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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↗
PubMed2002

Anomaloscope matches in patients with diabetes mellitus.

BACKGROUND: Functional visual deficits can occur in patients with diabetes mellitus who show no visible morphological alterations in the retina. In this study we examined the colour vision of diabetic patients using metameric matches. Patients with and without retinopathy, as well as those who had been treated with laser photocoagulation, were examined to ascertain how the functional alterations in the diabetic eye alter with disease status. METHODS: Rayleigh (red-green) and Moreland (blue-green) metameric matches were determined in a total of 51 diabetic patients (24 patients with no retinopathy, 12 patients with background retinopathy and 15 patients who had undergone laser therapy). Their results are compared to those of a control group of 25 subjects with normal colour vision. RESULTS: A deficit in blue-green colour discrimination found in patients without retinopathy becomes worse with the appearance of vascular alterations in the retina. There is also a significant shift towards green in the Rayleigh match midpoint and towards blue in the Moreland match midpoint, which is at least in part explicable by alterations in lens opacity. Patients who have undergone laser therapy show, on average, better colour discrimination than those with retinopathy, but there is a large variation in their results. CONCLUSION: The alterations in the colour vision of diabetics indicate that at least the early functional changes are occurring at an inner retinal location. Lens opacity changes also play a large role as the age of the patients increases.

Adolescent↗
PubMed2004

The Nagel anomaloscope: its calibration and recommendations for diagnosis and research.

BACKGROUND: The Nagel anomaloscope Model I is the definitive clinical instrument for classifying phenotypic variations in X-linked color-vision disorders. Its system of classification is based on the Rayleigh equation: the relative amounts of red and green primary lights required to match a yellow primary. Our aim was to characterize how changes in mains voltage and ambient temperature influence the wavelength and intensity of each primary and alter the Rayleigh matches of normal and anomalous trichromats. METHODS: A Nagel Model I anomaloscope was calibrated in wavelength and intensity while varying the temperature of its prism housing and the mains voltage. Three normal, three protanomalous and three deuteranomalous trichromats made Rayleigh matches at various temperatures and voltages. RESULTS: The intensities of the green and red primaries show an exponential growth with mains voltage. Additionally, the wavelengths and intensities of all three primaries change with prism housing temperature. As a result, the R-G match midpoints of normal and anomalous trichromats shift with increasing mains voltage, and more markedly with increasing prism housing temperature, to higher R-G settings. CONCLUSIONS: Rayleigh matches obtained with the Nagel I anomaloscope are sensitive to changes in voltage supply and prism housing temperature, arising largely from thermal effects of the internal light sources. However, the instrument may still be safely used for diagnostic and research purposes provided that: (1) a stable voltage supply is used; (2) it is kept at a constant temperature; and (3) the match midpoint of the reference population has been established under identical conditions.

Biomedical Research↗
PubMed2004

Longitudinal and cross-sectional study of patients with early-onset severe retinal dystrophy associated with RPE65 mutations.

PURPOSE: To quantify retinal function longitudinally and cross-sectionally in patients with autosomal-recessive early-onset severe retinal dystrophy (EOSRD) associated with RPE65 mutations. SUBJECTS AND METHODS: The ocular phenotype was characterized in four children from three families up to the second decade of life, and in three siblings from one family aged 43-54 years carrying compound heterozygous or homozygous mutations in RPE65. Standard clinical examination included colour vision testing, fundus photography and Goldmann visual fields (GVF). Full-field ERGs (in all) and multifocal ERGs (in two patients) were also recorded. Visual performance and fundus appearance were compared to literature data. RESULTS: In childhood, visual acuity (VA) ranged from 0.1 to 0.3, and GVF for target V4 was well preserved. VA and GVF were measurable in only one of the three adult siblings. Nystagmus was present in two of four children and two of three adults. Photophobia was absent in childhood and developed in adulthood. Funduscopic changes were discrete during the first decade of life in three of four children; one patient had clear macular changes already at age 5 years. All three adult siblings had distinct retinal changes including the macula. Bone spicules were not a feature. Residual colour vision was present in all patients with measurable VA. Rod ERGs were absent at any age; cone ERGs were detectable in early childhood. To date, VA data have been reported in 51 patients, visual fields in 29 patients, and a detailed fundus description in 34 patients. For all three parameters, data were comparable to the results in our patient cohort. CONCLUSION: In childhood, patients with RPE65 mutations have better visual functions than typically seen in Leber congenital amaurosis. The phenotype shows a common progressive pattern with intrafamilial and interfamilial variation. The data suggest a preserved retinal morphology at young ages, arguing for vision-restoring gene therapy trials in childhood.

Adolescent↗
PubMed2005

Visual acuity and X-linked color blindness.

PURPOSE: Optimal sampling for visual acuity requires a fine array of cones with identical sensitivity. Thus, dichromats, whose inner fovea is made up of cones having the same spectral sensitivity, may have better than normal visual acuity. We investigated this by comparing the visual acuities of trichromats and X-linked dichromats, while taking into account the different molecular genetics underlying the disorder. METHODS: Our subjects were age- and refraction-matched groups of normals (n=8) and X-linked dichromats (n=13). The dichromats (four protanopes and nine deuteranopes) were genotyped and classified according to whether they carried a single (n=6) or multiple (n=7) visual pigment genes on their X-chromosome. Visual acuity was measured in both eyes with the Freiburger Visual Acuity Test. RESULTS: Normal trichromats and ungenotyped dichromats do not significantly differ in visual acuity, nor do ungenotyped protanopes and deuteranopes. However, multi-gene dichromats, who possess more than one photopigment gene in the array, all of which encode for the same long- or middle-wavelength sensitive photopigment, have significantly higher visual acuity than either normal trichromats or dichromats who have only a single-gene. CONCLUSIONS: Multi-gene dichromats may benefit from a reduction in chromatic aberration and chromatic noise in the high acuity channel, normally a consequence of combining signals from different cone photoreceptor types and of cone-specific patterns of retinal image defocus and blur. Single-gene dichromats may not share in the advantage because of other molecular differences that influence the development of the retinal mosaic and/or its visual pathways.

Adult↗
PubMed1998

Anomaloscope examination in macular gliosis, macular holes and central serous choroidopathy.

BACKGROUND: Surgery for macular gliosis and macular holes has become increasingly successful with regard to anatomical outcome. Assessment of the damage to the receptors by these processes is still difficult, but is important in predicting functional outcome. METHODS: Examination with the Nagel II or the Neitz OT anomaloscope was performed in 36 patients with macular gliosis, 23 patients with full-thickness macular holes and 47 patients with central serous choroidopathy. The anomaloscope matches were expressed as the quotient of anomaly. RESULTS: In macular gliosis the mid-matching point is usually 1.0; there is no pseudoprotanomaly. In macular holes the mid-matching point is 1.0 when visual acuity is 0.3 or greater; in eyes with lower visual acuity there may be signs of diminished red sensitivity, but anomaloscope examination becomes difficult. In central serous choroidopathy the mid-matching point is shifted towards red, and pseudoprotanomaly is present, even when visual acuity is normal. CONCLUSIONS: Diseases of the inner retina, in early stages, do not alter colour vision substantially, whereas diseases of the outer retina give rise to early colour vision deficiency. In macular gliosis and macular holes, anomaloscope examination enables estimation of macular receptor misalignment.

Adolescent↗
PubMed1999

A temporal deficit in juvenile diabetics.

BACKGROUND: In this study we examined the temporal domain of visual function in diabetics without retinopathy by examining wavelength discrimination ability at two exposure durations. The results were compared to those found by heterochromatic brightness matching and anomaloscope matches. METHODS: Wavelength discrimination was performed between 440 and 540 nm at exposure times of 1 s and 0.04 s in eight juvenile diabetic patients without retinopathy. The monochromatic stimuli were presented in Maxwellian view and were set to be equally bright prior to the experiment using heterochromatic brightness matching. In addition, Rayleigh and Moreland anomaloscope matches were performed. The results of the diabetic group were compared to those of an age-matched control group of eight subjects with normal colour vision. RESULTS: Wavelength discrimination showed no difference between the groups for an exposure time of 1 s. With an exposure duration of 0.04 s, however, the diabetics show raised thresholds for the shortest wavelengths tested. In addition, brightness matches were increased at the short wavelengths, and anomaloscope matches showed a decrease in the match range for the Moreland (blue-yellow) equation. CONCLUSION: The results indicate post-receptoral alterations in diabetic patients with no visible changes in their retinae.

Adolescent↗
PubMed1997

Blue-yellow deficiency in workers exposed to low concentrations of organic solvents.

OBJECTIVES: To evaluate the effects of low concentrations of organic solvents on color vision. METHODS: Color vision was examined in 24 workers exposed to mixtures of solvents and in 24 control subjects. Exposure to mixtures was below the threshold-limit values. Color vision ability was assessed using the Ishihara plates (to screen for congenital dyschromatopsia), the Farnsworth panel D-15 test, the Lanthony desaturated panel D-15 test, and the Standard Pseudoisochromatic Plates part 2 (SPP2 test). RESULTS: The comparatively less sensitive Farnsworth panel D-15 test failed to show any difference between the groups, but the Lanthony panel D-15 desaturated test as well as the SPP2 test showed a significant impairment in the exposed group. Errors were of the blue-yellow type. CONCLUSION: This study gives further evidence that even mixtures of organic solvents at concentrations below the threshold-limit values may impair color vision.

Adult↗
PubMed1998

Qualitative color vision impairment in toluene-exposed workers.

OBJECTIVE: The aim of this study was to evaluate whether toluene, like many other organic solvents and solvent mixtures, could impair color vision. SUBJECTS AND METHODS: We investigated color vision impairment in three groups of workers, two groups occupationally exposed to toluene and a nonexposed group. The first exposed group, group E1, comprised 41 workers (median value of toluene in air 35.00 ppm, range 11.3-49.3 ppm) and the second exposed group, group E2, comprised 32 subjects (median value of toluene in air 156.00 ppm, range 66.0-250.0 ppm). The nonexposed group, group NE, comprised 83 subjects. Color vision was evaluated by the Lanthony D-15 desaturated test according to Verriest's classification: type I, loss in the red-green range; type II, loss in the blue-yellow and red-green ranges, and type III, loss in the blue-yellow range. Subjects were classified as dyschromates if specific acquired loss was determined in at least one eye. In both exposed groups, exposure was evaluated by measurement of the concentration of toluene in the ambient air and in the blood. In group E2, level of hippuric acid and orthocresol in urine after the work shift were also determined. The Mann-Whitney U-test, t-test, chi 2-test, and Spearman's rank correlation and multiple regression analysis were used for statistical analysis. RESULTS: Type III dyschromatopsia was detected in all groups examined: 26.6% of the workers in group NE, 31.7% of those in group E1, and 50% of those in group E2. As many as 15.6% of the workers in group E2, 4.8% of those in group E1, and only 1.2% of those in group NE had type II dyschromatopsia. A statistically significant difference in the prevalence of total dyschromatopsia (type III + type II) was established among the three examined groups together (chi 2 = 14.13; df = 2; P < 0.01), between group E2 and group E1 (chi 2 = 4.96; P < 0.05), and between group E2 and group NE (chi 2 = 12.50; P < 0.005), whereas no significant difference was found between groups E1 and NE. Type III dyschromatopsia was significantly correlated with age in group NE (P < 0.01) and in group E1 (P < 0.005). In group E2, both type II (P < 0.05) and type III dyschromatopsia correlated with toluene in ambient air and with the duration of exposure to toluene (both P < 0.005). In group E2, total dyschromatopsia correlated significantly with toluene in ambient air and in blood (both P < 0.05) as well as with hippuric acid in urine after the work shift (P < 0.001). CONCLUSION: This study suggests that toluene can impair color vision.

Adult↗
PubMed1998

Increased acquired dyschromatopsia among solvent-exposed workers: an epidemiology study on 249 employees of an aluminum-foil printing factory.

OBJECTIVE: To analyze the effects on color vision of chronic exposure to mixtures of solvents including ethyl acetate, ethanol, and ketones among the workers of a large factory specializing in the manufacture of photoengraved aluminum packaging. METHODS: We analyzed a group of 129 subjects who had been exposed to solvents for more than 3 years (mean age 40 years, range 25 59 years) and a nonexposed group of 120 subjects (mean age 41 years, range 21-57 years). The two groups had a similar length of service (17 and 19 years on average, respectively). The exposed subjects consumed more tobacco and alcohol than the nonexposed workers. The study involved administration of the Lanthony D-15 desaturated test. The subjects were classified as having or not having dyschromatopsia on the basis of Lanthony's criteria and the chromatic confusion index (CCI) was calculated according to Bowman's method. After observation of the work stations and analysis of an occupational questionnaire the findings were used to construct a cumulative exposure index covering the whole of each subject's working life. Air samples were taken at each work station and in each production sector to determine current exposure. RESULTS: The average cumulative exposure index was 194 (median 174, range 27-513). The average hygienic effect index (according to ACGIH recommendations), regularly used for atmospheres containing mixtures of products, varied between 12% and 27% of the occupational limit values permitted under French legislation. As regards color vision, 23% of the exposed group had dyschromatopsia, as did 13% of the nonexposed group, with the odds ratio (OR) adjusted for age and consumption of tobacco and alcohol being 1.99 (1.02, 3.89). The analysis of the dose-response relationship according to the cumulative exposure index showed an OR of 1.59 for the lowly exposed group (index < 174) and an OR of 2.40 for the highly exposed group (index > 174) as compared with the nonexposed group. Subjects with complex color vision loss (n=23) had a significantly higher cumulative exposure index than those with blue-yellow loss (n=23; 232 versus 155; P=0.04). The CCI was on average higher in the exposed group, but the difference between the two groups was not significant. CONCLUSION: The results of this study are in favor of an increased risk for impairment of chromatic discrimination among workers exposed to mixtures of solvents including mainly ethyl acetate, ethanol, and ketones.

Adult↗
PubMed1996

A new mechanism in blue cone monochromatism.

Blue cone monochromatism (BCM) is a rare X-linked colour vision disorder characterized by the absence of both red and green cone sensitivity. Most mutations leading to BCM fall into two classes of alterations in the red and green pigment gene array at Xq28. In one class the red and green pigment genes are inactivated by deletion in the locus control region. In the second class genetic rearrangements have created an isolated pigment gene that carries an inactivating point mutation. Here we describe a clinical case of BCM caused by a new mutation where exon 4 of an isolated red pigment gene has been deleted. The finding represents the first intragenic deletion yet described among red and green pigment genes.

Base Sequence↗
PubMed2004

An insertion/deletion TEX28 polymorphism and its application to analysis of red/green visual pigment gene arrays.

TEX28 gene (fTEX) is present immediately downstream of the red/green visual pigment gene array on the human X chromosome. Its pseudogene (pTEX) that lacks exon 1 is present within the array between pigment genes. We found that both fTEX and pTEX genes had a 697 bp insertion/deletion polymorphism in their introns 3. In color-normal male subjects, the frequency of the 697 bp region was 43% (40/94) in pTEX and 97% (91/94) in fTEX in the array of Red-pTEX-Green-fTEX and 10% (9/94) in pTEX and 87% (41/47) in fTEX in the array of Red-pTEX-Green-pTEX-Green-fTEX. These results suggest that normal arrays with multiple green genes may have arisen through gene duplication rather than unequal homologous crossover. In color-vision-deficient male subjects with a single-gene array, the frequency of the 697 bp region was 83% (25/30) in the array of Green-fTEX and 66% (74/112) in the array of Red-fTEX. In color-vision-deficient male subjects with a 2-gene array, the frequency of the region was 44% (16/36) in pTEX and 97% (35/36) in fTEX in the array of Green-pTEX-Green-fTEX and 75% (18/24) in pTEX and 92% (22/24) in fTEX in the array of Red-pTEX-Red-fTEX. These results suggest that 2-green-gene arrays have arisen through unequal homologous crossover between a normal 2-gene array and a single-green-gene array. With data from a long-range PCR method using the insertion/deletion polymorphism, we proposed a structure of the second gene of 3-gene arrays, Green-pTEX-Green-pTEX-Green-fTEX and Red-pTEX-Red-pTEX-Red-fTEX, in color-vision-deficient subjects.

Base Sequence↗
PubMed2006

Protan color vision deficiency with a unique order of green-red as the first two genes of a visual pigment array.

Normal visual pigment gene arrays on the human X chromosome have a red gene at the first and a green gene at the second positions. More than half of the arrays have additional green genes downstream, but only the first two genes of the array are likely to be expressed in the retina. An array consisting of four genes in two Japanese participants, A121 and A447, was detected either by pulsed field gel electrophoresis and subsequent Southern hybridization or by single nucleotide primer extension reaction. In both participants, the first gene of the array was green, downstream genes were red and green, and the fourth gene was green. The red gene was determined to be at the second position by comparison of polymorphic sites among the intergenic regions that had been amplified by long-range PCR. Such an array with a reverse normal order of pigment genes, green-red as the first two, has never been reported before. They were expected to have normal color vision but showed protan deficiency (protanomaly), a phenotype lacking the red pigment. The red gene had no mutations in the exons and exon/intron boundaries, but had an A-71C substitution in the promoter in both participants.

Adolescent↗
PubMed2003

Behavioral evidence of color vision deficiency in a protanomalia chimpanzee (Pan troglodytes).

Although color vision deficiency is very rare among Old World monkeys and apes, one male chimpanzee (Lucky) was identified as protanomalous by genetic and physiological analyses. This study assessed behavioral phenotypes of Lucky and four chimpanzees with normal color vision by discrimination task using the modified Ishihara pseudo-isochromatic plates. Lucky could not discriminate the stimuli that the other chimpanzees could. This is the first behavioral evidence of color vision deficiency in chimpanzees.

Animals↗
PubMed2002

Disorders of higher cortical visual function.

In the past few years, there have been significant advances in the understanding of how the so-called higher cortical functions are organized and mapped into various anatomic brain regions. There has been considerable refinement in lesion localization provided by magnetic resonance imaging (MRI), so the precise regions that are damaged in patients with particular types of visual perceptual problems can be demonstrated. In addition, functional MRI has provided insight into neural networks serving higher cortical functions in normal human subjects as they perform perceptual and cognitive tasks.

Blindness, Cortical↗
PubMed1975

Anosmia and hypogonadism with ovarian mosaicism.

An 18-year-old woman with anosmia and hypogonadotropic hypogonadism is presented. In addition endocrinologic evaluation revealed an apparent deficiency in pituitary growth hormone secretion in response to hypoglycemia and an ovarian insensitivity to exogenous gonadotropins. The ovaries, which on histologic examination appeared to be normal, upon karyotyping showed a chromosomal mosaicism, probably 46, XX/47, XXF+.

Adolescent↗