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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↗
PubMed2004

[A protanomalous female whose genotype of red/green visual pigment genes was determined by molecular analysis of her family members].

PURPOSE: To determine X-linked red/green visual pigment gene arrays of a female proband with protan deficiency. METHODS: We examined a brother and both parents as well as the proband. Severity, severe or mild form, of color vision deficiency was estimated with either failure or passing of the Farnsworth Panel D-15 test. Diagnosis of either anomalous trichromacy or dichromacy was performed using a Nagel Type I anomaloscope. Genotypes of red/green visual pigment genes were determined by quantitative polymerase chain reaction-single strand conformation polymorphism analysis. RESULTS: Color vision tests revealed that the proband, her brother, her father, and her mother had protanomaly(mild form), protanopia, protanomaly(severe form), and normal color vision, respectively. In analysis of gene arrays, the brother had a red-green hybrid gene(R1G2, Ser 180) and three green visual pigment genes, while the father had a red-green hybrid gene(R4G5, Ser 180) and a green visual pigment gene. CONCLUSIONS: It is impossible to directly determine each paternal or maternal X-linked red/green pigment gene array in the female proband. Molecular analysis of the family members revealed that the proband was a compound heterozygote for two R1 G2 and R4G5 hybrid genes encoding photopigments with different absorption maxima.

Chromosomes, Human, X↗
PubMed2001

[Daltonism and the genetics of aging].

In order to test whether mutations giving rise to color vision deficiencies are more frequently inherited from older fathers, an exhaustive screening of births in the Namur region has allowed to isolate a sample of 225 descending sons of maternal grandfathers who were older than 45 years at their daughter's birth. The incidence of color vision defects was compared between this set of cases and three control groups totalling 959 boys from independent families. While these comparisons were not conclusive, we propose new hypotheses concerning the population dynamics of color vision deficiencies. Neomutations in X-linked pigment genes may be a marker of the overall genetic load borne by the X chromosome. Selection against such loaded X chromosomes may occur in the second generation, either in the course of embryogenesis, or during female gametogenesis. The future assessment of these novel hypotheses relies on the arbitration of molecular genetics.

Aging↗
PubMed1981

Digoxin retinal toxicity. Clinical and electrophysiological evaluation of a cone dysfunction syndrome.

A 70-year-old man was studied both during and after resolution of clinical digoxin toxicity using color vision tests, ganzfeld electroretinography and electro-oculography. Concomitant administration of quinidine sulfate probably contributed to digoxin toxicity. Abnormalities in color vision and subnormal amplitude and prolonged implicit time for cone-mediated electroretinogram (ERG) responses suggested a cone dysfunction syndrome. The electro-oculographic light-to-dark ratio during clinical toxicity was high for our laboratory, but this is probably normal. Notable improvement was seen in color vision and the ERG after cessation of digoxin therapy. Inhibition of sodium-potassium adenosine triphosphatase by digoxin probably influences normal uptake of extracellular potassium by Müller's cells and other retinal neurons. This mechanism may contribute to subnormal, prolonged cone-mediated ERG responses in retinal toxic reactions from cardiac glycosides.

Adaptation, Ocular↗
PubMed2000

[Macular functions in professional divers].

PURPOSE: Air diving is frequently practiced by professionals or sportsmen. Controversial data exist in the literature on the existence of retinal abnormalities in divers. PATIENTS AND METHODS: 18 divers (aged: 27-58y) who dived around 2000 times in their life were studied: half of them dived only with air while the others used an O2-enriched gas mixture (40 to 60%). None of them had presented a bend (decompression sickness). Visual acuity and ocular fundus examination have been explored. A quantification of color vision and central visual field, so as a fluorescein angiography have been performed. RESULTS: No alteration of visual acuity was noted; abnormalities in the color vision and the visual field are reported; however the angiographic lesions described in the literature have not been observed. DISCUSSION: The alterations of color vision were quite severe but not very frequent. No correlation was found with any characteristics or type of diving. CONCLUSION: These observations are comforting for sportive divers who do not dive very often nor very deep but an individual predisposition is suspected.

Adult↗
PubMed1986

[The effect of cardiac glycosides on the visual system of man measured with cortical evoked potentials].

The effect of beta-acetyldigoxin (Novodigal) on color vision in normal, healthy subjects was studied using cortical evoked potentials. Initial results indicate a significant latency increase of one component of the visual evoked potential (VEP) and a dose dependency following a change of color from blue to red. The Farnsworth-Munsell-100-Hue test, however, showed no significant changes in color vision. It is postulated that the VEP is an even more sensitive measurement of color vision than subjective tests are.

Acetyldigoxins↗
PubMed1998

Complete sparing of high-contrast color input to motion perception in cortical color blindness.

It is widely held that color and motion are processed by separate parallel pathways in the visual system, but this view is difficult to reconcile with the fact that motion can be detected in equiluminant stimuli that are defined by color alone. To examine the relationship between color and motion, we tested three patients who had lost their color vision following cortical damage (central achromatopsia). Despite their profound loss in the subjective experience of color and their inability to detect the motion of faint colors, all three subjects showed surprisingly strong responses to high-contrast, moving color stimuli--equal in all respects to the performance of subjects with normal color vision. The pathway from opponent-color detectors in the retina to the motion analysis areas must therefore be independent of the damaged color centers in the occipitotemporal area. It is probably also independent of the motion analysis area MT/V5, because the contribution of color to motion detection in these patients is much stronger than the color response of monkey area MT.

Adult↗
PubMedDate not supplied

An adaptation of the Cambridge Colour Test for use with animals.

Recently, molecular biological techniques have presented new opportunities for addressing questions concerning the neural mechanisms involved in color coding, thereby rousing renewed interest in animal color vision testing. We have modified a computer-based assessment tool, the Cambridge Colour Test, to make it suitable for use with animals. Here, the validity and reliability of the testing method were evaluated using squirrel monkeys. Because the chromatic stimuli and the achromatic backgrounds of the test consist of dots that vary in lightness, the stimulus parameters can be adjusted so that animals are not able to use luminance differences to make correct discriminations. Thus, in contrast to methods used previously, this test does not require that time be spent equating the luminance of each chromatic stimulus examined. Furthermore, the computer video-display based design of the testing apparatus can be easily replicated and adapted for use with many species in a variety of settings. In the present experiments, the squirrel monkeys' behavioral results agreed with the predictions for their color vision based on genetic analysis and electroretinography (ERG) spectral sensitivity data. Repeated measurements were highly consistent. Thus, an adaptation of the Cambridge Colour Test provides a valid and reliable method for testing color vision in animals.

Animals↗
PubMed1982

Do visual evoked potentials give relevant information to the neuro-ophthalmological examination in optic nerve lesions?

The visual evoked potentials (VEPs) and neuro-ophthalmological examinations of 134 patients were compared. The VEPs were abnormal in 95% of the eyes with optic neuritis. Defective color vision was found in 99%, visual field defects in 88%, decreased vision in 66% and an afferent pupillary defect in 55%. 29 patients with optic neuritis were followed up with repeated tests. VEPs and color vision recovered more slowly than visual acuity and visual field. Abnormal VEPs were observed in 68% of 50 MS patients. An analysis of symptomatic and asymptomatic eyes showed that testing of color vision, visual field and red-free ophthalmoscopy were equally as useful diagnostic tools as VEPs. 4 (8%) of the MS patients had abnormal VEPs despite a normal neuro-ophthalmological examination; 94% of MS patients with symptoms and 47% of MS patients without visual symptoms had abnormal VEPs. VEPs were pathological in 59% of 24 patients with traumatic or compressive optic nerve diseases or optic atrophies of unknown etiology. The neuro-ophthalmological examination was more sensitive than VEPs in the diagnosis of these disorders. A neuro-ophthalmological examination is in most cases sufficient to diagnose optic nerve lesions. VEPs are of diagnostic aid especially in mild optic nerve lesions.

Diagnosis, Differential↗
PubMed1992

Effect of ibuprofen on contrast sensitivity.

Therapeutic doses of ibuprofen (2-4'-isobutylphenyl-propionic acid) have been shown to have many deleterious effects on the nervous system. However, visual disturbances have been reported in fewer than 1% of the patients taking recommended doses of ibuprofen. The most commonly reported visual disturbances include: amblyopia, scotomata, and changes in color vision. To our knowledge, no studies have examined the effects of ibuprofen therapy on the contrast sensitivity function of an affected individual. Contrast sensitivity, Snellen visual acuity, color vision (D-15 test), and Goldmann visual fields were measured on 1 affected subject during and after ibuprofen therapy (800 mg/day for 2 days). Snellen visual acuity, color vision, and Goldmann visual fields were unaffected by the treatment. However, the contrast sensitivity was significantly depressed at low spatial frequencies while the subject was taking ibuprofen. The results, in concert with previous reports concerning the visual effects of ibuprofen, suggest that this drug can result in transient multifocal lesions of the visual pathway.

Color Perception↗
PubMed1999

Blue-on-yellow perimetry in the complete type of congenital stationary night blindness.

PURPOSE: To resolve the discrepancy between nonrecordable full-field short wavelength cone electroretinograms (S-cone ERGs) and the presence of normal color vision in patients with the complete type of congenital stationary night blindness (CSNB1). METHODS: Conventional white-on-white (W-W) perimetry, blue-on-yellow (B-Y) perimetry, and the Farnsworth-Munsell 100-hue test were performed in five patients with CSNB1. Diagnosis of CSNB1 was made by clinical and electrophysiological examinations. Twelve normal, age-matched control subjects and an additional 7 normal, highly myopic subjects were tested. RESULTS: Color vision was normal in all the CSNB1 patients by the Farnsworth-Munsell 100-hue test. B-Y perimetry demonstrated that blue cone sensitivity in CSNB1 was normal in the fixation area, but the mean sensitivities of the entire 60 degrees field, the central 0 degrees-to-15 degrees, and 15 degrees-to-30 degrees ring were significantly decreased compared with the normal and myopic subjects. The sensitivity difference between 15 degrees-to-30 degrees and 0 degrees-to-15 degrees in B-Y perimetry increased significantly in CSNB1 compared with both normal and myopic control subjects. CONCLUSIONS: Our perimetric results demonstrated that the S-cone function in CSNB1 is preserved only in the fovea and becomes abnormal toward the peripheral retina. This accounts for the normal color vision that tests mainly foveal function and the nonrecordable S-cone ERGs that arise mainly from peripheral retina.

Adolescent↗
PubMed1999

Clinical characterization and linkage analysis of a family with congenital X-linked nystagmus and deuteranomaly.

OBJECTIVES: To identify a congenital nystagmus locus on the X chromosome and to characterize the phenotype of a 4-generation family affected with congenital nystagmus and color deficiency. METHODS: Sixty-five patients underwent an eye examination, including evaluation for the presence of nystagmus and color vision abnormalities. Affected patients and obligate carriers of the congenital nystagmus mutation were genotyped with short tandem repeat polymorphisms located on the X chromosome, and these data were subjected to linkage analysis. RESULTS: Fourteen patients were affected with a horizontal, conjugate, congenital nystagmus. All examined patients had a visual acuity of 20/60 or better. There were no associated ocular or systemic findings except that 18 of the family members had deficient red-green color vision, which was classified as deuteranomaly (the most common form of anomalous trichromacy). Five patients exhibited nystagmus and deuteranomaly. Significant linkage was demonstrated between the nystagmus phenotype and 11 markers from Xq. The maximum lod score was 4.84 (theta = 0) and was obtained with marker DXS8041. Analysis of recombinants defined the disease interval to lie between markers ATA59C05 and DXS1192 (a 5.4-centimorgan region). The proximity of this locus to the red-green opsin gene cluster (11 centimorgans more telomeric) explains the frequent coexistence of nystagmus and color vision deficiency in this family. CONCLUSIONS: We have identified the genetic locus of the X-linked congenital nystagmus gene in this family. The critical interval in this report is less than half the size of the previously described nystagmus locus. These findings will aid in identifying the gene responsible for this condition.

Chromosome Mapping↗
PubMed2000

Contrast is enhanced by yellow lenses because of selective reduction of short-wavelength light.

PURPOSE: Although many studies have shown a subjective preference for yellow lenses, there has been little success in determining the clinical nature of this benefit. METHOD: Contrast sensitivity, color vision, accommodative-convergence, and visual acuity were measured in a group of 20 young subjects along with subjective rating of their perception through clear control lenses (380-nm cut-off), yellow lenses (450-nm cut-off), dark yellow lenses (511-nm cut-off), and orange lenses (527-nm cut-off). RESULTS: A systematic detriment to color vision was found to occur with increasing cut-off wavelength of the yellow lenses (p < 0.001) and this was significantly correlated to subjective ratings of color (r = -0.66) and brightness (r = -0.34). Perceived brightness significantly improved for the yellow (450-nm cut-off) lens only (p < 0.001). Although tinted lenses reduced contrast sensitivity to a white on black grating, there was a significant improvement in low to midrange spatial frequencies when measured using a white-on-blue grating. CONCLUSIONS: The detriment in color vision caused by yellow-colored lenses enhances contrast when viewing bright objects against a blue-based background, such as the sky. Contrast of overlying objects is enhanced is due to the selective reduction of short-wavelength light by the yellow lenses.

Accommodation, Ocular↗
PubMed1982

Spectral sensitivity and color discrimination changes in glaucoma and glaucoma-suspect patients.

Color vision changes may occur early in the course of glaucoma and may precede visual field loss. Glaucoma suspects, having raised intraocular pressure and no diagnostic optic nerve head or visual field changes, may also have color vision loss. Unfortunately, the instruments used in the studies that have demonstrated these color vision changes were not feasible for routine clinical use; likewise, the studies did not carefully control for the effects of small pupil size and age or did not point to the underlying mechanisms responsible. We studied 19 glaucoma patients, 19 glaucoma suspects, and age-matched controls for each group by means of the Farnsworth D-15 panel test, a desaturated version of the D-15 test, and by measures of spectral increment threshold. Minor modifications of the Farnsworth D-15 panel test produce highly significant differentiation of glaucoma and glaucoma-suspect patients from age-matched normal groups. Further, spectral increment thresholds, with a two-degree spectral target flashed at either 1 or 25 Hz on a bright white background, show that both achromatic and chromatic sensitivity are significantly reduced when compared with their age-matched normals. Pupil size does not seem to be a significant factor. These results suggest that the function of two different ganglion cell populations is affected in glaucoma and that glaucoma may produce functional loss in the central foveal area earlier in the disease process than previously believed.

Adolescent↗
PubMed1989

Psychophysical changes in glaucoma.

Chronic glaucoma has been thought to spare the central vision until quite late in the disease process. This assumption is based on the use of the relatively insensitive Snellen chart to measure central vision and the relatively sensitive kinetic and static perimetry to measure the peripheral vision. In recent years, new measures of visual function have been utilized to assess patients with glaucomatous damage. Sensitive methods of measuring central visual function such as color vision, contrast sensitivity (both spatial and temporal), and macular light sensitivity have demonstrated defects early in the glaucomatous process - sometimes even before perimetry is affected. Since these visual functions are largely mediated by macular fibers, central vision may be affected earlier and more frequently in glaucoma than previously believed. Studies of both the nerve fiber layer of the retina and of quantitative light sense perimetry suggest that glaucomatous damage may occur diffusely across the population of nerve fibers, focally in the arcuate portion of the nerve fiber layer, or in both places. Color vision, contrast sensitivity and macular light sense appear to correlate with the diffuse type of nerve fiber layer damage. The exact utility of the psychophysical tests that assess central visual function for the clinical management of glaucoma has not yet been demonstrated. More work is needed to determine which tests are most useful, what parameters are most efficient, and what the diagnostic and prognostic significance of abnormal values may be. However, the studies of color vision, contrast sensitivity and macular light sensitivity have led to a better understanding of how glaucoma affects visual function.

Color Perception↗
PubMed1993

X-linked adrenoleukodystrophy: adult cerebral variant.

We report a unique case of a 43-year-old architect with adult-onset adrenoleukodystrophy who presented primarily with intellectual decline and no evidence of adrenal insufficiency. Serial MRIs taken over a number of months demonstrated the evolution of demyelination starting in the frontal white matter then shifting to the occipital white matter and finally resolving without any therapeutic intervention. Clinically, over this same period of time, the patient's symptoms resolved and he was able to return to work. The proband, his brother, and his nephew were found to have a color-vision defect. Each of these individuals had a red/green gene array that contained a 5' green-red 3' hybrid known to be associated with deutan color-vision defects. The proband's brother and nephew were otherwise normal. The gene that causes adrenoleukodystrophy appears not to be as close to the red/green color vision gene array on the X chromosome as previously reported.

Adrenoleukodystrophy↗
PubMed1996

Contrast sensitivity and other vision tests in the optic neuritis treatment trial.

PURPOSE: To determine the intercorrelation, prevalence of abnormality, and incremental detection value of vision tests in optic neuritis. METHODS: We calculated the linear correlation of paired vision tests and prevalence of abnormal test values from baseline and six-month measurements of Snellen visual acuity, Pelli-Robson contrast sensitivity, Humphrey Field Analyzer mean deviation, and Farnsworth-Munsell 100-hue color vision in 438 patients entered in the Optic Neuritis Treatment Trial from 1988 to 1991. The incremental detection value of nonvisual acuity tests was defined as their frequency of abnormality when visual acuity was 20/20 or better. RESULTS: All four vision-test results were highly intercorrelated at baseline and at six months. At baseline, contrast sensitivity had the highest prevalence of abnormality, but all vision tests were so often abnormal that differences were not clinically relevant. At six months, when visual recovery had occurred, contrast sensitivity was most often abnormal (2.2 X visual acuity; 1.8 X mean deviation; 1.5 X Farnsworth-Munsell 100-hue color vision test); when contrast sensitivity, mean deviation, or Farnsworth-Munsell 100-hue color vision was normal, visual acuity was 20/25 or better in 98% of patients. CONCLUSIONS: The high intercorrelation of four vision tests suggests that optic neuritis affects a broad range of visual functions. Among non-visual acuity tests, Pelli-Robson contrast sensitivity proved to be a particularly practical and sensitive indicator of visual dysfunction in optic neuritis.

Adolescent↗