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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↗
PubMed2001

Effects of low-level occupational exposure to styrene on color vision: dose relation with a urinary metabolite.

To investigate the threshold effects of chronic low-level occupational exposure to styrene on color vision, we examined color discrimination in 105 male workers exposed to styrene (mean age 37.7 years; mean length of exposure 6.2 years; mean urinary concentration of mandelic acid 0.21 g/L) and in 117 referents (mean age 37.7 years). We also assessed the effects of styrene by examination of the nature of the relation between disorders of nervous function and age, alcohol consumption, and other variables. A standardized questionnaire was adopted to collect information about work history, occupational or nonoccupational solvent exposure, alcohol consumption, and drug use. Color vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the color confusion index (CCI). There was a dose-dependent relationship between the urinary concentration of mandelic acid and color vision loss. The CCIs of the subgroups whose urinary mandelic acid levels were 0.1-0.2 and >0.2 g/L were significantly higher than those of each referent group (P<0.05 and P<0.01, respectively), but not in the subgroup whose urinary mandelic acid level was lower than 0.1 g/L. Our study suggests that a low level of styrene, presumably 0.1-0.2 g/L, involves the risk of inducing adverse effects on color vision. After confounding factors were adjusted for, the urinary mandelic acid level had a significant positive relationship with color vision.

Adult↗
PubMed2006

Categorical color naming of surface color codes by people with abnormal color vision.

PURPOSE: Past investigations of the ability of people with color vision deficiency (CVD) to name the colors of surface colors have been occupation-specific. This study was undertaken as a more generalized investigation to explore particularly the effects of stimulus size and shape. METHODS: One hundred CVD observers and 20 color vision normal (CVN) subjects named the colors of two sets of surface colors, each set presenting the same 10 colors (red, orange, brown, yellow, green, blue, purple, white, gray, black). One set presented dot stimuli in three sizes (2.4 degrees , 1.0 degrees , 0.27 degrees ) and the other line stimuli with three widths (0.50 degrees , 0.27 degrees , 0.14 degrees ). Color vision was diagnosed using the Ishihara test, the Farnsworth D15 test, the Medmont C100, and the Nagel anomaloscope. RESULTS: All CVN subjects and 37% of CVD subjects made no errors. Type of CVD and stimulus size were significant factors for probability of error and the effect of stimulus size is best described by 1/area. There were significant interactions between CVD type and 1/area and between shape and 1/area. Deuteranomals who passed the Farnsworth D15 test made significantly fewer errors than all other CVD types and 70% made no errors. Their common errors were to confuse red, orange, and brown. Protanomals who passed the Farnsworth D15 test made fewer errors than dichromats. CONCLUSIONS: Mild deuteranomals will make very few errors with a seven-color code that omits orange, brown, and purple and will make very few errors (approximately 0.3%) with a 10-color code when the stimuli are reasonably large (area >20 mm).

Adolescent↗
PubMed2003

Color vision impairment in workers exposed to neurotoxic chemicals.

Recent research shows that occupational exposure to several solvents, metals and other industrial chemicals can impair color vision in exposed workers. Occupation-related color vision impairment usually results in blue-yellow color discrimination loss or, less frequently, a combination of blue-yellow and red-green loss. The eyes may be unequally involved, and the course is variable depending on exposure and other factors. The pathogenesis of occupational color vision loss has not been elucidated; it may be due to, e.g. a direct action of neurotoxins on receptors, possibly on the cone's membrane metabolism, and/or to an interference with neurotransmitters within the retina. Other possible pathogenetic mechanisms, such as a direct effect to the optic nerve, have also been suggested. Occupational color vision loss is usually sub-clinical, and workers are unaware of any deficit. It can be assessed using sensitive tests, such as the Farnsworth-Munsell 100 Hue (FM-100) or the Lanthony D-15 desaturated panel (D-15 d). The latter is the most widely used for studies in groups of exposed workers, and offers the possibility of a quantitative evaluation of the results by calculation of the Bowman's Color Confusion Index (CCI), or of the Vingrys' and King Smith's Confusion Index (CI). Other advantages of D-15 d are the possibility to perform the test directly at the workplace, and the reproducibility when performed in standardized conditions. In most cases, occupation-related color vision impairment is correlated to exposure levels, and has often been observed in workers exposed to environmental concentrations below the current occupational limit proposed by the ACGIH. Progression with increasing cumulative exposure has been reported, while reversibility is still discussed. Acquired color vision impairment related to occupational exposure to styrene, perchloroethylene (PCE), toluene, carbon disulfide, n-hexane, solvent mixtures, mercury and some other chemicals are discussed. Results show that color vision testing should be included in the evaluation of early neurotoxicity of chemicals in exposed workers. The D-15 d would be useful in the surveillance of workers exposed to solvents and other chemicals toxic to the visual system.

Animals↗
PubMed2005

Demonstration of a genotype-phenotype correlation in the polymorphic color vision of a non-callitrichine New World monkey, capuchin (Cebus apella).

Color-vision polymorphism in New World monkeys occurs because of an allelic polymorphism of the single-copy red-green middle-to-long-wavelength-sensitive (M/LWS) opsin gene on the X chromosome. Because color-vision types can readily be estimated from allelic types of the M/LWS opsin gene, this polymorphic system offers researchers an excellent opportunity to study the association between vision and behavior. As a prerequisite for such studies, genetically determined color-vision types must be concordant with phenotypes determined directly by behavioral criteria (e.g., by a color discrimination test). However, such correlations between genotypes and phenotypes have been studied only for callitrichine species. Using genetic, electrophysiological, and behavioral approaches, we evaluated the color vision of brown capuchin monkeys (Cebus apella), a representative non-callitrichine model animal for physiology and behavior. Two allelic M/LWS opsins-P545 and P530-were identified in the studied captive population. Females had one or both of the alleles, and males had either one. The retinal sensitivity in P530 dichromats was short-wave shifted relative to that in P545 dichromats, whereas that in P530/P545 trichromats was between the two groups. In a discrimination task using Ishihara pseudo-isochromatic plates, P530/P545 trichromats were successful in discriminating stimuli that P530 and P545 dichromats were unable to discriminate. In a food-search task, P530/P545 trichromats were able to locate red targets among green distracters as quickly as among white distracters, whereas both types of dichromats took longer. These results demonstrate the mutual consistency between genotypes and phenotypes of color vision, and provide a solid genetic basis on which the ecology and evolution of color vision can be investigated.

Animals↗
PubMed1996

Visual pigment gene structure and the severity of color vision defects.

Rearrangements of the visual pigment genes are associated with defective color vision and with differences between types of red-green color blindness. Among individuals within the most common category of defective color vision, deuteranomaly, there is a large variation in the severity of color vision loss. An examination of specific photopigment gene sites responsible for tuning photopigment absorption spectra revealed differences that predict these variations in the color defect. The results indicate that the severity of the defect in deuteranomalous color vision depends on the degree of similarity among the residual photopigments that serve vision in the color-anomalous eye.

Blotting, Southern↗
PubMed1999

Impaired color vision associated with diabetic retinopathy: Early Treatment Diabetic Retinopathy Study Report No. 15.

PURPOSE: To report color vision abnormalities associated with diabetic retinopathy. METHODS: Color vision function was measured at baseline in 2,701 patients enrolled in the Early Treatment Diabetic Retinopathy Study, a randomized trial investigating photocoagulation and aspirin in the treatment of diabetic retinopathy. Hue discrimination was measured by the Farnsworth-Munsell 100-Hue test, and errors in color vision were reported as the square root of the total 100-Hue (SQRT 100-Hue) score. RESULTS: Approximately 50% of the Early Treatment Diabetic Retinopathy Study population had color vision scores (SQRT 100-Hue score) worse than 95% of the normal population reported by Verriest and associates. The factors most strongly associated with impaired hue discrimination were macular edema severity, age, and presence of new vessels. A tritan-like defect was prominent and increased in magnitude with increasing severity of macular edema. However, many patients had color discrimination impairment without macular edema. CONCLUSIONS: Impaired color vision is a common observation among participants enrolled in the Early Treatment Diabetic Retinopathy Study. Compared with published data on normal subjects, approximately 50% of the patients in the Early Treatment Diabetic Retinopathy Study had abnormal hue discrimination. Macular edema severity, age, and the presence of new vessels were the factors most strongly associated with impaired color discrimination. A tritan-like defect was prominent and increased in magnitude with increasing severity of macular edema. Impaired color vision should be considered in the evaluation and counseling of patients with diabetic retinopathy.

Adolescent↗
PubMed1976

Polymorphism of human color vision.

The genetic polymorphism of human color vision is examined within the framework of a photopigment replacement model. An analysis of the X-linked recessive dichromacies and anomalous trichromacies indicates that one source of variability of normal color perception may be the inclusion of several distinct phenotypes in what is usually described as normal color vision. This analysis also reveals the cause of the dominance hierarchy at the protan and deutan loci, the perceptual effects of dosage compensation, and the phenotypes of various compound hemizygotes.

Alleles↗
PubMed1990

The proportion of various types of congenital color vision defects.

One hundred and three color vision defective subjects were screened from 3456 middle school students with pseudoisochromatic plate test. One hundred subjects out of them were further examined with a test battery including Panel D-15 and FM 100-hue test and Neitz anomaloscope test. It was found that there were 21 protanopes (P), 3 extremely protanomalous (EPA), 13 protanomalous (PA), 25 deutenopes (D), 5 extremely deuteranomalous (EDA), 28 deuteranomalous (DA), 6 unclassified subjects in our investigation. The proportion of various types of congenital color vision defects was P:EPA:PA:D:EDA:DA = 1.00:0.14:0.62:1.19:0.24:1.33.

Adolescent↗
PubMed2005

Color vision pigment frequencies in wild tamarins (Saguinus spp.).

The adaptive importance of polymorphic color vision found in many New World and some prosimian primates has been discussed for many years. Polymorphism is probably maintained in part through a heterozygote advantage for trichromatic females, as such individuals are observed to have greater foraging success when selecting ripe fruits against a background of forest leaves. However, recent work also suggests there are some situations in which dichromatic individuals may have an advantage, and that variation in color vision among individuals possessing different alleles may also be significant. Alleles that confer a selective advantage to individuals are expected to occur at a higher frequency in populations than those that do not. Therefore, analyzing the frequencies of color vision alleles in wild populations can add to our understanding of the selective advantages of some color vision phenotypes over others. With this aim, we used molecular techniques to determine the frequencies of color vision alleles in 12 wild tamarin groups representing three species of the genus Saguinus. Our results show that allele frequencies are not equal, possibly reflecting different selective regimes operating on different color vision phenotypes.

Animals↗
PubMed2006

Contrast sensitivity and color vision in HIV-infected individuals without infectious retinopathy.

PURPOSE: To investigate the relationship between abnormal contrast sensitivity and abnormal color vision among human immunodeficiency virus (HIV)-infected individuals who have normal visual acuity and to seek host factors that predict these abnormalities. DESIGN: Noninterventional, cross-sectional study. METHODS: We evaluated 71 HIV-infected subjects with visual acuity of 20/25 or better, clear media, and no vision-threatening retinal lesions. Visual function was determined using the Pelli-Robson contrast sensitivity test and the Farnsworth-Munsell 100-Hue color test (FM-100). Results were compared with published values for normal populations and to measures of HIV disease severity. We evaluated two levels of impairment for each visual function. "Mild dysfunction" was defined as > or =1 standard deviation (SD), but <2 SD from normal means. "Abnormal" was defined as > or =2 SD from normal means. RESULTS: The prevalences of abnormal contrast sensitivity and abnormal color vision were 7.0% and 9.9%, respectively. We did not identify relationships between impaired contrast sensitivity and impaired color vision. Impaired color vision was associated with increasing age (r = 0.36, P = .002). We could not identify significant correlations between either contrast sensitivity or color vision values and the following factors: current or nadir (lowest previous) CD4+ T-lymphocyte count, HIV blood level, and Karnofsky score. CONCLUSIONS: Abnormal contrast sensitivity and abnormal color vision can occur independently in HIV-infected individuals and can be present in the absence of severe immunosuppression.

Adult↗
PubMed1988

[Color vision in cataract, aphakia and pseudophakia].

Color vision examinations were performed using a clinical test battery and two spectral laboratory methods. With aphakia and iris-clip lenses (ICL) there were slight acquired blue-yellow defects six months to three years after surgery, especially when the more sensitive laboratory methods were used. They were possibly caused by photochemical damage to the retina or by a barrier deprivation syndrome. Color vision with posterior chamber lenses (PCL) was superior to that with ICL, and in aphakic subjects it was quite normal. In the clinical tests no differences could be found between PCLs of clear PMMA material and those with UV absorbing properties. Slight acquired blue-yellow defects in the immediate postoperative phase after implantation of PCLs can be attributed to postoperative irritation and are reversible. Lasting and severe blue-yellow defects indicate inflammation or macular edema.

Adult↗
PubMed2005

Color vision tests for aviation: comparison of the anomaloscope and three lantern types.

INTRODUCTION: A comparison of the results obtained with the Nagel anomaloscope and the Holmes-Wright Type A, Spectrolux, and Beyne aviation color vision lanterns was undertaken. The Joint Aviation Requirements (JAR) specify pass/fail limits for these four secondary color vision tests and the Ishihara screening test. The results for individuals on all five tests were studied. METHODS: The color vision of 55 color-vision deficient and 24 color-vision normal subjects, mostly applicant pilots, was assessed using a battery of tests, including the Ishihara plates, the Nagel anomaloscope, and three lanterns. The testing methods and characteristics of the lanterns and anomaloscope were compared. RESULTS: Of the color-deficient applicants, only deuteranomalous trichromats passed more than one of the four secondary JAR tests, but a pass on one test did not reliably predict a pass on another test. Three out of nine protanomalous trichromats passed the Nagel anomaloscope but failed all three lantern tests. Of the normal trichromats, 12 failed the anomaloscope and 12 failed the Beyne lantern. DISCUSSION: Variability in pass/fail results can be attributed to many factors apart from loss of chromatic sensitivity. Some normal trichromats can fail both the Ishihara screening and the secondary tests. The approved secondary test varies between countries and the outcome of regulatory assessment depends on the color vision test used. Since the flight safety consequences of the current situation cannot be ignored, the development of a less variable technique for color vision assessment that is accepted internationally, allied with a better understanding of color vision requirements, is needed.

Aerospace Medicine↗
PubMedDate not supplied

Computerized color-vision test based upon postreceptoral channel sensitivities.

An automated, computerized color-vision test was designed to diagnose congenital red-green color-vision defects. The observer viewed a yellow appearing CRT screen. The principle was to measure increment thresholds for three different chromaticities, the background yellow, a red, and a green chromaticity. Spatial and temporal parameters were chosen to favor parvocellular pathway mediation of thresholds. Thresholds for the three test stimuli were estimated by four-alternative forced-choice (4AFC), randomly interleaved staircases. Four 1.5-deg, 4.2 cd/m2 square pedestals were arranged as a 2 x 2 matrix around the center of the display with 15-minute separations. A trial incremented all four squares by 1.0 cd/m2 for 133 ms. One randomly chosen square included an extra increment of a test chromaticity. The observer identified the different appearing square using the cursor. Administration time was approximately 5 minutes. Normal trichromats showed clear Sloan notch as defined by log (deltaY/deltaR), whereas red-green color defectives generally showed little or no Sloan notch, indicating that their thresholds were mediated by their luminance system, not by the chromatic system. Data from 107 normal trichromats showed a mean Sloan notch of 0.654 (SD = 0.123). Among 16 color-vision defectives tested (2 protanopes, 1 protanomal, 6 deuteranopes, & 7 deuteranomals), the Sloan notch was between -0.062 and 0.353 for deutans and was < -0.10 for protans. A sufficient number of color-defective observers have not yet been tested to determine whether the test can reliably discriminate between protans and deutans. Nevertheless, the current data show that the test can work as a quick diagnostic procedure (functional trichromatism or dichromatism) of red-green color-vision defect.

Automation↗