Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Children with autism demonstrate "atypical" gaze or social "looking" and frequently manifest such sterotypies as eye pressing, hand flicking, and light gazing. This study's purpose was to evaluate autistic children for visual dysfunction that may be related to the manifested visual signs and symptoms. Thirty-four autistic children, ages 2 to 11 years (median age = 7 years, 6 months) were evaluated for ocular alignment, refractive error, visual acuity, oculomotility skills, and stereopsis. None of the children manifested ocular disease, known seizure disorders, or dysmorphic features. Their developmental levels ranged from average intelligence to severely retarded. Binocular visual acuity was measured with the acuity card procedure. Monocular visual acuity was not obtained. Refractive errors ranged from -4.25 to +3.25 D; the median was plano with the near retinoscopy technique. Of the 34 children, 21% were strabismic at far and 18% were strabismic at near. Lang stereo testing was attempted on all children and completed on 17. Of the 17, all but 3 exhibited 550 sec arc. Only 14.7% of the children exhibited voluntary pursuit movements, and all the children demonstrated saccadic fixations. Thirty-one children had atypical optokinetic nystagmus (OKN) responses such as delayed onset, short duration, gaze avoidance, or stereotypic behavior. Repeated testing revealed consistent visual responses on OKN and visual acuity. Given these findings, research with this population should be pursued further.
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PMID:Assessment of visual function in autistic children. 164 Dec 24

In recent years, the ophthalmic examination of infants has been of increasing interest to both clinicians and vision researchers. Clinicians have documented a greater risk of retinopathy, strabismus and amblyopia in premature infants, especially those of low birthweight. In addition to the external and retinal examination of the infant eye, a number of clinical tests can help the ophthalmologist to detect visual dysfunction through the evaluation of pupillary responses and ocular motility. Recently, the development of objective techniques (optokinetic nystagmus, forced choice preferential looking, and visually evoked potentials) have not only aided in the detection of ophthalmic disorders in infants; they have contributed to useful definitions of "normal" vision at various ages and to the understanding of factors that influence the pre- and post-gestational development of visual function.
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PMID:Ophthalmological examination of the infant. Developmental aspects. 704 6

Retinal bipolar cells receive glutamatergic transmission from photoreceptors and mediate a key process in segregating visual signals into ON-center and OFF-center pathways. The segregation of ON responses involves a G protein-coupled metabotropic glutamate receptor (mGluR). The mGluR6 subtype is expressed restrictedly at the postsynaptic site of retinal ON-bipolar cells. Ablation of mGluR6 in the ON-bipolar cells by gene targeting results in a loss of ON responses but unchanged OFF responses in visual transmission. Thus, mGluR6 is essential for inducing ON responses. The aims of this study are analyses of visual responsiveness and possible visual dysfunction in mGluR6-deficient mice. We report here that mGluR6-deficient mice have unaltered locomotor activity in a daily light-dark cycle and exhibit light-stimulated induction of Fos immunoreactivity in the suprachiasmatic nucleus. These findings indicate that mGluR6-deficient mice are capable or responding to light stimulation. The mGluR6 deficiency, however, markedly reduces the sensitivity of pupillary responses to light stimulus and severely impairs the ability to drive optokinetic nystagmus in response to visual contrasts. This study thus demonstrates that mGluR6 contributes to discrimination of visual contrasts.
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PMID:Impairment of pupillary responses and optokinetic nystagmus in the mGluR6-deficient mouse. 914 50

Total colourblindness (OMIM 216900), also referred to as rod monochromacy (RM) or complete achromatopsia, is a rare, autosomal recessive inherited and congenital disorder characterized by photophobia, reduced visual acuity, nystagmus and the complete inability to discriminate between colours. Electroretinographic recordings show that in RM, rod photoreceptor function is normal, whereas cone photoreceptor responses are absent. The locus for RM has been mapped to chromosome 2q11 (ref. 2), however the gene underlying RM has not yet been identified. Recently, a suitable candidate gene, CNGA3, encoding the alpha-subunit of the cone photoreceptor cGMP-gated cation channel, a key component of the phototransduction pathway, has been cloned and assigned to human chromosome 2q11 (refs 3,4). We report the identification of missense mutations in CNGA3 in five families with RM. Homozygous mutations are present in two families, whereas the remaining families show compound heterozygous mutations. In all cases, the segregation pattern of the mutations is consistent with the autosomal recessive inheritance of the disease and all mutations affect amino acids that are highly conserved among cyclic nucleotide gated channels (CNG) in various species. This is the first report of a colour vision disorder caused by defects other than mutations in the cone pigment genes, and implies at least in this instance a common genetic basis for phototransduction in the three different cone photoreceptors of the human retina.
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PMID:Total colourblindness is caused by mutations in the gene encoding the alpha-subunit of the cone photoreceptor cGMP-gated cation channel. 966 98

The immature visual system is vulnerable to adverse events. Periventricular leukomalacia (PVL), an end-stage lesion after hypoxia-ischemia at gestational age 24-34 weeks affecting the visual radiation, has become a principal cause of visual impairment in children. Cerebral visual dysfunction caused by PVL is characterized by delayed visual maturation, subnormal visual acuity, crowding, visual field defects, and visual perceptual-cognitive problems. Magnetic resonance imaging is the method of choice for diagnosing this brain lesion, which is associated with optic disk abnormalities, strabismus, nystagmus, and deficient visually guided eye movements. Children with PVL may present to the ophthalmologist within a clinical spectrum from severe visual impairment in combination with cerebral palsy to only early-onset esotropia, normal intellectual level and no cerebral palsy. Optimal educational and habilitational strategies need to be developed to meet the needs for this group of children.
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PMID:Visual and perceptual characteristics, ocular motility and strabismus in children with periventricular leukomalacia. 1222 99

OPA1 mutations are known to cause autosomal dominant optic atrophy (ADOA), and some types of OPA1 mutations also cause auditory neuropathy. In the present study, we evaluated the vestibular dysfunction that accompanied auditory neuropathy in a patient with an OPA1 mutation. A caloric test failed to elicit nystagmus or dizziness in either ear. Vestibular evoked myogenic potentials (VEMPs) in the right ear were characterized by a normal biphasic waveform. In contrast, no VEMPs were evoked in the left ear. Model building suggested that the OPA1 mutation, p.R445H, indirectly distorts the catalytic structure of the GTPase reaction center and decreases GTPase activity. The patient complained of instability while walking or moving but thought these symptoms were caused by visual dysfunction. This is the first report of a detailed evaluation of vestibular dysfunction in a patient with an OPA1 mutation. This case suggests that vestibular dysfunction may be involved in motor instability in patients with an OPA1 mutation, even when patients do not complain of vestibular symptoms. Based on this case, we suggest that vestibular evaluation should be performed in auditory neuropathy patients carrying an OPA1 mutation, even if the patients are free of symptoms of vestibular dysfunction.
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PMID:Vestibular dysfunction in a Japanese patient with a mutation in the gene OPA1. 2038 91

Dissociated vertical deviation (DVD), a vertical strabismus, is often associated with infantile esotropia, latent nystagmus and excyclo-torsion. DVD usually becomes apparent at about three years of age. The authors wished to determine whether DVD is a manifestation of an abnormal motor vergence system or is part of a visual system disorder. Vertical eye movements of six subjects with DVD, on cover-uncover and alternate cover tests, were studied using the magnetic search eye coil system. Asymmetry between the eyes' saccades were quantified during the DVD upward movement and during a trial of pure vertical saccades. In three subjects the vertical deviation increased to its full amount through a smooth vertical divergence movement, and in the other three patients through a combination of smooth and asymmetrical saccade-like movements. The latencies of the DVD, the peak velocity of the deviation movements, its time constant and the asymmetries in the saccades suggest that DVD represents an abnormal vertical vergence system.
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PMID:Dissociated vertical deviation (DVD): The saccadic and slow eye movements. 2131 45

Abnormal eye movements in multiple sclerosis (MS) are often persistent and known to be associated with general disability. However, there is no precise knowledge concerning their incidence and resulting visual handicap. The aim of our study was to describe the persistent ocular motor manifestations in MS and relate them to visual functions tested with visual acuity and with a vision-related questionnaire. We selected 24 MS patients complaining of persistent visual disability associated with ocular motor manifestations without any anterior visual pathway deficit. Internuclear ophthalmoplegia was the most frequently observed symptom, followed by gaze-evoked nystagmus, saccadic hypermetria, and then pendular nystagmus. Pendular nystagmus, saccadic hypermetria, and the association of internuclear ophthalmoplegia and gaze-evoked nystagmus were associated with decreased visual acuity and visual functional scores. There was a correlation between the number of abnormal eye movements and visual functions. This study demonstrates that ocular motor dysfunction in MS induces specific visual dysfunction and handicap.
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PMID:Persistent ocular motor manifestations and related visual consequences in multiple sclerosis. 2195 Oct 12

Uniplanar nystagmus has been described in relation to pathology of the brain stem, retina, optic nerve, sensory visual deprivation, periventricular leucomalacia, and drug toxicity. This paper describes a case of uniplanar nystagmus associated with features of higher visual dysfunction and a presumed focal insult to the occipital lobes following an episode of neonatal apnea.
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PMID:Uniplanar Nystagmus Associated with Perceptual and Cognitive Visual Dysfunction due to Presumed Focal Ischemic Occipital Cortical Atrophy: A Missed Diagnosis and New Observation. 2305 80

A developmentally normal infant presented with repeated episodes of afebrile status epilepticus following nutmeg ingestion. He had developed two episodes of afebrile status epilepticus and had received different treatments earlier, but the details of treatment were not available. On admission, he redeveloped convulsions and loading doses of phenytoin, phenobarbitone and midazolam were administered. However, seizures persisted and extrapyramidal movements, nystagmus and visual dysfunction were noted. Iatrogenic phenytoin toxicity was considered and confirmed by drug levels. His symptoms completely disappeared after discontinuation of phenytoin therapy. The initial seizures were attributed to myristicin, an active component of nutmeg, because of the temporal association. However, the subsequent seizures were due to phenytoin toxicity caused by administration of multiple loading doses. This case highlights that nutmeg, a spice, can cause serious toxic effects like status epilepticus. Furthermore, treatment of status epilepticus with phenytoin can cause iatrogenic seizures due to its narrow therapeutic range.
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PMID:Myristicin and phenytoin toxicity in an infant. 2490 24


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