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Varying degrees of deficient color perception along the Deutan axis within one family have been studied and presented. All seven family members exhibit manifest color blindness. The question of the phenotype among heterozygotic females is discussed on the basis of the data found by anomaloscope testing and the hue tests of Farnsworth D-15 and Farnsworth 100.
We examined the effect of variations in viewing distance and viewing duration on the performance of color-normal observers with four standard tests of color vision. Significant effects of the experimental manipulations were obtained: both increasing viewing distance and decreasing viewing duration significantly increased the number of errors made by observers. Moreover, the four tests differed widely in their sensitivity to the variations in viewing conditions. Practical implications of the findings for the administration and selection of plate tests are discussed, and possible mechanisms underlying the results are suggested.
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.
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The Ishihara plates are widely used as a test for colour vision. Originally designed for the purpose of detecting congenital red-green colour blindness, the test also has some value in demonstrating acquired colour vision defects. There are, however, several disadvantages in the present arrangement of the plates. A modification of the test, involving the rearrangement of the order of the plates, is presented which, together with a new recording chart, simplifies both the administration and the interpretation of the test.
The color vision of nine patients aged from 13 to 52 years with Stargardt's disease was studied with the following tests: Standard Pseudoisochromatic Plates part 2 (SSP2), Farnsworth-Munsell 100 hue test (FM100), Nagel (red-green) anomaloscope and Besançon (blue) anomalometer. At the beginning of the disease, a very slight defect in red-green color vision could be demonstrated. Later, a distinct acquired red (pseudo-protanomalous) defect in the Nagel anomaloscope and an abnormal error score in the FM100 test were observed. In advanced stages, the red defect became stronger (scotopization) and the FM100 test showed a red-green axis. In the course of the disease, a blue defect with the SPP2 plates and with the Besançon anomalometer could also be found. The visual acuities of the patients had a significant correlation with the matching ranges of the Rayleigh equation and the Moreland equation. The duration of the disease did not show any correlation with the color vision tests.
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.
A 31-year-old white male deutan produced reliably different profiles when examined binocularly and monocularly with a Farnsworth-Munsell 100-hue test. Discrimination in the long wavelengths improved under the binocular conditions. Intensive testing yielded no information to account for the phenomenon.
An influence of visual field disorders on sorting performance in the FM 100-hue test is reported. Patients with left-sided field disorders performed worse in the conventional testing direction, i.e. from left to right, compared with patients with right-sided defects. Reversing the direction of sorting led, however, to a similar impairment in patients with right-sided field defects. Observations in normals tested under different conditions of hue sorting support the view that the difference obtained cannot be accounted for by a hemisphere difference in colour processing but by the strategy adopted by subjects.
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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.
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.
Earlier findings showed that redundant colour coding decreased response times and reduced errors in carrying out various tasks that required information acquisition from the video display of an electronic flight instrument system. The results of this experiment showed that observers with defective colour vision have slower response times and higher error rates than normal observers for some of the tasks and that their performance is similar to that of colour-normal observers for a monochrome display. However, they were not disadvantaged when blue was used to colour code the target feature. Protanopes were shown to be especially disadvantaged in responding to a red 'fail' message.
The present work extends the findings of previous efforts examining the comparability of current colour-screening tests. Several popular tests are shown to differ greatly in the performance exhibited by colour-normal observers as well as in their differential sensitivity to experimental manipulations of viewing duration and viewing distance. Those tests designed to identify yellow-blue dichromacy are especially sensitive to the manipulation of viewing distance, which is interpreted as reflecting 'small-field tritanopia' and the asymmetry in retinal density of the three cone types. These findings are discussed in terms of factors that influence the comparability of current colour-screening devices and the particular need for close adherence to standardized conditions with such instruments.
Colour contrast sensitivity (CCS) of a large cohort of glaucomatous patients, ocular hypertensive patients (OH), and normal persons was measured at six-month intervals during a two-year period. The OHs were graded into high, medium, and low risk groups. 69% of glaucomatous patients and 32% of all OHs had CCS thresholds greater than the mean plus 2 SDs of the controls. Satisfactory specificity and sensitivity could not be obtained by adjusting the criterion of threshold. In abnormal eyes, progressive small increases of threshold occurred during the study, but glaucomatous eyes with normal thresholds on the first visit retained normal thresholds in the subsequent visits. Although our system is very sensitive and precise, the proportion of abnormalities detected is no greater than with other techniques. In some glaucomatous patients there is a true preservation of colour vision which does not merely reflect the limitations of the test employed.
Colour vision function was assessed in 38 non-complicated type 1 diabetic patients in whom fluorescein angiography was normal, and was compared with that in 36 age-matched, non-diabetic controls. All of the patients were healthy and none were taking medication except insulin. The eye examination, which was normal in every patient, included the Ishihara and City University tests, measurement of Snellen acuity, slit-lamp examination, tonometry, and fundal photography as well as fluorescein angiography. Colour discrimination ability was measured with the Farnsworth-Munsell 100-hue test. Mean (SE) 100-hue test error score for the diabetic group was 86.8 (8.1) compared with 28.2 (3.3) for controls, p<<0.001. There was no relation between colour vision abnormalities and diabetes duration (r = 0, p>0.05), blood glucose at the time the colour tests were performed (r = 0.4, p > 0.05), most recent glycated haemoglobin result (r = 0.3, p>0.05), or the mean of all previous glycated haemoglobin results (r = 0, p>0.05). It is concluded that colour discrimination may be abnormal in uncomplicated type 1 diabetic patients before the onset of retinopathy, and that colour discrimination losses in diabetes may not be of vascular aetiology.