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PubMed1980

A recommendation for illumination of the Farnsworth-Munsell 100-hue test.

The effect of illuminance on the performance of the Farnsworth-Munsell 100-hue (FM 100) test has previously been reported for young observers with normal color vision. However, information regarding these effects for older persons is lacking. This study reports the effect of illuminance level, over a wide range, on the FM100 performance of 10 elderly subjects with normal color vision compared to a control group of five young adult normal subjects. A recommendation is made for a standard level of illuminance for administration of the FM100-hue test.

Adult↗
PubMed1981

Chromatic adaption and the fundamental stimuli.

A bipartite adaption stimulus with a horizontal dividing line adapted the upper half of the retina to red or yellow light and the lower half to white light. Monochromatic test stimuli between 460 and 520 nm were presented to the red or yellow adapted portion of the retina. After desaturating the test stimulus with red light, it was possible to match it to a mixture of 458 and 520 nm. From these data one can plot on a mixture diagram the shifts in color produced by the two kinds of adaption. The data support a zone theory of color vision similar to that proposed by Adams.

Adaptation, Ocular↗
PubMed1983

Reaction time to spatial frequencies using yellow and luminance-matched neutral goggles.

The popularity of yellow goggles for outdoor activities has long been a paradox to visual scientists as previous tests of their effectiveness have failed to show any visual advantage. The achromatic/chromatic theory of color vision suggests a possible solution to the paradox which was tested by measuring reaction times to spatial frequencies of varying contrast. Reaction times were faster with yellow goggles than with luminance-matched neutrals under certain conditions. These conditions included frequencies in the middle of the range of human sensitivity and, specifically, the lower contrasts of these frequencies. The theoretical and practical applications of the results are discussed.

Color Perception↗
PubMed1983

Variation of the green-red ratio with refractive error.

The relationship of refractive error to green-red ratios among color normals was investigated by asking 27 subjects to match a standard yellow with a mixture of red and green primaries using a Nagel anomaloscope. Green-red ratios did not show any regular change with refractive error. Differences in refractive error, natural or induced, among color normal persons did not change the measurements of color vision with the Nagel anomaloscope.

Color Perception↗
PubMed1983

Chromatic adaptation and the blue-green side of the color triangle.

This is an attempt to show with chromatic adaptation data that the line tangent to the spectrum locus at about 460 nm and passing through the tritanopic confusion point represents the blue-green leg of the triangle of fundamental colors. The inability to use chromatic adaptation to produce colors in the green corner of the triangle has been explained in terms of a zone theory of color vision.

Adaptation, Ocular↗
PubMed1985

Effect of restricted viewing time on mid-match points for normal observers on the Moreland and Pickford Nicolson anomaloscopes.

Restricted viewing time has previously been shown to produce a tritan classification for color normal observers on the City University Colour Vision Test (CUCVT). The present investigation, which uses the Moreland anomaloscope, studies the effect of restricted viewing time on mid-match point (MMP). It shows that a color normal observer requires more green in a match under these conditions. A study of the Rayleigh equation using the Pickford Nicolson anomaloscope shows that restricted viewing time does not affect the MMP for this metameric match for color normal observers.

Adult↗
PubMed1988

D-15 performance with short wavelength absorbing filters in normals.

Short wavelength absorbing filters (SWAF's) have become very popular in the prescription and commercial sunglass markets. Like other chromatic filters SWAF's have the potential to alter color vision. Performance on the Farnsworth Panel D-15 (D-15) test was measured to determine whether any of 4 popular SWAF's, in the form of sunglasses, produced color vision changes in 22 color normal adults. Using standard illuminant C, observers were tested under the following conditions: wearing no filter, a 1.0 log unit neutral density filter (NDF), or one of the following SWAF's: Corning CPF 550; NolR Amber 40%; Blu Blocker; and Vuarnet 4006. In addition, the Vuarnets were tested outdoors in shaded daylight to determine the effects of increased illumination. The NDF served as the control and had no effect on D-15 performance. Compared to it, only the Blu Blockers and Vuarnets affected D-15 cap arrangements for these SWAF's significantly. Blu Blocker error patterns had no predominant axis, whereas the predominant axis of errors in both Vuarnet conditions was tritan. Results of quantitative analysis performed on three factors confirmed these findings and indicated the Blu Blockers and Vuarnet SWAF's caused moderate and moderate-to-severe levels of color confusion, respectively. Increasing the illumination level improved performance with the Vuarnets, but it remained significantly outside the normal range.

Adult↗
PubMed1988

Meridional differences in the directional sensitivity of the human color mechanisms.

The directional sensitivity (DS) of the red (pi 5), green (pi 4), and blue (pi 1) color mechanisms was measured for both the horizontal and vertical pupil meridians, thus localizing the peak of each pi-mechanism DS function within the two-dimensional pupillary aperture. In the horizontal meridian, there were greater differences among observers in DS function peak locations than there were for any one observer. Along the vertical meridian, peak location differences within observers were similar to those found in the horizontal meridian, whereas among-observer differences were much smaller. Significant differences between horizontal and vertical DS function halfwidths were also found for at least one pi-mechanism of each observer. It is concluded that meridional variations exist in either the morphology or orientational distribution of foveal photoreceptors, and that more than one alignment mechanism is responsible for photoreceptor orientation in the human fovea.

Accommodation, Ocular↗
PubMed1989

Dichoptic opponent hue cancellations.

Relative to monoptic opponent hue cancellations, dichoptic cancellations, which were possible over most of the visible spectrum, generally required more blue or less yellow to cancel the opponent yellow or blue response and less green to cancel the opponent red response. Differences between dichoptic and monoptic red-to-cancel-green functions were wavelength dependent. These data were approximately predicted by a model in which monoptic cancellations are based at the receptor level, whereas dichoptic cancellations are based upon cancellations of postreceptor opponent hue responses at a central level in the visual system. The model also makes reasonable predictions of other dichoptic hue-matching data.

Color Perception↗
PubMed2002

The validity of the University of Waterloo Colored Dot Test for Color Vision Testing in adults and preschool children.

PURPOSE: Most color vision tests require a high level of cognitive ability and as such are problematic for preschool children and multiply challenged individuals. Our goal was to design a color vision test for these groups and evaluate the clinical utility for preschool children. METHODS: The University of Waterloo Colored Dot Test (UWCDot) for Color Vision Testing requires the subject to distinguish a colored disc from seven gray discs. The target disc was a Munsell color along the deutan, protan, or tritan confusion line with gray. The first phase estimated the sensitivity and specificity of the test for adults. Thirty-one adults with normal color vision and 21 adults with congenital red-green defects participated. In the second phase, the utility of the UWCDot test for screening preschool children was determined. Subjects were 281 males and 269 females aged 2.5 to 5 years with normal vision. Their color vision was also assessed with the Standard Pseudoisochromatic Plates, Part 1 (SPP1). RESULTS: The sensitivity and specificity of UWCDot for adults approached the values for the desaturated D-15 when subjective responses were scored. Monitoring fixational eye movements produced sensitivity and specificity values that were similar to the anomaloscope. After adjusting the scoring criterion for the preschool children by using the females as a control, 2.9% of the males were identified as red-green deficient, 1.8% were blue-yellow deficient, and 3.2% had an unclassified deficiency. By definition, 1% of the females failed the test. Counting fixational eye movements was not a useful scoring method in the preschool children. Comparisons with SPP1 indicated that the UWCDot uncovers approximately 35% of the individuals with definite red-green color vision defects. CONCLUSIONS: Our results indicate that the UWCDot is capable of detecting approximately 35% of the preschool children who have a congenital red-green color vision defect. These individuals are likely to have a more severe deficiency.

Adult↗
PubMed2001

Chromatic contrast thresholds as a prognostic test for visual improvement after macular hole surgery: color vision and macular hole surgery outcome.

PURPOSE: To evaluate the relationship between preoperative chromatic contrast thresholds, postoperative visual acuities (VA), and visual improvement after macular hole surgery. METHODS: A consecutive series of patients with Stage II to IV macular holes was studied before macular hole surgery. Preoperative chromatic contrast thresholds, VA, and reading acuity were analyzed in relation to the postoperative visual function. The chromatic contrast thresholds were measured using a computerized cathode ray tube-based system along red-green and tritan confusion axes. RESULTS: Preoperative and postoperative chromatic contrast thresholds were elevated significantly in affected eyes (P < 0.001). Preoperative VA showed a strong correlation with postoperative VA (r = 0.66, P < 0.001) but a weak correlation with visual improvement (r = -0.33, P = 0.03). Red-green contrast threshold correlated strongly with both the distance visual improvement (r = -0.77, P < 0.001) and reading visual improvement (r = -0.61, P < 0.001). Tritan contrast threshold, however, showed a slightly weaker correlation (distance: r = -0.63, P < 0.001; reading: r = -0.47, P < 0.005). CONCLUSIONS: These results suggest that chromatic contrast thresholds, especially the red-green contrast threshold, represent a better prognostic guide for visual improvement after macular hole surgery than VA measurement.

Aged↗
PubMed2006

The segregation and integration of colour in motion processing revealed by motion after-effects.

Analysis of the colour and motion of objects is widely believed to take place within segregated processing pathways in the primate visual system. However, it is apparent that this segregation cannot remain absolute and that there must be some capacity for integration across these sub-modalities. In this study, we have assessed the extent to which colour constitutes a separable entity in human motion processing by measuring the chromatic selectivity of two kinds of after-effect resulting from motion adaptation. First, the traditional motion after-effect, where prolonged inspection of a unidirectional moving stimulus results in illusory motion in the opposite direction, was found to exhibit a high degree of chromatic selectivity. The second type of after-effect, in which motion adaptation induces misperceptions in the spatial position of stationary objects, was completely insensitive to chromatic composition. This dissociation between the chromatic selectivities of these after-effects shows that chromatic inputs remain segregated at early stages of motion analysis, while at higher levels of cortical processing there is integration across chromatic, as well as achromatic inputs, to produce a unified perceptual output.

Adaptation, Physiological↗
PubMed1994

Detection of functional vision loss using the Ishihara plates.

Many techniques have been described for the detection of functional visual loss. We report four cases in which Ishihara pseudo-isochromatic colour plates gave objective evidence of functional vision loss. In all cases the patients were able to read the first test pattern (No. 12), but could not distinguish any of the following pseudo-isochromatic numbers (plates 2-17). However, they experienced no difficulty in tracing the winding lines (plates 18-24), demonstrating that they in fact had normal colour vision.

Adolescent↗
PubMed2006

From lower to higher colour metrics: a historical account.

BACKGROUND: 'Lower colour metrics' describes the laws of colour mixture as manifest in trichromatic colour space and best known in its two-dimensional projection, the chromaticity diagram. 'Higher colour metrics' describes how distance in this colour space translates into perceptual difference. It is higher in the sense that it builds on the fundamentals of lower colour metrics. METHODS: A historical account is given of the development of higher colour metrics, with many ups and downs, since Helmholtz started it at the end of the 19th Century. RESULTS: Despite long periods of silence, Helmholtz's basic ideas have survived by successfully extended modelling, which could also account for seemingly paradoxical effects of luminance and saturation on colour discrimination. CONCLUSION: The subject theme, which presently is at a low tide of interest, deserves the renewed interest of colour vision researchers.

Color Perception↗
PubMed1986

Origins of colour vision standards within the transport industry.

Colour vision standards should reflect changes in our understanding of the nature of these defects as well as technological advances that place less importance upon the visual senses of the human operator. Therefore it is suggested that visual standards be subject to routine reviews in order to assess their suitability for modern work environments. This paper gives a chronological account of the introduction of colour vision standards by several national transport authorities and identifies historical reasons that led to their implementation. It is concluded that the same factors that gave rise to the adoption of early colour vision standards are still relevant for modern transport systems. However the recent deployment of automatic or semi-automatic control or navigational systems has substantially altered man's role from being the primary source of information input to one of a monitoring process. This has generated a good deal of debate and uncertainty regarding the level of responsibility that a human operator has for the control of modern transport vehicles. Nevertheless, it is argued that in the absence of complete automation some type of visual standard is needed whenever visual judgements must be made by human observers.

Aerospace Medicine↗
PubMed2004

Chromatic and luminance losses with multiple sclerosis and optic neuritis measured using dynamic random luminance contrast noise.

We measured thresholds for detecting changes in colour and in luminance contrast in observers with multiple sclerosis (MS) and/or optic neuritis (ON) to determine whether reduced sensitivity occurs principally in red-green or blue-yellow second-stage chromatic channels or in an achromatic channel. Colour thresholds for the observers with MS/ON were higher in the red-green direction than in the blue-yellow direction, indicating greater levels of red-green loss than blue-yellow loss. Achromatic thresholds were raised less than either red-green or blue-yellow thresholds, showing less luminance-contrast loss than chromatic loss. With the MS/ON observers, blue-yellow and red-green thresholds were positively correlated but increasing impairment was associated with more rapid changes in red-green thresholds than blue-yellow thresholds. These findings indicate that demyelinating disease selectively reduces sensitivity to colour vision over luminance vision and red-green colours over blue-yellow colours.

Adult↗
PubMed2006

The effects of supplementation with lutein and/or zeaxanthin on human macular pigment density and colour vision.

BACKGROUND: Both yellow-blue (YB) discrimination thresholds and macular pigment optical density (MPOD) measurements in the eye exhibit large variability in the normal population. Although it is well established that selective absorption of blue light by the macular pigment (MP) can significantly affect trichromatic colour matches, the extent to which the MP affects colour discrimination (CD) sensitivity remains controversial. OBJECTIVE: In this study, we assess whether the variability in YB thresholds is attributable to differences in MPOD, both at the fovea and in the paracentral visual field. We also investigated whether higher levels of MP offer any advantage in other visual functions such as red-green (RG) CD sensitivity. DESIGN: CD thresholds and spatial MPOD profiles were measured in 24 normal trichromats supplemented with zeaxanthin (OPTISHARP) and/or lutein. Novel stimulus conditions that isolate YB and RG chromatic mechanisms were employed and MPOD profiles were measured up to an eccentricity of 8 degrees. RESULTS: The data reveal an increase in MPOD in the supplemented subjects that was almost uniform within a centre region around the fovea subtending +/-4 degrees. RG sensitivity was high in all subjects with thresholds well within the normal range. Unexpectedly, YB thresholds were also normal and showed no correlation with MPOD. A model for threshold CD based on appropriate combinations of cone contrast signals was developed to explain the experimental findings. CONCLUSIONS: YB thresholds remain unaffected by supplementation with lutein and/or zeaxanthin rather, at increased MPOD levels, RG vision tends to be improved. The model accounts for the absence of correlation between MPOD and YB thresholds and predicts a marginal improvement in RG discrimination when MPOD is high.

Adult↗