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PubMedDate not supplied

Scotopic vision, color vision, and stereopsis in infants.

Infants as young as 1 month postnatal have scotopic spectral sensitivity closely resembling the CIE standard curve and thus appear to have a functional, rhodopsin-based rod system. Neutrally adapted photopic spectral sensitivities are broad and roughly equal to those of adults tested under similar conditions, although infants may show an elevated sensitivity in the short-wavelength region of the spectrum. Spectral sensitivity has been shown to change with changes in chromatic adaptation. Some wavelength discriminations are possible under conditions in which brightness artifacts can be ruled out. All of these factors support the conclusion that young infants are at least dichromats. However, 2-month-olds to date have shown some unpredicted failures of chromatic discrimination (for example, yellow-greens from white), and the percentage of infants who demonstrate discriminations (for example, among wavelengths greater than or equal to 550 nm) improves with age in early infancy. Thus the status of young infants as trichromats is not yet clearly established. Stereopsis develops rapidly during months 3 to 7, and stereoacuities as good as 1' have been reported by 5 months postnatal. In summary, a variety of visual capabilities can now be measured in infants. Infants' visual capacities are rather surprisingly well established shortly after birth and undergo clear improvements during the first few postnatal months. The interpretation of developmental data and their bearing on visual theory are discussed.

Adult↗
PubMed1999

Evaluation of a new color vision test: "color vision testing made easy".

PURPOSE: A new pseudoisochromatic color plate test, "Color Vision Testing Made Easy" (CVTMET) has recently been introduced. Said to be designed for all age groups, including pre-school children, it uses the identification of simple shapes and objects to detect red-green color deficiencies. We evaluated the CVTMET to determine if the test is suitable for color vision screening of young children. METHODS: Forty-one adults predetermined to be color normal (n = 20) or to have hereditary red-green color deficiency (n = 21), served as subjects. A battery of color vision tests including the Ishihara, Panel D-15, and the anomaloscope were used for diagnosis and color deficiency classification. Subjects were then tested with Part I and Part II of the CVTMET test and results were compared to the Ishihara, Panel D-15, and anomaloscope. In addition, the CVTMET was used to screen for color vision deficiency in 152 kindergarten children 5 to 7 years of age. RESULTS: The pass/fail results for the adult subjects were the same for Parts I and II and compared favorably with the anomaloscope. There were no false positives (100% specificity) and only a few (2 of 21) false negatives (90.5% sensitivity). The two color-deficient subjects who passed the CVTMET had the mildest color deficiencies (simple deuteranomaly) and also passed the Ishihara test. Testability of kindergarten children was found to be 100%. Color vision deficiency occurred in 5.06% of the boys, which is about the same frequency found in older boys of similar ethnic background. CONCLUSION: This preliminary study indicates that the CVTMET appears to be an excellent screening instrument for red-green color deficiency in adults and has been shown to be useful for examining color vision in children 5 to 7 years of age.

Adult↗
PubMed2000

Molecular genetics of color vision and color vision defects.

Color is an extremely important component of the information that we gather with our eyes. Most of us use color so automatically that we fail to appreciate how important it is in our daily activities. It serves as a nonlinguistic code that gives us instant information about the world around us. From observing color, for example, we can find the bee sting on an infant's arm even before it begins to swell by looking for the little spot where the infant's skin is red. We know when fruit is ripe; the ripe banana is yellow not green. We know when meat is cooked because it is no longer red. When watching a football game, we can instantly keep track of the players on opposing teams from the colors of their uniforms. Using color, we know from a distance which car is ours in the parking lot--it is the blue one--and whether we will need to stop at the distant traffic light, even at night, when we cannot see the relative positions of red and green lights.

Color Perception↗
PubMed1984

Within-species variations in visual capacity among squirrel monkeys (Saimiri sciureus): color vision.

Color vision was studied in 27 squirrel monkeys (Saimiri sciureus) of Peruvian origin (Roman Arch variety). Tests of wavelength discrimination and Rayleigh matching as well as a search for a spectral neutral point were carried out in a behavioral paradigm involving a three-alternative, forced-choice discrimination. Significant individual variations in color vision were found in this species. Some squirrel monkeys have trichromatic color vision, others are dichromats. Within each of these catagories there appear to be three subtypes. Each of these color vision phenotypes can be interpreted as reflecting the presence of a different combination of the types of cone photopigments known to characterize this species. There is a striking gender difference in squirrel monkey color vision; whereas both trichromatic and dichromatic female monkeys were found, all of the males tested were dichromats.

Animals↗
PubMed2003

Color vision.

Color vision starts with the absorption of light in the retinal cone photoreceptors, which transduce electromagnetic energy into electrical voltages. These voltages are transformed into action potentials by a complicated network of cells in the retina. The information is sent to the visual cortex via the lateral geniculate nucleus (LGN) in three separate color-opponent channels that have been characterized psychophysically, physiologically, and computationally. The properties of cells in the retina and LGN account for a surprisingly large body of psychophysical literature. This suggests that several fundamental computations involved in color perception occur at early levels of processing. In the cortex, information from the three retino-geniculate channels is combined to enable perception of a large variety of different hues. Furthermore, recent evidence suggests that color analysis and coding cannot be separated from the analysis and coding of other visual attributes such as form and motion. Though there are some brain areas that are more sensitive to color than others, color vision emerges through the combined activity of neurons in many different areas.

Animals↗
PubMed1999

Evolution of color vision.

Color vision is achieved by comparing the inputs from retinal photoreceptor neurons that differ in their wavelength sensitivity. Recent studies have elucidated the distribution and phylogeny of opsins, the family of light-sensitive molecules involved in this process. Interesting new findings suggest that animals have evolved a strategy to achieve specific sensitivity through the mutually exclusive expression of different opsin genes in photoreceptors.

Animals↗
PubMed1986

Effects of ethyl alcohol on the electrooculogram and color vision.

Color vision tests and electrooculography (EOG) were performed in 6 male and 2 female healthy young trichromatic volunteers between 60 and 130 min after finishing consumption of ethyl alcohol leading to blood levels of approximately 0.07% to 0.16%. The average number of errors in the desaturated Panel D-15 arrangement test rose from 0.86 to 2.0; the average error score in the Farnsworth-Munsell 100-Hue test rose from 26 to 79. The axis of errors in both tests was clearly tritanopic and tetartanopic, pointing to a specific effect of ethyl alcohol on the function of blue-sensitive cones and/or their interaction with longer wavelength-sensitive cones. Ethyl alcohol decreased the size of the light-peak, apparently in a dose-dependent fashion, in each of the 16 eyes by values between 3% and 79%. The effect of alcohol on the EOG light peak was stronger between 30 and 95 min (23% decrease in average) than between 95 and 130 min (14% decrease) after the finish of alcohol administration.

Color Perception↗
PubMed1995

Color vision and color pattern visual evoked cortical potentials in a patient with acquired cerebral dyschromatopsia.

We examined a 74-year-old man because of difficulty seeing green and the presence of prosopagnosia. His visual acuity was 0.8 in both eyes. He was not congenitally color blind, and there was no family history of color blindness. A left superior homonymous quadrantanopsia was found. The dyschromatopsia ws identical in both eyes. The patient showed red-green deficiency on testing with Ishihara plates a deutan defect with Tokyo Medical College plates, strong blue-yellow defects and medium red-green defects with Standard Pseudochromatic Plates II and a tritan defect with the Panel D-15. He failed the New Color separation test with scores of 160 and could not carry out the Farnsworth-Munsell 100-hue test, but his color naming test results were normal. Visual evoked cortical potentials to black-and-white checkerboard and color pattern reversal (Red and Blue-Green, Green and Red-Purple, Purple and Yellow-Green: isochromatic paired checks) stimuli were normal. Bilateral inferior occipital lesions were found by computed tomography and T2-weighted magnetic resonance imaging. Our findings suggested that luminance and color channels up to area 17 in our patient were intact. We believe that our patient's acquired cerebral dyschromatopsia is rare.

Aged↗
PubMed1988

Molecular basis of abnormal red-green color vision: a family with three types of color vision defects.

The molecular nature of three different types of X-linked color-vision defects, protanomaly, deuteranomaly, and protanopia, in a large 3-generation family was determined. In the protanomalous and protanopic males the normal red pigment gene was replaced by a 5' red-3' green fusion gene. The protanomalous male had more red pigment DNA in his fusion gene than did the more severely affected protanopic individual. The deuteranomalous individual had four green pigment genes and one 5' green-3' red fusion gene. These results extend those of Nathans et al., who proposed that most red-green color-vision defects arise as a result of unequal crossing-over between the red and green pigment genes. The various data suggest that differences in severity of color-vision defects associated with fusion genes are caused by differences in crossover sites between the red and green pigment genes. Currently used molecular methodology is not sufficiently sensitive to define these fusion points accurately, and the specific color-vision defect within the deutan or protan class cannot be predicted. The DNA patterns for color-vision genes of female heterozygotes have not previously been described. Patterns of heterozygotes may not be distinguishable from those of normals. However, a definite assignment of the various color pigment gene arrays could be carried out by family study. Two compound heterozygotes for color-vision defects who tested as normal by anomaloscopy were found to carry abnormal fusion genes. In addition, a normal red pigment gene was present on one chromosome and at least one normal green pigment gene was present on the other.(ABSTRACT TRUNCATED AT 250 WORDS)

Blotting, Southern↗