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PubMedDate not supplied

[Color vision in diabetics].

Color perception is often already altered even if the ocular, anatomic and functional exams maintain their results within the normal limits. This fact is more important in diabetes, where chromatic abnormalities exist at half of the subjects, even if they do not reveal any signs of diabetic retinopathy. The authors present some of the methods in clinical exam of color perception, the characters of dyschromatopsia and glycemic self control using the method of coloured bandelets, types of dyschromatopsia which may appear during the evolution of the diabetes, and also the predictive effect of dyschromatopsia for the appearance of diabetic retinopathy.

Color Perception↗
PubMedDate not supplied

Visual acuity and color vision deficiency in amblyopia.

PURPOSE: To investigate color vision and its relation with the type of amblyopia and visual acuity of amblyopic eyes. METHODS: In this prospective study, 67 amblyopic eyes of 64 patients, aged from 4 to 13 years (mean 6.8 +/- 2.1) and 26 eyes of 13 control subjects aged from 5 to 13 years (mean 7.3 +/- 1.6) were examined with the Farnsworth-Munsell 100 Hue Test (FM-100). Amblyopic eyes were grouped as strabismic (21 eyes) and anisometropic (46 eyes). Each group was subdivided according to their visual acuity, as less than 5/10 and 6/10 or better. The total errors, blue-yellow (B-Y) and red-green (R-G) partial error scores were obtained for each group. One-way ANOVA was used to assess differences between groups. RESULTS: The error scores of all axes were lower in the control group than the amblyopic groups (p<0.001), but the differences within amblyopic groups were not significant (p>0.05). CONCLUSIONS: Deficient color vision in the amblyopic eyes was not related to the visual acuity and type of amblyopia.

Adolescent↗
PubMed1981

Color vision defects in retinitis pigmentosa.

Sixty-seven patients with retinitis pigmentosa underwent color vision testing with the Nagel anomaloscope and Farnsworth-Munsell (FM) 100-hue test. Results showed both similarities and differences among different genetic types. The presence of an atrophic-appearing foveal lesion found in individual cases served as a reliable indicator of performance on color vision testing as did a reduction in visual acuity to less than 20/30. When no foveal lesion was apparent in patients with visual acuity better than 20/30, patients with autosomal dominant disease showed superior performance on color vision testing when compared to autosomal recessive, X-linked recessive, and isolated cases. Regardless of genetic type, the FM 100-hue test was more sensitive in detecting poor color vision performance than the Nagel anomaloscope.

Adolescent↗
PubMed1992

Color vision deficits and Rorschach performance in aged persons.

Forty-two community residing older adults (M age = 69.28) (32 color normal, 10 color deficient) were administered the Rorschach and measures of both verbal and nonverbal intelligence in order to explore the effect of color vision deficiencies on affective responsivity. Among the sample of older persons screened for both visual and auditory acuity, when controls for intelligence and numbers of responses were made, greater affective constriction was found in the protocols of color vision deficient persons, relative to color normal individuals. These data suggest that Rorschach indicators of affective constriction may be biased in the case of individuals who have experienced color vision decrements. Consequently, first screening for color vision decrements when assessing older persons' personality dynamics may be desirable.

Aged↗
PubMed2000

A lantern color vision test for the rail industry.

BACKGROUND: Correct identification of wayside signal colors is critical for safe operation of railway equipment. However, evaluating color discrimination using just a screening test may not be occupationally relevant. METHODS: A lantern test (CNLAN) was designed to provide a functional assessment of color discrimination for the rail industry. It was validated against a simulated field trial. 81 individuals with normal color vision and 74 individuals with congenital red-green defects participated. Color vision was classified using the Nagel Anomaloscope. RESULTS: Using a criterion based on the worst-normal performance, 97% of the individuals with a color vision defect failed both the CNLAN and simulation trial. This value is slightly lower than the 100% who failed both the Ishihara test and simulation. However, the Ishihara test also failed 3.7% of the color-normals who passed both the simulation and lantern, whereas by definition none of the color-normals failed the lantern. CONCLUSIONS: This lantern test provides a reasonable functional assessment of one's ability to identify rail signal colors; especially when a strict failing criterion is applied to screening tests.

Accidents, Occupational↗
PubMed1996

Comparison of the standard pseudoisochromatic plates--Parts 1 and 2--As screening tests for congenital red-green color vision deficiencies.

BACKGROUND: The Standard Pseudoisochromatic Plates-Part 2 (SPP-2) are designed primarily as a screening test for acquired color vision deficiencies. However, results from several studies suggest that the SPP-2 may also be effective as a screening test for congenital red-green color vision defects. METHODS: In this study, the screening effectiveness of the SPP-2 was compared with the Standard Pseudoisochromatic Plates-Part 1 (SPP-1) to determine whether clinicians must use both tests: the SPP-1 to screen for congenital color vision defects and the SPP-2 to screen for acquired color vision defects. RESULTS: The results showed that, when using the recommended scoring criterion for the SPP-1, the SPP-2 test is slightly more sensitive in detecting congenital red-green defects. CONCLUSIONS: Clinicians can use the SPP-2 to screen for both congenital and acquired color vision defects.

Adolescent↗
PubMed1990

Color vision defect as first symptom of progressive cone-rod dystrophy.

A 15-year-old girl complained of color vision difficulties and was found to have an acquired color vision defect with no other abnormalities in the eyes. After 9 years, in addition to the color vision defect, there was gradual loss of visual acuity in both eyes, small central scotomas in the visual fields, elevation of the cone and rod thresholds in the dark adaptation, and decreased response in the photopic and scotopic electroretinogram. The diagnosis of a progressive cone-rod dystrophy was made. It is unusual for cone-rod dystrophy to begin with a distinct color vision defect only; the case report is presented.

Adolescent↗
PubMed1986

Color vision in the peripheral retina.

Until recently, color vision in the peripheral field has been thought to be substantially less developed than color vision in the central field. Although the exact dimensions vary from study to study, most estimates of peripheral chromatic perception place the limit of trichromatic vision at no more than 30 degrees from fixation; the visual field is thought to be completely color blind at about 50 degrees of eccentricity. Within the last 10 years, an increased understanding of the changing spatial scale in the peripheral field has led researchers to reevaluate what is believed about peripheral function. We now know that virtually every measure of peripheral color perception can be improved by using a suitably large stimulus in the peripheral field. This paper examines current and past perspectives on peripheral color function, and describes two studies which demonstrate that peripheral and central chromatic processing are the same to the first order if the changes in spatial scale and photopic sensitivity with eccentricity are considered.

Color↗
PubMed1984

Individual variations in color vision among squirrel monkeys (Saimiri sciureus) of different geographical origins.

A forced-choice discrimination procedure was used to test color vision and visual sensitivity in 10 squirrel monkeys (Saimiri sciureus) originating from three geographical locations (Bolivia, Colombia, Guyana). In agreement with results from an earlier study of vision in squirrel monkeys of Peruvian origin, striking individual variations in color vision were found among these squirrel monkeys. Some of these animals had trichromatic color vision, while others were dichromats. Within these two categories, a total of five color vision phenotypes could be discerned. Most of these types are qualitatively similar to common forms of human color-defective vision.

Animals↗
PubMed2002

Color and defective color vision as factors in the conspicuity of signs and signals.

The conspicuity of road traffic signs and signals for a group of observers with the color vision defect of deuteranopia is compared with that for a control group of observers with normal color vision. Conspicuity was measured by the proportion of reports of target objects detected in 300-ms presentations of projected slides of road scenes. There were two instructions, one designed to measure attention conspicuity and the other, search conspicuity. The attention conspicuity of red, orange, and green color-coded traffic control devices was significantly less for deuteranopes than for the observers with normal color vision, but this was not true for yellow and blue color-coded signs. This result is consistent with our understanding of the color perceptions of deuteranopes. The reduction of conspicuity was not so great for the search conspicuity condition. We conclude that redundant color coding does contribute to the conspicuity of signs and signals and that deuteranopes--and probably those with other severe forms of defective color vision--have a significantly reduced ability to notice colored targets, such as road signs and signals, in complex visual environments. The actual and potential application of this work is in the design of signs so they are conspicuous, especially when the user group includes people with defective color vision.

Adolescent↗
PubMed2005

Color vision and contrast sensitivity in epilepsy patients treated with initial tiagabine monotherapy.

The purpose of the study was to determine whether the use of a GABAergic antiepileptic drug (AED), tiagabine, affects color vision and contrast sensitivity. Twenty newly diagnosed patients with partial epilepsy (aged 19-72 years), receiving tiagabine as their initial monotherapy for 5-41 months were examined. Color vision was examined with the Standard Pseudoisochromatic Plates 2 (SPP2), with the Farnsworth-Munsell 100 Hue Test (FM100) and with the Color Vision Meter 712 (CVM) anomaloscope. Contrast sensitivity was measured with the Pelli-Robson letter chart. Three patients excluded from the color vision evaluation for congenital red-green color vision defects. Seven out of 17 patients (41%) had acquired color vision deficit examined with the FM100. The CVM anomaloscope revealed minor defects in two patients. Contrast sensitivity function was within normal ranges. The present study suggests that AED therapy with tiagabine, like with other established and newer AEDs may interfere with color perception.

Adult↗
PubMed2003

Achromatopsia, color vision, and cortex.

Brain damage can entirely abolish color vision in cases of complete achromatopsia. Other processes that depend on wavelength differences, however, can be retained. Form and motion defined by pure color differences can be perceived readily even when the colors themselves cannot be told apart. The loss of color vision in cerebral achromatopsia has been equated with the loss of a "color center" presumed indispensable for the phenomenal experience of hue. The "color center" has been assigned a role in the cortical construction of color, specifically in implementing the computations that underlie color constancy. Many features of the condition are consistent with this account. Other neurologic patients, however, retain conscious experience of hue, yet fail to disentangle the illuminant and the reflectance properties of surfaces. For them, color experience is determined by the wavelength composition of light reflected from a surface. If their wavelength-dependent vision is mediated by activity in early visual areas, then it is difficult to understand why these areas are unable to perform a similar role when they remain intact in achromatopsic observers. The prevalence of cells in the ventral visual areas of the monkey brain that code color and the further fractionation of color-related areas in human observers revealed by functional imaging suggest multiple color areas. Their different contributions are only just beginning to become apparent.

Brain Diseases↗
PubMed1992

The True Daylight Illuminator (TDI): a less expensive source of illumination for color vision screening.

This experiment was designed to examine the feasibility of using the True Daylight Illuminator (TDI) as an illumination option for conducting color vision screening with the Ishihara Test(s). The MacBeth Easel Lamp was designed to provide proper illumination for performing color vision screening with a variety of pseudoisochromatic (PIC) plate tests including the Ishihara. However, over the years, the MacBeth Lamp has become so expensive that many smaller programs cannot afford to purchase one. This problem has promoted the use of alternate light sources that have had a deleterious effect on test results and in some instances contributed to job discrimination. Recently the MacBeth Division of the Kollmorgan Corporation discontinued the manufacture of the MacBeth Lamp due to lack of demand. Thus, it is important to find an inexpensive illumination option for conducting color vision screening. Two groups of subjects were used to compare test results for the 24-plate edition of the Ishihara Test using both the MacBeth Lamp and the True Daylight Illuminator. The first group contained 45 subjects with inherited color defective vision. The second group was made up of 30 color normals. The Nagel anomaloscope was used to confirm the color vision status of the subjects in both groups. Statistics to test the significance of differences between group means clearly demonstrated that there were no significant differences between the mean error scores of the two groups for these two pieces of equipment. Thus, it was concluded that the TDI can be used in lieu of the MacBeth Easel Lamp for screening color vision with the Ishihara test.

Adolescent↗
PubMed1984

Correlation of color vision deficits and observable changes in the optic disc in a population of ocular hypertensives.

Both glaucomatous cupping and the presence of acquired color vision deficits have been reported to be precursors to the onset of visual field defects in patients with suspected glaucoma. To examine the relationship between early glaucomatous cupping and acquired color vision anomalies, we performed anomaloscope (Pickford-Nicholson) and Farnsworth-Munsell 100-Hue color vision tests in 48 ocular hypertensive eyes with either clinical evidence of early glaucomatous cupping (group 1) or no evidence of glaucomatous cupping (group 2). All patients had normal visual fields, as determined by extensive static perimetry of the central visual field and kinetic perimetry of the peripheral visual field. Although the overall incidence of blue and blue-green color vision anomalies in the ocular hypertensives was comparable with that reported in previous studies, we found no clear association between early glaucomatous cupping and color vision anomalies. The relationship between these two precursors to visual field loss remains unclear.

Adult↗
PubMed1994

Visual acuity, color vision, and visual search performance at sea.

Visual acuity and color vision were tested during a search and rescue exercise at sea. Fifty-seven watchkeepers searched for orange and yellow life rafts during daylight and for lighted and unlighted life rafts at night with night vision goggles. There were 588 individual watches of one hour each. Measures of wind, waves, and weather were used as covariates. Daytime percentage detection was positively correlated with low-contrast visual acuity and negatively correlated with error scores on Dvorine pseudoisochromatic plates and the Farnsworth color test. Performance was better during the first half-hour of the watch. Efficiency calculations show that color vision selective screening at one standard deviation above the mean would increase daylight search performance by 10% and that one standard deviation visual acuity selection screening would increase performance by 12%. There was no relationship between either acuity or color vision and life raft detection using night vision goggles.

Color Perception↗
PubMed2003

An A-71C substitution in a green gene at the second position in the red/green visual-pigment gene array is associated with deutan color-vision deficiency.

We studied 247 Japanese males with congenital deutan color-vision deficiency and found that 37 subjects (15.0%) had a normal genotype of a single red gene followed by a green gene(s). Two of them had missense mutations in the green gene(s), but the other 35 subjects had no mutations in either the exons or their flanking introns. However, 32 of the 35 subjects, including all 8 subjects with pigment-color defect, a special category of deuteranomaly, had a nucleotide substitution, A-71C, in the promoter of a green gene at the second position in the red/green visual-pigment gene array. Although the -71C substitution was also present in color-normal Japanese males at a frequency of 24.3%, it was never at the second position but always found further downstream. The substitution was found in 19.4% of Chinese males and 7.7% of Thai males but rarely in Caucasians or African Americans. These results suggest that the A-71C substitution in the green gene at the second position is closely associated with deutan color-vision deficiency. In Japanese and presumably other Asian populations further downstream genes with -71C comprise a reservoir of the visual-pigment genes that cause deutan color-vision deficiency by unequal crossing over between the intergenic regions.

Asian People↗
PubMed1996

Molecular genetics of human color vision.

The significant advances in our understanding of color vision has been due to the convergence of information from behavioral and molecular genetic analyses. The molecular biology of the visual pigments; molecular genetic basis of variation in normal and abnormal color vision, and regulation of the genes at the LWS-MWS pigment gene locus are discussed.

Animals↗
PubMed2003

Color vision with rapid-onset acceleration.

INTRODUCTION: Only sporadic information exists concerning perceived color shifts at increased G-loads. The purpose of this study was to investigate whether or not color vision is affected by rapid onset high G7-loads up to +9 Gz, and specifically whether perception of hue changes. METHODS: There were 10 male subjects, 9 with normal color vision and 1 with red-green protanomaly, all accustomed to Gz-loads in a human centrifuge. Each subject was tested on a total of 60 Gz-exposures with 10 s periods at +3, +5, +7, and +9 Gz in the centrifuge on three different days. G-onset rate was 6 G x s(-1). The subjects wore an anti-G suit and performed straining maneuvers if necessary to maintain vision. Five square color stimuli of medium saturation (yellow, red, blue, green, and gray) were projected one at a time on a screen in front of the subject, who gave his hue response orally. RESULTS: In 96.6% of exposures to various Gz-loads, the subjects responded by correctly naming colors. (The statistical analyses of the results were done for the subjects with normal color vision, with the protanomalous subject excluded.) Hue shifts occurred at the higher +Gz-levels, including 7.7% of the +9 Gz exposures. Yellow was the hue most frequently perceived as changed. Hue shifts were reported for yellow in 11% and 16% of the +7 and +9 Gz exposures, respectively. Hue shifts at +9 Gz occurred as frequently as blackout and G-LOC together. However, statistical analyses showed no significant effects for +Gz-load. CONCLUSIONS: Absolute identification of the color stimuli of medium saturation was stable and was not significantly affected by the rapid onset +Gz-loads up to and including +9 Gz.

Acceleration↗