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PubMed2003

Detecting color vision in a malingerer.

A patient describing himself as totally color blind was ordered by the judicial system to have his color vision investigated in order to establish his suitability for military service. Basic clinical (Farnsworth Panel D-15, Moreland and Rayleigh anomaloscope equations), electroretinographic (ERG) and psychophysical techniques (spectral sensitivities) were applied to determine the extent of his color discrimination performance and cone function. These standard procedures were complemented by a test for cone interaction (transient tritanopia) and by newly developed cone-isolating flicker large-field ERG recordings. The patient's data consistently indicate the function as well as the functional interaction of the middle-wavelength-sensitive (M-) and the short-wavelength-sensitive (S-) cones. But the function of the long-wavelength-sensitive (L-) cones was completely absent. Hence the patient was correctly demonstrated to be a protanope. This study establishes that standard classical procedures, in combination with newly developed and easy to apply psychophysical and ERG ones, which can be reliably used to assess true color discrimination performance, in difficult cases of malingering.

Adult↗

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↗

PubMed1993

Longitudinal comparison of temporal-modulation perimetry with white-on-white and blue-on-yellow perimetry in ocular hypertension and early glaucoma.

We obtained data over 3 years on temporal-modulation perimetry (TMP), standard automated [white-on-white (W/W)] perimetry, and short-wavelength-sensitive [blue-on-yellow (B/Y)] perimetry in ocular hypertensive (OH) patients and patients with early glaucomatous visual-field loss (EG). Evidence of visual-field defects was obtained with the use of both B/Y perimetry and TMP in the majority of OH and EG eyes that demonstrated progression on W/W perimetry as well as in all stable EG eyes. Using the nerve-fiber-bundle pattern to compare testing procedures, we determined that these defects were generally as extensive or more extensive than the concurrent W/W abnormalities. In terms of location over the 3 years of testing, TMP and B/Y defects were reasonably consistent in the EG eyes, somewhat less consistent in the OH eyes demonstrating progression, and both inconsistent and infrequent in the stable OH eyes. The greatest degree of overlap occurred between the location of defects obtained by use of the higher TMP frequencies (8 and 16 Hz) and that of defects obtained by use of B/Y perimetry. Since these two methods are thought to isolate different visual mechanisms subserved by different visual pathways, these results suggest that early glaucomatous visual-field damage as revealed by TMP and B/Y perimetry may not be specific to a single visual pathway.

Color Perception Tests↗

PubMed2004

Colour blindness in everyday life and car driving.

PURPOSE: The aim of the present work was to ascertain, through the administration of a psychosocial questionnaire, the difficulties that subjects with defective colour vision experience in carrying out everyday tasks and work, including driving a car with a driver's licence held for no more than 3 years. METHODS: Subjects with defective colour vision (n = 151) and subjects with normal vision (n = 302) completed a psychosocial questionnaire regarding the difficulties associated with congenital colour vision deficiency in daily life, work and driving a car. Subjects were diagnosed as colour-blind using the Ishihara test. RESULTS: Statistically significant differences between the two samples were found for daily life activities. Subjects with defective colour vision preferred daytime driving. At night, subjects with defective colour vision had difficulty identifying reflectors on the road and the rear signal lights of cars ahead of them. CONCLUSION: Colour-blind Calabrian subjects admitted to experiencing colour-related difficulties with a wide range of occupational tasks and leisure pursuits. In particular, colour-blind Calabrian subjects preferred daytime driving, and fewer drove regularly, compared to orthochromatics, who were indifferent to night or daytime driving.

Activities of Daily Living↗

PubMed2006

Color vision assessment: fail rates of two versions of the Farnsworth lantern test.

INTRODUCTION: The Farnsworth lantern test has long been used to assess the color vision of those seeking to enter the aviation industry and other occupations that require recognition of signal lights. A new version of the Farnsworth lantern, the Optec 900, is now produced because the original version is no longer manufactured. This paper reports the pass/ fail rates of a production model of the new version compared with an original one. METHODS: There were 100 male subjects with abnormal color vision who were given 3 runs with each lantern test. Their color vision deficiency was diagnosed using a battery of tests including the D15 test and the Nagel anomaloscope. RESULTS: A total of 19% passed the new lantern test compared with 24% for the original Farnsworth using the usual fail criteria. The pass rates become 17% and 21%, respectively, when adjusted for the expected proportions of the types of abnormal color vision. There was agreement between the two lantern tests for 89% of subjects: 8% passed the old Farnsworth and failed the new version, and 3% failed the original Farnsworth and passed the new. There was a practice effect: when one lantern was passed and the other failed, the lantern passed was, with one exception, given second. Both lantern tests passed subjects who made no errors on the first run who subsequently made many errors when given further runs. Only 4% of subjects made no errors on all runs. CONCLUSION: The Optec 900 can be considered equivalent to the Farnsworth lantern and might be preferred because it is slightly more stringent, reducing the risk of passing those who will make errors with signal lights. The practice of passing applicants who make no errors on the first run should be abandoned since 10% of those who pass in this way make many errors when additional runs are given.

Adolescent↗

PubMed1987

An averaging method for the interpretation of the Farnsworth-Munsell 100-Hue Test--II. Colour vision defects acquired in diabetic retinopathy.

The Farnsworth-Munsell 100-Hue test is frequently used to assess acquired colour vision defects. In diabetic retinopathy the acquired defect is a mild or severe type III (Tritan) defect which may be coupled with poor overall hue discrimination. In consequence, error scores are often high and the 100-Hue polar diagram is difficult to interpret. In this study the averaging method of analysis proposed by Dain and Birch is used to examine 120 100-Hue plots obtained by patients with proliferative diabetic retinopathy. These plots have either moderate (150-300) or high error scores (greater than 300). The method of analysis is found to be effective in determining whether a Tritan defect is present or not.

Adult↗

PubMed1996

Acetazolamide affects performance on the Nagel II anomaloscope.

BACKGROUND: Recent reports have indicated that acetazolamide alters human electroretinograms. We wished to determine the effects of administering acetazolamide on performance on the Nagel II anomaloscope. METHODS: We tested 15 subjects matches of blue-green light to a mixture of blue and green lights (luminance match) on a Nagel type II anomaloscope 2.5 h after ingesting 500 mg of acetazolamide or a placebo. RESULTS: The mean of the luminance settings for the subjects was 54.4 for the placebo condition and 58.5 for the acetazolamide condition. The mean difference of 4.1 was statistically significant, indicating that following ingestion of acetazolamide subjects were less sensitive to a blue-green light. In two supplementary experiments we tested (1) a second group of four normal subjects using the Nagel type II anomaloscope and (2) the previously untreated eyes of four patients with primary open-angle glaucoma before and after placing them on acetazolamide therapy. In both groups, more blue-green light was needed to make the match after ingestion of acetazolamide. CONCLUSIONS: Acetazolamide alters the sensitivity of one or more cone populations, probably the carbonic anhydrase-containing cones. The sensitivity loss is reversible and does not appear to be clinically significant. However, the results suggest that patients administered acetazolamide should be excluded from studies which compare the color vision of glaucomatous patients to that of normals.

Acetazolamide↗

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↗

PubMed1997

The objective measure of color vision in primary open angle glaucoma.

PURPOSE: To objectively evaluate the clinical application of color pattern reversal visual evoked potential (CPR-VEP) on primary open angle glaucoma (POAG). METHODS: CPR-VEP and FM 100-hue test were performed in 31 eyes with POAG and 33 normal eyes. Color pattern stimulation was presented by color monitor controlled by computer program. The reversal rate of the stimulating pattern was 2 Hz and the spatial frequency of the stimulating was 0.53 cycle/degree. The color stimulating pattern include White/Black, Red/Black, Green/Black, Blue/Black, Yellow/Black, Red/Green and Blue/Yellow. RESULTS: CPR-VEP P1 latencies were obviously prolonged in POAG group in comparison with normal control group in equiluminance. All CPR-VEP P1 amplitudes, except Blue/Black P1 amplitude, show no differences between POAG group and normal control group. CONCLUSION: P1 latencies of all CPR-VEP and P1 amplitude of Blue/Black CPR-VEP were parameters for identifying acquired dyschromatopsia caused by POAG. The results showed nonselective damages in color channels and luminance channel in POAG. CPR-VEP is helpful in detecting acquired dyschromatopsia.

Adolescent↗

PubMedDate not supplied

Prevalence of colour blindness in young Jordanians.

Colour blindness is one of the common genetic disorders observed in all human populations. It is a sex-linked recessive trait. The genes are located on the X chromosome within the Xq28 band. 1,418 university students (1,200 female and 218 male) from Zarka Private University and the Hashemite University were randomly selected and tested for congenital red/green colour blindness, by using Ishihara pseudo-isochromatic colour plates. A total of 23 individuals were found to be colour blind. In females, 4 students (0.33%) were colour blind: 1 of them showed protanomalia, 1 protanopia and 2 deuteranomalia. In males, 19 students (8.72%) were colour blind: 4 showed protanomalia, 3 protanopia, 8 deuteranomalia and 4 deuteranopia. The allelic frequencies of the colour vision gene were found to be 0.087 in males, 0.003 in females and 0.016 in the total population. Studies on colour blindness in Jordan are very few; this population-based investigation is meant to fill a gap in this field.

Adolescent↗

PubMed1999

Color spaces of color-normal and color-abnormal observers reconstructed from response times and dissimilarity ratings.

With multidimensional scaling analysis, color spaces were reconstructed from reaction times (RTs) required to make same-different judgements of pairs of 15 equiluminant colors and from dissimilarity ratings between them. In addition to normal trichromats, observers with red-green color deficiency were tested. Two main purposes were served by this study: (1) to compare spatial representations of colors derived from discriminative RTs with those derived from dissimilarity measures and (2) to examine whether the task may selectively affect the dimension reflecting, in color-abnormal spaces, the deficient red-green mechanism. Contradicting our hypothesis of lower dimensionality of RT spaces, as compared with rating spaces, no consistent differences in solution dimensionality were found. However, configurations derived from the two measures diverged. The rating procedure yielded the most logical results for recovering color space. The RT configuration revealed contraction in the tritanopic direction, indicating longer color processing when the short-wavelength mechanism is involved, and in addition, for color-abnormal observers, clustering in the protanopic and deuteranopic directions, indicating even longer processing by the deficient red-green mechanism. This finding implies that RTs are suitable for detecting temporal differences in color processing but, for that very same reason, rather ill-suited for reconstructing color spaces.

Adult↗

PubMed1992

[PC software for evaluating the Farnsworth-Munsell 100-Hue test].

This computer program is designed for faster elaboration of the Farnsworth-Munsell 100-Hue test. It is thus made user friendly, in that faultless input of data can be achieved, even by an untrained person. Evaluation is facilitated by the opportunity of representing two results at the same time. Examples of typical colour vision deficiencies are stored in a file and can then also be called up. Storing the results in a special data file helps to avoid the time consuming printing process. However, a hardcopy is supported by storing the last grafic in a standard PostScript-file, thus giving easy access to any printer. This program is applicable for IBM- or compatible PCs. Extensive use is possible by means of a software interface with the wide spread database-system DBASE.

Color Perception Tests↗

PubMed1990

[The use of the panel D-15 test in estimating the convergence points for deuteranopia].

In order to study the deuteranopic convergence points we compared the patterns of the simulated panel D-15 test with the actual data from 73 cases of deuteranopia. It was found that 39 of the 73 cases matched one of the four simulation patterns perfectly while another 25 cases showed similar patterns. Of the 64 cases, 9 cases matched the simulated pattern obtained when the x chromaticity coordinates were between 1.1810 and 1.4319, 42 cases when they were between 1.4320 and 2.2588, 7 cases when they were between 2.2589 and 3.6255 and 6 cases when they were between 3.6256 and 4.6572. These results confirm that there are significant individual differences in the convergence points of deuteranopes and support the theory that the confusion lines meet at a specific point rather than running parallel.

Adolescent↗

PubMed1997

Distorted colour discrimination in Parkinson's disease is related to severity of the disease.

The Farnsworth-Munsell 100-hue test (FMT) may be used for measurement of colour discrimination and error scores of the FMT provide an unspecific biological marker for the distinction between parkinsonian patients (PP) and healthy controls. The aim of this study was to examine the possible association between distorted colour discrimination and disease severity in untreated "de novo" PP Error scores of the FMT were significantly (P<0.0001) elevated in PP compared to age- and sex-matched controls and correlated to severity of the disease. We conclude that impaired colour discrimination is related to pathophysiology of Parkinson's disease. But it remains unclear whether these alterations of colour vision reflect striatal dopamine deficiency or changes of retinal dopaminergic pathways in PP.

Adult↗

PubMed1989

[Final clarification of Goethe's findings in the examination of color blind patients].

During his researches on colour-vision Goethe has examined two colour blind students. The reports and the colour tests made by Goethe himself are mostly preserved. Due to the colour confusions in the whole purple zone Goethe decided that the subjects were blue blind. During the 19th century-- however--the supposition arose that it must have been a red-green-blindness. It was Trendelenburg, who supposed a deuteranopia. On the other hand reconstructions of Goethe's examinations had the result that it was in all probability a protanopia. A final solution of this discussion is now possible after a great-grandson of Goethe's subject Gildemeister was found out and examined at Nagel's anomaloscope. He is a typical protanope. According to the pedigree demonstrating the typical x-linked hereditary transmission, we can be sure that Goethe's subjects were protanopes.

Color Perception Tests↗

PubMed2002

New Farnsworth-Munsell 100 hue test norms of normal observers for each year of age 5-22 and for age decades 30-70.

AIMS: To provide normative data for chromatic discrimination on the Farnsworth-Munsell 100 hue test particularly for observers under 23 years of age. METHODS: Normal observers were screened for congenital colour vision deficiencies using the Ishihara test leaving 382 observers. RESULTS: New total error score (TES) norms (means and 95th percentiles) are presented for each year of age from 5-22 and for 10 year age groups from the 30s to the 70s. These norms are presented as actual values (TES) and also as square root values ( radical TES). Other data include partial error scores for red-green and blue-yellow axes discrimination. CONCLUSION: This study provides the most detailed set of normative data to date. The data are also in agreement with other reports of chromatic discrimination, showing that the performance in this task varies as a U-shape function with age, the best being achieved at 19 years of age.

Adolescent↗

PubMedDate not supplied

Achromatic parvocellular contrast gain in normal and color defective observers: Implications for the evolution of color vision.

The PC pathway conveys both chromatic and achromatic information, with PC neurons being more responsive to chromatic (L-M) than to achromatic (L+M) stimuli. In considering the evolution of color vision, it has been suggested that the dynamic range of chromatic PC-pathway processing is tuned to the chromatic content of the natural environment. Anomalous trichromats, with reduced separation of their L- and M-cone spectral sensitivities, have diminished chromatic input to PC-pathway cells. Dichromats, with absent L or M cones, should have no chromatic input to PC-pathway cells. Therefore, the PC-pathway dynamic range of color defectives should be released from any constraint imposed by the chromatic environment. Here we ask whether this results in compensatory enhancement of achromatic PC-pathway processing in color defectives. This study employed a psychophysical method designed to isolate PC-pathway processing using achromatic stimuli. In a pulsed-pedestal condition, a four-square stimulus array appeared within a uniform surround. During a trial, one of the test squares differed from the other three, and the observer's task was to choose the square that was different. A four-alternative, forced-choice method was used to determine thresholds as a function of the contrast of the four-square array to the surround. Seven color defective and four normal observers participated. Results showed no systematic differences between normals and color defectives. There was no enhancement of achromatic processing as compensation for reduced chromatic processing in the PC-pathway system in color defectives. From physiological recordings, PC-pathway achromatic contrast gains of dichromatic and trichromatic New World primates and trichromatic Old World macaques have also been shown to be similar to each other. Our study and the animal studies imply that PC-pathway contrast gain parameters were regulated by factors other than the environmental chromaticity gamut, and may have arisen in a nontrichromatic common ancestor to both Old and New World primates.

Animals↗

PubMed2004

Progressive cone dystrophy associated with mutation in CNGB3.

PURPOSE: To determine the molecular basis for phenotypic variability in a three-generation consanguineous family containing a single individual with complete achromatopsia and three individuals with progressive cone dystrophy. METHODS: Four affected individuals underwent ophthalmic examination, electrophysiological assessment, color fundus photography, and psychophysical testing. Blood samples were obtained for DNA extraction and mutation screening of the cone-specific cGMP-gated (CNG) channel protein gene CNGB3 was undertaken. RESULTS: The clinical findings in one family member were consistent with a diagnosis of complete achromatopsia, with nystagmus, photophobia, and poor visual acuity from early infancy and complete color-blindness, normal fundi, and absent cone responses with normal rod responses on electroretinography (ERG). Mutation analysis revealed her to be homozygous for the common CNGB3 achromatopsia mutation, 1148delC (Thr383fs). In contrast, the three other symptomatic individuals in the family had findings consistent with progressive cone dystrophy. Their visual problems began later in childhood (ranging from 3 to 14 years of age) and there was evidence of progressive deterioration in cone function. All three had a marked tritanopic color vision defect and fundoscopy revealed bilateral macular atrophy. Electrophysiological testing of these three subjects demonstrated clear evidence of progressive deterioration of cone responses over time; rod responses were normal. All three individuals with this progressive phenotype were found to be compound heterozygotes for the 1148delC (Thr383fs) frameshift mutation and a novel Arg403Gln missense mutation in CNGB3. CONCLUSIONS: Mutations in CNGB3, which have been shown to cause achromatopsia, are now shown to be associated with autosomal recessive progressive cone dystrophy. In this study, a novel Arg403Gln mutation was identified, located in the middle of the pore domain of the cone CNG cation channel beta-subunit, which when associated with the nonsense mutation Thr383fs, resulted in progressive cone dystrophy.

Adult↗