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PubMed1997

Rayleigh match ranges of red/green color-deficient observers: psychophysical and molecular studies.

Large-field Rayleigh match ranges were measured in 27 red/green color-deficient male observers, using bright, temporally alternating, 3-9 deg annular test fields. The observers' X-linked opsin gene arrays were characterized by molecular genetic techniques, and used to infer the absorption maxima of each observer's L and/or M cone photopigment(s). Measured match ranges decreased rapidly as the inferred separation in pigment absorption maxima increased from 0 to 2-3 nm, and varied irregularly thereafter. Following He & Shevell [(1995) Vision Research, 35, 2579-2588] predicted match ranges were calculated for various pigment separations and assumed values of pigment optical density. The predicted variations in match range encompassed the measured match ranges of most (but not all) of the color-deficient observers. The calculations also showed that differences in pigment optical density, in two cone types containing the same pigment, are sufficient to allow a moderate degree of chromatic discrimination. Such models thus provide a possible account of the fact that some color-deficient observers, with only a single X-linked opsin gene, can make red/green chromatic discriminations.

Adolescent↗
PubMed1994

[Evaluation of desaturated Panel D-15. III. Evaluation of the validity of the desaturated Panel D-15].

The estimation of the validity of a test refers to whether this test measures what it claims to measure. The validity of the desaturated panel D-15 was estimated in 248 subjects with congenital hereditary dyschromatopsia. The method used was based on a qualitative and quantitative study of the so-called lines of confusion joining the positions of the colored caps on the classical Farnsworth's diagram. The qualitative estimation was evaluated according to the prevailing number of lines of confusion which were parallel to a given line of reference of the diagram; it was related to the axis of the dyschromatopsia. The comparison of the results with results of Nagel's anomaloscope used as a reference test, demonstrated an overvaluation of the number of the protan subjects (anomaloscope: 77; desaturated D-15: 107) and an undervaluation of the number of deutan subjects (anomaloscope: 169; desaturated D-15: 70). This kind of discrepancy was not apparent with the standard Panel D-15. The quantitative estimation was evaluated according to the whole number of lines of confusion whatever their directions; it was related to the severity of the dyschromatopsia. The comparison of the results with the results of Nagel's anomaloscope demonstrated that the dichromatic and extreme anomalous trichromatic subjects nearly always (40 subjects out of 42) had 7 lines of confusion, or more; the simple anomalous trichromatic subjects had a variable number of lines of confusion, from 1 to 8, without any prevalence in the great majority of cases (193 subjects out of 204).(ABSTRACT TRUNCATED AT 250 WORDS)

Color Perception Tests↗
PubMed1978

Clinical experience with the Lovibond Colour Vision Analyser. Results from the examination of normal and congenital colour-deficient subjects.

The Colour Vision Analyser was used for testing 98 persons of both sexes, aged from 10 to 70 years, and recognized as normal by means of pseudo-isochromatic plates and an anomaloscope. A drop of the saturation thresholds from yellow to green and from blue to purple was observed from the age of 40 years. The saturation thresholds from yellow to green was found lower in every age group than that from blue to purple. Congenital colour defects could be completely distinguished from normal subjects. As for the classification in types, those diagnosed as deutan by means of the anomaloscope were also diagnosed as deutan by the Analyser, however, there were, among those diagnosed as protan by the anomaloscope, some subjects who were diagnosed as deutan by the Analyser. Nearly all cases could be classified as anopia or anomaly.

Adolescent↗
PubMed1978

Clinical analysis of colour vision deficiencies with The City University test.

The City University colour vision test (CUCVT) was used for the examination of 158 subjects suffering from congenital colour vision defects (36 protanopes, 122 deutanopes) and its results were compared with that of an anomaloscope and of the panel D-15. 23% of the subjects classified as protanopes and 98% of the subjects classified as deuteranopes by means of the anomaloscope were also classified as such by means of the CUCVT, while 93% of the subjects classified as protanomalous and 90% of the subjects classified as deuteranomalous by means of the anomaloscope gave normal answers at the CUCVT. The results of the CUCVT were almost the same as with panel D-15 except protanopia. The colour spots of each plate of the CUCVT were plotted on a CIE chromaticity diagram and the results of this study are also reported.

Adolescent↗
PubMed1985

Wavelength discrimination deteriorates with illumination in blue cone monochromats.

Two types of incomplete congenital achromats were studied: one type (blue cone monochromats) has a conspicuous short wavelength cone mechanism, and the other type (deutan incomplete achromats) has a conspicuous long wavelength cone mechanism. The photoreceptor mechanisms were inferred from color matches and from test action spectra measured on rod-saturating backgrounds of different wavelengths. Interestingly, the illumination-dependency of color discrimination (for 5 degrees bipartite fields that were centrally fixated) differed between the two patient types, even though rhodopsin photoreceptors were common to both. As illumination level increased, the ability to discriminate wavelength differences deteriorated for the blue cone monochromats, whereas, for the deutan achromats, wavelength discrimination remained relatively constant even near 100,000 scotopic trolands. The performance decrement in the blue cone monochromats was probably not associated with rod saturation, as the field action spectrum to cause a just-noticeable-difference (jnd) decrement in discrimination was poorly fitted by a rhodopsin action spectrum. In addition, the blue cone monochromats had rhodopsin photoreceptors that did not saturate in bright illuminations. The authors hypothesize that the deterioration of wavelength discrimination at high illuminations is not an abnormality of blue cone monochromacy. Rather, it may be a property of the normal color mechanism through which signals from the short wavelength cones pass.

Adolescent↗
PubMed1979

Large-field color naming of dichromats with rods bleached.

A color-naming method was used to examine the large-field red/green discriminations of dichromats screened with standard tests. The stimulus was a 12 degrees annular field with the central 4 degrees removed, flashed for 300 ms. Four wavelengths were equated in brightness for each observer at two retinal illuminance levels, approximately 10 and 100 trolands. The stimuli were then presented in random order and the observer was asked to name each, using one of four color terms. The entire experiment was done with the observers dark-adapted and also with the rods bleached. For all four deuteranopes and two of four protanopes, color names were very significantly related to both illuminance and wavelength in both adaptation conditions. The relationship between name and wavelength was similar to that of a normal trichromat, but the performance of a dichromat was very poor by comparison. Performance was generally somewhat better in the dark than with the rods bleached. However, the result in the bleached condition is consistent with recent evidence that at least some observers who are classified as dichromats with standard small-field screening procedures actually have a weak residual third cone mechanism.

Adaptation, Ocular↗
PubMed1996

Color vision measured with pseudoisochromatic plates at five-and-a-half years in eyes of children from the CRYO-ROP study.

PURPOSE: To investigate the prevalence of color deficits at age 5 1/2 years in preterm children with birth weights of less than 1251 g who participated in the multicenter Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) study. METHODS: Two cohorts of CRYO-ROP participants served as subjects: 1055 children who participated in a long-term study of the natural history of ROP at 5 of the 23 CRYO-ROP centers, and 187 children (from all 23 study centers) who had threshold ROP in both eyes and who were randomized to receive cryotherapy in 1 eye. Monocular color vision was tested at age 5 1/2 years, using the Standard Pseudoisochromatic Plates, part 2 (SPP2) for acquired color vision defects. RESULTS: In the Natural History cohort, prevalence of red-green (R-G) color deficits was 6.6% for males and 1.0% for females, similar to that of the general adult population. Prevalence of blue-yellow (B-Y) color deficits was 2.8% for males and 2.2% for females, more than 200 times that in the general adult population. Prevalence of B-Y deficits was not related to birth weight, gestational age, acute-phase ROP, optic atrophy, or retinal residua of ROP, but was related to visual acuity. In the Threshold ROP cohort, color vision deficits were no more likely in eyes that had received cryotherapy than in control eyes. CONCLUSIONS: The results confirm an increased prevalence of B-Y deficits in children born before term, and provide evidence that the increased prevalence is not related to birth weight, gestational age, or severity of ROP within this group of preterm children. No evidence was found to indicate that cryotherapy increased the rate of color vision deficits in eyes with threshold ROP.

Birth Weight↗
PubMed1978

Psychophysical flicker thresholds and ERG flicker responses in congenital and acquired vision deficiencies.

Psychophysical flicker thresholds and ERG flicker responses were compared with Farnsworth's 100-hue colour test data in cases of congenital and acquired vision deficiences. The results, evaluated in term of sensitivity and specificity lead to some practical and theoretical suggestions. In most cases, flicker responses and colour tests results were better than other classical tests for evaluating the first signs or gravity importance of a macular disturbance. Relatively minor differences between the 3 tests may be related to the observed or supposed extension of lesion in the macular area, but in some cases the observed functional changes can be understood only by admitting some lateral effect from one area to another. Generally acquired colour differences are associated with flicker response changes. In congenital red-green blindness of different gravity, moderate abnormal white light flicker responses could be observed. But they do not seem to be associated clearly with a type and gravity of the deficiency. With coloured stimuli, the difference between normal and red-green colour-blindness is more clear-cut, and red-blind can be discriminated from green-blind. Subclinical retinal pathology as well as specific stimulus conditions in normal and red-green colour-blind subjects reveal some non-linear processes in the low-frequency range of the temporal attenuation characteristics.

Adolescent↗
PubMed1976

An acquired color defect of the opponent-color system.

An acquired unilateral color defect in a 22-year-old man has been investigated with standard clinical tests and by using techniques which, it is thought, test specifically for the sensitivity of the luminance and opponent-color systems. The spectral sensitivity of the defective left eye, using 1 degree 200 ms. test flashes on a white background, has a single broad peak at about 550 nm. and resembles the photopic luminosity curve; in contrast, the normal curve, measured in the same conditions, has three peaks at about 440, 520, and 600 nm. However, the subject's spectral sensitivity curve for detecting 20 Hz. flicker is quite normal and is similar to his curve for 200 ms. flashes. It has recently been proposed that the three peaks of the normal curve for 200 ms. flashes reflect the activity of the opponent-color system, whereas the single peak for flicker detection is related to the luminance system. The preceding observations may thus be interpreted in terms of a specific loss of the subject's opponent-color system and this would explain his poor color discrimination. His luminance system appears to be normal, and evidence is presented for the maintained function of red- and green-sensitive (but not blue-sensitive) cones. The spectral sensitivity of the subject's right eye is nearly normal, suggesting a precortical origin of the defect; however, there seems to be some abnormality in this eye, indicating a less developed form of the same defect.

Adult↗
PubMed1990

The dyschromatopsia of optic neuritis is determined in part by the foveal/perifoveal distribution of visual field damage.

Most hypotheses of acquired dyschromatopsia invoke the mechanism of selective damage to specific components of the afferent visual system to explain the predominance of red-green and blue-yellow hue-discrimination defects found in neural and retinal disorders, respectively. However, this pattern of hue-discrimination disturbance in ocular disease may vary. There are frequent exceptions which are inadequately explained by existing hypotheses. In an effort to explain the pattern and pathogenesis of acquired dyschromatopsias better, the authors examined patients with nonproliferative diabetic retinopathy (DR) and late-stage retrobulbar neuritis (RBN) using age-corrected Farnsworth-Munsell 100-hue testing and threshold static perimetry. As expected, most DR eyes showed some degree of relative blue-yellow dyschromatopsia (89%) with few showing a greater weighting towards red-green dyschromatopsia (11%). However, an approximately equal number of RBN eyes had a relative blue-yellow (48%) versus red-green dyschromatopsia (52%). For RBN, the authors found a strong association between the spatial distribution of field defect and the type of relative hue-discrimination disturbance. Eyes with greater field depression at the fovea relative to the perifovea showed a relative preponderance of red-green dyschromatopsia (68%) as opposed to blue-yellow dyschromatopsia (32%), whereas eyes with greater relative perifoveal impairment showed a relative preponderance of blue-yellow dyschromatopsia (100%). This relationship between the relative spatial distribution of visual field damage and the relative hue-discrimination deficit in RBN was statistically significant (P = 0.002). Such an association was not found for DR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Chronic carbon disulphide poisoning: a 4 year follow-up study of the ophthalmological signs.

Thirty workers of a viscose rayon industry had a complete eye examination in 1979 including visual acuity, perimetry, colour vision testing, fluorescein angiography, ERG and EOG, for possible signs of chronic carbon disulphide poisoning. They were divided into two groups, group A included workers exposed to relatively high CS2 levels (at least 50 mg/m3), group B working in the relatively safe bleaching division. In both groups fundus anomalies and abnormal EOG's en ERG's were found. Twenty-nine of these thirty workers were reexamined in 1983. A number of them were no longer exposed to CS2 for a period varying between 1 and 43 months. The fundus signs (pigmentary changes and vascular lesions) increased in frequency, even if the patient was no longer exposed. The light/dark ratio of the EOG after 4 years was decreased in comparison with the first EOG, although this was not statistically significant. The ERG improved on follow-up. This could be related either to a shift to supranormal amplitudes or to recovery from subnormal amplitudes after the patient was no longer exposed.

Carbon Disulfide↗
PubMed1995

Impaired colour discrimination among workers exposed to styrene: relevance of a urinary metabolite.

OBJECTIVES: To survey the loss of colour vision among Japanese workers who have been exposed to styrene concentrations currently considered low (about 20 ppm). Also to assess the effects of styrene by examination of the nature of the relation between disorder of colour vision and age, alcohol consumption, and other variables. METHODS: Colour discrimination was examined in 64 male workers exposed to styrene (mean age; 38.0, mean exposed years; 7.0) and in 69 controls (mean age; 38.0). A standardised questionnaire was adopted to collect work history, occupational or non-occupational solvent exposure, alcohol consumption, and drug use. Colour vision was evaluated by the Lanthony desaturated panel D-15 test. The results of the test were expressed as the colour confusion index (CCI). RESULTS: The mean atmospheric styrene concentration was about 20 ppm. The mean urinary concentration of mandelic acid was 0.22 g/l. There was a significant difference in CCI between exposed workers and age matched controls. Colour vision of workers whose concentration of urinary mandelic acid was > or = 0.42 g/l was significantly impaired when compared with workers whose concentration was < 0.42 g/l. Multiple linear regression analysis that controlled confounding variables such as age, alcohol consumption, smoking, and educational attainment showed that the CCI was significantly related to the concentration of urinary mandelic acid. In both exposed workers and controls, the types of defects were mostly blue-yellow loss, although a few subjects showed complex loss. No one showed only red-green loss. CONCLUSIONS: These findings suggest that exposure to moderate styrene concentrations can lead to impairment of colour vision, and that there is a significant correlation with the urinary metabolite of styrene.

Adult↗
PubMed1996

Behavioural and electrophysiological chromatic and achromatic contrast sensitivity in an achromatopsic patient.

OBJECTIVES: In cases of incomplete achromatopsia it is unclear whether residual visual function is mediated by intact striate cortex or results from incomplete lesions to extrastriate cortical visual areas. A patient with complete cerebral achromatopsia was tested to establish the nature of his residual vision and to determine the integrity of striate cortex function. METHODS: Behavioural contrast sensitivity, using the method of adjustment, and averaged visually evoked cortical potentials were measured to sinusoidally modulated chromatic and achromatic gratings in an achromatopsic patient and a normal observer. Eye movements were measured in the patient using a Skalar infrared monitoring system. RESULTS: The patient's chromatic contrast sensitivity was normal, indicating that despite his dense colour blindness his occipital cortex still processed information about spatial variations in hue. His sensitivity to achromatic gratings was depressed particularly at high spatial frequencies, possibly because of his jerk nystagmus. These behavioural results were reinforced by the nature of visually evoked responses to chromatic and achromatic gratings, in which total colour blindness coexisted with an almost normal cortical potential to isoluminant chromatic gratings. CONCLUSIONS: The results show that information about chromatic contrast is present in some cortical areas, and coded in a colour-opponent fashion, in the absence of any perceptual experience of colour.

Adult↗
PubMed1998

Colour vision abnormalities do not correlate with dopaminergic nigrostriatal degeneration in Parkinson's disease.

Sensory disturbances such as olfactory or visual dysfunctions are common in Parkinson's disease (PD). A possible relationship between distorted colour discrimination and the nigrostriatal dopamine deficit is still a matter of debate. We examined 31 de novo Parkinsonian patients with [123I]beta-CIT single photon emission tomography (SPECT). We used a single-head gamma-camera and calculated the binding ratio striatum/cerebellum (specific/nonspecific binding) of [123I]beta-CIT uptake. On the same day, we performed the Farnsworth-Munsell 100 Hue Test (FMT) in these patients and estimated the total error score, in order to investigate abnormalities of colour vision. Parkinsonian patients' total error score was higher compared with an age- and sex-matched control group (P = < 0.0001), whereas disability scores of the Hoehn and Yahr scale (P = 0.019, Spearman r = 0.419) and the Unified Parkinson's Disease Rating Scale (P = 0.039, Spearman r = 0.373) correlated with total error score. No significant association appeared between total error score (Spearman r = -0.119, P = 0.525) and [123I]P-CIT-SPECT ratio. Thus both total error scores of the FMT and [1231]beta-CIT-SPECT binding ratios have been found to reflect the severity of PD. However, only [123I]beta-CIT SPECT reflects degeneration of dopaminergic neurons of the basal ganglia, but does not reflect alterations of the visual system and/or extranigral lesions in PD. From our results, we speculate that FMT may be a valuable clinical method to measure extranigral lesions of the visual system in PD.

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↗
PubMed1995

Colour contrast sensitivity in patients with age-related Bruch's membrane changes.

Patients with bilateral drusen as a manifestation of early age-related macular degeneration (AMD) may have minor psychophysically detectable visual defects in the presence of normal visual acuity. In a variety of retinal diseases, one of the earliest changes in visual processing is an impairment of normal colour vision. This study was undertaken to evaluate colour vision deficits in patients with macular drusen and to determine whether changes in colour contrast sensitivity may occur over time. In a prospective study, colour vision in 84 eyes of 84 patients aged 55-84 years (mean, 68.89 +/- 6.23 years) with macular drusen and clear media was tested using a computer graphics technique. A total of 47 patients were reviewed annually for up to 2 years and measurements were obtained at annual intervals. Colour contrasts sensitivity along protan, deutan and tritan colour confusion lines was determined at a foveal and a parafoveal region. The sensitivity to all stimuli showed large variations between patients. The thresholds for foveal blue-colour contrast sensitivity were elevated and increased during the review period. In contrast, there was no significant change in sensitivity with time for red and green at the foveal or parafoveal region. Tritan threshold changes suggest that the SW cone-receptor population is more susceptible to damage associated with early age-related macular disease than are red or green cones. The results indicate that blue colour contrast sensitivity determined over time may serve as a measure to assess the progression of age-related maculopathy prior to the manifestation of atrophic or exudative macular lesions associated with visual loss.

Aged↗
PubMed1997

Spectral sensitivity in patients with dysthyroid eye disease.

The majority of patients with dysthyroid eye disease have an acquired colour vision defect. However, no psychophysical investigation of selective damage to colour or flicker pathways has been carried out. In order to clarify the nature of the visual pathology, we have used a psychophysical technique (spectral sensitivity) to selectively stimulate the chromatic and achromatic mechanisms. Spectral spots of size 1 degree presented at a rate of 1 Hz on a bright 1000 td white background are detected by the chromatic mechanism but a rate of 25 Hz reveals the achromatic mechanism. Fifteen patients (28 eyes) between the ages of 50-70 years were tested. The study showed that all patients had reduced spectral sensitivity, either 1 Hz, 25 Hz or both. The patients with reduced 1 Hz or 25 Hz spectral sensitivity only had a shorter systemic and ocular duration of the condition, had no proptosis, normal intraocular pressures in primary gaze, slightly higher intraocular pressures on upgaze, normal visual field plots and FM 100-Hue error scores higher than the normal age-matched values. The patients with reduced both 1 Hz and 25 Hz spectral sensitivities had a longer systemic and ocular duration of the condition, had proptosis, normal intraocular pressures in primary position, higher intraocular pressures on upgaze and higher FM 100-Hue error scores than the age-matched normals and those in Groups 1 and 2. A total of 50% of patients in Group 3 had defective visual field plots. These data suggest that there is a damage of the large achromatic fibres and small chromatic fibres in dysthyroid eye disease. The mechanism of the damage could be one of ischaemic or mechanical or both.

Aged↗
PubMed1998

[Individual variations in color vision and its molecular biology].

Individual variations in normal color vision and congenital red-green color vision defects in Japanese males were investigated using both psychophysics and molecular biology techniques. 1. Normal color vision. We studied 72 Japanese males who were diagnosed as having normal color vision using the Ishihara plates test and Nagel model I anomaloscope. The structure of the gene arrays of the X-linked L- and M-pigment genes was determined using quantitative PCR-SSCP (polymerase chain reaction-single strand conformation polymorphism). We found the following variations of the number of M-pigment genes: 27 (38%) of these men had only one M-pigment gene, 29 (40%) had two, 13 (18%) had three and 3 (4%) had four. Two common polymorphisms were found at amino acid residue 180 of both L- and M-opsin, of the total 56 (78%) were Ser and the other 16 (23%) were Ala in the L-pigment and of the total 65 (90%) were Ala and the other 7 (10%) were Ser in the M-pigment. The Rayleigh match midpoints fell within the normal range, however there were two fairly distinct groups with consistent differences in each group. The mean values of the proportion of red in a mixture of red and green were 0.564 +/- 0.026 (mean +/- standard deviation). Correlation was found only between the Rayleigh match midpoint and the polymorphism at residue 180 of L-pigment. In order to estimate the variations of L/M cone ratio in the retinae the spectral sensitivities using heterochromatic flicker method were measured. Using the hypothesis that the luminosity function is proportional to the sum of L- and M-cone spectral sensitivity (k L (lambda) + M (lambda)), the constant k values were obtained. The k values for the subjects with Ser180 and Ala180 L-pigment were 1.89 +/- 1.44 and 1.85 +/- 1.02 respectively. Furthermore, in order to study the variation of information processing system, the spectral sensitivities for 1 degree, 200-ms test flash on a white background were measured. Using the hypothesis that the spectral sensitivity is proportional to the difference of L- and M-cone spectral sensitivity (L (lambda) - k' M (lambda)), the k' values were obtained. The k' values for the subjects with Ser180 and Ala180 L-pigment were 1.38 +/- 0.06 and 1.49 +/- 0.07 respectively. As a result, it was suggested that there are individual variations in both the L/M cone ratio and the color opponent system. 2. Congenital red-green color vision deficiencies. We studied the structure of the gene arrays of the X-linked L- and M-pigment genes and investigated the relationship between genotype and phenotype in 21 Japanese males comprising 4 protanopia, 6 protanomaly, 7 deuteranopia and 4 deuteranomaly. All of the protan subjects had 5' L-M fusion gene with/without the M gene. All of the deutan subjects had a normal L gene with/without 5' M-L fusion gene. Genotype agreed with phenotype in 8 of 10 protan subjects and 10 of 11 deutan subjects. Two of them were diagnosed as abnormal trichromatism in spite of having only one gene. One of them was diagnosed as dichromatism in spite of having two genes that encoded spectrally different pigments. As a result, it was felt that the diagnosis of dichromacy and abnormal trichromacy with an anomaloscope has limitations.

Asian People↗