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PubMed1994

[Dependence of the sensitivity of the central visual field on hemoglobin-oxygen saturation].

Retinal function is very sensitive to changes in hemoglobin oxygen saturation. Characteristic ophthalmological symptoms of oxygen deficiency are: changes in color perception, visual field defect, eye flickering, reduction of visual acuity, seeing double images, defects in neural image interpretation. To test the dependency of changes in the central visual field sensitivity on different degrees of oxygen saturation, 48 probands (48 monocular tests) 20-50 years of age were examined in the altitude simulation chamber of the Aviation Medicine Institute of German Air Force at zero altitude (= 500 m) and at 10,000 ft (ca. 3,500 m height). Three types of experiments were performed: determination of abnormal quotient using a Heidelberg anomaloscope; determination of changes in color vision by saturated and disaturated panel D-15 test; determination of differences in light sensitivity for white, red, blue and green light by a threshold test using a Humphrey Field Analyzer (640) as perimeter. At zero level (500 m) hemoglobin-oxygen saturation was 97% +/- 1%. At 10,000 ft this value decreased to 83% +/- 3%. Hypoxic hypoxia caused neither significant AQ changes nor did it induce reproducible changes in color vision by the panel D-15 test. However, anoxia resulted in significant (P < 0.01) differences in light sensitivity in phototopic range.

Adult↗
PubMed1997

The characteristics of interaction between color and motion perception in primary open angle glaucoma.

PURPOSE: To investigate the characteristics of interaction between color and motion perception in primary open angle glaucoma (POAG) and measure motion perception of B, G and R cones, thus find a more sensitive method to diagnose the visual nerve damage in POAG. METHODS: Motion perceptions of B, G and R cones were isolated by blue, green and red vertical line stimulus displayed on the yellow, purple and blue background respectively, then measured the displacement threshold and flicking threshold of motion perception from each cones in POAG, and compared it with the age-match normals. RESULTS: The displacement threshold and flicking threshold of motion perception from B, G and R cones were all damaged in POAG compared with the normals, and the motion perception of G and B cones was deficits more obviously than the R cones. CONCLUSION: These findings support the suggestion that color provides an input to human motion perception. Magnocellular and parvocellular pathway may be significantly damaged in POAG, which indicates, that the combination of Motion Perception and color testing may reveal preclinical visual nerve damage in early POAG.

Adult↗
PubMed1993

Positron-emission tomographic localization of abnormalities of brain metabolism in patients with minimal hepatic encephalopathy.

Many patients with compensated cirrhosis without overt hepatic encephalopathy have deficits in visual-spatial perception, a condition we call minimal hepatic encephalopathy. Five patients with alcohol-induced cirrhosis and nine control subjects underwent positron-emission tomographic imaging of the brain with 18F-fluorodeoxyglucose. Patients also underwent neuropsychological and clinical chemistry tests. The patients had mild arterial hyperammonemia (62 +/- 13 mumol/L, range = 11 to 35 mumol/L) and other abnormalities typical of patients with cirrhosis. The patients' mean percentile scores on the digit symbol and block design subtests, from the Wechsler Adult Intelligence Scale (revised), and Purdue pegboard test were 11 +/- 7, 24 +/- 7 and 7 +/- 8 (right hand). Tests of vocabulary, memory, and new learning were normal. The technique of statistical parametric mapping was used to identify regions where cerebral 18F-fluorodeoxyglucose uptake and metabolism were abnormal. We noted significant reductions in the cingulate gyrus, a center mediating attention, target analysis and response formulation and significant increases in visual associative regions subserving motion and color perception and object orientation. We suggest that minimal hepatic encephalopathy is due to a deficit in the detection and formulation of responses to visual stimuli, a function of the cingulate, which is a part of the anterior attentional system of the brain. Increases in 18F-fluorodeoxyglucose metabolism may be compensatory. These studies show that brain regions differ in their sensitivity to the agents that cause hepatic encephalopathy and that positron-emission tomography is useful in studying the pathophysiology of this disorder.

Adult↗
PubMed1995

Vision in dogs.

Compared with the visual system in human beings, the canine visual system could be considered inferior in such aspects as degree of binocular overlap, color perception, accommodative range, and visual acuity. However, in other aspects of vision, such as ability to function in dim light, rapidity with which the retina can respond to another image (flicker fusion), field of view, ability to differentiate shades of gray, and perhaps, ability to detect motion, the canine visual system probably surpasses the human visual system. This has made the dog a more efficient predator in certain environmental situations and permits it to exploit an ecological niche inaccessible to humans.

Animals↗
PubMed1987

A central binocular mechanism affects chromatic adaptation.

Two experiments explored the role of central binocular mechanisms in color perception. The first experiment examined the effect of adapting to simultaneous, binocularly fused fields. Each eye adapted to a slowly flickering (0.5 Hz) long-wavelength light. The two eyes were adapted either inphase (both eyes stimulated at the same moment) or out-of-phase (only one eye stimulated at any given moment). Both adapting procedures shifted equilibrium yellow toward longer wavelengths, but a significantly greater shift was found when adapting light stimulated both eyes simultaneously. This reveals that a central binocular mechanism affects chromatic adaptation. The second experiment tested whether the binocular mechanism could shift equilibrium yellow measurements made with both eyes (identical, binocularly fused fields presented to each eye) outside of the range of measurements established by left-eye monocular viewing and right-eye monocular viewing. Differences were found between monocular left-eye and monocular right-eye color appearance under conditions of moderate chromatic adaptation, but binocularly fused measurements fell within the range established by the monocular results. This is consistent with the view that central mechanisms serve to keep the two eyes in balance, rather than systematically alter color appearance from colors perceived under monocular viewing.

Adaptation, Ocular↗
PubMedDate not supplied

[Spectral filters as a method of therapeutic correction].

Spectral filters were used for additional correction of vision in 67 patients: in 15 adults with initial cataracts (intensive yellow filter), 26 children with albinism (yellow-brown filter), 14 children with macular hypoplasia (orange filter), and 12 children with aphakia after removal of congenital cataracts (yellow filter). Selection of the filter density is carried out using a special method including visocontrastometry, examination of sensitivity to lateral light, and study of color perception thresholds. Use of filters resulted in improvement of the vision acuity by 43.5% in patients with initial cataracts, by 10% in those with albinism, by 20% in those with macular hypoplasia, and by 22% in those with aphakia; moreover, an improvement of the frequency-contrast characteristics was observed, as well as a reduction of photophobia, and a reduction of vision amplitude in patients with nystagmus. The possible applications of spectral correction are discussed.

Adult↗
PubMed1976

Color vision and hue categorization in young human infants.

Two studies examined the organization of color perception in 4-month-old human infants. In Study 1, infants looked at selected spectral stimuli repeatedly until their visual attention waned. The stimuli represented instances of basic adult hue categories - blue, green, yellow, and red. Following habituation, infants were shown a series of wavelengths which were the same as or different from the stimuli first seen. Analyses of infant attention during this dishabituation phase of the study indicated that infants categorize wavelengths by perceptual similarity; that is, they see hues in the spectrum much as adults do. In Study 2, a group of infants who looked at the alteration of two wavelengths from the same hue category habituated as did the group of infants who looked at the repitition of a single wavelength from that category, but a group of infants who looked at two wavelengths from different categories habituated at a slower rate. Data from the two studies suggest a high degree of organization of the color world prior to language acquisition.

Association↗
PubMed1998

Visual dysfunction in Parkinson's disease.

Several abnormalities of visual function have been demonstrated in Parkinson's disease (PD) by both electrophysiologic and psychophysical testing. Prolonged visual evoked potential latencies and abnormal electroretinographic patterns, both of which respond to levodopa therapy, have been demonstrated in Parkinson's disease patients and in primates with experimental parkinsonism suggesting that retinal dopamine deficiency is an important factor in the pathogenesis of PD visual dysfunction. Abnormalities of color perception, especially in the blue-green axis, and of visual contrast sensitivity (VCS) have also been well documented in PD patients. Although VCS impairment is likely related to retinal dopaminergic dysfunction, the fact that this visual abnormality is orientation-specific raises the possibility of visual cortex involvement as well. Visual abnormalities in PD are usually clinically occult and not likely to be uncovered during a routine neurological examination or by ordinary high contrast visual acuity testing. The clinician must be aware, however, that several forms of disability ranging from gait freezing to visual hallucinations may be linked to an underlying impairment of visual function in Parkinson's disease.

Color Perception↗
PubMed1968

The LSD syndrome. A review.

lsd (lysergic acid diethylamide) is a powerful bio-active substance related to serotonin in structure. Its actions generally affect autonomic, sensory and psychological functions. Autonomic stimulation is varied. Sensory responses are usually visual, involving heightened and distorted color perception and fusion of sensory impressions. Psychological responses include a feeling that a unique experience is occurring; feelings of depersonalization; pronounced fluctuation of mood; time and space distortions; autistic phenomena; fluctuation of aggressive drives (usually reduction); and spontaneous reoccurrence of the lsd experience. THE SUBJECTIVE RESPONSES CAN BE RELATED TO THREE BASIC PHENOMENA: (1) expectation; (2) loss of characteristic modes of perceptual and cognitive patterning; and (3) hypersuggestibility. THE MAJOR ADVERSE REACTIONS ARE: (1) chronic drug dependence including subsequent personality changes and depressive reactions; and (2) acute ego dissolution. These reactions usually occur in already emotionally ill people. Most of these users fall into two groups, those with unresolved identity problems and those with severe ego abnormality. The majority of adverse reactions are of the chronic drug dependence type and are usually seen in adolescents and young adults who have not negotiated the age-appropriate tasks of forming and integrating the various identities that are the composite of their life experiences.lsd helps alleviate these stresses via some of its psychological properties as discussed. It also provides a nidus for the formation of a subculture where goals for social, sexual and vocational achievement are lower and idiosyncratic modes of adaptation are better tolerated. A smaller group of users who have serious reactions such as psychosis, rage reactions, homicidal and suicidal ideation are usually found to have preexisting ego abnormality such as ambulatory schizophrenia, chronic impulse disorders and borderline states. Although adverse reactions most often appear to be related to pre-morbid psychopathology, this is not invariably so. Further, there is as yet no reliable method to determine who will have an adverse reaction and what the nature of that reaction will be.

Color Perception↗
PubMed1996

Visual cortical dysfunction in Alzheimer's disease evaluated with a temporally graded "stress test" during PET.

OBJECTIVE: Visual-processing abnormalities commonly contribute to typical Alzheimer's disease symptoms, but their detailed pathophysiology remains unknown. To investigate why patients with Alzheimer's disease have greater difficulty performing visuoconstructive (magnocellular-dominated) tasks than face- or color-perception (parvocellular-dominated) tasks, the authors measured brain activation in response to a temporally graded visual stimulus (neural stress test) during positron emission tomography. METHOD: The stress test measured regional cerebral blood flow (CBF) in response to a patterned flash stimulus in the resting state (0 Hz in the dark) and at frequencies of 1, 2, 4, 7, and 14 Hz. Ten patients with Alzheimer's disease and 12 age- and sex-matched comparison subjects were studied. RESULTS: The striate response at 7 Hz and 14 Hz (the degree of regional CBF increase from that at 0 Hz) was significantly less in the patients than in the comparison subjects, whereas the change in regional CBF at the lower frequencies did not differ between groups. In bilateral middle temporal association areas activated by motion and dominated by magnocellular input, regional CBF at 1 Hz (the frequency with maximal apparent motion) was significantly greater than at 0 Hz in the comparison subjects but not in the patients. CONCLUSIONS: The magnocellular visual system normally responds to high-frequency input and motion; the failure of response in the striate cortex at high but not low frequencies in the Alzheimer's patients suggests greater magnocellular than parvocellular dysfunction at these levels. Activation failure in the middle temporal areas in the patients supports magnocellular dysfunction. The finding that the Alzheimer's disease group had abnormal visual cortical function emphasizes the importance of clinical visuospatial evaluation of patients with Alzheimer's disease to fully understand symptom production and to plan interventions.

Aged↗
PubMed1976

Color perimetry.

Seven subjects were studied to determine the reproducibility of color isopters utilizing a Tubingen perimeter with targets equated for radiant energy and separate for heterochromatic flicker luminance. Achromatic threshold recognition of targets for equal luminance gave smaller isopters with longer wavelengths (red). Color recognition thresholds, on the other hand, showed large blue, midzone red and green, and small yellow isopters. The target recognition and color recognition thresholds for equal energy targets gave smaller red isopters. The data support Traquair's contention that all color isopters would be equivalent if hue, saturation, and intensity were equated. Clinically, the detection of subtle peripheral and central field defects might reside in the use of appropriately selected equally bright-colored targets.

Color Perception↗
PubMed1979

Photoreceptor misalignment accompanying a fibrous scar.

A 9-year-old boy with dense fibrous scars at the macula had visual acuities of 6/12 and 6/9 and an abnormal color match (pseudoprotanomaly). The Stiles-Crawford effect functions were abnormal in both eyes, showing maximal sensitivity at the nasal edge of each pupil. The data suggest that the foveal photoreceptors, although spared destruction by an adjacent focus of healed chorioretinitis, have been distorted by fibrous traction arising from that defect.

Child↗
PubMed1981

Digoxin retinal toxicity. Clinical and electrophysiological evaluation of a cone dysfunction syndrome.

A 70-year-old man was studied both during and after resolution of clinical digoxin toxicity using color vision tests, ganzfeld electroretinography and electro-oculography. Concomitant administration of quinidine sulfate probably contributed to digoxin toxicity. Abnormalities in color vision and subnormal amplitude and prolonged implicit time for cone-mediated electroretinogram (ERG) responses suggested a cone dysfunction syndrome. The electro-oculographic light-to-dark ratio during clinical toxicity was high for our laboratory, but this is probably normal. Notable improvement was seen in color vision and the ERG after cessation of digoxin therapy. Inhibition of sodium-potassium adenosine triphosphatase by digoxin probably influences normal uptake of extracellular potassium by Müller's cells and other retinal neurons. This mechanism may contribute to subnormal, prolonged cone-mediated ERG responses in retinal toxic reactions from cardiac glycosides.

Adaptation, Ocular↗
PubMed1983

Clinical studies of color vision with Gunkel's chromagraph.

Color thresholds in a series of patients with local or systemic diseases were determined by a chromagraph method and subjected to computer analysis. When compared with normal persons, those with optic nerve disease (multiple sclerosis, optic neuritis, and optic atrophy) showed an overall weakness for all colors (enlarged neutral areas), with an additional specific defect in the orange-cyan (greenish blue) axis. Those with the two retinal diseases studied (macular degeneration and retinitis pigmentosa) also showed threshold elevation for all colors, but with a special defect in the yellow-blue axis. The general elevation was greater for patients with retinitis pigmentosa than for those with macular degeneration, regardless of the visual acuity. In patients undergoing treatment for systemic lupus erythematosus and rheumatoid arthritis, there was a mild elevation of the color threshold, especially for yellow.

Arthritis, Rheumatoid↗
PubMed1984

Correlation between color vision scores and quantitative perimetry in suspected glaucoma.

The mean differential threshold, studied on the Octopus perimeter, and color vision, estimated by the Farnsworth-Munsell 100-Hue test, were studied in glaucoma suspects and patients with questionable early field defects. The results of both tests were significantly correlated. The color vision scores correlated with the central, paracentral, and midperipheral parts of the visual field. This result suggests that both functions are disturbed in glaucoma and that the disturbance may be present diffusely throughout the visual field.

Aged↗
PubMed1985

Association of hue discrimination loss and diabetic retinopathy.

The results of Farnsworth-Munsell 100-hue, visual acuity, and visual field testing were compared with the severity of retinopathy in a group of 90 diabetic patients. The patients showed significantly higher than expected Farnsworth-Munsell 100-hue scores, with a tritanlike axis, compared with published age norms for nondiabetic individuals. The magnitude of the acquired blue-yellow hue discrimination defect correlated significantly and to a similar extent with both the severity of overall diabetic retinopathy and the severity of macular edema and hard exudate formation. Visual acuity loss correlated somewhat more significantly with macular edema than with overall retinopathy, whereas the converse was true for visual fields. For all visual function tests, the correlations were more significant for fluorescein leakage in the macula than for capillary nonperfusion in the macula. Abnormal hue discrimination was found in 65% (32/49) of eyes with proliferative diabetic retinopathy, suggesting a potential role for this test in screening for proliferative diabetic retinopathy in primary care facilities. Also, because the ability of diabetic patients with color vision deficiency to perform color-dependent tests for urinary and blood glucose may be impaired, such patients should be made aware of this potential problem.

Adult↗
PubMed1987

Age covariance between 100-Hue color scores and quantitative perimetry in primary open angle glaucoma.

Color vision tests have shown promise as an early indicator of optic nerve compromise in primary open angle glaucoma (POAG). In this context, it is of interest to know how well color test performance correlates with an accepted measure of glaucomatous optic nerve damage, such as is provided by quantitative static perimetry. We found correlation values for 96 glaucoma suspects (ocular hypertensive patients) and 110 patients with POAG. No significant correlation values were found for the suspect group when age correction was applied to the color variable. Similarly, for the patients with POAG, age correction of the color test scores reduced all age group correlation values below significance, except for the age group 60 to 69 years. These findings conflict with another recent study reporting significant correlation between Farnsworth-Munsell 100-hue color test scores and visual field performance for glaucoma suspects but which did not correct for age. We interpreted our results for the glaucoma suspects and patients with glaucoma to indicate some independence of mechanisms responsible for early color loss compared with visual field loss.

Adult↗
PubMed1987

Clinical measures of central vision function in glaucoma and ocular hypertension.

A generalized loss of visual sensitivity, even for foveal targets, has been reported as an early sign of glaucoma. In the present study of central vision, we used relatively simple and rapid clinical tests of color thresholds, color discrimination, and spatial contrast sensitivity to compare the vision of three age-matched groups of patients who had primary open angle glaucoma (n = 33) or ocular hypertension (n = 32) as well as normal subjects (n = 24). The largest sensitivity losses for both glaucoma and ocular hypertensive groups were disclosed by a color threshold test with blue lights designed to isolate the blue-sensitive pathways of the visual system. The loss of sensitivity for both the glaucoma group and the ocular hypertensive group is consistent with recent reports (from postmortem studies of human eyes) of extensive axon death even in the absence of glaucomatous field defects.

Aged↗