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At least 1,135 records · Page 63Linked to original sources
PubMed1988

Dissociation of visual deficits in ocular hypertension.

Both acquired color vision deficiencies and abnormal pattern electroretinograms (PERGs) are observed in patients with ocular hypertension (OHT) as well as in patients with glaucoma. In the present study we determined the prevalence of both of these functional deficits in a large group of OHT patients (N = 130). Color vision was tested with the desaturated D-15 and a color confusion score was used to quantitatively assess the magnitude of the color vision deficiency. Steady-state PERGs were evoked with rapidly alternating high contrast checkerboard patterns. Color vision deficits were detected in 23% of OHTs while 11.5% of the patients exhibited significant PERG amplitude reductions. Only 2.3% exhibited both abnormalities. The results suggest that although color vision deficiencies and PERG abnormalities are both evident in OHT, they are often dissociated findings.

Adult↗
PubMed2005

Evaluation of a chromatometer: a new method for blue-yellow or green-red visual comparisons, and anomaly screening techniques.

BACKGROUND: Malbrel's chromatometer is a new apparatus which allows color vision to be monitored. The aim of this study was to assess the accuracy of this new examination method. MATERIAL/METHODS: The color vision of a patient was analyzed using a chromatometer for direct heterochromatic visual comparisons. The patient's task was to adjust, using one eye only, the brightness of a yellow (or red) window to the one of a fixed blue (or green) window. Overall, 158 patients, aged 20 to 28, took part in the experiment. First, parametric means were used to study the response distributions and the luminous effects on the responses. Second, using non-parametric means, we considered that a patient had an anomalous color vision according to the chromatometer if the response was higher than the 95th percentile or lower than 5th percentile. Third, anomalous responses were compared with the Ishihara plates and Farnsworth 28-hue responses. RESULTS: The effect of a luminous stimulus on the response was significant (adjusted to the patient effect). Thus, the chromatometer appears to be a good method to analyze color vision. This apparatus was easy to use and constituted a sensitive and specific test with high negative predictive value. CONCLUSIONS: The chromatometer can be used as a first-line screening test to detect color vision anomalies during ophthalmology consultations. The chromatometer can be useful in identifying early ocular disease, monitoring disease development, or checking possible iatrogenic effects of a specific treatment.

Adult↗
PubMed2003

Color discrimination impairment in workers exposed to mercury vapor.

OBJECTIVE: To study color discrimination impairment in workers exposed to elemental mercury (Hg) vapor. SUBJECTS: Twenty-four male workers from a chloralkali plant exposed to Hg vapor, aged 42+/-9.8 years, duration of exposure 14.7+/-9.7 years, were examined. The 8h TWA air-borne Hg concentration in workplace was 59 microg/m(3); mean Hg urinary excretion (HgU) was 20.5+/-19.3 microg/g creatinine; mean Hg urinary excretion after the administration of a chelating agent, sodium 2,3-dimercapto-1-propane-sulfonate (DMPS), was 751.9+/-648 microg/48h. Twenty-four age- and gender-matched control subjects were compared. Visual acuity, alcohol intake, smoking habits, and history of diseases or drugs potentially influencing color vision were registered. METHODS: The Lanthony 15-Hue desaturated test (L-D15-d) was used to assess color vision. The results were expressed quantitatively as Bowman's Color Confusion Index (CCI), and qualitatively according to Verriest's classification of acquired dyschromatopsias. RESULTS: The CCI was significantly higher in the exposed group than in the control (mean CCI 1.15 versus 1.04; P=0.04). The proportion of subjects with errorless performance on the Lanthony test was significantly lower in the Hg exposed group compared to referents (52% versus 73%; P=0.035). The exposed group showed higher frequency of type III dyschromatopsias (blue-yellow confusion axis) in comparison with the control group (12.5% versus 8.3%), however, the difference did not reach statistical significance. Multiple regression did not show any significant relationship between the CCI, and age, alcohol consumption, or measures of exposure. CONCLUSION: In agreement with previous studies by Cavalleri et al. [Toxicol. Lett. 77 (1995) 351; Environ. Res. Sec. A 77 (1998) 173], the results of this study support the hypothesis that exposure to mercury vapor can induce sub-clinical color vision impairment. This effect was observed at an exposure level below the current biological limit for occupational exposure to mercury. This raises doubts on the actual protection afforded by this limit concerning the effect of mercury on color vision.

Adult↗
PubMed1987

Neuro-ophthalmic presentation of cone dysfunction syndromes in the adult.

Cone dysfunction syndromes are probably part of the spectrum of cone-rod degenerations and can present with widely varying clinical pictures. Thus, although the age of onset is usually before the third decade, patients can present at any age, and, although family history is usually positive, in typical cases it may be quite negative. Patients can have initially very subtle, bizarre, or poorly described visual complaints so that numerous examiners may label them "functional" or "malingering." They can present with the classic symptoms of hemeralopia, poor acuity, and reduced color vision, but these complaints may be absent. Visual acuity and color vision can be normal or severely reduced and the fundi may show classic changes such as bulls-eye maculopathy, macular choroidal atrophy, pigment clumping in the maculae, mild peripheral pigmentary changes, or a fundus flavimaculata-like change. The patients here reported were considered as having normal fundi by several competent ophthalmologists as a rule, however. Visual fields can vary from normal to ring scotomas, central scotomas, and other interesting types of defects, even simulating a hemianopia. Although involvement is usually symmetrical between the two eyes, this is not always the case, and one of our patients had a strictly uniocular cone dystrophy. Cone dysfunction can be considered in a patient of any age even with normal acuity, good color vision, and a normal ophthalmoscopic examination. A high index of suspicion should prompt specific questioning about hemeralopia, or reduced visual function in brightly illuminated situations, and better vision in twilight or under dim illumination. Patients may falsely describe hemeralopia as "glare" or "photophobia." Careful testing of color vision, a meticulous tangent screen examination, and specifically looking for diffuse narrowing of retinal arterioles in a patient with an otherwise normal fundus appearance will usually suffice to prompt the clinician to order electroretinography, which is the definitive diagnostic criterion for the cone dystrophies. It is important to consider this diagnosis before embarking on an otherwise fruitless and expensive neuroimaging investigation.

Adult↗
PubMedDate not supplied

Cone visual pigments of aquatic mammals.

It has long been hypothesized that the visual systems of animals are evolutionarily adapted to their visual environment. The entrance many millions of years ago of mammals into the sea gave these new aquatic mammals completely novel visual surroundings with respect to light availability and predominant wavelengths. This study examines the cone opsins of marine mammals, hypothesizing, based on previous studies [Fasick et al. (1998) and Levenson & Dizon (2003)], that the deep-dwelling marine mammals would not have color vision because the pressure to maintain color vision in the dark monochromatic ocean environment has been relaxed. Short-wavelength-sensitive (SWS) and long-wavelength-sensitive (LWS) cone opsin genes from two orders (Cetacea and Sirenia) and an additional suborder (Pinnipedia) of aquatic mammals were amplified from genomic DNA (for SWS) and cDNA (for LWS) by PCR, cloned, and sequenced. All animals studied from the order Cetacea have SWS pseudogenes, whereas a representative from the order Sirenia has an intact SWS gene, for which the corresponding mRNA was found in the retina. One of the pinnipeds studied (harp seal) has an SWS pseudogene, while another species (harbor seal) appeared to have an intact SWS gene. However, no SWS cone opsin mRNA was found in the harbor seal retina, suggesting a promoter or splice site mutation preventing transcription of the gene. The LWS opsins from the different species were expressed in mammalian cells and reconstituted with the 11-cis-retinal chromophore in order to determine maximal absorption wavelengths (lambda(max)) for each. The deeper dwelling Cetacean species had blue shifted lambda(max) values compared to shallower-dwelling aquatic species. Taken together, these findings support the hypothesis that in the monochromatic oceanic habitat, the pressure to maintain color vision has been relaxed and mutations are retained in the SWS genes, resulting in pseudogenes. Additionally, LWS opsins are retained in the retina and, in deeper-dwelling animals, are blue shifted in lambda(max).

Amino Acid Sequence↗
PubMed2000

Eye design and color signaling in a stomatopod crustacean Gonodactylus smithii.

Many species of stomatopod crustaceans have multiple spectral classes of photoreceptors in their retinas. Behavioral evidence also indicates that stomatopods are capable of discriminating objects by their spectral differences alone. Most animals use only two to four different types of photoreceptors in their color vision systems, typically with broad sensitivity functions, but the stomatopods apparently include eight or more narrowband photoreceptor classes for color recognition. It is also known that stomatopods use several colored body regions in social interactions. To examine why stomatopods may be so 'concerned' with color, we measured the absorption spectra of visual pigments and intrarhabdomal filters, and the reflectance spectra from different parts of the bodies of several individuals of the gonodactyloid stomatopod species, Gonodactylus smithii. We then applied a model of multiple dichromatic channels for color encoding to examine whether the finely tuned color vision was specifically co-evolved with their complex color signals. Although the eye design of stomatopods seems suitable for detecting color signals of their own, the detection of color signals from other animals, such as reef fishes, can be enhanced as well. Color vision in G. smithii is therefore not exclusively adapted to detect its own color signals, but the spectral tuning of some photoreceptors (e.g. midband Rows 2 and 3) enhances the contrast of certain color signals to a large enough degree to make co-evolution between color vision and these rather specific color signals likely.

Animals↗
PubMed1951

COLOUR vision.

Explore the source record for details and available documents.

Color Perception↗
PubMed1988

Progressive peripheral cone dysfunction.

A 22-year-old man had a three-year history of progressive day blindness, most notably peripherally, and denied difficulty with central vision or color vision. Visual function studies demonstrated a diffuse dysfunction of the photopic system and normal scotopic function. The central cone function, however, was essentially normal. Visual acuity was 20/20 in each eye, results on AO-HRR and Ishihara color plate testing were normal, color naming visual fields demonstrated color discrimination in the central 10 degrees, and foveal adaptation was normal.

Adult↗
PubMed1990

Normative data for the standard pseudoisochromatic plates--Part 2.

The Standard Pseudoisochromatic Plates--Part 2 are designed as a screening test for acquired color vision deficiencies. In order to control for age-related changes in color vision, it is necessary to establish norms for this test. Results from this study suggest that, disregarding one figure on the first test plate, one or more blue-yellow errors indicate a blue-yellow color vision defect for patients between 20 and 60 years, whereas two or more blue-yellow errors are indicative of a blue-yellow color vision defect for patients under 20 years and over 60 years. For modified red-green test figures, one or more errors are suggestive of a red-green defect for patients under 60 years, whereas two or more errors indicate red-green vision defect for patients over 60 years. Asking patients to judge which figure is more distinct on each test plate is not useful in comparing responses between patients.

Adolescent↗
PubMed2003

The performance of color deficient individuals on airfield color tasks.

BACKGROUND: The pseudo-isochromatic plate (PIP) test (e.g., Ishihara test) is the clinical test commonly used to assess color vision. Upon failure of this test, candidates are typically reassessed using the Farnsworth Lantern (FALANT) test to determine their fitness for occupations which require normal color vision. We were interested in determining to what extent clinical tests can predict real life color naming performance, particularly in the context of "airside drivers" (any airport vehicle operators who drive on the airfield). METHODS: There were 24 male subjects with a color vision deficiency, as defined by the Ishihara test, who participated in this study. They were further assessed using the D-15 and lantern color vision tests. All subjects then participated in two separate color naming tasks. These tasks consisted of naming surface colors and colored-lights of the type used on the airfield of the Hong Kong International Airport (HKIA). RESULTS: Of the 24 subjects, 15 failed both D-15 and the FALANT tests. Out of these 15 subjects, 8 also failed the naming tasks. The FALANT test showed very good agreement (87.5%) with the Ishihara test. Similar to the Ishihara, FALANT tests had 100% sensitivity in identifying the subjects who failed the naming tasks. The agreement between the Ishihara and D-15 tests was 62.5%. DISCUSSION: In common with previous studies, our results show that clinical tests cannot predict accurately who will fail color naming tasks of the type normally encountered in the real-life work environment. The high false positive values of the clinical tests in relation to color naming tasks suggest that people with color deficiency may not be given a fair opportunity to demonstrate their true ability in performing the task.

Adult↗
PubMed1988

Sahlgren's Saturation Test for acquired dyschromatopsia: increased lightness enhances sensitivity.

Sahlgren's Saturation Test (SST) is a simple sorting test designed for the detection and grading of acquired color vision defects. Like other pigment-based color vision tests, the SST color samples have medium lightness, i.e., they belong to the intermediate part of the gray scale. We tested normal controls and subjects with congenital or acquired dyschromatopsia with five SST versions that differed only in the amount of lightness. The sensitivity of the test increased considerably with increasing lightness. Therefore, the lightness level of SST has now been changed from 30 to 10 Natural Color System units.

Color↗
PubMedDate not supplied

Incomplete achromatopsia in Alzheimer's disease.

We report that patients with Alzheimer's disease (AD) have a selective deficit in blue hue discrimination, as assessed with three clinical measures of color vision. The Farnsworth D-15 Test, the Lanthony New Color Test, and the City University Color Vision Test were administered to 32 patients with AD (ranging in dementia severity from mild to severe) and 32 age-matched normal control subjects (NCS). Of the AD patients, 11 who were representative of the larger group for age, education level, and dementia severity received a complete neuro-ophthalmological examination that ruled out obvious disorders of the anterior visual structures. AD patients made significantly more tritan (blue) errors than NCS on all three color vision tests but did not make more protan (red) or deutan (green) errors on two of the three tests. The results support the conclusion that there is a deficit in color discrimination in AD that is specific to blue hues, and oppose the hypothesis that AD does not deleteriously affect the color-opponent visual channel. In the absence of obvious damage to anterior visual structures, the likely substrates for the observed deficit are peristriate and inferotemporal visual cortices, which are subject to significant neuropathology in AD.

Aged↗
PubMed1995

Molecular patterns and sequence polymorphisms in the red and green visual pigment genes of Japanese men.

The red-green pigment gene arrays of 203 (101 from a previous study and 102 from this study) randomly selected men of Japanese ancestry from the Seattle area were screened for the abnormal molecular patterns (deletions and red/green or green/red hybrid genes) that are usually associated with defective color vision. Such molecular patterns were found in approximately 5% of these individuals, which is equivalent to the frequency of phenotypic color vision defects in Japanese males in Japan. Thus, the majority of hybrid genes carried by Japanese males appear to be associated with defective color vision. In contrast, the frequency of hybrid genes among Caucasians and African-Americans is approximately two and five times the frequency of color vision defects in these two ethnic groups, respectively. The coding sequences of 50 males of Japanese ancestry were determined. All the polymorphisms in the red and green pigment genes that were detected in the Japanese sample had been observed in Caucasians and African-Americans. The same polymorphisms of the red pigment gene were present in the green pigment gene, suggesting that gene conversion contributes to sequence homogenization between these pigment genes. As is the case for Caucasians, exon 3 of the red and green pigment genes was observed to be a hot spot for recombination and gene conversion. Fewer polymorphic sites (4 vs 11) and haplotypes (5 vs 14) of the red pigment gene were observed in Japanese than in Caucasians. The Japanese population was more uniform with respect to the red pigment gene, with 70% of individuals having the same haplotype, as compared with the 43% for the Caucasian population. This difference was largely due to the lower degree of polymorphism at position 180 of the red pigment gene in Japanese (84% Ser and 16% Ala vs 62% Ser and 38% Ala.) The number of polymorphic sites and haplotypes in the green pigment gene was similar in the two populations. Nevertheless, the Japanese population was more uniform with 65% having the same haplotype. The difference in the frequency of alleles at position 283 accounted for this difference in haplotype distribution.

Amino Acid Sequence↗
PubMed2005

Photopic vision in eels: evidences of color discrimination.

Several classes of second-order retinal neurons have been studied electrophysiologically in European eel (Anguilla anguilla) from two different localities, Lake Seliger in Russia and the coastal waters of the Adriatic Sea in Montenegro. The majority of L-horizontal cells (68 explored) had both rod and cone inputs, an uncommon phenomenon among teleosts. Pronounced color-opponent properties, often taken as pointing to the capacity of color vision, were identified in one amacrine cell, apparently of the "blue/yellow" (or "blue/green") type. Microspectrophotometric measurements revealed two different spectral classes of cones with absorption maxima at about 525 and 434 nm. The existence of green-sensitive and blue-sensitive cone units was thus revealed by both electrophysiological and microspectrophotometric techniques.

Adaptation, Ocular↗
PubMed1988

[The effect of combined iodine treatment in Bad Hall on the color perception of patients].

After taking a cure with iodine treatments in Bad Hall (Upper Austria), patients with eye diseases repeatedly report improvements in their color vision. They state that colors are once again "more saturated, richer, and more distinct." These statements were checked using the Farnsworth Panel D-15 dicotomous test and the Lanthony desaturated 15 Hue test. The analysis of the results showed that there is indeed a statistically significant improvement in color vision after the cure. The spontaneous observations of the patients were therefore confirmed by the study.

Adult↗
PubMed2004

Identification of a protanomalous chimpanzee by molecular genetic and electroretinogram analyses.

We determined the structures of long (L)-wavelength-sensitive and middle (M)-wavelength-sensitive opsin gene array of 58 male chimpanzees and we investigated relative sensitivity to red and green lights by electroretinogram flicker photometry. One subject had protanomalous color vision, while others had normal color vision. Unlike in humans, a polymorphic difference in the copy number of the genes and a polymorphic base substitution at amino acid position 180 were not frequently observed in chimpanzees.

Animals↗
PubMed1991

[Ocular side effects of beta-pyridylcarbinol].

Derivatives of nicotinic acid such as beta-pyridylcarbinol play an important role in the therapy of lipoprotein disorders. In 1973, J.D. Gass reported the development of cystoid macular edema provoking metamorphosia during the course of nicotinic acid treatment. The aim of this study was to determine subtle changes in ocular function induced by beta-pyridylcarbinol. We investigated 16 patients prior to and after 6 months of beta-pyridylcarbinol treatment and compared the results of clinical and color vision tests in 9 patients after 2-25 years of continuous beta-pyridylcarbinol treatment. After 6 months, significant blue-yellow color vision changes (total error scores within normal ranges) were detected by the Farnsworth-Munsell 100 hue tests in all patients. One patient demonstrated macular edema. Fluorescein angiography, however, showed no evidence of fluorescein leakage. Beta-pyridylcarbinol treatment lasting for years led to diffuse color vision disturbances (total error score = 195). To the best of our knowledge neither macular edema nor color vision disturbances following beta-pyridylcarbinol treatment have been reported so far.

Adolescent↗
PubMed1995

A gene for autosomal dominant progressive cone dystrophy (CORD5) maps to chromosome 17p12-p13.

Inherited retinal dystrophy is a common cause of visual impairment. Cone dystrophy affects the cone function and is manifested as progressive loss of the central vision, defective color vision, and photophobia. Linkage was demonstrated between progressive cone dystrophy (CORD5) and genetic markers on chromosome 17p12-p13 in a five-generation family. Multipoint analysis gave a maximum lod score of 7.72 at the marker D17S938. Recombinant haplotypes in the family suggest that the cone dystrophy locus is located in a 25-cM interval between the markers D17S926/D17S849 and D17S804/D17S945. Furthermore, one recombination was detected between the disease locus and a microsatellite marker in the candidate gene RCV1, encoding the retinal protein recoverin. Two additional candidate genes encoding retinal guanylate cyclase (GUC2D) and pigment epithelium-derived factor (PEDF) are located at 17p13.1. Moreover, loci for retinitis pigmentosa and Leber congenital amaurosis have been mapped to the same region. Identification of the cone dystrophy locus may be of importance not only for identifying functional genes in the cone system, but also for identifying genes for other retinal disorders.

Chromosome Mapping↗