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At least 253 records · Page 14Linked to original sources
PubMed1983

A time induced tritan defect.

It is hypothesized that if blue is signalled more slowly than red in the visual system, and if integration time is longer for blue than for red, then a tritan defect should be apparent for normal observers. Data from short-exposure viewing of the City University Colour Vision Test indicate that, at 3.75 msec. a significant tritan error occurs.

Adult↗
PubMed1994

Perchloroethylene exposure can induce colour vision loss.

We evaluated colour vision in 35 dry-cleaners exposed to perchloroethylene (PCE) and in a paired number of controls matched for sex, age, alcohol consumption and cigarette smoking. A subclinical colour vision loss, mainly in the blue-yellow range, was present in dry-cleaners. This effect was related to PCE exposure levels, and appeared at environmental concentrations of the solvent well below the current exposure limits for exposed workers. The results suggest that PCE exposure, even at low environmental levels, can induce a dose-related impairment of colour vision.

Adult↗
PubMed1985

Color-axis determination on the Farnsworth-Munsell 100-hue test.

Error scores on the Farnsworth-Munsell 100-hue test were partitioned into those representing red-green and those representing blue-yellow losses. Data from two groups of normal observers were used. One group showed results characteristic of published norms; one group showed superior performance. Both observers showed a correlation between red-green and blue-yellow scores indicative of a strong performance factor in this test. The difference between blue-yellow and red-green scores eliminates their correlated variance and allows evaluation of the axis. Both groups showed an increase in difference scores, with age indicating development of a blue-yellow axis. This increase was significant for the observers characteristic of the norms. We suggest cutoff scores to allow a decision as to whether a given patient shows a blue-yellow or red-green axis.

Adolescent↗
PubMed1982

A new assessment of the normal ranges of the Farnsworth-Munsell 100-hue test scores.

We gave the Farnsworth-Munsell 100-hue color vision test to 232 normal subjects between 10 and 80 years of age. One half the subjects underwent binocular testing followed by monocular testing. In the other half monocular testing preceded binocular testing. Performance was better with both eyes than with either eye alone. The worst performance occurred on monocular tests in subjects without previous experience with the task (that is, those for whom this was the first test). The well-known age trend was apparent (children and elderly have the worst color vision). New data are provided for judging the point at which the total error score may be considered pathologic.

Adolescent↗
PubMed1991

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↗
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↗
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↗
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↗