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PubMed1983

A time induced tritan defect.

It is hypothesized that if blue is signalled more slowly than red in the visual system, and if integration time is longer for blue than for red, then a tritan defect should be apparent for normal observers. Data from short-exposure viewing of the City University Colour Vision Test indicate that, at 3.75 msec. a significant tritan error occurs.

Adult↗
PubMed1993

A study of women heterozygous for colour deficiencies.

We have examined the colour vision of 43 female subjects in the age range 30-59 yr of whom 31 were obligate carriers of various forms of colour deficiency and the rest were women who had no known colour-deficient relatives. In the case of all the carriers we established the phenotypes of their colour-deficient sons. As a group, carriers made significantly more errors on the Ishihara plates and showed enlarged matching ranges on the Nagel anomaloscope, but we could not replicate earlier reports of increased error scores on the Farnsworth-Munsell 100-Hue test or of systematic shifts in Rayleigh match mid-points. We did find that the colour matches of carriers of deuteranomaly were significantly displaced from those of normals in a ratio-matching task in which a mixture of 546 and 600 nm was matched with a mixture of 570 and 690 nm. Owing to X-chromosome inactivation, women who are heterozygous for anomalous trichromacy ought to have at least four types of cone in their retinae and we ask whether this affords them an extra dimension of colour vision, by analogy to New World monkeys where heterozygous females gain trichromacy in a basically dichromatic species. Many carriers of anomalous trichromacy exhibited no evidence for tetrachromacy, in that they accepted large-field Rayleigh matches following a rod bleach and they were unable to set unique matches in our ratio-matching task. However, eight carriers of anomalous trichromacy--and no other subject--refused large-field Rayleigh matches; and we found one carrier of deuteranomaly who was apparently able to make unique matches in the ratio-matching task.

Adult↗
PubMed1994

Perchloroethylene exposure can induce colour vision loss.

We evaluated colour vision in 35 dry-cleaners exposed to perchloroethylene (PCE) and in a paired number of controls matched for sex, age, alcohol consumption and cigarette smoking. A subclinical colour vision loss, mainly in the blue-yellow range, was present in dry-cleaners. This effect was related to PCE exposure levels, and appeared at environmental concentrations of the solvent well below the current exposure limits for exposed workers. The results suggest that PCE exposure, even at low environmental levels, can induce a dose-related impairment of colour vision.

Adult↗
PubMed2005

Numerical confusion errors in ishihara testing: findings from a population-based study.

PURPOSE: To describe the prevalence of numerical confusion errors in Ishihara testing in a representative sample of Australian children. DESIGN: Cross-sectional, population-based study. METHODS: The Sydney Myopia Study examined a representative stratified random cluster sample of 1,741 children (aged 6 years) attending 34 schools in Sydney, Australia (response rate, 78.9%), including color vision tests in 1,735 children. Those with any color vision defects (n = 33; 1.9%; 97% boys) were excluded. Responses for each Ishihara plate were recorded. RESULTS: Numerical confusion errors were made by 75.8% of children with normal color vision; there was no gender difference. Plates 3 and 7 were particularly prone to numerical confusion errors; 48.4% and 40.8%, respectively, of children misread these plates. CONCLUSION: Numerical confusion errors in the Ishihara test were relatively common in children with normal color vision. The frequency of such errors could indicate an inherent deficiency in this commonly used test.

Child↗
PubMed2006

Introducing a new computer-based test for the clinical evaluation of color discrimination.

PURPOSE: To evaluate the Portal color sort test (PCST), a new computer-based test of color vision, by comparing it with a series of clinical tests of color vision in normal and color deficient subjects. DESIGN: Prospective clinical laboratory study. METHODS: Fifty-nine subjects with normal trichromatic vision or with congenital color vision defects underwent a series of color vision tests that included the 15-plate Ishihara test, the D-15 Farnsworth-Munsell test (D-15), the Farnsworth-Munsell 100-Hue test (FM 100-Hue), and the PCST under rigorous standardized conditions, as recommended by the respective manufacturers. The PCST generates a numerical discrimination score comparable to the FM 100-Hue. RESULTS: To test validity, discrimination scores generated by the PCST were compared with scores on the FM 100-Hue. The Spearman rank correlation between discrimination scores on the FM 100-Hue and the PCST was 0.8 (P < .001). Reliability was assessed by asking patients to retake the PCST at a later sitting. Patients retaking the PCST achieved similar scores on their second sitting as on the first. The correlation in the score between the two tests was 0.7 (95% confidence interval [CI]: 0.4-0.9, P < .001). Median (quartiles) time to complete the PCST was 3.1 minutes. This was faster than the FM 100-Hue time (P < .001), but slower than both the Ishihara and the D-15 (both P < .001). CONCLUSIONS: This study suggests that the PCST, a test of color vision deficiency, can be used effectively and reliably as a tool for screening (comparable to the Ishihara plates and the D-15) and grading (comparable to the FM 100-Hue) color discrimination ability.

Adolescent↗
PubMed2005

AcrySof Natural SN60AT versus AcrySof SA60AT intraocular lens in patients with color vision defects.

PURPOSE: To determine whether implantation of the AcrySof Natural intraocular lens (IOL) worsened the severity of existing color deficit in congenital partial red-green color deficient individuals (CPRG). METHODS: A prospective controlled randomized double-masked analysis of 30 consecutive patients with CPRG defect and bilateral cataracts received a Natural IOL (test group) in 1 eye and a single-piece AcrySof IOL (control group) in the other eye. Patients were tested unilaterally to detect CPRG defect using Ishihara pseudoisochromatic plates and the Farnsworth D-15 test. Plates 1 to 21 measured the Ishihara error score; plates 22 to 25 indicated severity of defect based on clarity of both numerals as partial mild/moderate (both visible), partial severe defect (only 1 visible). The D-15 test is based on number of diametrical crossings on the circular diagram; severity is graded as mild (1 crossing), moderate (2 crossings), or severe (>2 crossings). Tests were performed before and after IOL implantation at 1, 3, and 6 months. At mean follow-up of 6.13 months +/- 1.2 (SD), analysis of variance test judged the difference in error scores and cross tabulation represented change in number of diametrical crossings. RESULTS: The mean age was 62.3 +/- 8.5 years. All patients were men. Before IOL implantation, all patients had moderate CPRG defect on both tests. The Ishihara error score in the test and control groups did not reveal statistically significant differences (P = .505 and P = .119, respectively). With D-15, none of the patients in the test or control group showed >2 crossings. CONCLUSION: The implantation of AcrySof Natural IOL did not worsen the preexisting severity of color defect in CPRG individuals.

Acrylic Resins↗
PubMed2006

Acquired dyschromatopsia among petrochemical industry workers exposed to benzene.

Exposure to organic solvents, which are widely used in industry, can lead to dysfunction of the nervous system. However, controversy continues about the nature of early-stage damage to the nervous system from low-grade chronic exposure to organic solvents. Since loss of color-vision can be a sensitive early marker of neurotoxic damage, the main aim of this study was to investigate the association between low-level chronic exposure to organic solvents, especially benzene, and acquired dyschromatopsia. The study initially comprised 1236 workers who were employed at a large petrochemical distillation factory. After excluding those workers who may have had color-vision impairment due to congenital or acquired eye diseases and those with other medical conditions, 908 males who had worked for at least 6 months were included in the final analysis. Those who worked only in the office were categorized as nonexposed, while those who worked at outside facilities were divided into three groups of approximately equal size according to their estimated cumulative exposure levels to benzene (low, medium, high). Color-vision was assessed using the Lanthony D-15 desaturated panel color test. The results showed that the color-confusion index (CCI) was positively related to age. In the qualitative assessment of types of color-vision loss, the prevalence of total dyschromatopsia was significantly higher with increasing cumulative exposure levels in the left eye (p<0.05) but not in the right eye. The significance for the prevalence of type III dyschromatopsia was borderline in the left eye (p=0.0571). The relationship between acquired dyschromatopsia and exposure level also showed an increase in the odds ratio in the left eye but not in the right eye. Taken together, these results suggest that chronic low-level exposure to benzene can lead to acquired dyschromatopsia.

Adult↗
PubMed2006

Color vision screening for individuals with intellectual disabilities: a comparison between the Neitz Test of Color Vision and Color Vision Testing Made Easy.

BACKGROUND: The Neitz Test of Color Vision (Neitz) and Color Vision Testing Made Easy(trade mark) (CVTME) were compared to determine which test was more effective in evaluating patients with intellectual disability (i.e., mental retardation) and developmental delay. METHODS: Two hundred eight Special Olympics floor hockey athletes were screened in San Diego, California, and 93 athletes were screened in Long Beach, California for a total of 301 athletes. Each athlete was administered the CVTME and the Neitz tests. RESULTS: The pass rate for the CVTME was 94.6% (n = 93) at Long Beach and 96.2% (n = 208) at San Diego. Every athlete was able to complete the CVTME. The pass rate for the Neitz was 38.7% at Long Beach and 56.7% at San Diego. Additionally, 10.8% of the Long Beach athletes and 12.5% of the San Diego athletes were unable to understand the Neitz. In addition, there was a low level of agreement between the results from the 2 tests with kappa = 0.081 for the San Diego data and 0.028 for the Long Beach data. CONCLUSIONS: This study suggests that the CVTME continues to be the screening test of choice in evaluating color vision in individuals with intellectual disability. The Neitz had more failing scores on the first attempt and more total failing scores leading to over-referrals, making it an inappropriate screening test for individuals with intellectual disability and developmental delay.

Adolescent↗
PubMed2004

Topographical cone photopigment gene expression in deutan-type red-green color vision defects.

Eye donors were identified who had X-chromosome photopigment gene arrays like those of living deuteranomalous men; the arrays contained two genes encoding long-wavelength sensitive (L) pigments as well as genes to encode middle-wavelength sensitive (M) photopigment. Ultrasensitive methods failed to detect the presence of M photopigment mRNA in the retinas of these deutan donors. This provides direct evidence that deuteranomaly is caused by the complete absence of M pigment mRNA. Additionally, for those eyes with mRNA corresponding to two different L-type photopigments, the ratio of mRNA from the first vs. downstream L genes was analyzed across the retinal topography. Results show that the pattern of first relative to downstream L gene expression in the deuteranomalous retina is similar to the pattern of L vs. M gene expression found in normal retinas.

Adolescent↗
PubMed2006

Color discrimination in carriers of color deficiency.

Carriers of X-linked color vision deficiencies have previously been reported to exhibit mild abnormalities of color matching and discrimination. In a sample of 55 carriers of protan and deutan deficiencies and 55 age-matched normal controls, we measured chromatic discrimination along a red-green axis. We found that discrimination was impaired in the case of carriers of deutan deficiencies (which affect the middle-wave-sensitive cones of the retina), but was normal in the case of carriers of protan deficiencies (which affect the long-wave-sensitive cones). We argue that this result can be explained by the difference in the relative numbers of middle- and long-wave cones in heterozygous retinae: the imbalance of the two cone types is predicted to be much greater in the case of the deutan heterozygote than in the case of the protan heterozygote. In future studies it will be necessary to consider separately the two types of heterozygote.

Adult↗
PubMed2006

A low-power, LED-based, high-brightness anomaloscope.

Color matches made with a Nagel anomaloscope are used in the differentiation of color vision deficiencies. When these color matches are made over a wide range of retinal illuminances, the changes in the color match provide information about the regeneration kinetics and the absorption spectra of the middle- and long-wavelength cone photopigments. These steady-state color matches vary with a variety of conditions, and may have value in screening for eye disease. Recently, high-brightness LEDs have become available that allowed us to construct a LED-based, high-brightness anomaloscope. We used inexpensive, low-energy components to replicate an earlier instrument, getting a maximum retinal illuminance over 5.6 log Trolands.

Adaptation, Ocular↗
PubMed1985

Color-axis determination on the Farnsworth-Munsell 100-hue test.

Error scores on the Farnsworth-Munsell 100-hue test were partitioned into those representing red-green and those representing blue-yellow losses. Data from two groups of normal observers were used. One group showed results characteristic of published norms; one group showed superior performance. Both observers showed a correlation between red-green and blue-yellow scores indicative of a strong performance factor in this test. The difference between blue-yellow and red-green scores eliminates their correlated variance and allows evaluation of the axis. Both groups showed an increase in difference scores, with age indicating development of a blue-yellow axis. This increase was significant for the observers characteristic of the norms. We suggest cutoff scores to allow a decision as to whether a given patient shows a blue-yellow or red-green axis.

Adolescent↗
PubMed1982

A new assessment of the normal ranges of the Farnsworth-Munsell 100-hue test scores.

We gave the Farnsworth-Munsell 100-hue color vision test to 232 normal subjects between 10 and 80 years of age. One half the subjects underwent binocular testing followed by monocular testing. In the other half monocular testing preceded binocular testing. Performance was better with both eyes than with either eye alone. The worst performance occurred on monocular tests in subjects without previous experience with the task (that is, those for whom this was the first test). The well-known age trend was apparent (children and elderly have the worst color vision). New data are provided for judging the point at which the total error score may be considered pathologic.

Adolescent↗