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At least 109 records · Page 6Linked to original sources
PubMed1992

Color vision testing for the U.S. Naval Academy.

Normal color vision is a prerequisite for admission to the United States Naval Academy. The Farnsworth Lantern (FALANT) is the Navy's definitive test for color vision. A FALANT is not available at many locations where candidates are examined, so satisfactory performance on pseudoisochromatic plates has been considered an acceptable alternative. Until recently, the Farnsworth Dichotomous Test Panel D-15 had also been used as an alternative test, but is now considered unacceptable. In the summer of 1991, a large number of candidates reported for induction who were unable to pass the FALANT. Since their screening physical examinations had been reported to show normal color vision, a shadow of doubt was cast upon the ability of the alternative tests to predict performance on the FALANT. Four hundred subjects were then tested on several color vision tests to determine if these tests could predict FALANT success. The results of this study and recommendations are presented.

Adolescent↗
PubMed1989

Molecular patterns of X chromosome-linked color vision genes among 134 men of European ancestry.

We used Southern blot hybridization to study X chromosome-linked color vision genes encoding the apoproteins of red and green visual pigments in 134 unselected Caucasian men. One hundred and thirteen individuals (84.3%) had a normal arrangement of their color vision pigment genes. All had one red pigment gene; the number of green pigment genes ranged from one to five with a mode of two. The frequency of molecular genotypes indicative of normal color vision (84.3%) was significantly lower than had been observed in previous studies of color vision phenotypes. Color vision defects can be due to deletions of red or green pigment genes or due to formation of hybrid genes comprising portions of both red and green pigment genes [Nathans, J., Piantanida, T.P., Eddy, R.L., Shows, T.B., Jr., & Hogness, D.S. (1986) Science 232, 203-210]. Characteristic anomalous patterns were seen in 15 (11.2%) individuals: 7 (5.2%) had patterns characteristic of deuteranomaly (mild defect in green color perception), 2 (1.5%) had patterns characteristic of deuteranopia (severe defect in green color perception), and 6 (4.5%) had protan patterns (the red perception defects protanomaly and protanopia cannot be differentiated by current molecular methods). Previously undescribed hybrid gene patterns consisting of both green and red pigment gene fragments in addition to normal red and green genes were observed in another 6 individuals (4.5%). Only 2 of these patterns were considered as deuteranomalous. Thus, DNA testing detected anomalous color vision pigment genes at a higher frequency than expected from phenotypic color vision tests. Some color vision gene arrays associated with hybrid genes are likely to mediate normal color vision.

Color Perception↗
PubMed1996

Primate photopigments and primate color vision.

The past 15 years have brought much progress in our understanding of several basic features of primate color vision. There has been particular success in cataloging the spectral properties of the cone photopigments found in retinas of a number of primate species and in elucidating the relationship between cone opsin genes and their photopigment products. Direct studies of color vision show that there are several modal patterns of color vision among groupings of primates: (i) Old World monkeys, apes, and humans all enjoy trichromatic color vision, although the former two groups do not seem prone to the polymorphic variations in color vision that are characteristic of people; (ii) most species of New World monkeys are highly polymorphic, with individual animals having any of several types of dichromatic or trichromatic color vision; (iii) less is known about color vision in prosimians, but evidence suggests that at least some diurnal species have dichromatic color vision; and (iv) some nocturnal primates may lack color vision completely. In many cases the photopigments and photopigment gene arrangements underlying these patterns have been revealed and, as a result, hints are emerging about the evolution of color vision among the primates.

Animals↗
PubMed2002

Color vision in 42 Congolese patients with tuberculosis receiving ethambutol treatment.

PURPOSE: To study color vision in Congolese patients with tuberculosis receiving ethambutol therapy. METHODS: A prospective, descriptive study of color vision test in patients with systemic tuberculosis receiving ethambutol was performed between April 1995 and January 1998 at the Department of Ophthalmology, University of Kinshasa. Color vision tests were assessed with pseudoisochromatic plates (the Ishihara Pseudo-isochromatic Plates), the AO-HRR (American Optical Handy Rand Rittler), the Bölle and Kastel anomaloscope, Farnsworth-Munsell test (the D-15 and the FM-100). RESULTS: There were 42 patients with a mean age of 33 years (range, 14 to 75 years). The color vision of all the patients was found to be normal as measured by the Ishihara pseudoisochromatic plates. One (2%) patient showed color vision defect (anarchic axis] with the OA-HRR test. Three (7%) of 42 patients displayed blue-yellow color axis or anarchic axis color vision test on the D-15 test. Fifteen (36%) of 42 patients had high total error scores at the Farnsworth-Munsell 100 test. The color axis was as follows: anarchic axis (13.1%), red-green-color and blue-yellow-color combined axis (13.1%), blue-yellow color axis (7.5%). Results of the Bölle and Kastel anomaloscope were normal in all patients. CONCLUSION: Our results confirm the importance of color vision examinations in the detection of the complications of ethambutol treatment.

Adolescent↗
PubMed1982

Color vision in the spider monkey (Ateles).

Spectral sensitivity and color vision were investigated in 2 spider monkeys (Ateles) using a forced-choice discrimination paradigm. The increment-threshold spectral sensitivity functions of both animals were very similar to those of normal human trichromats; all had three regions of peak sensitivity located at 440-460, 520-540, and 670-620 nm. However, color vision tests (neutral point, anomaloscope, and wavelength discrimination) indicated that at least two qualitatively different types of color vision exist among spider monkeys. The female tested had essentially normal trichromatic color vision (although her anomaloscope match was shifted slightly in the deutan direction) with acute wavelength discrimination. The male, however, was clearly a protanomalous trichromat. He required much more red light in a red/green mixture to match a standard yellow than did normal trichromats. This variation in color vision is discussed in the context of an analogous variation known to exist among other South American monkeys.

Animals↗
PubMed1996

Clinical vision characteristics of the congenital achromatopsias. II. Color vision.

Twelve X-linked (XL) achromats and 43 autosomal recessive (AR) achromats were tested using the Farnsworth D-15, Nagel anomaloscope, Sloan achromatopsia test, and Berson test using standard procedures. All of the tests identify achromatopsia, but very few differentially diagnose the various types. AR achromats were subclassified as complete (rods only) or incomplete (residual cone function present) by additional psychophysical testing. Complete and incomplete ARs do not perform differently on any clinical color vision measure, indicating that (1) rods predominantly mediate vision in both groups and (2) these tests are not useful for distinguishing between the groups. Both groups show considerable interindividual variation on all measures. Only one of the measures, the Berson test, designed to distinguish XLs from ARs, does so reliably. XLs and ARs do not differ significantly on the Nagel anomaloscope or most of the Sloan plates. The confusion angles of the D-15 do differ for the two groups, but the variability in each group makes the measure unreliable for classifying individuals. The Berson test is recommended to distinguish the XL from AR achromats.

Adolescent↗
PubMedDate not supplied

A sweep VEP test for color vision deficits in infants and young children.

PURPOSE: Color vision testing in young children typically is precluded by the motor and cognitive skills required by standard tests; yet this information can be useful for diagnosis and counseling in many conditions. The purpose of this study is to evaluate a visual evoked potential (VEP) method for assessing red-green color vision anomalies in pediatric patients. METHOD: The relative chromatic luminance (C = R/R + G) of a rapidly reversing red-green checkerboard was varied across a wide range within a short viewing period (10 sec). Swept-parameter VEP methods were used to measure the cortical response to the range of C presented. RESULTS: Individuals with normal color vision exhibit a VEP response that exceeds noise levels across all values of C, often with an amplitude minima near the photopic equiluminant point (C = 0.5). Results from children with established protan and deutan color vision anomalies show loss of VEP amplitude and phase at values of C consistent with the respective color defect. A patient with achromatopsia showed a generalized depression of VEP response across all values of C tested. CONCLUSION: Color sweep VEP techniques appear promising for the clinical assessment of color status in pediatric patients.

Child↗
PubMed1995

Effect of subacute occupational exposure to toluene on color vision.

The subacute effect of toluene on color vision was examined in 59 rotogravure workers exposed to toluene. Toluene and ethanol were determined in blood and color vision testing was performed on Monday before shift and on Friday after shift. The battery included the Ishihara plates, the Velhagen plates, the Standard Pseudoisochromatic Plates part 2, the Farnsworth panel D-15 test, and the Lanthony desaturated panel D-15 test. The concentrations of toluene in blood ranged from < 0.22 to 7.37 mg/l. No effect of toluene on color vision could be observed even in a subgroup of highly exposed workers. So their ability to judge colored products was not impaired.

Adolescent↗
PubMed1994

Does color vision deficiency in the endoscopist influence the accuracy of endoscopic diagnosis? An anonymous study with Dutch gastrointestinal endoscopists.

Colors play a major role in the endoscopic diagnosis of many gastrointestinal conditions. Gastrointestinal endoscopists in the Netherlands are predominantly male (> 90%), and from population data it is to be expected that approximately 8% will have a color vision deficiency. The present study was designed to assess the prevalence of color vision deficiencies amongst Dutch gastrointestinal endoscopists and to determine whether color vision deficiency affects an endoscopist's diagnostic skill. One hundred and thirty-nine gastroenterologists and physicians of internal medicine took an F2 color vision test and assessed nine videofragments of endoscopies. Color vision deficiencies were detected in 8% of Dutch gastrointestinal endoscopists. In one out of the nine video excerpts of endoscopies, a statistically significant difference was detected between test subjects with and without a color vision deficiency. However, this video excerpt showed a green pea, which could not be mistaken for a polyp at polypectomy. The study therefore does not show any effect of color vision deficiencies on endoscopic skills, nor does it show any deviant prevalence of color vision deficiencies amongst Dutch gastrointestinal endoscopists.

Adult↗
PubMed1998

Reversible color vision loss in occupational exposure to metallic mercury.

Color vision was evaluated in twenty-one mercury exposed workers and referents matched for sex, age, tobacco smoking, and alcohol habits. The Lanthony 15 Hue desaturated panel (D-15 d) was applied. In the workers, mean urinary Hg (HgU) was 115+/-61.5 microg/g creatinine; in all but one the values exceeded the biological limit (BEI) proposed by the American Conference of Governmental Industrial Hygienists. A dose-related subclinical color vision impairment was observed in Hg-exposed workers compared to the referents. Just after the survey, working conditions were improved. Twelve months later the workers were reexamined. Mean HgU was 10.0 microg/g creatinine and in no subjects was the BEI exceeded. Color perception was significantly improved compared to the first examination and, furthermore, no differences were observed between exposed workers and referents. The results add evidence that the color vision loss observed during the first part of the study was related to Hg exposure and, moreover, show that this effect is reversible. These data indicate that metallic Hg can induce a reversible impairment in color perception. This suggests that color vision testing should be included in studies on the early effects of Hg. The possibility of applying the D-15 d as an early effect index in the biological monitoring of Hg exposed workers should also be entertained.

Adult↗
PubMed1983

Color vision in albino subjects.

Color vision testing was performed on a group of ten black tyrosinase-positive albino patients and a group of normal subjects. Testing was accomplished by means of a Farnsworth-Munsell (F-M) 100-hue test and Nagel anomaloscope. As a group, the albino patients showed an increase in number of errors scored on the FM-100 hue test, without any specific axis in the majority of cases. Results on the Nagel anomaloscope showed a 'widening' into the red end of the Rayleigh equation. A possible explanation for this apparent widening is discussed, which emphasizes anticipated results of matching ranges obtained on extrafoveal cones.

Adolescent↗
PubMed1996

Performance of color-dependent air traffic control tasks as a function of color vision deficiency.

BACKGROUND: This experiment was conducted to validate the requirement for normal color vision in Air Traffic Control Specialist (ATCS) personnel who work at en route center, terminal, and Flight Service Station (FSS) facilities. METHODS: A data base was developed involving 121 individuals with normal color vision, 31 simple and 44 extreme anomalous trichromats, and 48 dichromats; both protans and deutans were included. The performance of subjects with normal color vision was compared with the performance of individuals with various classifications of color vision deficiencies on a battery of color-dependent ATCS tasks. Simulations of the ATC color tasks concerned color coding in flight progress strips (at en route centers), aircraft lights and Aviation Signal Light indicator (in tower operations), and color weather radar (at FSS's). RESULTS: Errors were rare among normal trichromats. Mean errors were significantly higher at every level (degree) of color vision deficiency. Approximately 6% of color deficient subjects were able to perform ATC color tasks without error. The 6% were all from the simple anomalous trichromat category; all extreme anomalous trichromats and dichromats were prone to error on ATC tasks. CONCLUSIONS: We conclude that these findings provide support for the requirement of normal color vision in the initial medical screening of ATCS personnel.

Accidents, Aviation↗
PubMed1981

[Trial and evaluation of a new test to examine color vision (author's transl)].

With the new Rodenstock color test disk it is possible to distinguish with 99% accuracy between deuteranopia and protanopia. In addition, the diagnosis is quantitatively correct (anomaly or anopia) in 92% of deuteranopia and 98% of protanopia cases. A special scheme for evaluation is presented. Special emphasis was placed on describing exactly the function of this new method of examining inherited color vision deficiencies. Only persons who were already known to have defective color vision were tested. Therefore, no conclusions can be drawn regarding the efficiency of detection of color vision deficiencies.

Color Perception Tests↗
PubMed1997

Color vision tests for early detection of antiepileptic drug toxicity.

A previous suggestion that antiepileptic drugs may induce color vision deficiencies prompted us to examine whether color vision deficiencies may occur at lower drug serum concentrations than those associated with symptoms of neurotoxicity. Eighty patients presenting with epilepsy received monotherapies of valproic acid, phenytoin, or carbamazepine; 18 patients did not receive antiepileptic drug therapy. Color vision was tested by the Farnsworth-Munsell 100-hue test, spectral sensitivity, and the newly developed tritan screening plates. Patients treated with phenytoin or carbamazepine developed blue-yellow color vision deficiencies. In contrast, patients exposed to valproic acid or receiving no drug treatment showed normal color vision. There was a significant correlation (p < 0.0001) between signs of neurotoxicity induced by phenytoin or carbamazepine and blue-yellow color vision deficiencies. In contrast, we found no correlation between these signs of neurotoxicity and the drug serum concentrations (p = 0.0637). Color vision testing in epileptic patients treated with phenytoin or carbamazepine appears to be a sensitive method for early detection and monitoring of clinical neurotoxicity.

Adolescent↗
PubMed2000

Aircrew visors and color vision performance: a comparative and preliminary pilot study analysis.

BACKGROUND: A very important aspect of visual performance to consider, for present and future recommendations regarding aircrew visors, concerns their impact on color vision. The literature has remained mostly inconclusive with respect to the human perceptual process of colors during actual mission employment. OBJECTIVE: This study uses active duty military aircrews to provide objective and valuable information on the effects of Short Wavelength Absorbing Filters (SWAFs), such as the High Contrast Visor (HCV), and some selected waveband type Laser Eye Protection (LEP) visors on color vision. It provides a direct comparison of several current and proposed aircrew eye protective visors with respect to their effects on color vision. The data analyzed in this study will also be used to support a recommendation regarding a new optimal visor for aircrew wear during air to air (and ground) engagements, for sun protection, and possible visual enhancement in order to improve user compliance. METHODS: Seven volunteers on active flying status each underwent comprehensive color vision testing with and without seven of the U. S. Air Force's (USAF's) current or proposed aircrew visors/filters. Spectral transmissions of these visors/filters were obtained to identify and determine their individual characteristics which included their ability to induce acquired color vision decrements in "color normal" individuals. RESULTS: The widely utilized USAF HCV significantly degraded color vision more than luminosity matched neutral density visors. Abrupt color vision decrements for specifically fielded LEP visors were also noted. Their objective data supported theoretical and speculated color vision effects. Even though low transmittance neutral density visors did have some effect on color vision, decrement severity was not considered significant enough to affect overall performance during color vision testing. CONCLUSIONS AND DISCUSSION: Because of their ability to significantly affect color vision, concerns regarding the use of HCV and LEP visors should entail age, baseline color vision, environmental, and mission factors. Further testing should be done to evaluate the definitive effects that these visors actually have on the recognition of color symbology of Multi Function and Electronic Flight Information Displays. Findings in this study also support theoretical opinions that encourage the fielding of a neutral density filter (mildly tinted) with an overall transmission of 25-49%. Its use by flyers during low and bright illuminant conditions may greatly enhance visual performance by encouraging wearer compliance while allowing colors to be perceived normally.

Adult↗
PubMedDate not supplied

Color vision screening of young children.

Early detection of congenital color vision defects is desirable, but school screening studies have been stymied by lack of a suitable test. We evaluated a new color vision test, the APT-5, for use by volunteer screeners in schools and preschools. The screeners tested 1794 children, ages 3 to 13 years, and found the APT-5 easy to use with young children ages 5 years and up. Children who failed the screening were recruited for diagnostic color vision testing; for the children ages 5 to 13 years, 56% of those who failed the screening were successfully recruited. Data analysis indicated that the false-positive rate in this age group was 1% to 2%, and that for boys in this age group the positive predictive value was 71% to 81%. Retest data indicated that most false-positives were not due to the test itself, but to other factors in the school screening situation. Two thirds of all children scored as abnormal by anomaloscopy were simple deuteranomalous, indicating that the APT-5 effectively identified even mild color defects. The results of this trial indicate that the APT-5 is suitable for school color vision screening of children ages 5 years and up.

Adolescent↗
PubMed1992

Different patterns of X inactivation in MZ twins discordant for red-green color-vision deficiency.

Two female identical twins who were clinically normal were obligatory heterozygotes for X-linked deuteranomaly associated with a green-red fusion gene derived from their deuteranomalous father. On anomaloscopy, one of the twins was phenotypically deuteranomalous while the other had normal color vision. The color vision-defective twin had two sons with normal color vision and one deuteranomalous son. X-inactivation analysis was done with the highly informative probe M27 beta. This probe detects a locus (DXS255) which contains a VNTR and which is somewhat differentially methylated on the active and inactive X chromosomes. In skin cells of the color vision-defective twin, almost all paternal X chromosomes with the abnormal color-vision genes were active, thereby explaining her color-vision defect. In contrast, a different pattern was observed in skin cells from the woman with normal color vision; her maternal X chromosome was mostly active. However, in blood lymphocytes, both twins showed identical patterns with mixtures of inactivated maternal and paternal X chromosomes. Deuteranomaly in one of the twins is explained by extremely skewed X inactivation, as shown in skin cells. Failure to find this skewed pattern in blood cells is explained by the sharing of fetal circulation and exchange of hematopoietic precursor cells between twins. These data give evidence for X inactivation of the color-vision locus and add another MZ twin pair with markedly different X-inactivation patterns for X-linked traits.

Chromosome Mapping↗