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At least 1,513 records · Page 84Linked to original sources
PubMed2002

Phenotypes of 16 Stargardt macular dystrophy/fundus flavimaculatus patients with known ABCA4 mutations and evaluation of genotype-phenotype correlation.

PURPOSE: To determine the phenotypic variability in patients with compound heterozygous or homozygous ABCA4 mutations, and to correlate the phenotypes with the functional properties of the altered protein. METHODS: Sixteen patients from 13 families with signs of Stargardt macular dystrophy/fundus flavimaculatus and known mutations on both alleles of the ABCA4 gene (15 compound heterozygous, one homozygous) were characterized by clinical examination, fundus autofluorescence, psychophysics (color vision, kinetic and two-color dark- and light-adapted static threshold perimetry), and electrophysiology (Ganzfeld, multifocal ERG, EOG). RESULTS: The homozygous 5917delG mutation resulted in the earliest disease manifestation (at 5 years) and a general cone-rod dysfunction, whereas the compound heterozygous mother (5917delG, G1961E) exhibited a very mild phenotype. Compound heterozygotes for the IVS40+5G-->A and the C1488Y or Y362X mutation showed also an early age of onset but only a central dysfunction. The effect of the 2588G-->C mutation, the G1961E mutation, and the complex mutation L541P-A1038V depended on the mutation in the second allele. Genotype-phenotype correlation appeared possible in most instances. Psychophysics revealed a simultaneous yet not necessarily congruent cone and rod dysfunction. CONCLUSIONS: The type and combination of ABCA4 mutations in compound heterozygous patients determined were compatible with the severity of the phenotype as to age of onset and the functional consequences in the majority of patients. Unexplained phenotypic differences indicate the influence of other factors. ABCA4 mutations result in cone and rod dysfunction. Different disease durations limit the power of presently available genotype-phenotype correlations.

ATP-Binding Cassette Transporters↗
PubMed1993

[Visual function in pseudophakia].

Visual function of 33 pseudophakic eyes of 28 persons were examined and compared with control group of 27 persons without any changes in visual system. In pseudophakia there was a distinct decrease of mesopic vision and increased glare sensitivity. Color vision was not significant affected. The authors consider that only few professional drivers, engine drivers and pilots with pseudophakia would be able to get positive evaluation of visual function for further usefulness in their profession.

Adolescent↗
PubMed2001

Color discrimination in heterozygous deutan carriers.

PURPOSE: The color discrimination abilities of heterozygous deutan female carriers were measured using color mixture thresholds and compared with those of suspected nonheterozygous normal subjects. METHODS: Eight test subjects and 26 control subjects were run on a computer-controlled color test (color mixture thresholds) that presented 1 degree diameter spots on a color television monitor for 1/60 of a second. A QUEST procedure was used to determine visual thresholds for spots varying in brightness and/or color. Individual data points were graphed on an X/Y plot and fitted with an ellipse. The major and minor diameters of the ellipse represent the color and brightness thresholds, respectively. RESULTS: The mean axis angle of the ellipse for the heterozygous carriers did not differ from that for the controls (15.75 degrees vs. 14.93 degrees, p = 0.428, Mann-Whitney test). The carriers did show, however, a larger mean major axis length (68.79 vs. 46.78, p = 0.0218, Mann-Whitney test). Additionally, the length-to-width ratios for the carriers were higher than the controls (9.34 vs. 6.80, p = 0.0403, Mann-Whitney test). CONCLUSIONS: Deutan-carriers do show reduced color purity discrimination as measured using color mixture thresholds compared with nonheterozygous, color vision normals.

Adolescent↗
PubMed1995

Visual dysfunction among styrene-exposed workers.

OBJECTIVES: The present study was undertaken to examine the relation between visual functions and occupational exposure to styrene. METHODS: A total of 128 workers (85% of the total population), from three glass-reinforced plastics plants in Canada, agreed to participate in the study. Environmental and biological measures were made on the day(s) prior to the assessment of near visual acuity (National Optical Visual Chart), chromatic discrimination (Lanthony D-15 desaturated panel), and near contrast sensitivity (Vistech 6000). The analyses were performed on 81 workers with near visual acuity of at least 1 min of arc at 0.5 m. RESULTS: The subjects were relatively young [29 (SD 8) years], with little seniority [5 (SD 4) years]. Styrene exposure for 8 h ranged from 6 to 937 (first quartile 21 mg.m-3, third quartile 303 mg.m-3), depending on the job site. The end-shift concentrations of urinary mandelic acid ranged from nondetectable to 1.90 mmol.mmol creatinine-1. Significant positive relations were found between the internal and external styrene exposure measurements and color vision loss adjusted for age, alcohol consumption, and seniority in a multiple regression analysis. The multiple regression analysis is also showed that the end-shift concentration of urinary mandelic acid was inversely related to contrast sensitivity at 6 and 12 cycles.degree-1. Logistic multiple regression models indicated that the end-shift concentration of urinary mandelic acid was related to the prevalences of blurred vision, tearing, and eye irritation. CONCLUSIONS: These findings suggest that there is a positive relation between styrene exposure and early color and contrast vision dysfunction.

Adult↗
PubMed1994

Hemiachromatopsia of unilateral occipitotemporal infarcts.

Two patients developed unilateral occipitotemporal infarcts that produced inferior quadrantic achromatopsia and an accompanying superior quadrantanopia. Magnetic resonance imaging and single-photon emission computed tomographic studies of both patients supported the current view that color vision is encoded in the lingual and fusiform gyri. Although the quadrantic defect in color processing was profound, neither patient was aware of it. Simple bedside testing of patients with superior quadrantanopia may disclose an unrecognized quadrantic achromatopsia.

Aged↗
PubMed2002

Mutations in the RPGR gene cause X-linked cone dystrophy.

X-linked cone dystrophy is a type of hereditary retinal degeneration characterized by a progressive dysfunction of the day vision or photopic (cone) system with preservation of night vision or scotopic (rod) function. The disease presents with a triad of photophobia, loss of color vision and reduced central vision. This phenotype is distinct from retinitis pigmentosa (RP) in which there are prominent night and peripheral vision disturbances. X-linked cone dystrophy is a genetically heterogeneous disorder, with linkage to loci on Xp11.4--Xp21.1 (COD1, OMIM 304020) and Xq27 (COD2, OMIM 303800). COD1 maps to a region that harbors the RPGR gene, mutations in which account for >70% of patients with X-linked RP. The majority of these mutations reside in one purine-rich exon, ORF15, encoding 567 amino acids with a repetitive domain rich in glutamic acid residues. We mapped two families with X-linked cone dystrophy to the COD1 locus and identified two distinct mutations in ORF15 in the RPGR gene (ORF15+1343_1344delGG and ORF15+694_708del15) leading to a frame-shift and premature termination of translation in one case and a deletion of five amino acids in another. Consistent with expression of RPGR in rods and cones, our results show that mutations in RPGR, in addition to X-linked RP, can also cause cone-specific degeneration.

Amino Acid Sequence↗
PubMed1986

Monochromatic electroretinogram of deutan defect in the presence of intense red adaptation.

Monochromatic electroretinograms (ERGS) of deutans were recorded in the presence of intense red adaptation. The responses of some deutans were barely detectable or remarkably reduced, with the maximum response at the same wavelength (570-580 nm) as that under white adaptation. Those of other deutans showed a slight shift of the peak wavelength and the spectral pattern toward the shorter wavelength side although the amplitudes of the responses were much lower than those of normals under the same adaptation. These two types of change of spectral response patterns by intense red adaptation were investigated in relation to the anomaloscopic findings. The presence of the peak shift of the spectral pattern caused by red adaptation may depend on the degree of contribution of the green cone system to color vision in the deutan.

Adaptation, Physiological↗
PubMed1996

Preserved color imagery in an achromatopsic.

The loss of color vision secondary to central nervous system disease (achromatopsia) is thought to preclude visual imagery of colors. We report a patient with achromatopsia, secondary to bilateral temporo-occipital infarcts inclusive of the lingual and fusiform gyri, with preserved color imagery. Our findings, in conjunction with previous cases in the literature, are consistent with a single neural network for color processing in which a disconnection of internal activation from stored color representations produces impaired color imagery with preserved color perception, whereas a disconnection of visual input to these representations produces achromatopsia with preserved color imagery.

Cerebral Infarction↗
PubMed1983

Effect of X-Chrom lens wear on chromatic discrimination and stereopsis in color-deficient observers.

Four color-deficient observers and one normal trichromatic subject were evaluated with color vision and stereoacuity tests during 1 month of X-Chrom lens wear. For all color tests, performance of the normal subject was unaltered by X-Chrom lens wear. Color-deficient subjects demonstrated improved performance on the Ishihara pseudoisochromatic color plates, but either degraded performance or no change on the Farnsworth-Munsell 100-hue or Pickford-Nicolson red-green anomaloscope test. Three of the five subjects exhibited degraded stereoacuity in conjunction with X-Chrom lens wear. We conclude that the X-Chrom lens does not improve discrimination in color-deficient subjects and may alter stereopsis.

Color Perception Tests↗
PubMed1991

[The Nagel anomaloscope in the diagnosis of eye diseases].

The Nagel anomaloscope can be incorporated in the diagnosis of eye diseases. Three parameters are relevant: 1. The measure of the absolute matching range (scale units) 2. The preferred direction of the widened matching range (to red or to green) 3. The luminance matches with the yellow (decreasing matches indicating a pathologic scotopisation). - Six pathologic anomaloscope findings can be differentiated: 1. Pseudoprotanomaly (retinal diseases; type III acquired blue-yellow defects) 2. Symmetrically widened absolute matching range (reduced hue discrimination without reference to its etiopathology) 3. Absolute matching range asymmetrically widened to red with scotopisation (retinal diseases; type III acquired blue-yellow defects or type I acquired red-green defects) or without scotopisation (retinal diseases or optic nerve diseases; type III acquired blue-yellow defects) 4. Absolute matching range asymmetrically widened to green (mostly optic nerve diseases; type II acquired red-green defects) 5. Acceptance of both end matches ("0" up to "73") with scotopisation (retinal diseases) or without scotopisation (optic nerve diseases) 6. Achromatic matches (selective cone diseases, such as Stargardt's dystrophy or progressive cone dystrophy). Indications for anomaloscope examinations and clinical application of the method are discussed in ten cases. The utility of the Rayleigh-equation consists in diagnosing pathologic scotopisation (differential diagnosis between retinal diseases and optic nerve diseases) and in making a quantitative evaluation of the acquired color vision defect (follow-up examination).

Color Perception Tests↗
PubMed1995

Centrally tinted contact lenses. A useful visual aid for patients with achromatopsia.

Achromatopsia (rod monochromacy) is a congenital color-vision defect of autosomal recessive inheritance due to severely abnormal or totally absent cone function. The disease is characterized by markedly reduced visual acuity, nystagmus, and, often, ametropia. Even under normal daylight conditions, these patients are extremely handicapped by glare because of a lack of rod inhibition by the abnormal or deficient cones. Light-absorbing glasses (absorption > 90%) can ameliorate this visual impairment to a certain extent but are sometimes not accepted by the patient since they are felt to disfigure the face. Especially during the first few years of school, this can lead to psychological problems. A special contact lens (Hydroflex, Wöhlk Company, Kiel) with a centrally tinted area (absorption 80%) that is slightly greater in diameter than the pupil under daylight conditions can correct ametropia and reduce light exposure and dazzle in a cosmetically much better way. Our first experience with this kind of visual aid in a 9-year-old girl suffering from incomplete achromatopsia is presented.

Child↗
PubMed1998

The contribution of color to visual memory in X-chromosome-linked dichromats.

We used a recognition memory paradigm to assess the visual memory of X-chromosome-linked dichromats for color images of natural scenes. The performance of 17 protanopes and 14 deuteranopes, who lack the second (red-green opponent) subsystem of color vision, but retain the primordial (yellow-blue opponent) subsystem, was compared with that of 36 color normal observers. During the presentation phase, 48 images of natural scenes were displayed on a CRT for durations between 50 and 1000 msec. Each image was followed by a random noise mask. Half of the images were presented in color and half in black and white. In the subsequent query phase, the same 48 images were intermixed with 48 new images and the subjects had to indicate which of the images they had already seen during the presentation phase. We find that the performance of the color normal observers increases with exposure duration. However, they perform 5-10% better for colored than for black and white images, even at exposure durations as short as 50 msec. Surprisingly, performance is not impaired for the dichromats, whose recognition performance is also better for colored than for black and white images. We conclude either that X-chromosome-linked dichromats may be able to compensate for their reduced chromatic information range when viewing complex natural scenes or that the chromatic information in most natural scenes, for the durations tested, is sufficiently represented by the surviving primordial color subsystem.

Adult↗
PubMed2026

Guidance (challenges and priorities) in the assessment of children with low vision: ERN-EYE clinical consensus statement.

Across Europe, children living with low vision often face inconsistent approaches to the assessment of their visual function, leading to delays in diagnosis and unequal access to care. To address this gap, a multidisciplinary group of experts from 8 European countries developed a clinical consensus statement (CCS), using a modified Delphi process. This CCS provides guidance on evaluation of primary visual functions in children with low vision, regardless of etiologies. Assessing visual function can be challenging and cannot be limited to testing visual acuity. It requires a comprehensive approach that takes into account the child's developmental age and necessary adjustments for vision loss. This consensus statement presents different validated tools to evaluate visual acuity, contrast sensitivity, visual field, and color vision. It provides practical guidance for their use across developmental stages, including infancy and in children with syndromic or neurodevelopmental conditions, and highlights the critical role of caregivers in ensuring reliable assessments. The recommendations emphasize the need for age-appropriate testing strategies, tailored adaptations for low vision and additional impairment, and the importance of early assessment to support timely habilitation and optimize developmental outcomes.

Assessment↗
PubMed1965

ELECTRORETINOGRAM IN NEWBORN HUMAN INFANTS.

The electroretinogram of the newborn human shows the x-wave component which was demonstrated by Adrian and others to be a concomitant of photopic visual function in the adult. This finding may provide electrophysiological support for behavioral observations indicating that infants have some color vision and ability to resolve visual stimuli.

Adult↗