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Contrast/color card procedure: a new test of young infants' color vision.

We have developed a new test which can rapidly evaluate basic color vision in individual infants. The test consists of a series of large cards constructed with Munsell Hues. It uses a modified preferential looking procedure (FPL) and, to control brightness cues, incorporates a two-phase systematic variation of luminance. First, we evaluate an infant's ability to discriminate 9.5 by 16 degrees achromatic patches of varying luminance from a 26 by 65 degrees achromatic background of midrange luminance. In the second phase the test patch is chromatic and its luminance, relative to the background, is varied over a range of about 1.0 log cd/m2. The number of relative luminances chosen for each infant depends upon his/her performance in phase 1. Seventy 2- and 3-month-olds were tested with 4 broad-band chromatic patches, a red (dominant lambda = 660 nm), a yellow (dominant lambda = 580 nm), a green (dominant lambda = 520 nm), and a blue (dominant lambda = 475 nm). Results showed that 3-month-olds had little difficulty making any of the chromatic-achromatic discriminations but many 2-month-olds appeared to fail to discriminate the yellow and green from the background at relative luminances close to an adult brightness match. Most importantly, the test shows promise as a relatively simple, time-efficient, and portable tool for the assessment of early color vision.

Color Perception Tests

Acquired 'tritan' deficiencies in macular pathology.

14 patients with maculopathy (18 eyes affected, 10 eyes clinically normal) were examined using the HRR plates, the Farnsworth F2 (tritan) plate, the Farnsworth panel D15 test, the Nagel anomaloscope (model I) and on a 'blue-green' equation for 2 degrees and 11 degrees fields on the Moreland anomaloscope. The correlation of tritan-like responses to each test and the differences between the 2 degrees and 11 degrees equations are discussed.

Adult

Colorimetry by a new principle.

A simple and informative method is described for determining the type and extent of color defects. The subjects' responses are registered automatically on a chromaticity diagram that is based on the newtonian model. Color defects are readily identifiable by a skewing of the normal central gray area toward the defectively perceived color. The examination permits independent variation of hue and saturation for each color and requires less than five minutes for the entire procedure. Unlike conventional color tests, the present method indicates exactly what colors are or are not seen at any level of saturation.

Adolescent

Discrepant results obtained with two versions of the Farnsworth Panel D-15 test in patients with acquired blue-yellow defects.

Two commercially available Panel D-15 tests were administered to two patients with acquired blue-yellow defects. The results obtained with each test were different and apparently influenced by the cap construction which is the only difference between the two tests. In one test the surface of the cap is concave and polished while in the other test the cap surface is flat and has a matte or dull finish. The mechanism accounting for the different results is not obvious.

Adult

Ability of deutan color defectives to perform simulated air traffic control tasks.

Air traffic controllers perform a variety of tasks which require them to identify, discriminate, and name colors. Qualification standards for this occupation require applicants and incumbents to have normal color vision. The validity of this standard has been questioned and is currently under review. In this study, 22 deutans and 78 normals were tested on a set of tasks which simulated critical tasks performed daily by air traffic controllers. The four tasks included discriminating red from black pencil marks on flight progress strips, color-naming of 1 degree and 0.1 degree discs, and identification of colored line segments embedded in a multicolored background. Deutans classified as mild were found to perform all tasks as well as normals. Moderate deutans performed only the large disc color-naming task as well as normals, whereas severe deutans performed none of the tasks as well as normals. Different methods for scoring the color vision tests were explored to determine their value as predictors of task performance. The D-15 relative error score was found to be the single best predictor of performance on the tasks (r-square = 0.602). It is concluded that mild deutan color defectives have adequate color vision for safe performance of several critical air traffic control tasks. Moderate and severe deutans do not. In addition, the results of several methods for scoring color vision tests can be used to predict group, but not individual, performance with high reliability.

Aviation

Testing of colour vision for vocational purposes.

All red-green defects of colour vision can be effectively screened with a combination of two pseudo- isochromatic tests. Severe (major) colour vision defects regarded as a serious handicap in all occupations needing colour naming ability can be quickly detected with the Panel D-15 dichotomous test. Only a trained ophthalmologist can make the detailed estimation of the type and degree of the colour vision defect with the aid of the anomaloscope and the Farnsworth-Munsell 100-hue test. In the diagnosis of a congenital colour vision defect the exclusion of an eye disease with a consecutive acquired colour vision defect is important.

Color Perception Tests

[The Ohkuma's test: an evaluation].

Ohkuma's pseudoisochromatic test was evaluated in 147 subjects including 130 cases with hereditary dyschromatopsias, and compared with the color vision tests of Ishihara, the HRR, the Farnsworth Panel D-15 and the City University Color Vision Test. Qualitatively, Ohkuma's test was more exact for the diagnosis of the axis of the dyschromatopsia (protan or deutan); quantitatively, Ohkuma's test was of good efficiency for screening, but the quantitative gradation was mediocre, indicating dichromatism in only 3/4 of the cases.

Adolescent

Color vision: blue deficiencies in children?

Recent publicized reports based on the use of the Farnsworth Panel D-15 test suggest that a large percentage of young children have a deficiency of blue vision (tritan type). In our study, 413 school children (ages 3 to 10) were tested with both the Farnsworth Panel D-15 test, as well as the A.O. H-R-R plates. None of the children failed either test for blue-yellow vision when traditional scoring instructions were observed. As in previous reports, we find that the children make a number of minor errors which adults rarely make. These errors show marked age-related patterns, being more frequent in younger children. However, further analysis of these errors revealed that the relative frequency with which particular error types were made on the D-15 test was significantly correlated with the existing perceived color difference data for the visually normal adult population. In addition, retesting significantly reduced all error types and reversing the test sequence demonstrated that most of the minor errors were made in the last half of the test regardless of the color vision task. The overall increase in the number of minor test errors seen with young children seems unrelated to color defects. The modified scoring methods in conjunction with the characteristics of the Panel D-15 test design account for the high percentage of errors classified as errors of blue vision.

Age Factors

Sahlgren's Saturation Test for acquired dyschromatopsia: increased lightness enhances sensitivity.

Sahlgren's Saturation Test (SST) is a simple sorting test designed for the detection and grading of acquired color vision defects. Like other pigment-based color vision tests, the SST color samples have medium lightness, i.e., they belong to the intermediate part of the gray scale. We tested normal controls and subjects with congenital or acquired dyschromatopsia with five SST versions that differed only in the amount of lightness. The sensitivity of the test increased considerably with increasing lightness. Therefore, the lightness level of SST has now been changed from 30 to 10 Natural Color System units.

Color

The Ishihara Test: on the prevention of job discrimination.

Experiments were carried out to answer questions relative to the use of the 24-plate edition of the Ishihara Test for Colour-Blindness as a screening instrument for detecting the presence of inherited color defective vision. Subjects and their numbers varied between some experiments. Some subjects had normal color vision and others had inherited color defectiveness as confirmed with a Nagel anomaloscope. Most of the 157 subjects who participated in the experiments were either young deaf college students or police recruits with normal hearing who did not pass the Ishihara Test during their respective visual screening processes. Some hearing faculty and staff participated as part of Experiment 2. Item analysis and statistics applied to test the significance of differences between group means were applied to derive the following results: (a) test-retest reliability for the Ishihara is high both for persons with inherited color defectiveness and normal color vision; (b) persons making fewer than five errors on the first 13 plates made common incidental (nontypical) errors not related to color defective vision; and (c) five (5) or more errors was identified with some degree of inherited color defective vision, and subsequent referral for additional color vision diagnostics is warranted. Failure to utilize the recommended "pass-fail" criterion and/or to allow clients who fail color vision screening recourse to additional testing to establish type and degree of color defective vision may unnecessarily lead to job discrimination and/or interfere in a negative manner with the career selection process.

Adolescent

[Value of very low voltage halogen lighting of desaturated panel D 15 test in established glaucoma].

The colour vision of a first group of glaucomatous patients was tested with the desaturated Panel D 15 test, first illuminated by a 300 lux Macbeth lamp, then with a very low voltage 1000 lux halogen lamp. In addition to the recording of 80% cases of dyschromatopsia, in line with previously published data, we demonstrated a great number (33.3%) of red-green axis anomalies under Macbeth light and, paradoxically, even more under halogen light (53.3%). To explain this high percentage of red-green axes under halogen light, we discuss the influence of luminance and emission spectrum of the light source. We conclude that the use of high luminance halogen light is capable of revealing concealed Verriest type II dyschromatopsias probably due to a specific fragilisation of the red-green channels induced by the glaucoma disease. This original colour vision testing procedure applied on established glaucomatous patients enabled us to easily obtain a factor of severity in the course of the disease.

Adult

[Discrimination curve of color hues].

The hue discrimination curve has been studied in 48 cases of acquired dyschromatopsias not as it is the rule in relation with the nosology but in relation with the classifications as they are given by the test of Farnsworth. The results show with evidence different characters according to the type of dyschromatopsia: protan deutan or tritan.

Color Perception Tests

Clinical implications of color vision research.

The attributes of color and the mechanisms underlying normal and defective color vision are reviewed. The clinical implications of some research efforts bearing on congenital and acquired color defects, peripheral color vision, and the influence of photostable pigments on color vision and color vision tests is presented. This presentation is intended to illustrate how selected avenues of research have contributed to our understanding of color vision and to demonstrate the clinical utility of that research.

Color Perception

Color vision defects in ocular hypertension and glaucoma. Quantification with a computer-driven color television system.

In order to detect early defects of color vision caused by increased intraocular pressure, a computer graphics device and color monitor system were used to measure color contrast sensitivity. The system determines the threshold chrominance of a colored grating in which there is no change in luminance. The study included 13 control subjects aged 10 to 57 years and 19 patients with ocular hypertension or glaucoma aged 20 to 58 years. In the 13 eyes with visual field loss, color contrast sensitivity was profoundly reduced when the grating colors fell on a tritan color confusion line. In the eyes without visual field loss, tritan color contrast sensitivity was reduced to an average level considerably below the extreme limits of the control group. These results were compared with those of other color vision tests and diagnostic criteria for glaucoma. The findings suggest that among the tests used, color contrast sensitivity testing was able to discriminate most effectively between patients who had retinal damage and the normal population.

Color Perception Tests

Colour contrast sensitivity changes caused by peripheral retinal laser photocoagulation.

Macular phototoxicity is known to occur with laser use, and there is evidence that the wavelength of the light used influences this effect. In this study, a computer based colour contrast sensitivity test was used to assess the immediate macular effects of photocoagulation of peripheral flat retinal holes in otherwise normal retinas, using blue-green (488 and 514 nm), yellow (577 nm), orange (595 nm) or red (647 nm) laser light. The laser aiming beam was not allowed to traverse the macula at any stage during treatment. No protan or deutan axis threshold changes were noted in the 17 patients tested irrespective of the laser wavelength used. Tritan axis sensitivity was significantly reduced one hour after treatment with the blue-green laser, but no tritan axis change was found after treatment with longer wavelength lasers. The effect was no longer present the day after treatment in the subjects tested. The results show that even peripheral retinal treatment with blue-green laser can cause acute macular phototoxicity.

Color Perception

A new test for screening color vision: concurrent validity and utility.

Recognizing the need for an effective test for screening color vision in young children, we have developed a new pseudoisochromatic (PIC) plate test which is useful for a wide variety of observers at different ages. The test consists of four plates and responses can be used to categorize color vision as normal or as either red-green or blue-yellow defective. Results of this validation study with adults, both color normal and red-green defective, show a high degree of correlation between the new test and the Nagel anomaloscope: there were no false positives and only a few false negatives, which occurred with mild deuteranomalous observers. The validity of the test compares favorably to the Ishihara, F-2, and the AO-HRR screening plates. Results with toddlers (3 to 6 years) indicate that the task demands of the test are well suited for testing young children. The percentage of color defectives identified in the toddler sample using the new test is closer to the adult prevalence than results obtained with the F-2 and AO-HRR screening plates, which gave dramatically higher failure rates. The new test is culture-free and can be administered rapidly to both verbal and nonverbal observers using pointing or preferential looking.

Adult