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Results for “Color Vision Defects”

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PubMed1976

The inheritance of affective disorders: a review of data and of hypotheses.

A genetic factor in affective disorders is suggested by twin and family history studies. The form of disorder (BP or UP) is transmitted within families. Early onset of affective disorder is associated with increased morbid risk of the disorder in relatives, but age at onset is not itself a transmitted factor. Female relatives have higher prevalence of illness, but sex of the ill person does not appear to be a factor in transmission. Genetic models of multifactorial or single-gene autosomal inheritance are compatible with some but not all of the family history studies reported. The hypothesis of sex-linked transmission of BP illness has been proposed, and some pedigrees compatible with X-linkage have been reported, but family studies do not suggest that this is generally present. Other possible modes of inheritance remain to be tested. Investigative strategies for identification of the "affective genotype" are discussed on the basis of biochemical, pharmacological, or other characteristics of persons with the disorders and their relatives, and on the basis of studies of known linkage markers.

Age Factors↗
PubMed1977

A study of X chromosome linkage with field dependence and spatial visualization.

The purposes of this report are to describe a design for the study of X linkage, to illustrate its application using cognitive test scores, and to offer a linkage hypothesis suggested by these data. Sixty-seven three-son families were examined for two X chromosome marker variables--red-green color vision and Xg(a) blood groups--and given a battery of cognitive tests of field dependence and spatial visualization abilities. Evidence was found to suggest that brothers who are identical in Xg(a) phenotype are more similar to each other in extent of field dependence than brothers who are different in Xg(a) phenotype. This result is tentative because of the small number of informative cases and the many linkage associations examined. If cross-validated, such a finding would be consistent with the proposition that an X chromosome gene contributes to the field dependence cognitive style.

Blood Group Antigens↗
PubMed1993

Cone dysfunction and supernormal scotopic electroretinogram with a high-intensity stimulus. A report of three cases.

An unusual form of scotopic electroretinogram with a bright white stimulus, which consisted of a rectangular a-wave of normal amplitude and a b-wave of supernormal amplitude, was recorded in three patients with cone dysfunction. In addition to poor visual acuity, abnormal color vision and reduced amplitude of the photopic electroretinogram, these patients showed a 2-log unit elevation of the dark-adaptation threshold. Funduscopic examination and fluorescein angiography revealed fine granular pigment disturbances at the macula. The relationship between the response of the dark-adapted electroretinogram versus stimulus intensity was unique to these patients. The b-wave thresholds were elevated by 1 log unit. The b-waves were reduced in amplitude and markedly delayed in implicit time to dim stimuli, but supernormal in amplitude and normal in implicit time to bright stimuli.

Adolescent↗
PubMedDate not supplied

Reappraisal of a short-wavelength-sensitive (S-cone) recording technique in routine clinical electroretinography.

The recording of blue cone (S-cone) responses as described by Gouras and MacKay was slightly modified and incorporated into our routine ganzfeld electroretinogram protocol. We found a mean S-cone amplitude of 5.0 microV (range 2.9-6.9 microV) and a mean S-cone implicit time of 41.5 msec (range 40-46 msec). Separation between the combined red and green cone (L-M-cone) response and the S-cone response was obtained with blue flash stimuli on a yellow adapting background.

Adolescent↗
PubMed1985

Eye movement abnormalities in rod monochromatism and blue-cone monochromatism.

Eye movements were recorded with electro-oculography in seven patients with rod monochromatism (RM) and five with blue-cone monochromatism (BCM). The continuous horizontal nystagmus was similar in both groups. However, three patients with BCM demonstrated an intermittent, high-frequency nystagmus, in addition to the continuous nystagmus. The most striking differences between the groups were present during monocular smooth pursuit and optokinetic tracking. Patients with RM demonstrated better tracking when targets moved in the temporal-to-nasal (T-N) direction in the visual field of the viewing eye, than when targets moved in the nasal-to-temporal (N-T) direction. The velocity of optokinetic nystagmus (OKN) increased gradually over several seconds during T-N target movement. Patients with BCM did not show a directional asymmetry or a slow build-up of OKN during monocular tracking. Differences in eye movement abnormalities can be useful in differentiating these two forms of congenital color blindness from other forms of congenital nystagmus and from each other.

Adolescent↗
PubMed1982

Classification of complete and incomplete autosomal recessive achromatopsia.

We studied color vision in 32 patients with autosomal recessive achromatopsia. Color matching revealed complete achromatopsia (rod monochromasy) in ten patients (Group I) and incomplete achromatopsia in the remaining twenty-two patients. Amongst the incomplete achromats, were three groups distinguishable by their color matching. Patients in Group II were dichromats; their color matches were mediated by rods and MWS (middle-wavelength sensitive) cones. Patients in Groups III and IV were trichromats. Color matches of patients in Group III were mediated by rods, LWS (long-wavelength sensitive) cones and MWS cones. Group III patients showed no evidence of SWS (short-wavelength sensitive) cones. Color matches of patients in Group IV were mediated by rods, LWS cones and SWS cones; color matching did not reveal MWS cones.

Adolescent↗
PubMed1996

Acetazolamide affects performance on the Nagel II anomaloscope.

BACKGROUND: Recent reports have indicated that acetazolamide alters human electroretinograms. We wished to determine the effects of administering acetazolamide on performance on the Nagel II anomaloscope. METHODS: We tested 15 subjects matches of blue-green light to a mixture of blue and green lights (luminance match) on a Nagel type II anomaloscope 2.5 h after ingesting 500 mg of acetazolamide or a placebo. RESULTS: The mean of the luminance settings for the subjects was 54.4 for the placebo condition and 58.5 for the acetazolamide condition. The mean difference of 4.1 was statistically significant, indicating that following ingestion of acetazolamide subjects were less sensitive to a blue-green light. In two supplementary experiments we tested (1) a second group of four normal subjects using the Nagel type II anomaloscope and (2) the previously untreated eyes of four patients with primary open-angle glaucoma before and after placing them on acetazolamide therapy. In both groups, more blue-green light was needed to make the match after ingestion of acetazolamide. CONCLUSIONS: Acetazolamide alters the sensitivity of one or more cone populations, probably the carbonic anhydrase-containing cones. The sensitivity loss is reversible and does not appear to be clinically significant. However, the results suggest that patients administered acetazolamide should be excluded from studies which compare the color vision of glaucomatous patients to that of normals.

Acetazolamide↗
PubMed1996

Molecular genetics of human color vision.

The significant advances in our understanding of color vision has been due to the convergence of information from behavioral and molecular genetic analyses. The molecular biology of the visual pigments; molecular genetic basis of variation in normal and abnormal color vision, and regulation of the genes at the LWS-MWS pigment gene locus are discussed.

Animals↗
PubMed1975

[Acquired and congenital monocular pendular nystagmus. A comparative electronystagmographic study of two cases (author's transl)].

Comparative analysis of two cases of monocular pendular nystagmus (MPN). The nystagmus was acquired in one case of multiple sclerosis, and congenital in the other patient who had achromatopsia. A postsaccadic inhibition of 0.6-1 sec duration was seen only in the case of acquired MPN. All the other characteristics of the acquired and congenital monocular nystagmus were identical. The waveform of the nystagmus was sinusoidal, triangular or mixed. There was no modification of the MPN by eye position or by smooth pursuit. The nustagmus was inhibited by lid closure. Oscillopsia was reported by both patients. A peculiar disturbance of the sensorimotor feedback loop of the visual system is discussed as the possible common pathogenesis of acquired and congenital pendular nystagmus.

Cerebral Cortex↗