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At least 1,243 records · Page 69Linked to original sources
PubMed2006

A novel homozygous GRK1 mutation (P391H) in 2 siblings with Oguchi disease with markedly reduced cone responses.

PURPOSE: The only mutations reported to date in Japanese patients with Oguchi disease, a rare form of stationary night blindness with autosomal recessive transmission, have been in the SAG (arrestin) gene. The objective of this study was to describe the ophthalmic features and a novel mutation in the GRK1 (rhodopsin kinase) gene in 2 Japanese patients with Oguchi disease. DESIGN: Molecular genetic and observational case study. PARTICIPANTS: A consanguineous family including 2 siblings with Oguchi disease (a 35-year-old man and a 31-year-old woman). METHODS: Best-corrected visual acuity (BCVA), fundus examinations, Goldmann perimetry, color vision tests, and full-field electroretinograms (ERGs) were evaluated. Mutation screening of the SAG and GRK1 genes was performed with polymerase chain reaction amplification and direct sequencing. MAIN OUTCOME MEASURES: Mutations in the GRK1 gene, BCVA, color vision, fundus photographs, visual fields, and ERG findings. RESULTS: Molecular analysis revealed a novel homozygous missense mutation (p.P391H) in the GRK1 gene in both patients. Proline 391 is not only within the functionally important catalytic domain, but is also a phylogenetically conserved amino acid residue among GRK1 orthologs and homologs. No mutation was found in the SAG gene. The unaffected parents were heterozygous carriers of the mutation. Both patients had night blindness, 1.5 BCVA for each eye, normal color vision, and typical fundus appearance with golden-yellow discoloration. The visual fields were normal in the male sibling. The ERGs showed no rod B waves, reduced standard combined responses, and markedly reduced single-flash cone and 30-Hz flicker responses in both patients. CONCLUSIONS: A novel homozygous GRK1 mutation (p.P391H) was found in 2 Japanese siblings with Oguchi disease. Visual function in the 2 patients has not deteriorated with age, indicating that the disease is stationary. This is the first report of any patient with GRK1-associated Oguchi disease with markedly reduced cone responses.

Adult↗
PubMed1997

Visual function in young IDDM patients over 8 years of age. A 4-year longitudinal study.

OBJECTIVE: To carry out a longitudinal study of visual functions in young patients over the age of 8 years with IDDM and to assess the impact of metabolic control on the presence of diabetic retinopathy. RESEARCH DESIGN AND METHODS: There were 37 young IDDM patients from the Paediatric and Adolescent Clinic at the University Hospital of Wales studied annually for 4 years, with a control group of 24 healthy subjects observed over a 2-year period. Assessment of visual functions included visual acuity, color vision, and contrast sensitivity. Ophthalmoscopy and retinal photography were used to determine the presence or absence of diabetic retinopathy. In addition, pubertal status and metabolic control (glycosylated hemoglobin) were determined at each visit. RESULTS: Patients with IDDM demonstrate abnormal color vision and contrast sensitivity compared with the control group (P < 0.05), but visual acuity was unaffected. Visual functions were not significantly different between those IDDM patients with and without retinopathy. After 4 years, diabetic retinopathy was present in 43% of the group and was related to diabetes duration and metabolic control (P < 0.05). CONCLUSIONS: Visual function testing could not distinguish between those IDDM patients with and without retinopathy, but the color vision and contrast sensitivity in those with IDDM were significantly impaired compared with the control group. The presence of retinopathy was related to the duration of diabetes and metabolic control. It is important to ensure that good glycemic control and regular attendance for retinopathy screening is encouraged in the adolescent patients.

Adolescent↗
PubMed2004

Variant phenotypes of incomplete achromatopsia in two cousins with GNAT2 gene mutations.

PURPOSE: The present study was designed to elucidate the molecular genetic basis of a congenital stationary cone dysfunction characterized by congenital nystagmus, moderate visual impairment, and markedly disparate color vision deficiencies between two affected cousins. METHODS: Ophthalmic examinations with emphasis on color vision and electrophysiology. Molecular genetic analysis of the X-linked cone opsin genes, mutation screening of the CNGA3, CNGB3, and GNAT2 genes, and heterologous splicing experiments. RESULTS: Whereas the proband was found to carry a homozygous frameshift mutation (Tyr95fs) in GNAT2, her cousin was compound heterozygous for the Tyr95fs and a new intronic mutation c.461 + 24G-->A. Heterologous expression in COS7 cells showed that the latter causes a splicing defect that results in early translation termination. Yet, this mutation is leaky, giving rise to small amounts of correctly spliced transcripts and offer an explanation for the diverging clinical findings in the cousins, one best described as incomplete achromatopsia and the other with oligocone trichromacy. CONCLUSIONS: The cases presented broaden the phenotypic spectrum of GNAT2 mutations and underline the increasing importance of molecular genetics in the clinical diagnosis of atypical ophthalmic phenotypes.

Adolescent↗
PubMed2005

Vision requirements for driver's license examiners.

PURPOSE: The purpose of this study was to determine the vision requirements for licensing and registration examiners (LREs) of motor vehicle drivers in the state of California. METHODS: A comprehensive investigation was conducted that included a literature review, consideration of the Americans with Disabilities Act, analysis of materials with a subject matter expert panel, an overview of visual function tests, a formal job analysis, job audits and site visits to licensing offices, analysis of accidents and critical incidents, performance of simulation studies, and a review and evaluation of all materials collected during the study. RESULTS: Based on this analysis, three visual functions (best-corrected visual acuity, peripheral visual field extent, and color vision) were determined to be important for performing the essential job functions of an LRE. It was recommended that LREs demonstrate a best-corrected visual acuity of at least 20/20 in each eye, a peripheral visual field of at least 100 degrees diameter of horizontal and vertical extent in each eye (with no evidence of scotomas or pathologic areas of nonseeing within the visual field), and color vision capabilities that permit a passing score on the Farnsworth Panel D-15 color vision test. DISCUSSION: The findings of this investigation provide a strong basis for specifying and justifying vision requirements for performing essential job functions for an LRE in the state of California.

Adult↗
PubMedDate not supplied

Visual function in young adults following intrauterine growth retardation.

BACKGROUND: Intrauterine growth retardation (IUGR) resulting in infants born small for gestational age is a known risk factor for neurologic deficits and may predispose to poor cognitive development later in life. We recently found an association between IUGR and a reduced neuroretinal rim area at 18 years of age. We evaluated the possible association between IUGR and visual function. SUBJECTS AND METHODS: We studied 26 subjects who had been born small for gestational age and 20 subjects whose birth weights were appropriate for gestational age (controls) using letter acuity thresholds, color vision testing, full-threshold frequency doubling technology perimetry, and rarebit perimetry at 18 years of age. gestational age had a rarebit hit rate below the normal range as compared with none of the controls (P = .006). These 8 subjects had a significantly smaller rim-disc ratio compared with the subjects who were small for gestational age who had a normal rarebit hit rate (P = .047). The frequency doubling technology indices did not differ significantly between the control group and the group that was small for gestational age, nor did the visual acuity, refraction, and color vision test results. CONCLUSION: These data indicate that IUGR is associated with an increased rate of impaired visual function, which can be detected by using rarebit perimetry but not frequency doubling technology perimetry, visual acuity, or color vision tests.

Adolescent↗
PubMed2006

Color discrimination in the red range with only one long-wavelength sensitive opsin.

The basic precondition for color vision is the presence of at least two receptor types with different spectral sensitivities. The sensitivity of a receptor is mostly defined by the opsin-based visual pigment expressed in it. We show here, through behavioral experiments, that the nymphalid butterfly Heliconius erato, although it expresses short and medium wavelength opsins and only one long wavelength opsin, discriminates colors in the long-wavelength range (590 nm, 620 nm and 640 nm), whereas another nymphalid, Vanessa atalanta, despite having color vision, is unable to do so. In the eyes of H. erato we identified filtering pigments very close to the rhabdom which differ between ommatidia and produce the yellow and red ommatidial reflection seen under orthodromic illumination. The eyes of V. atalanta lack the filtering pigments, and reflect a homogeneous orange. We hypothesize that the filtering pigments found in the eyes of H. erato may shift the spectral sensitivity peak of the long wavelength receptors in some ommatidia towards longer wavelengths. The comparison of the signals between the two new receptor types makes color discrimination in the red range possible. To our knowledge, this is the first behavioral proof of color vision based on receptors expressing the same opsin.

Animals↗
PubMed2002

Trichromacy in Australian marsupials.

Vertebrate color vision is best developed in fish, reptiles, and birds with four distinct cone receptor visual pigments. These pigments, providing sensitivity from ultraviolet to infrared light, are thought to have been present in ancestral vertebrates. When placental mammals adopted nocturnality, they lost two visual pigments, reducing them to dichromacy; primates subsequently reevolved trichromacy. Studies of mammalian color vision have largely overlooked marsupials despite the wide variety of species and ecological niches and, most importantly, their retention of reptilian retinal features such as oil droplets and double cones. Using microspectrophotometry (MSP), we have investigated the spectral sensitivity of the photoreceptors of two Australian marsupials, the crepuscular, nectivorous honey possum (Tarsipes rostratus) and the arhythmic, insectivorous fat-tailed dunnart (Sminthopsis crassicaudata); these species are representatives of the two major taxonomic divisions of marsupials, the diprotodonts and polyprotodonts, respectively. Here, we report the presence of three spectrally distinct cone photoreceptor types in both species. It is the first evidence for the basis of trichromatic color vision in mammals other than primates. We suggest that Australian marsupials have retained an ancestral visual pigment that has been lost from placental mammals.

Animals↗
PubMed1994

Solvents and color discrimination ability. Nonreplication of previous findings.

Previous research has shown exposure-related increases in the prevalence of acquired color vision deficits among printers. We administered the Lanthony D-15 desaturated test of color vision to 82 print shop workers. Two tests of cognitive function, Trails A and B and the Symbol Digit Modalities Test, were also administered. Personal air sampling indicated that current exposure to organic solvents was highest among printers and lowest among bindery workers. In contrast to previous studies, the age-adjusted quantitative Lanthony D-15 desaturated test error scores did not differ significantly between exposure groups, and the proportion of subjects with > or = 1 error was greater in the lower-exposure, rather than higher-exposure, groups (P = .03). Of note, the proportion of subjects with > or = 2 errors did not differ significantly between groups (P = .24). Cognitive tests showed no significant association with exposure. These results are discussed in the context of methodological issues related to lighting sources, reliability of test results, and establishment of criteria for identifying deficits.

Adult↗
PubMed2005

Behavioral deficits and cortical damage loci in cerebral achromatopsia.

Lesions to ventral occipital cortex can produce severe deficits in color vision, a syndrome known as cerebral achromatopsia. Because most studies examine relatively few cases, however, uncertainty remains about precisely which cortical loci, when damaged, produce the syndrome. In addition, the extents of the associated perceptual deficits remain unclear. To address these issues, we performed a meta-analysis of 92 case reports from the literature. The severity of color vision deficits of the cases varied greatly, although nearly all showed some deficit in color discrimination. Almost all cases tested also showed some loss of spatial vision. Lesion overlap analyses revealed a relatively small region of high overlap in ventral occipital cortex. The region of high overlap was located near areas identified by neuroimaging studies as important for color perception. For comparison, we performed a similar analysis of prosopagnosia, a disorder of face perception, and found several regions of high lesion overlap adjacent to the region associated with achromatopsia. Because the behavioral deficits in achromatopsia are often incomplete and never restricted to color vision, the region of high lesion overlap may be one critical stage within a stream of many visual areas that participate nonexclusively in color perception.

Cerebral Cortex↗
PubMedDate not supplied

[The characteristics of the color perceptive space in protanomals].

Color vision of three protanomal subjects was studied by means of direct paired comparison technique using 25 colors with different brightness. It was shown that the characteristics of their color vision could be completely and adequately described in the frames of the four-dimensional spherical model of color perception. The spatial axes could be identified as the two color-opponent mechanisms (red-green and blue-yellow) and the two achromatic mechanisms (brightness and darkness). Deformation of the color axes in protanomals (as compared with the normal trichromatics) was demonstrated in the "red" and "yellow" spectral region. The visual disturbance in protanomal subjects involves not only color but also achromatic mechanisms. This is manifested in the a deformation of perceptual brightness scale. In comparison with normal trichromatic subjects, the protanomals perceive the red and adjacent colors as achromatic while green, yellow-green, and orange as more bright but low-saturated colors.

Adolescent↗
PubMed1988

Dysthyroid optic neuropathy. The crowded orbital apex syndrome.

The authors have reviewed the clinical presentation, visual fields, color vision testing, visual-evoked potentials, and computed tomographic (CT) findings of 58 patients (95 eyes) with dysthyroid optic neuropathy. The authors compared these findings to a control group of 60 patients (119 eyes) with thyroid eye disease who underwent CT scanning and did not exhibit evidence of optic neuropathy. Clinically, dysthyroid optic neuropathy is an insidious disease; when compared with the usual Graves' orbitopathy patient, the optic neuropathy group presented at a later age and with a later onset of thyroid eye disease. The patients in this group were more likely to be male and/or diabetic, and often presented with desaturation of color vision. Asymmetrical extraocular muscle restriction and vertical tropias were more frequent in the optic neuropathy group. The most sensitive indicators of optic nerve dysfunction appeared to be visual-evoked potentials and color vision. Computed tomographic studies confirmed that apical orbital crowding was a characteristic feature of optic neuropathy. These findings should alert the clinician to a more aggressive approach to these patients.

Adult↗
PubMed1990

[The Ohkuma's test: an evaluation].

Ohkuma's pseudoisochromatic test was evaluated in 147 subjects including 130 cases with hereditary dyschromatopsias, and compared with the color vision tests of Ishihara, the HRR, the Farnsworth Panel D-15 and the City University Color Vision Test. Qualitatively, Ohkuma's test was more exact for the diagnosis of the axis of the dyschromatopsia (protan or deutan); quantitatively, Ohkuma's test was of good efficiency for screening, but the quantitative gradation was mediocre, indicating dichromatism in only 3/4 of the cases.

Adolescent↗
PubMed2006

A low-power, LED-based, high-brightness anomaloscope.

Color matches made with a Nagel anomaloscope are used in the differentiation of color vision deficiencies. When these color matches are made over a wide range of retinal illuminances, the changes in the color match provide information about the regeneration kinetics and the absorption spectra of the middle- and long-wavelength cone photopigments. These steady-state color matches vary with a variety of conditions, and may have value in screening for eye disease. Recently, high-brightness LEDs have become available that allowed us to construct a LED-based, high-brightness anomaloscope. We used inexpensive, low-energy components to replicate an earlier instrument, getting a maximum retinal illuminance over 5.6 log Trolands.

Adaptation, Ocular↗
PubMed1980

The status of color fields today.

Pathology of the visual system can alter perception in the central and peripheral visual field. Pseudoisochromatic plates and pigment panel tests can be used to study macular color vision. Perimetric techniques using color targets extends testing to the peripheral field. This facilitates detection of early, sometimes subtle defects that are missed with conventional white-target perimetry. The stimulus conditions and methods of color perimetry are reviewed in this paper, particularly recent methodological advancements which offer a potential for increased sensitivity in detection of pathology.

Color Perception↗
PubMed2006

Choroideremia: variability of clinical and electrophysiological characteristics and first report of a negative electroretinogram.

PURPOSE: To analyze the variability of clinical and electrophysiological characteristics in X-linked choroideremia and provide the first report of a negative electroretinogram in choroideremia. DESIGN: Retrospective study. PARTICIPANTS: The records of 18 male patients with choroideremia and 8 female carriers were evaluated. METHODS: The data were reviewed regarding visual acuity (VA), color vision, perimetry, fundus autofluorescence, and full-field electroretinography (according to standards of the International Society for Clinical Electrophysiology of Vision). MAIN OUTCOME MEASURES: Morphological and functional phenotype characteristics, fundus autofluorescence, electroretinography, and Rab escort protein 1 (REP-1) mutations. RESULTS: Four unrelated families with choroideremia (9 affected males, 7 carriers) and 10 unrelated individuals (9 affected males, 1 carrier) were included. Mutational analysis, performed in 2 families and 3 individual males, revealed REP-1 mutations in all except 1 male. The age of the males ranged from 5.9 to 63.0 years (mean, 33.9), and VA ranged from hand movements to 1.0 (median, 0.7). Fundus autofluorescence (n = 7) showed defects in the retinal pigment epithelium in all males. Electroretinography (n = 13) was almost undetectable in 6 males and reduced in 6, indicating a rod-cone dystrophy. A further male showed a negative electroretinogram, with a b:a wave ratio of 0.5. Visual acuity of the 8 carriers (age, 4.8-56.8 years [mean, 24.0]) ranged from light perception to 1.2 (median, 1.0). Light perception was present in 1 carrier manifesting choroideremia with distinct chorioretinal atrophy. Pigmentary stippling, seen in the other carriers, was seen in fundus autofluorescence (n = 1) with a distinct speckled pattern. Electroretinograms were normal in 6 of 7 and reduced in the manifesting carrier. Defects in color vision and visual field were found in affected males and in the female carriers. CONCLUSIONS: The phenotype of choroideremia presents with high variability. In addition to the previously reported findings, we observed a negative electroretinogram, indicating a postreceptoral retinal dysfunction, in 1 affected male; severe course of choroideremia with early blindness in 1 manifesting carrier; color vision deficits in the majority of affected males and carriers; and characteristic alterations in fundus autofluorescence.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Predicting Farnsworth Lantern success with a six-plate series of the Ishihara pseudoisochromatic plates.

The Farnsworth Lantern (FALANT) is the definitive color vision test for the Navy, Marine Corps, and Coast Guard. It is also the definitive color vision test for aviation personnel in the Army. Results from it are also accepted by the Federal Aviation Administration. For various reasons, it is desirable to have an alternative test that can predict success (i.e., a passing score) on the FALANT. In 1991, it was shown that a 14-plate series of Ishihara pseudoisochromatic plates could predict FALANT success provided the proper passing criteria was chosen. Interest has arisen regarding whether or not a 6-plate series of Ishihara plates can predict FALANT success. A study was undertaken to answer this question. It appears that a 6-plate series of Ishihara pseudoisochromatic plates can predict FALANT success.

Adolescent↗
PubMed2004

Multifocal electroretinographic evaluation of long-term hydroxychloroquine users.

OBJECTIVES: To observe the long-term effects of hydroxychloroquine sulfate on retinal electrical activity by multifocal electroretinography (mfERG) and to evaluate the regional variation of retinal dysfunction in subjects with hydroxychloroquine retinopathy. METHODS: Multifocal ERG with 103-hexagon stimulation was performed on 19 patients (36 eyes) treated with hydroxychloroquine for systemic lupus erythematosus, rheumatoid arthritis, or localized atypical scleroderma. Visual acuity testing, Amsler grid testing, and Ishihara color vision testing were also performed. In 2 of the patients, hydroxychloroquine was discontinued due to concerns about toxicity. Both of these patients had additional mfERG performed after discontinuation of medication. RESULTS: Twelve patients (19 eyes) had a normal response density in one or both eyes, including 6 patients (12 eyes) with a low lifetime dose (< or =438 g) of hydroxychloroquine who had normal response densities in both eyes. Eleven patients (17 eyes) had abnormal response densities in one or both eyes, and 2 of these patients (4 eyes) had significant attenuation of response densities in almost the whole tested field; 4 patients had a normal mfERG result for one eye but had a slight decrease of response densities for the other eye. There were 4 patterns of abnormal mfERG amplitude change observed: (1) paracentral loss, (2) foveal loss, (3) peripheral loss, and (4) generalized loss. Implicit times were abnormal for pericentral responses in 3 patients. The results of color vision and Amsler grid testing were normal, except for one patient with a generalized loss pattern. In 2 subjects in whom hydroxychloroquine toxicity was suspected, response densities improved after termination of hydroxychloroquine. CONCLUSIONS: Long-term hydroxychloroquine use may be associated with mfERG abnormalities. The mfERG appears to detect retinal physiological change earlier than visual acuity testing, color vision testing, or Amsler grid testing can. The greatest value of the mfERG is in differentiating a retinal cause and, hence, providing important evidence for hydroxychloroquine toxicity, for whatever visual field loss is apparent on perimetry.

Adult↗