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Results for “Color Vision Defects”

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At least 1,405 records · Page 78Linked to original sources
PubMed1997

Preserved imagery for colours in a patient with cerebral achromatopsia.

We report the case of a patient who, after sequential bilateral strokes in the occipital regions sparing the primary visual cortex, developed a severe deficit of colour perception. At variance with other reports of acquired achromatopsic patients, she showed a perfectly vivid visual imagery for colours. These findings, together with similar data in domains other than colour processing, challenge the theories which posit that the same cognitive processes are involved in both the perception and the retrieval from memory of a given stimulus.

Aged↗
PubMed1989

A disorder of lightness discrimination in a case of visual form agnosia.

Benson and Greenberg (1969) described an "agnosic" patient whose severe visual recognition disorder could be accounted for in terms of a deficit in the perception of shape. We report here on a recent case of this disorder (visual form agnosia), and have found that she performs very poorly on tasks of discriminating shades of grey, although she is able to discriminate between hues. This sensory deficit helps to explain some of her perceptual difficulties; it also provides further evidence for parallel feature-processing in the human brain complementary to and consistent with recent physiological data on the visual cortex in animals.

Adult↗
PubMed2004

My two blues.

Explore the source record for details and available documents.

Archaeal Proteins↗
PubMedDate not supplied

Correlation of blue chromatic macular sensitivity with optic disc change in early glaucoma patients.

PURPOSE: To investigate the relationship between morphological changes of the optic nerve head (ONH) and macular sensitivity determined with blue on yellow (B on Y) and white on white (W on W) perimetry in normal subjects and patients with glaucoma. METHODS: One randomly chosen eye was evaluated in each of 28 healthy subjects, 23 patients with ocular hypertension (OH), and 23 patients with early primary open-angle glaucoma (POAG). The mean macular sensitivity determined with B on Y and W on W perimetry was obtained by a macular program using a modified Humphrey field analyzer. The Heidelberg retina tomograph with software version 2.01 was used to evaluate the temporal topographic measurements of ONH. RESULTS: There was no significant difference in temporal ONH parameters among the three clinical groups. The mean macular sensitivity of B on Y and W on W perimetry in early POAG patients was significantly lower than that in healthy subjects and in patients with OH. The mean macular sensitivity of W on W perimetry showed no significant correlation with temporal ONH parameters in any clinical groups. In patients with early POAG, the mean macular sensitivity of B on Y perimetry was significantly related to cup area and volume, cup/disc area ratio, and rim volume in the temporal sector of the ONH. CONCLUSION: The measurement of the mean macular sensitivity of B on Y perimetry might make it possible to detect functional damage prior to morphological changes in the ONH due to elevated intraocular pressure in glaucoma.

Color Vision Defects↗
PubMedDate not supplied

New color vision tests to evaluate faulty color recognition.

PURPOSE: To develop and assess new color vision tests to be used in evaluating faulty color recognition. METHODS: We developed new color vision tests to evaluate faulty color recognition. The two types of color vision tests, designed to assess faulty color recognition in color vision deficiencies, are based on principles that are different from those of the conventional color vision tests. In the first test plate, the subject is asked to choose either a red, green, or gray line from among 10 lines that are randomly colored red, green, gray, yellow, or blue. The score is the difference between the number of correct answers and the number of incorrect answers. In the second test plate, the subject is asked to identify a total of 10 red azalea blossoms, which are dispersed among numerous green leaves. Seventy-five persons with congenital color deficiencies and 20 subjects with normal color vision were examined using these new test plates. RESULTS: The scores differed significantly between dichromats and anomalous trichromats, and between anomalous trichromats and subjects with normal color vision. CONCLUSIONS: The new tests are easy to use, sensitive, and have good reproducibility for use in discriminating subjects with color vision anomalies. These tests reveal the faulty color recognition that occurs unconsciously in persons with color deficiencies, and are useful in judging the quantification of color vision required in their daily life and occupations.

Adolescent↗
PubMedDate not supplied

Measuring short-wavelength-sensitive cone discrimination thresholds using pseudoisochromatic figures displayed on a color monitor.

PURPOSE: To simplify the testing of short-wavelength-sensitive (SWS) cone function in the clinic. METHODS: SWS-cone discrimination thresholds were measured along the tritan axis using pseudoisochromatic figures displayed on a color monitor. A circular 6 degrees field, containing spatially discrete patches of varying sizes and luminances, was presented on a background. A subset of patches formed the target patch in the shape of a C. Eight subjects with normal color vision reported the direction of the gap in the C using a cursor controlled by a joystick. DATA: were expressed in units of SWS-cone trolands. RESULTS: SWS-cone discrimination threshold increased slowly as the SWS-cone trolands of the starting chromaticity increased. The dependence of the threshold on the SWS-cone activation level was similar to literature reports of chromatic discrimination measured with conventional paradigms. CONCLUSIONS: The advantages of this method: (a) It is a simple intuitive task for patients. (b) The paradigm can be implemented with an 8-bit/gun color monitor. (c) The test avoids the need to define equiluminance for the individual patient before the color test is administered. This method can provide a useful technique for measuring SWS-cone function in a clinical population.

Adult↗
PubMed2001

Color vision deficiencies in Gilles de la Tourette syndrome.

Color perception was tested using the Farnsworth-Munsell 100-Hue Test in a sample of persons with Gilles de la Tourette syndrome (GTS), and compared to norms from three age cohorts in the early second, fourth and sixth decades. Red-green color errors on the Farnsworth-Munsell did not appear to change appreciably as a function of age or GTS. Blue-yellow error scores did, however, increase with age and were exaggerated in the GTS group. It is concluded that sensory and perceptual disturbances are present in GTS as in other basal cell ganglia disorders. The results are discussed in terms of converging retinal dopaminergic mechanisms also associated with Parkinson's and Huntington's diseases and even with normal aging. Suggestions are offered that daily activities and behavior may be affected by spatial and chromatic deficiencies.

Adult↗
PubMed2000

Decreased color discrimination and contrast sensitivity in Parkinson's disease.

Patients with Parkinson's disease (PD) often complain of blurred vision or even of distinctive visual disturbances like hallucinations and illusions. Recent studies have emphasized the potential influence of primary visual deficits of color and contrast discrimination. To study primary visual function, we studied color discrimination (CD) and contrast sensitivity (CS) during 'on' medication in PD patients and compared them to non-PD subjects. Twenty one PD patients were compared to 30 age-matched controls using CD tested by the D-15 Lanthony test (D15) and the Farnsworth-Munsell 100 Hue test (FM) and CS tested by the Pelli-Robson (PL) and the Vis-Tech tables (VT). We excluded subjects with a visual acuity </=0.6 Snellen fraction or known ophthalmological diseases. PD patients showed greater impairment on all visual tests than controls. This difference was significant for the FM test (P<0.001), the spatial frequencies 12 and 18 cpd (cycles per degree) of the VT test (P<0.05) and both the monocular and binocular PR tests (P<0.05). Most tests for CS and CD showed statistical independency. CS deficits, but not CD deficits, correlated with age in both patients and controls. This study documents major and independent impairment of both color and contrast discrimination in PD patients. Further studies should elucidate possible clinical implications and correlations, such as the frequency of falls or visual hallucinations.

Aged↗
PubMed2000

A functional MRI case study of acquired cerebral dyschromatopsia.

Evidence from imaging studies suggests that primary visual cortex and multiple areas in ventral occipitotemporal cortex subserve color perception in humans. To learn more about the organization of these areas, we used structural and functional MRI (fMRI) to examine a patient with damage to ventral cortex. An art professor, KG, suffered a cerebrovascular accident during heart surgery that impaired his ability to perceive color. The Farnsworth-Munsell 100-Hue test was used to assess the extent of his deficit. When tested 12 months after the lesion, KG performed worse than 95% of age-matched normals on the 100-Hue test, but well above chance. Structural and functional MRI studies were conducted 3 years after the lesion to investigate the neuroanatomical correlates of KG'ss remaining color ability. Structural MRI revealed bilateral damage to ventral occipitotemporal cortex. In young and age-matched normal controls, an fMRI version of the 100-Hue reliably activated bilateral, color-selective regions in primary visual cortex and anterior and posterior ventral cortex. In subject KG, color-selective cortex was found in bilateral primary visual cortex. In ventral cortex, no color-selective activity was observed in right ventral cortex, and only a small area of activity was observed in left anterior ventral cortex. However, significant color-selective activity was observed in posterior left ventral cortex spared by the lesion. This posterior left ventral activation was similar in extent, position, and degree of color-selectivity to the posterior left posterior activation observed in normal controls, suggesting that this focus may be the cortical substrate underlying KG's remaining color perception.

Adult↗
PubMed2003

Attentional capture by colour and motion in cerebral achromatopsia.

Cerebral achromatopsia is a rare condition in which damage to the ventromedial occipital area of the cortex results in the loss of colour experience. Nevertheless, cortically colour-blind patients can still use wavelength variation to perceive form and motion. In a series of six experiments we examined whether colour could also direct exogenous attention in an achromatopsic observer. We employed the colour singleton paradigm, the phi motion effect, and the correspondence process to assess attentional modulation. Although colour singletons failed to capture attention, a motion signal, based solely on chromatic information, was able to direct attention in the patient. We then show that the effect is abolished when the chromatic contours of stimuli are masked with simultaneous luminance contrast. We argue that the motion effect is dependent on chromatic contrast mediated via intact colour-opponent mechanisms. The results are taken as further evidence for the processing of wavelength variation in achromatopsia despite the absence of colour experience.

Analysis of Variance↗