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PubMed1982

[Suggestions for the design of a modern anomaloscope].

Three variants of a new anomaloscope principle are described. This principle is distinguished by the fact that for generation of the mixed color and the reference color three interference filters with narrow band widths are used instead of an expensive dispersion prism. In the first variant the brightness of the mixed color field and the reference field is determined by three detectors (silicon diodes) and kept constant taking the relative spectral response into consideration. The degree of anomalous color vision present is indicated digitally by a microprocessor whose interface also permits data processing equipment to be connected. The second variant uses only one detector which sequentially pulses the three light sources and distributes the results to different signal channels for further processing. In the third variant, measurement is performed in the same way as in the second variant but with only one light source. Fiber optic bundles illuminate of the mixed color and reference fields and also permit adaptation of the eye to neutral. In this case additional optical attenuators are required to keep the luminance of the fields constant. An advantage shared by all three variants is that they have virtually no moving parts, employing monochromatic filters and cemented prism blocks with high-quality electronics. This has made it possible to produce a compact, rugged and efficient new-generation anomaloscope, which renders the considerable calibration and maintenance work previously necessary superfluous.

Color Perception↗

PubMed2000

Use of the Mollon-Reffin minimalist color vision test with young children.

PURPOSE: We evaluated the Mollon-Reffin Minimalist (M-R M) color vision test to determine how successfully young children can perform the task and to compare success rates with the American Optical Hardy Rand Rittler (HRR) test and a preferential-looking type test based on the F2 plates (the Pease-Allen color test [PACT]). METHODS: Participants included 146 children (aged 3-10 years) and 32 older subjects (aged 11-39 years). The M-R M test uses 3 series of colored caps coinciding with protan, deutan, and tritan confusion axes, with 6 saturations along each axis. The observer must identify a single colored cap from gray caps of varying lightness. The PACT test consists of 2 cards with targets for detecting red-green and blue-yellow color deficiencies. The tester judges the location of the target on the basis of the child's looking and/or pointing responses. The HRR was performed according to standard instructions, although a more flexible scoring protocol was also used. RESULTS: A significant difference in the children's performance between the "test" item of the 3 tasks emerged (Cochran Q test, P<.001): all children successfully completed the M-R M, 90% successfully completed the PACT, and 88% successfully completed the HRR. Few errors were made on the M-R M red-green series, even among children aged 3 to 4 years, although errors were made with the least saturated blue-yellow cap at all ages. Recommendations are made for the use of the M-R M with children. CONCLUSIONS: The M-R M test can be performed by young children and may prove to be especially useful for detecting and monitoring acquired color vision defects.

Adolescent↗

PubMed2004

Color vision testing.

The science of color vision testing has evolved since its inception in the late 1700s. Since then, the rudimentary technique of comparing color names has been replaced by more sophisticated methods. Commonly used tests in clinical practice today include isochromatic plates, arrangement tests, anomaloscopes, and lantern tests. Each category has unique attributes that make it suitable for a particular clinical situation. The clinician should be aware of the requirements for administering and grading each test type. Factors such as the quality of the illuminant and the size of the field of view are important elements in setting up a proper color vision laboratory. Currently, no treatment exists for congenital color vision defects. However, studies show that diagnosis of these defects early in life may help children adjust better to tasks at school and may help adults understand their limitations at work. Acquired color vision defects are often used as markers of ocular pathology in the clinical setting. Different color vision tests are appropriate for diagnosing the different categories of defects. Sometimes, a battery of tests may be appropriate. This paper is a review of the current knowledge in the field of color vision testing.

Color Perception↗

PubMed1973

Color-vision mechanisms in the peripheral retinas of normal and dichromatic observers.

It is possible that so-called normal trichromatic vision occurs only between the central blue-blind fixation area and about 30 degrees peripherally. Beyond about 30 degrees vision has been alleged to become dichromatic (red-green blind), and beyond about 60 degrees , monochromatic. Hence every form of color blindness may characterize various zones of the normal retina. We have studied mechanisms of peripheral color vision, mainly by measuring the spectral sensitivities of the blue-, green-, and red-sensitive systems, isolated by differential color adaptation. In normal observers the sensitivity of the blue-mechanism falls off about 2 log units by 80 degrees out. The green- and red-sensitive systems decline only about 0.7 log unit over the same range. Protanopes, deuteranopes, and tritanopes exhibit comparable changes. We have not found any color mechanism present centrally to be wholly lost peripherally. Nor, for dichromats, have we found any mechanism missing centrally to be present peripherally. Whatever evidences of peripheral color blindness have been observed appear to involve other mechanisms than failure of receptors, probably including some fusion of neural pathways from receptors to centers.

Color Perception↗

PubMed2003

Colour vision deficiencies in Alzheimer's disease.

OBJECTIVE: visual disorders are among the earliest symptoms of Alzheimer's disease. It is, however, still controversial as to whether Alzheimer's disease impairs colour vision. In this study, colour vision of Alzheimer's disease patients was tested using the Ishihara test and the PV-16 choice test. The latter test, primarily designed for children, was chosen in order to avoid problems due to cognitive decline. METHODS: 26 patients with mild to severe Alzheimer's disease (M:F=5:21; mean age: 80+/-9 years, range: 53-95 years) and 25 controls (M:F=5:20; mean age 80+/-10 years, range: 56-100 years) were rated after undergoing complete neuro-ophthalmologic examination. RESULTS: the Alzheimer's disease patients made significantly more unspecific errors in the Ishihara test (P=0.02) and in the PV-16 choice test (P=0.0008) than the controls. No relation between test performance and severity of Alzheimer's disease was found. CONCLUSIONS: Alzheimer's disease patients have an unspecific colour vision deficiency independent of the severity of the disease.

Aged↗

PubMed1991

The use of the Lanthony New Color Test in determining the effects of aging on color vision.

The primary purpose of this study was to collect data on the loss of color vision as a function of age. The Lanthony New Color Test (NCT), which measures acquired losses of color vision in the dimensions of hue, saturation, and brightness, was used to compile data on 68 subjects. The minimum number of subjects were 10 per decade from age 30 to 90 years. An age gradient of selective loss of discrimination of saturation beginning at age 50 was demonstrated, with rapid change noted after age 60. Similar findings were seen for hue but were not evident for brightness. By age 70, a neutral zone emerged at blue/purple, Munsell chroma level 2. The instrument was shown to be reliable and valid in comparison to the Farnsworth Dichotomous Panel D.15. It is seen that this information will provide a basis for planning safer, more functional environments for elderly people.

Adult↗

PubMed1980

The absence of the Ives effect in a deuteranope.

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.

Adult↗

PubMed1984

Mixture and luminosity data for dichromats.

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.

Adult↗

PubMed1984

Mixture and luminosity data for anomalous trichromats.

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.

Color↗

PubMed1985

Adverse consequences of altering the Farnsworth-Munsell 100-Hue test.

Modifications of the Farnsworth-Munsell 100-Hue test (e.g., selection of new fixed-reference caps from within the test) have been proposed, with little or no theoretical justification or experimental verification. Predictions based on theoretical considerations of the underlying nature of the test and verified by experimental measurements on subjects with known color defects demonstrate that (1) modification can destroy the very nature of the test; (2) modification can alter axis determination and therefore, potentially, the diagnosis; (3) the resulting test scores cannot be compared reliably to established norms; and (4) accurate predictions of test performance can be made from theoretical considerations.

Color Perception↗

PubMed1985

Performance of air traffic control tasks by protanopic color defectives.

Air traffic controllers perform a number of tasks which involve color identification, color discrimination, and color naming. Normal color vision is required for air traffic controllers, although the requirement is currently under review. The most critical task involving color is the distinction of red and black on flight strips; the distinction must be made reliably, quickly, and routinely for flight safety. In this study of four protanopes and three normals, all the protanopes were unable to make this distinction reliably under the lighting levels encountered at air traffic control (ATC) centers, whereas none of the normals had any difficulty. Protanopes also made numerous errors with other ATC tasks involving color. The use of a red filter, often recommended to aid color defectives, actually made performance worse and additionally compounded the usual protanopic loss of brightness for red light. When Snellen visual acuity was tested using the red filters, protanopes needed up to four times larger letters than the color normals. It is concluded that protanopes have inadequate vision for safe performance of some current ATC tasks.

Aviation↗

PubMed1995

Colorimetric analyses of various light sources for the D-15 color vision test.

Colorimetric analyses were performed in both normal trichromatic and dichromatic color spaces to determine whether several light sources were suitable illuminants for the Farnsworth-Munsell Panel D-15 (D-15) color vision test. Results for fluorescent lamps showed that lamps with a correlated color temperature (CCT) of 7200 degrees K and a general color rendering index (GCRI) of at least 90 are acceptable substitutes for illuminant C. Predictions for filtered tungsten light indicated that lights with a color temperature near 5000 degrees K are unsuitable because of nonuniformities in the glass daylight filter transmittance. Conclusions based on these analyses are conservative because, with exception of the GCRI, color adaptation effects were not taken into account.

Adaptation, Ocular↗

PubMed1996

Clinical vision characteristics of the congenital achromatopsias. II. Color vision.

Twelve X-linked (XL) achromats and 43 autosomal recessive (AR) achromats were tested using the Farnsworth D-15, Nagel anomaloscope, Sloan achromatopsia test, and Berson test using standard procedures. All of the tests identify achromatopsia, but very few differentially diagnose the various types. AR achromats were subclassified as complete (rods only) or incomplete (residual cone function present) by additional psychophysical testing. Complete and incomplete ARs do not perform differently on any clinical color vision measure, indicating that (1) rods predominantly mediate vision in both groups and (2) these tests are not useful for distinguishing between the groups. Both groups show considerable interindividual variation on all measures. Only one of the measures, the Berson test, designed to distinguish XLs from ARs, does so reliably. XLs and ARs do not differ significantly on the Nagel anomaloscope or most of the Sloan plates. The confusion angles of the D-15 do differ for the two groups, but the variability in each group makes the measure unreliable for classifying individuals. The Berson test is recommended to distinguish the XL from AR achromats.

Adolescent↗

PubMed1997

Long wavelength pass filters designed for the management of color vision deficiencies.

This study reports on the effectiveness of long wavelength pass filters dispensed as tinted spectacles as an aid for individuals with congenital red-green color vision deficiencies. The effectiveness of the filters was evaluated by the performance on a series of clinical color vision tests and a questionnaire after the subjects had tried the lenses for 1 week. The lenses improved performance on color vision tests that required discrimination between large color differences, particularly between red and green hues. However, performance was degraded on tests which required fine color discrimination or used colors that were located parallel to the tritan confusion axis. The improved performance on certain tests was primarily based on brightness artificats induced by the filters, whereas the degraded performance on the other tests was due to the absorption of short- to midwavelength light by the filters. A slight majority (56%) of the subjects rated the filters as being moderate to highly effective in improving their color discrimination. Nevertheless, only 17% were interested in actually purchasing a pair. Common reasons for rejecting the filters were the color distortions produced by the red filters and fewer colors were actually perceived when wearing the filters.

Adolescent↗

PubMed1997

Evaluation of Kojima-Matsubara color vision test plates: validity in young children.

PURPOSE: We examined a pseudoisochromatic color plate test by Kojima and Matsubara for young children which uses drawings of familiar objects rather than letters or numbers. First, we evaluated the test's efficacy as a color deficiency screener and its validity in classifying the types of color deficiencies by comparing its results with those from the Moreland anomaloscope. Second, we eliminated the chromatic factor and evaluated the functional ability of young children to perform the task by determining how many correct responses were obtained using modified black/white replicas of the test plates. METHODS: Part 1: Twenty color-normal and 13 color-deficient adults were diagnosed and classified with the Ishihara test, Panel D-15 test, and anomaloscope. Subjects were then tested with the Kojima-Matsubara test and result were compared with those from the anomaloscope. Part 2: Fifty children aged 3 to 7 years were tested with modified black/white test plate replicas. The number of correct responses for each plate was determined for five different age groups. RESULTS: Part 1: Among the 20 color-normal subjects, 18 read all 10 plates correctly and 2 subjects missed 1 of the 10. Only 1 of the 13 color-deficient subjects exhibited the expected responses for plates 2 to 6 (used for color deficiency screening). The color-deficient subjects' responses for plates 7 to 10, which are used to classify red-green defects, were varied and only the protanomalous subjects (n = 2) followed the expected response pattern. Part 2: Of the 10 black/white modified plates, only 2 were correctly identified by all 50 children. The other plates had a recognition rate that ranged from 32 to 98%. CONCLUSIONS: Because the response patterns given by most of the color-deficient adult subjects were different from those in the test manual, ambiguous results would occur if the Kojima-Matsubara test were used for color vision screening or the diagnosis of color deficiency. In addition, the difficulty that many of the young children exhibited in identifying the objects in the black/white replica plates suggests that there would be a large number of false positive errors (classifying a color normal as color deficient) when using this test in young children.

Adult↗

PubMed1998

A modified card procedure for measuring human infant color vision.

To improve test efficiency, we modified our previously introduced contrast/color card test by including a patterned test stimulus and reducing the number of stimuli in both experimental phases. Compared with the prototype, completion rate improved substantially (79 vs. 37%) but test time decreased only modestly (19 vs. 21 min). Achromatic contrast discrimination improved threefold (mean, 0.06 vs. 0.20 log units), but the percentage of 2-month-old infants who discriminated (from gray) 660-nm red (86 vs. 80%) and 580-nm yellow (52 vs. 55%) was consistent. In addition, 48% discriminated 574-nm yellow-green. Moreover, because 88% of infants' failures included the respective adult brightness/luminance match, a small range of relative luminances is adequate for testing infant color vision.

Color Perception↗

PubMed1999

Evaluation of a new color vision test: "color vision testing made easy".

PURPOSE: A new pseudoisochromatic color plate test, "Color Vision Testing Made Easy" (CVTMET) has recently been introduced. Said to be designed for all age groups, including pre-school children, it uses the identification of simple shapes and objects to detect red-green color deficiencies. We evaluated the CVTMET to determine if the test is suitable for color vision screening of young children. METHODS: Forty-one adults predetermined to be color normal (n = 20) or to have hereditary red-green color deficiency (n = 21), served as subjects. A battery of color vision tests including the Ishihara, Panel D-15, and the anomaloscope were used for diagnosis and color deficiency classification. Subjects were then tested with Part I and Part II of the CVTMET test and results were compared to the Ishihara, Panel D-15, and anomaloscope. In addition, the CVTMET was used to screen for color vision deficiency in 152 kindergarten children 5 to 7 years of age. RESULTS: The pass/fail results for the adult subjects were the same for Parts I and II and compared favorably with the anomaloscope. There were no false positives (100% specificity) and only a few (2 of 21) false negatives (90.5% sensitivity). The two color-deficient subjects who passed the CVTMET had the mildest color deficiencies (simple deuteranomaly) and also passed the Ishihara test. Testability of kindergarten children was found to be 100%. Color vision deficiency occurred in 5.06% of the boys, which is about the same frequency found in older boys of similar ethnic background. CONCLUSION: This preliminary study indicates that the CVTMET appears to be an excellent screening instrument for red-green color deficiency in adults and has been shown to be useful for examining color vision in children 5 to 7 years of age.

Adult↗

PubMed2001

Color discrimination in heterozygous deutan carriers.

PURPOSE: The color discrimination abilities of heterozygous deutan female carriers were measured using color mixture thresholds and compared with those of suspected nonheterozygous normal subjects. METHODS: Eight test subjects and 26 control subjects were run on a computer-controlled color test (color mixture thresholds) that presented 1 degree diameter spots on a color television monitor for 1/60 of a second. A QUEST procedure was used to determine visual thresholds for spots varying in brightness and/or color. Individual data points were graphed on an X/Y plot and fitted with an ellipse. The major and minor diameters of the ellipse represent the color and brightness thresholds, respectively. RESULTS: The mean axis angle of the ellipse for the heterozygous carriers did not differ from that for the controls (15.75 degrees vs. 14.93 degrees, p = 0.428, Mann-Whitney test). The carriers did show, however, a larger mean major axis length (68.79 vs. 46.78, p = 0.0218, Mann-Whitney test). Additionally, the length-to-width ratios for the carriers were higher than the controls (9.34 vs. 6.80, p = 0.0403, Mann-Whitney test). CONCLUSIONS: Deutan-carriers do show reduced color purity discrimination as measured using color mixture thresholds compared with nonheterozygous, color vision normals.

Adolescent↗