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PubMed1990

[Color vision disturbance in laser operators and patients: comparison of argon and dye lasers].

Color contrast sensitivity was measured in laser operators before and after laser sessions. The tritan threshold was elevated after the sessions in all laser operators who had used argon (blue-green) lasers. No change was observed when lasers with longer wave-lengths were used. Elevation of the tritan threshold to above-normal levels was observed even before laser sessions. The thresholds remained increased even when the laser operator did not use a laser for 3 weeks. Thus, it appears that the damage caused by the argon blue-green laser is cumulative. Elevated tritan thresholds were also observed in patients with peripheral retinal breaks who were treated with an argon (blue-green) laser.

Adolescent↗
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↗
PubMed1968

The luminosity curve of the protanomalous fovea.

Threshold spectral sensitivities (in the dark, or against bright colored backgrounds) are identical in the red-green range for both protanopes (dichromats) and protanomalous trichromatic color defectives. The latter, however, must have an additional photolabile cone pigment in the red-green range, and its presence is revealed by heterochromatic brightness matching through the spectrum (i.e. luminosity curves). The absorption spectrum of the anomalous cone pigment can be inferred from the protanomalous and protanopic luminosity curve, given reasonable assumptions as to how the different cone mechanisms pool their responses. Depending upon these assumptions, the pigment inferred is either (a) dilute solution of the normal red pigment (assumed density 1.0 for the deuteranope) or (b) similar in its absorption spectrum to the normal green pigment but shifted slightly toward the long wave end of the spectrum. Experimental attempts to choose between these alternatives have so far proved equivocal though (b) seems more likely on the basis of indirect evidence.

Color Perception Tests↗
PubMed1968

The luminosity curve of the deuteranomalous fovea.

Analogous to protans, the two types of deutan color-defectives-the dichromats (deuteranopes) and the anomalous trichromats (deuteranomalous)-do not differ in spectral sensitivity in the red-green range at threshold (either in the dark or against bright colored backgrounds). However, luminosity curves obtained by heterochromatic brightness matching show the latter to be slightly more sensitive in the blue-green, and slightly less so in the red, than the former. Experiment proves that these differences are due (at least in part) to contributions of cones containing the deuteranomalous anomalous pigment which are missing from the deuteranope's eye. The absorption spectrum of the anomalous pigment can be inferred with assumptions (analogous to those already made with protanomalous trichromats) about how the different cone mechanisms pool their responses to yield luminosity. Two alternatives thus revealed are (a) the normal red pigment in dilute solution or (b) a spectrum very similar to that of the normal red pigment but shifted slightly toward the short wave end of the spectrum. Since the spectrum inferred by (a) has the same lambda(max) as the normal red pigment, (a) predicts that deuteranomalous observers will require a negative red primary when matching monochromatic lights of wavelengths near the lambda(max). This is not observed.

Color Perception Tests↗
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↗
PubMed1977

The locus of unique green in deuteranomalous trichromats.

A method of color naming was used to determine the spectral locus for unique green (UG) as it was perceived by 20 color normals and 24 deuteranomalous trichromats. The loci for the normal group were distributed bimodally, as earlier investigators had reported, and a bimodal distribution was also found for the deuteranomalous group. In the latter group, UG was located at long wavelengths only by those who had been classified as mild deuteranomals according to several clinical criteria. Those who located UG at shorter wavelengths included individuals whose defects ranged from mild to severe. This result is discussed in the context of theories of deuteranomaly and is presented as further evidence for the existence of 2 types of deuteranomaly.

Adolescent↗
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↗
PubMed1981

Dichoptic color perception and the X-chrom lens.

Dichoptic color experiments were performed with color normals and with protanopes and deuteranopes. Different targets were presented to each eye in a stereoscope. Experiment 1 used homogeneous chromatic targets. Experiment 2 involved black and white photographs taken and viewed through various filters. Experiment 3 utilized a dichromat wearing an X-Chrom lens. The experiments indicate that the cortical perception achieved by summing input of each eye when one eye has a filter in front of it may aid color discrimination for dichromats.

Color Perception↗
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↗