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At least 415 records · Page 23Linked to original sources
PubMed1999

Color vision deficits and laser eyewear protection for soft tissue laser applications.

PURPOSE: Laser safety considerations require urologists to wear laser eye protection. Laser eye protection devices block transmittance of specific light wavelengths and may distort color perception. We tested whether urologists risk color confusion when wearing laser eye protection devices for laser soft tissue applications. MATERIALS AND METHODS: Subjects were tested with the Farnsworth-Munsell 100-Hue Test without (controls) and with laser eye protection devices for carbon dioxide, potassium titanyl phosphate (KTP), neodymium (Nd):YAG and holmium:YAG lasers. Color deficits were characterized by error scores, polar graphs, confusion angles, confusion index, scatter index and color axes. Laser eye protection device spectral transmittance was tested with spectrophotometry. RESULTS: Mean total error scores plus or minus standard deviation were 13+/-5 for controls, and 44+/-31 for carbon dioxide, 273+/-26 for KTP, 22+/-6 for Nd:YAG and 14+/-8 for holmium:YAG devices (p <0.001). The KTP laser eye protection polar graphs, and confusion and scatter indexes revealed moderate blue-yellow and red-green color confusion. Color axes indicated no significant deficits for controls, or carbon dioxide, Nd:YAG or holmium:YAG laser eye protection in any subject compared to blue-yellow color vision deficits in 8 of 8 tested with KTP laser eye protection (p <0.001). Spectrophotometry demonstrated that light was blocked with laser eye protection devices for carbon dioxide less than 380, holmium:YAG greater than 850, Nd:YAG less than 350 and greater than 950, and KTP less than 550 and greater than 750 nm. CONCLUSIONS: The laser eye protection device for KTP causes significant blue-yellow and red-green color confusion. Laser eye protection devices for carbon dioxide, holmium:YAG and Nd:YAG cause no significant color confusion compared to controls. The differences are explained by laser eye protection spectrophotometry characteristics and visual physiology.

Adult↗
PubMed2001

The dissociation of color from form and function knowledge.

We report on two brain-damaged subjects who exhibit the uncommon pattern of loss of object color knowledge, but spared color perception and naming. The subject P.C.O., as in previously reported patients, is also impaired in processing other perceptual and functional properties of objects. I.O.C., in contrast, is the first subject on record to have impaired object color knowledge, but spared knowledge of object form, size and function. This pattern of performance is consistent with the view that semantic information about color and other perceptual properties of objects is grounded in modality-specific systems. Lesion analysis suggests that such grounding requires the integrity of the mesial temporal regions of the left hemisphere.

Adult↗
PubMed2004

[The analysis of refractive error in children and adolescents from 6-15 years of age based on 1000 examinations in two major Polish regions].

PURPOSE: The aim of this study is to present the results of screening examinations of refractive errors, taken on 1002 of school children ranging from 6 to 15 years of age. MATERIAL AND METHODS: As the result of Internet screening visual acuity and color perception tests named "I can see..." in 10,021 children from randomly chosen schools in Poland in the year 2002, the group of 1002 children was chosen. In this group, the subjective and objective refractive error examination was taken as well as the visual acuity test, color perception with the use of Ishihara tables and full ophthalmologic examination. RESULTS: Average visual acuity was RE: 0.72 (SD +/- 0.31) and LE: 0.72 (SD +/- 0.31). The prevalence of emmetropia was 34%. In the examined group myopia in 17%, hyperopia in 20%, astigmatism in 5.5% of children was found, and in 24.5% of patients complex errors occur such as myopic and hyperopic astigmatism.

Adolescent↗
PubMed1991

[Dyschromatopsias and pictorial art].

The influence of color vision defects on pictorial art was studied using three methods. 1) From a theoretical standpoint, the possibilities of choice of the color-blind painter are determined by the nature of his color perception. Characteristic errors result from the fact that he has to choose between many hues which are different to a normal individual but which all look the same to him. 2) Evaluation of the clinical cases of painters with dyschromatopsias has shown evidence of the following: a) the color-blind painter makes mistakes according to the type of color defect; b) if the color-blind painter makes several copies of the same model, he makes different mistakes at each attempt; c) when several color-blind painters make copies of the same model, they also make different mistakes, even when they suffer from the same type of color vision defect. Preferences for some colored patterns were studied by means of a forced choice procedure and choices of color-blind individuals were often characteristic of their dyschromatopsia. Recent clinical case of acquired dyschromatopsia reported in the literature are discussed, as is a personal case of a painter suffering from tapeto-retinal degeneration. This was a severe dyschromatopsia with a neutral zone in purple (so-called scotpic axis, by Verriest's terminology). The painting of this artist tended to be monochromatic, mainly in green and green-blue colors. 3) Recent studies in art history have shown that only the romantic etcher Meryon was definitively color deficient. The more dubious cases of the Polish painter Grottger and of Eugène Carrière are discussed and conclusions are negative. Among acquired dyschromatopsias, there have been many recent papers devoted to cataract dyschromatopsias, concerning the cases of Rouault, Monet and Mary Cassatt. The hypothesis of a degree of chromatopsia or dyschromatopsia of toxic origin in the case of Van Gogh is also assessed. In conclusion, the problem of the relations between congenital or acquired dyschromatopsias and pictorial art seems very complex and great care is required when making deductions and advancing hypotheses.

Color Perception↗
PubMed1983

Color "amnesia" without aphasia.

Following an apparent left parietal CVA, a patient developed a severe and nearly complete color amnesia which was not associated with any disturbance in color vision or color perception. Like all previously reported cases with color amnesia, this patient was alexic but, unlike most previously reported cases, he was not aphasic.

Agnosia↗
PubMed2002

Cues and strategies for color constancy: perceptual scission, image junctions and transformational color matching.

The identification of objects, illuminants, and transparencies are probably the most important perceptual functions of color. This paper examines the effects of perceptual scission, image junctions, color adaptation, and color correlations on identification. Simulations of natural illuminants, materials, and filters were used in a forced-choice procedure to simultaneously measure thresholds for identifying filters and objects across illuminants, and discrimination thresholds within illuminants. In the vast majority of the cases, if observers could discriminate within illuminants they could identify across illuminants. Since results were similar for identical color distributions, whether transparency cues like X-junctions were present or not, the primary cues for color identification were systematic color shifts across illuminants. These color shifts can be well described by three-parameter affine transformations, and the parameters can be derived from differences and ratios of mean chromaticities. A strategy based on post-transformation color matching predicts generally accurate identification despite perceptible color shifts, and also provides plausible reasons for those few conditions where identification thresholds are significantly higher than discrimination thresholds.

Color Perception↗
PubMed2004

The primacy of chromatic edge processing in normal and cerebrally achromatopsic subjects.

The local chromatic contrast between surfaces in a visual scene plays an important role in theories of color perception. Our studies of cerebral achromatopsia suggest that this contrast signal is computed independently of the more complex processes such as edge integration and anchoring. We report a study in which we attempted to determine whether local-contrast signals also drove behavior in normal subjects. We sought to reduce the role of edge integration and anchoring by using stimuli whose background varied very gradually in color from top to bottom. The local chromatic contrast of patches relative to such backgrounds depends upon the position at which they are presented. It is therefore possible for patches with identical spectral composition to have opposite contrasts. We constructed stimuli in which two of three vertically arranged discs had the same contrast while the third had opposite contrast. The stimuli were also constructed so that the contrast-odd disc and one of the other two had identical spectral composition while the third disc had different composition. We used these stimuli in an attentional task where, after a brief delay, a letter discrimination target was presented in the location of one of the discs. Attention should automatically be attracted to the odd disc in such a display. Normal observers were faster at making the letter discrimination when the target appeared at the contrast-odd as opposed to spectrally odd location. We conclude that local chromatic contrast, but not raw spectral composition, is accessible to normal observers at an appropriate stage in visual processing to drive attention.

Adult↗
PubMed1990

[Retinal function under conditions of artificial illumination with varying spectral makeup in patients with sclerotic macular dystrophy].

In conditions of a laboratory experiment using illumination of various light sources (by incandescent, luminescent, arc-mercury, natrium lamps), determination of visual acuity, visual field, color perception, restoration time of visual acuity after macular flash lighting (photostress test), Heidinger's phenomenon as well as visocontrastometry after V. V. Volkov, Weston's correction test were conducted in 46 patients (92 eyes) with macular dystrophy and 50 healthy persons in the dynamics of a working day. It was found that the spectral composition of the visible light has a remarkable influence on the function of color perception, contrast sensitivity, reaction of visual analyser on light load, visual ability to work. In patients with macular dystrophy, the dependence on the light medium was expressed much greater than in healthy persons. The highest functional state of the retina and visual ability to work in patients with macular dystrophy were provided by natrium lamps having a maximum radiation in the yellow part of the spectrum. The short-wave visible light of arc-mercury and luminescent lamps somewhat suppressed the functional state of the retina and reduced visual ability to work. The results obtained are important for selection of optimal conditions of work for patients with macular dystrophy.

Adult↗
PubMed2002

Illuminant estimation as cue combination.

This work briefly describes a model for illuminant estimation based on combination of candidate illuminant cues. Many of the research issues concerning cue combination in depth and shape perception translate well to the study of surface color perception. I describe and illustrate a particular experimental approach (perturbation analysis) employed in the study of depth and shape that is useful in determining whether hypothetical illuminant cues are actually used in color vision.

Color Perception↗
PubMed2004

Red-green chromatic mechanisms in normal aging and glaucomatous observers.

PURPOSE: This study was designed to determine whether normal aging and glaucoma are associated with red-green (R/G) chromatic processing abnormalities, a function that is primarily performed by the parvocellular visual pathway. METHODS: Chromatic processing mechanisms were examined in 98 glaucomatous observers (between the ages of 49 and 93 years; mean age, 70.8 +/- 9.4 [SD]) and 67 normal observers (between the ages of 49 and 88; mean age, 70.6 +/- 10.6 years) with the use of the minimum-motion and motion-nulling paradigms. Phakic glaucomatous (n = 60; mean age, 68.7 +/- 8.9 years) and normal (n = 32; mean age, 69.8 +/- 10.6 years) and pseudophakic glaucomatous (n = 38; mean age, 74 +/- 9.4 years) and normal (n = 35; mean age, 71.4 +/- 10.6 years) subjects were tested to evaluate the effects of lenticular aging on color perception. RESULTS: Phakic observers (normal or glaucomatous) displayed significantly different minimum-motion values than did both their younger counterparts and all the pseudophakic subjects. These results suggest that normal aging with the presence of a natural lens is accompanied by a significant decrease in green-light sensitivity, an effect that is not exacerbated by glaucoma and is primarily related to optical factors. The data also revealed no differences in color motion perception between groups, indicating that the higher cortical mechanisms of the parvocellular pathway implicated in the analysis of information about the middle and long wavelengths of the visible spectrum are not selectively affected by the disease process and normal aging. CONCLUSIONS: Normal aging and glaucoma do not produce significant R/G chromatic processing deficits at retinal and postretinal levels when optical factors are excluded. The authors propose the hypothesis that glaucoma-related effects on motion perception and blue-on-yellow perimetry should be viewed as evidence of loss of ganglion cells that necessitates integration of information over larger retinal areas and more receptor cells than in the R/G chromatic system. Ganglion cells with large receptive fields involve more neural connections and are less numerous than those that respond to R/G information. The functional consequence of this could be that the loss of a single ganglion cell with a larger receptive field would have a greater impact on visual function than the loss of a ganglion cell with a smaller receptive field, such as the ones that process R/G information. The authors believe that glaucoma-induced functional loss is best viewed as related to receptive field structure and function rather than to anatomic cell-type damage.

Aged↗
PubMed1976

Perceptions of color preferences-a clue to marital prediction?

In a study of marital adjustment prediction (N = 75 couples), each spouse was asked to indicate a color preference for nine common household articles and predict which color the spouse would choose. A discrepancy score between perceived and actual choices was calculated and compared with scores on the Nye-MacDougall Martial Adjustment Scale. The correlation coefficient between the discrepancy score and ego's marital adjustment was -.27 for the sample as a whole, -.33 for husbands, and -.21 for wives. The correlation between the discrepancy score and mate's marital adjustment was -.17 for the whole sample, -.10 for husbands, and -.23 for wives.

Adaptation, Psychological↗