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PubMed1989

The ocular findings in glucose-6-phosphate dehydrogenase deficiency.

57 cases with G6PD deficiency and 62 with normal G6PD activities as controls in Chonghua County, Guangdong Province were examined in the respects of visual acuity, color vision, corneal sensitivity, lens, vitreous and fundus. The results showed that the incidences of congenital lenticular opacities and congenital color blindness in G6PD deficiency group were higher than those in the controls. However, there were no findings such as pale conjunctiva, sallow sclera, pallor papillae and macular edema, which could be seen frequently in patients with favism. The hemoglobin values of all the cases were within normal range, which indicated that the subjects with G6PD deficiency usually didn't manifest hemolysis but only had a hereditary susceptibility, and the ocular findings in favism might result from hemolytic anemia, tissue anoxia and unknown toxic substances from vicia faba.

Cataract↗
PubMed2002

Color perception is mediated by a plastic neural mechanism that is adjustable in adults.

An intensely debated issue concerning visual-experience-dependent neural plasticity is whether experience is required only to maintain function or whether information from experience is used actively, relieving the necessity to hard-wire all connections and allowing adaptive adjustments. Here, an active role for experience is demonstrated in circuits for color vision. Chromatic experience was altered using colored filters. Over days there was a shift in color perception, as measured by the wavelength of unique yellow, which persisted 1-2 weeks after the filters were discontinued. Moreover, color-deficient adults were shown to have altered weightings of inputs to chromatic channels, demonstrating a large neural adjustment to their inherited photopigment defect. Thus, a neural normalization mechanism for color perception, determined by visual experience, operates to compensate for large genetic differences in retinal architecture and for changes in chromatic environment.

Adaptation, Physiological↗
PubMed1993

Comparison of the Farnsworth-Munsell 100-Hue, the Farnsworth D-15, and the L'Anthony D-15 desaturated color tests.

OBJECTIVE: The Farnsworth-Munsell 100-Hue, the Farnsworth D-15, and the L'Anthony D-15 desaturated color tests were administered to patients with glaucoma to determine whether the D-15 or D-15 desaturated color tests could be used to predict performance on the 100-Hue test in clinical populations. METHODS: The three color tests were administered to 35 patients with glaucoma. The results were analyzed using the method of Vingrys and King-Smith that calculates an angle (type of color loss) score, S-index (measure of the randomness of cap arrangement), and a C-index (a measure of the severity of color loss) based on the cap arrangement. RESULTS: The 100-Hue error score was significantly related to the D-15 and D-15 desaturated C-indexes. Furthermore, the 100-Hue S-index could be predicted from the D-15 or D-15 desaturated S-indexes. The 100-Hue angle could not be predicted from the D-15 or D-15 desaturated color tests. CONCLUSIONS: The D-15 desaturated color test (which requires significantly less time to administer) may be used to assess the severity of color vision deficit in some patient populations.

Color Perception Tests↗
PubMed1998

[Standardized evaluation of red, green and blue perception. Comparison between color arrangement and computer-assisted test procedures].

BACKGROUND: Computerized colortests offer the possibility of determining quantitative color contrast thresholds under standardized conditions. Arrangement tests allow semi-quantitative evaluation of the red, green and blue color sense. To validate the results of a new computerized test, its results are compared to those of arrangement tests. PATIENTS AND METHODS: Thirty-five patients with retinitis pigmentosa (RP, mean age 38.51, +/- 15.14) as well as 30 normal observers (mean age 36.52, +/- 14.33) were evaluated. The computerized color test COLDEF was used, which is a calibrated screen that presents color optotypes on a colored background. All colors are chosen from three-color confusion axes of the CIE-Lu'v' color chart (protan, deutan and tritan axis). By a staircase procedure, the colors of the optotype and background were varied until the observers minimal color contrast threshold is detected. To compare the results of COLDEF with a routine diagnostic tool, the Farnsworth panel D-15 and Lanthony désaturé test were chosen. The results of the arrangement tests were scored by a categorization scheme. RESULTS: Normal observers showed no elevated thresholds either in COLDEF nor in the panel tests. In the RP group increased thresholds along the blue confusion axis could be detected in most cases. Furthermore, COLDEF showed increased thresholds along the red and green axes in some patients. With the computerized test it is always possible to identify the color axis concerned. The new test allows a fast and quantitative assessment of acquired color vision deficiencies.

Adult↗
PubMed1994

Spatial integration in human vision with bichromatically-mixed adaptation field.

The present study showed that the spatial integration area was expanded even if the background energy was increased, provided that the background consisted of the two colors which were opponent to each other (red/green). This expansion was not found for the subjects with dichromatic color vision even though the same condition was utilized. It was suggested that polarization and its release (the change of adaptation level) of the chromatically-opponent red/green system were involved in control of spatial integration area.

Adaptation, Ocular↗
PubMedDate not supplied

Ophthalmologic findings in fifteen patients with Wolfram syndrome.

PURPOSE: To look for ophthalmologic abnormalities in 15 patients with Wolfram syndrome, also known as DIDMOAD syndrome (diabetes insipidus, diabetes mellitus, optic atrophy and deafness). METHODS: Fifteen patients from four inbred families diagnosed as having Wolfram syndrome at the National Center for Diabetes, Endocrinology and Genetics, in Amman, Jordan, were evaluated ophthalmologically. Their examination included best-corrected visual acuity, color vision testing, pupillary light reflexes, slit-lamp biomicroscopy and fundus examination. Fundus fluorescein angiography was done in all patients. RESULTS: The prevalence of optic atrophy was (93.3%), colordefect (92.9%), cataract (66.6%), pigmentary retinopathy (30%) and diabetic retinopathy (20%). Abnormal pupillary light reflexes and nystagmus were also reported. CONCLUSIONS: Although ourgroup of patients was genetically heterogeneous, the ophthalmic findings are consistent with those reported in other series, except for cataract which was highly prevalent but mild and did not contribute significantly to loss of vision.

Adolescent↗
PubMed1981

[Morphological and functional findings in a family with aniridia (author's transl)].

The history of a family with aniridia (11 patients) is presented. Morphologically the following changes were found: Ptosis, microcornea, anterior embryotoxon, defects of the iris ranging from corectopia and coloboma to hypoplasia of the iris and clinical aniridia cataracts and hypoplasia of the fovea. Functionally there was reduced visual acuity (best vision 0.2), nystagmus and strabismus. Dark adaptation, electrooculogram, photopic and scotopic electroretinogram were within normal limits. The patients were found to have a red-green color vision deficiency, which was perhaps caused by foveal hypoplasia and nystagmus, and a trito defect which could not be explained.

Adolescent↗
PubMed1976

Vision profile of deaf children.

The vision status of 77 deaf children from Beverly School for the Deaf, Beverly, Massachusetts, was investigated in 6 general areas: visual acuity, refractive status, binocularity, color vision, pathology, and visual perceptual motor function. The significant results of this study that were different from the previously investigated work were in the areas of myopia and visual perceptual motor function. Myopia of only moderate to low degree was found in about 5.8% of the total poulation, which is significantly below the mean percentage found in a normal population. Almost 50% of the children showed deficiencies in and 1 or more of the 3 perceptual motor areas investiaged, i.e., visual memory, spatial organization, and Gesell copy forms.

Adolescent↗
PubMed1990

Electrophysiology and anatomy of medulla interneurons in the optic lobe of the cockroach, Periplaneta americana.

1. Medulla interneurons of the optic lobe of P. americana were studied to determine their spectral properties. These neurons exhibited tonic firing which changed with monochromatic broadfield illumination of the ipsilateral eye. The response patterns of these neurons were analyzed by inferring their relation to the ultraviolet (UV) and green (G) photoreceptor groups of the eye. Their anatomy was described after injection of Lucifer yellow. 2. Broadband neurons received either excitatory or inhibitory input from both UV and G receptors. These neurons were not strictly sensitive to luminosity levels and had large cell bodies in the central rind of the medulla and wide dendritic arbors in the medulla neuropil. 3. Narrow band neurons received input from predominantly one receptor type. Their spectral sensitivity curves were more finely tuned than those of the primary receptors presumably due to neural interactions within the optic lobe. 4. Color opponent neurons were inhibited by UV and excited by G inputs in their sustained response. Under certain conditions, some of these neurons also showed G inhibition. These neurons suggested the presence of a subsystem involved in color vision. 5. Broadband, narrow band and color opponent properties were seen in some single neurons when tested over a 5-6 log unit range of intensity. The responses of some of these neurons changed when stimulus duration was increased. These findings indicated that functional classification for these neurons was dependent on stimulus intensity and duration. 6. Polarizational sensitivity was tested in preliminary experiments. Two neurons responded to the movement and direction of polarized light.

Animals↗
PubMed1989

Review of dichoptic color mixing.

Dichoptic color mixing has been a controversial issue for nearly two centuries. The first dispute arose from the fact that dichoptic color mixtures occur only under certain conditions. A later controversy arose over the implications of dichoptic color mixtures to color vision theories. The present consensus is that dichoptic color mixtures occur under conditions which apparently minimize chromatic differences between the two monocular impressions. However, dichoptic mixtures do not match the corresponding monoptic mixtures. Dichoptic mixtures appear dimmer, and if a green light is mixed with either a red or violet light, then the dichoptic mixture appears greener relative to the monoptic mixture.

Color Perception↗
PubMed2006

Disinfecting solutions for soft contact lenses using different color indicators.

PURPOSE: The color change reached in two commercial disinfecting solutions for soft contact lenses using new color indicators has been analyzed, and its relationship with the temporal evolution of the hydrogen peroxide concentration, responsible for the disinfection process, has been examined. The results are compared with another commercial solution using a different color indicator. METHODS: Color measurements of the disinfecting solutions were performed at 2-minute intervals for over 2 hours using a Photo-Research PR-704 spectroradiometer with horizontal optical axis. Samples were placed at the floor of a VeriVide CAC 120 light booth with a Munsell gray mask behind them. Two different standard light sources, representative of outdoor and indoor illumination, were used. The hydrogen peroxide concentration during the disinfection process was measured for each commercial solution using a Beckman DU-7 spectrophotometer. RESULTS: The temporal evolutions of color for the two new disinfecting solutions were qualitatively different. CIELAB color differences induced in these two new disinfecting solutions were 1.5 and 2.2 times greater than that measured in the earlier comparative solution and occur in a more appropriate direction of color space for users with defective color vision. Although the earlier solution generated color changes close to the deutan confusion line, the changes produced by the new solutions are close to the tritan confusion line. After 2 hours, the hydrogen peroxide concentration for the two new solutions was approximately one-third the one reached by the earlier solution. There are statistically significant correlations (p < 0.01) between color change and hydrogen peroxide concentration for the two new solutions (r = -0.878 and r = -0.990). CONCLUSIONS: Color changes in these hydrogen peroxide systems can be used as a safe and useful tool by contact lens wearers. The two new disinfecting solutions analyzed in this article show noteworthy improvements over the earlier solution.

Color↗
PubMed1988

On the trichromatic and opponent-process theories: an article by E. Schrödinger.

A translation of Schrödinger's paper, 'On the relation of the tetrachromatic theory to the trichromatic theory' (1925), is accompanied by a commentary. Schrödinger applies a projective transformation to a standard chromaticity diagram, to demonstrate the common geometry of the chromaticity diagrams derived from the trichromatic and opponent-process theories of color vision.

Color Perception↗
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↗
PubMed1990

Operating illumination to differentiate dental hard tissues.

This in vitro study was designed to evaluate the ability of fluorescent tubes and dental lights to help operators distinguish tissues (fissures), differentiate between tissues (at the dentinoenamel junction or between carious and sound dentin), and distinguish form of a tooth preparation (Class II and Class V cavities). Operators with "normal" color vision ranked the lights in order of preference for each type of specimen. In general, for the fluorescent illuminants, operators preferred lights with high color temperature values and high color rendering index values. A small group of color-blind observers indicated a preference for an illuminant of low color temperature and low color rendering index value. For dental lights, operators preferred a higher color temperature for examining fissures, the dentinoenamel junction, and the cavity preparation. No particular illuminant was preferred for distinguishing between carious and sound dentin. Many observers had difficulty in choosing a preferred dental luminaire.

Color↗
PubMedDate not supplied

The color of night: Surface color perception under dim illuminations.

Several studies document rudimentary color vision under dim illumination. Here, hue perceptions of paper color samples were determined for a wide range of light levels, including very low light levels where rods alone mediate vision. The appearances of 24 paper color samples from the OSA Uniform Color Scales were gauged under successively dimmer illuminations from 10-0.0003 Lux. Triads of samples were chosen representing each of eight basic color categories; red, pink, orange, yellow, green, blue, purple, and gray. Samples within each triad varied in lightness. Observers sorted samples into groups that they could categorize with specific color names. Above 0.32 Lux, observers sorted the samples into the originally chosen color groups with few exceptions. For 0.1-0.01 Lux, the red and orange samples were usually correctly identified as either red or orange. The remaining samples tended to be grouped into two categories, associated with the scotopic sample reflectance. The lowest reflectance samples were below threshold and were named black. The higher reflectance group was named predominately as green or blue-green (three observers; the fourth observer used blue or achromatic). At the three dimmest levels (< or = 0.0032 Lux) there continued to be conspicuous color percepts. Color categories were reliably assigned based on relative sample scotopic lightness. Of the samples above threshold, those with lower reflectance were classified as red or orange (all observers) and the higher reflectance samples as green or blue-green (three observers) or achromatic or blue (the fourth observer). Rods and L-cones presumably mediated color percepts at the intermediate light levels used in the study. At the three lowest light levels there were distinct color appearances mediated exclusively by rods. We speculate that at these light levels the visual system estimates probable colors based on prior natural experience.

Color↗
PubMed2006

Contribution of chromatic aberrations to color signals in the primate visual system.

We measured responses to red-green color variation in parvocellular (PC) neurons in the lateral geniculate nucleus of dichromatic ("red-green color blind") marmoset monkeys. Although these animals lack distinct visual pigments to distinguish between wavelengths in this range, many of the colored stimuli nevertheless produced robust responses in PC cells. We show that these responses, which are restricted to high stimulus spatial frequencies (fine image details), arise from chromatic aberrations in the eye. The neural signals produced by chromatic aberrations are of comparable magnitude to signals produced by high-frequency luminance (LUM) modulation and thus could influence cortical pathways for processing of color and object recognition. The fact that genetically "color-blind" primates are not necessarily blind to wavelength-dependent contours in the visual world may have enabled red-green color vision to become linked with high-acuity spatial vision during primate evolution.

Animals↗
PubMed2004

Modeling color percepts of dichromats.

Protanopes and deuteranopes, despite lacking a chromatic dimension at the receptor level, use the color terms "red" and "green", together with "blue" and "yellow", to describe their color percepts. Color vision models proposed so far fail to account for these findings in dichromats. We confirmed, by the method of hue scaling, the consistent use of these color terms, as well as their dependence on intensity, in subjects shown to have only a single X-chromosomal opsin gene each. We present a model for the processing of photoreceptor signals which, under physiologically plausible assumptions, achieves a trichromat-like representation of dichromatic receptor signals. Key feature of the dichromat model is the processing of the photoreceptor signals in parallel channels with different gains and nonlinearities. In this way, the two-dimensional receptor signals are represented on a manifold in a higher-dimensional space, supporting categorization for efficient image segmentation. Introducing a third cone opsin yields a model that explains normal, trichromat hue scaling.

Base Sequence↗
PubMed1988

Pure homonymous hemiachromatopsia. Findings with neuro-ophthalmologic examination and imaging procedures.

The study describes neuro-ophthalmologic findings in two patients with brain infarction who developed homonymous hemiachromatopsia with resolution to pure homonymous achromatopsia in an upper quadrant. All other visual parameters were normal; only color perimetry was capable of demonstrating the visual disorder. The results are presented with special emphasis on the macular region. Computed tomography studies and magnetic resonance imaging revealed lesions in the caudal and medial occipitotemporal gyri as well as in adjacent cortical regions. The lesions were secondary to disordered circulation in a proximal occipitotemporal branch of the posterior cerebral artery. The anatomical findings and functional relations of color vision in man are discussed in the light of animal findings.

Adult↗