichromacies indicates that one source of variability of normal color perception may be the inclusion of several distinct phenotypes in what is usually described as normal color vision. This analysis also reveals the cause of the dominance hierarchy at the protan and deutan loci, the perceptual effects of dosage compensation, and the phenotypes of various compound hemizygotes.
The statistical measures and definitions currently in use for screening programs are discussed. Sensitivity, specificity, false negative, and false positive rates are defined and illustrated. The positive and negative predictive values and the over- and underrefferal rates are also discussed, and an example of these measures is provided. The relationship of rates to prevalence and expected screening results is shown. A method for calculating the standard error of sensitivity and specificity is also given.
The Roth 28-hue test, first described in 1966, uses every third color cap from the Farnsworth-Munsell 100-hue (85-color-cap) test. Protans, deutans, and tritans exhibit slightly different confusion axes on the Roth 28-hue test and the Farnsworth D-15 test. These axes are illustrated on a CIE chromaticity diagram. The little-used Roth 28-hue test may be a good compromise between the D-15 and 100-hue tests, but clinical trials for verification are needed.
Three patients with congenital cone dysfunction are described with their clinical findings, including electrophysiologic and color vision evaluation, diagnostic criteria, and rehabilitative regimes. A classification system for this rare spectrum of disorders is presented.
Some visual characteristics of the chronic alcoholic were investigated in a sample of 100 male alcoholic patients and 100 matched controls. The purpose of the retrospective study was to determine whether these characteristics may contribute to an increased motor vehicle accident rate among alcoholics. Significant differences between the two groups, which might affect driving abilities, were found for color vision deficiencies and the breakage and loss rate of spectacles. No significant differences were found for stereopsis deficiencies, limitation of visual field, distance phorias, ductions, or the need to wear spectacles for driving. An analysis of the refractive data suggests that alcoholic patients may be slightly more hyperopic and less astigmatic than others; however, these differences are not sufficient to influence driving ability.
Thirty-one normal and 20 color vision-deficient persons were tested with the Hardy-Rand-Rittler (HRR) Pseudoisochromatic Plates, Farnsworth's D-15 and 100-Hue tests, and the Davidson & Hemmendinger (D & H) Color Rule using Vita-Lite, Ultralume, and Cool White fluorescent lamps to determine their usefulness for color vision measurement. The persons with deficient color vision were classified with a Nagel anomaloscope. The Macbeth Easel lamp was the reference for determining relative lamp performance. No normal was misclassified with any of the lamps. Scores with the Vita-Lite lamp were qualitatively and quantitatively most similar to those with the Macbeth lamp. The Ultralume gave intermediate results, and the Cool White was the least satisfactory substitute. Norms for the metameric D & H Color Rule for each lamp were different, which prevented intercomparisons. Best separation of the scores of deficient from normal persons with the D & H Rule occurred with the Macbeth and Vita-Lite lamps. Better performance with the Vita-Lite and Ultralume lamps can be expected from protans with the HRR and 100-Hue Tests and poorer performances from deutans on the HRR tests than with the standard Macbeth Lamp. The Cool White lamp was judged an unsuitable substitute for color vision testing.
Ives found that when monochromatic stimuli are matched to white by flicker photometry, they are not equal in brightness to the white by direct comparison, and the discrepancy is minimal for yellow but is increased for longer and shorter wavelengths. On the two sides of yellow, the colors are more saturated, and Ives postulated that brightness involves the sum of a chromatic component and an achromatic component and that the chromatic component varies with the saturation. In the case of a deuteranope, one would expect a vigorous chromatic response for yellow and blue stimuli but a poor response for the neutral part of the spectrum. The Ives effect is virtually nonexistent for subject SR, who is a deuteranope. In terms of the zone theory of color vision, this would mean that the blue-yellow chromatic channel contributes little or nothing to brightness. In a normal observer, the blue-yellow mechanism can be isolated by using blues and yellows depurified with white, but in this case the Ives effect is found to exist.
A method is described for improving color discriminations in dichromats by means of glasses with one magenta and one cyan eyepiece. A modest improvement is reported and discussed.
Dichoptic color experiments were performed with color normals and with protanopes and deuteranopes. Different targets were presented to each eye in a stereoscope. Experiment 1 used homogeneous chromatic targets. Experiment 2 involved black and white photographs taken and viewed through various filters. Experiment 3 utilized a dichromat wearing an X-Chrom lens. The experiments indicate that the cortical perception achieved by summing input of each eye when one eye has a filter in front of it may aid color discrimination for dichromats.
Color vision loss can be an early sign of eye disease; in many retinal disorders the loss precedes any change in visual acuity. Noninvasive psychophysical methods allow factoring out of preretinal, receptoral, and postreceptoral (neural) components of the color vision change. A loss of chromatic but not achromatic sensitivity occurs for diabetics; the loss is selective for pathways subserving blue-sensitive photoreceptors. Both chromatic and achromatic pathways are altered in glaucoma and senile macular degeneration; the most marked change in central serous choroidopathy is loss of sensitivity somewhere in the blue-sensitive cone pathway. There is evidence that the pathways subserved by blue-sensitive cones have anatomically and physiologically different properties from those served by other receptor types, and they appear particularly vulnerable to disturbances of retinal integrity.
The visual performance of nine rod monochromats was measured with photopic stimuli viewed through filters that attenuated the ambient illuminance. In kinetic perimetry experiments, eight of nine patients showed substantially larger visual field size under the experimental as compared to the control conditions. In increment threshold or brightness-matching experiments, long wavelength sensitivity was shown to be enhanced under the experimental conditions.
Four color-deficient observers and one normal trichromatic subject were evaluated with color vision and stereoacuity tests during 1 month of X-Chrom lens wear. For all color tests, performance of the normal subject was unaltered by X-Chrom lens wear. Color-deficient subjects demonstrated improved performance on the Ishihara pseudoisochromatic color plates, but either degraded performance or no change on the Farnsworth-Munsell 100-hue or Pickford-Nicolson red-green anomaloscope test. Three of the five subjects exhibited degraded stereoacuity in conjunction with X-Chrom lens wear. We conclude that the X-Chrom lens does not improve discrimination in color-deficient subjects and may alter stereopsis.
Results of several previous reports have questioned the occurrence of the tritan color deficiency independently of dominantly inherited optic atrophy. This report describes the results of testing 34 members of a pedigree (including four tritans) for whom optic atrophy can be ruled out according to criteria previously described by Krill et al.
The mixture diagram for a dichromat reduces to a single line connecting two points that represent the surviving fundamental colors. The intermediate colors match mixtures of the two fundamentals. The luminous efficiency curve can be split into its red and blue, or red and green, or green and blue components which represent the response curves. These response curves can be compared to the response curves of a normal trichromat. The curves derived for a trichromat depend upon the points chosen to represent the three fundamentals. The rationale involved in the choice of fundamentals is explained. The choice depends on (1) the shape of the spectrum locus, (2) adaptation data, and (3) the directions of the confusion lines for dichromats. The red curve derived for a trichromat in this way has two peaks, one at each end of the spectrum. The peak at the short wave end is missing in the case of deuteranopes. Otherwise, the curves in dichromats and trichromats are similar. No allowance has been made for effects of macular pigment and transmission of the media.
In a previous paper a procedure was outlined for locating the red, green, and blue fundamental colors on a color mixture diagram. This makes it possible to derive the red, green, and blue response curves from the mixture data and the luminous efficiency curve. Curves were derived in a similar way for dichromats and compared to those for normal observers. In this paper, the study has been extended to include anomalous trichromats. In normal observers, tritanopes, and deuteranomalous subjects, the red response curve has two peaks, one at the red end and one at the blue end. The red response can be analyzed into long wave and short wave components. The short wave component is missing in deuteranopes and in the protanomalous observer investigated in this study. The data based on the one protanomal point to the possibility that the long wave component of the red response of the protanomal is similar to that of the normal but reduced in magnitude. In the deuteranomal, the green response is similar to that of a normal but reduced in magnitude.