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At least 433 records · Page 24Linked to original sources
PubMed1992

[Unusual pathological ocular movement caused by dysfunction of the saccade generation mechanism].

We describe a patient with abnormal ocular movement, probably due to dysfunction of saccade generation mechanism in the lower pons involving the omnipause neuron and a feed-back circuit. A 26-year-old man had fever, mild headache and sore throat for a few days and also noted unstable gait and diplopia. These symptoms subsided, but he noticed oscillopsia about 2 months later. On admission in our hospital, the neurological examination revealed no abnormalities except for abnormal eye movements, which were induced by voluntary or involuntary ocular movement and lasted for a few minutes. The abnormal ocular movement was irregular in direction, amplitude and rhythmicity, and the voluntary and involuntary ocular movements could not be elicited during the period of this abnormal ocular movement. The abnormal ocular movement completely disappeared for about 1 hour by intravenous injection of TRH. At this time bilateral mild abducens palsy was demonstrated by EOG examination. The abnormal ocular movement in this patient, which has nerve been reported in the literature, was considered to be due to a disinhibition of excitatory burst neuron (EBN) caused by the dysfunction of omnipause neuron, and possibly due to a delay of feed-back information of saccade to the EBN.

Abducens Nerve↗
PubMedDate not supplied

Experimental and clinical studies on corneal grafts from donors dying of drug overdose: a review.

In order to determine whether or not corneal tissues from donors dying of drug overdose are safe to be used as grafts, animal experiments and a small retrospective clinical study (in which the patients received corneal grafts from donors dying of drug overdose) were done. In rabbits, the drug (ethanol, phenobarbital, pentobarbital, methyprylon, salicylate, or morphine) was injected intravenously in one lethal or sublethal dose. The quantity of the agent was determined in various eye tissues using appropriate techniques. Rabbits were also grafted interlamellarly with full-thickness corneas from animals dying from drug overdose. Concentrations of the agent that reduced cellular proliferation and protein synthesis to 50% were determined using corneal cell culture. Chemical analysis of some eyes of Coroner's cases was done. In animals, all grafts carried the drug to the recipient eye, but none of them (except a few from donors killed with phenobarbital) became opaque or produced any abnormal eye reaction. Only salicylate was found in the cornea and aqueous humor of the drugged animals in a cytotoxic concentration, but only for a short time. Ethanol was found in human eyes for up to 4 days. Clinical investigation revealed no obvious relationship between graft failure and drug content of the donor's blood.

Animals↗
PubMed2001

Reduced binocular beat visual evoked responses and stereoacuity in patients with Duane syndrome.

PURPOSE: To study the effects that the abnormal eye movements of patients with Duane retraction syndrome have on the development of binocular function. METHODS: Pattern reversal visual evoked responses (VEPs) to 15-minutes-of-arc and 60-minutes-of-arc checks and binocular beat VEPs to diffuse sinusoidally modulated 18- and 20-Hz stimuli were recorded in 10 patients with Duane retraction syndrome who maintain binocular function by using an abnormal head posture. Visual acuity, stereoacuity, and eye movements were measured. The results have been compared to those from 10 normal subjects. RESULTS: The patients with Duane retraction syndrome had reduced stereoacuity compared to the normal control group (TNO mean, 82.5 seconds of arc compared to 37.5 seconds of arc; Titmus mean, 143 seconds of arc compared to 44 seconds of arc). The binocular beat VEPs showed a significantly reduced difference beat response at 2 Hz in the patients with Duane syndrome compared to normal subjects (mean signal-to-noise ratio 2.40 +/- 1.05 compared to 4.30 +/- 2.66; t = 2.21, df = 18, P < 0.05). Binocular enhancement of the P100 pattern reversal amplitude to 15-minute checks was increased in these patients, because of a reduction of the monocular P100 amplitudes compared to the normal group. CONCLUSIONS: Patients with Duane syndrome who maintain binocular function using an abnormal head posture have reduced stereoacuity and show electrophysiological evidence of reduced cortical binocular interaction.

Adolescent↗
PubMed1977

Eccentric head positions reveal disorders of conjugate eye movement.

The effect of head position on conjugate horizontal gaze was studied in healthy adults, in patients with multiple sclerosis without eye movement signs, and in patients with downbeat nystagmus indicative of low brain stem lesions. Displacements of gaze from primary position to 30 degrees left and right were recorded using the electro-oculogram, with the head in the primary position, and turned voluntarily to the left and right (in yaw). The quality of eye movements was noted and peak velocities of saccades were measured. The head turning test trebled the incidence of abnormal eye movements found in the multiple sclerosis patients and increased it by tenfold in the patients with downbeat nystagmus. Disorders of eye movement were also found in approximately 20--30% of healthy subjects tested. Weakness of abduction was the most common eye movement defect and appeared to be posterior internuclear ophthalmoplegia. A hypothesis is made which unifies the theoretical explanations of anterior and posterior internuclear ophthalmoplegia. The most likely cause of the disorders of eye movement observed is vertebrobasilar ischaemia induced by stretching and compression of the vertebral arteries during eccentric head posture.

Adult↗
PubMed1992

Mosaic analysis gives an estimate of the extent of genomic involvement in the development of the visual system in Drosophila melanogaster.

To investigate the role of vital loci in the development of the visual system of Drosophila, we induced mitotic recombination in individuals heterozygous for recessive organismal lethals and selected for analysis the resulting mosaics with homozygous mutant eye clones. Heads bearing clones were serially sectioned, silver-stained and examined for aberrations in the ommatidia and the neural structures to which they project. In our screen of 68 lines bearing diepoxybutane-induced X-linked lethals, 26 yielded few or no homozygous mutant clones (putative cell-lethals). Of the rest, 20 lines produced individuals with morphologically abnormal eye clones showing various degrees of aberrations in the ommatidial architecture. In 14 of these 20, the laminar cartridges innervated by the mutant clones were also disorganized. Clones with normal structure were found in 18 of the lines, and three lines were resistant to the induction of mitotic recombination. In a single line, comparatively normal clones in the eye projected to a lamina with subtle but consistent abnormalities. To the extent that we have a representative sample, these results suggest that about two-thirds of all vital genes may be essential for the normal assembly and neural connectivity of the eye. This points to a high degree of pleiotropy in the manner in which information in the genome of the fly is used in development.

Animals↗
PubMed1980

Arteriohepatic dysplasia: radiologic features of a new syndrome.

The radiographic features of five patients with arteriohepatic dysplasia are presented. These patients had congenital intrahepatic cholestasis with elevated serum bile acids, vertebral body abnormalities of shape and/or segmentation, shortened digits, and congenital heart disease, particularly peripheral pulmonic stenosis. They also had dysmorphic facies, eye abnormalities, hypercholesterolemia, and mild fat malabsorption. Some of the patients had neurologic, endocrine, and/or renal abnormalities as well, and they may have had hoarse voices due to vocal cord nodules. Variability in expression of the syndrome and vertical transmission suggest an autosomal dominant pattern of inheritance.

Abnormalities, Multiple↗
PubMed1997

Orientation anisotropy and strabismus.

Monocular contrast sensitivity (CS) measurements were obtained in the two principal meridians of eight constant unilateral strabismic subjects and four subjects diagnosed with alternating strabismus. The results indicated that: (1) the CS of both the fellow and deviating eyes of patients with a constant unilateral deviation is significantly less than that of visually normal eyes at high spatial frequencies; (2) both the fellow and deviating eyes reveal a significant reduction in CS to vertically oriented gratings. This effect is frequency-specific, occurring only at the highest spatial frequencies; (3) the magnitude of the orientation anisotropy did not vary systematically with the degree of amblyopia; and (4) a mild orientation anisotropy was observed in only three of the eight alternating strabismic eyes tested. The etiology of the vertical effect is examined with respect to the role of anomalous binocular competition, suppression and abnormal eye movements.

Amblyopia↗
PubMed1994

Adenovirus E1A expression controlled by the red pigment promoter in transgenic mice: a model for developmental abnormalities of the eye.

Four transgenic founder mice were produced that carry the adenovirus E1A gene under control of the human red pigment promoter. Two of the founder animals passed the transgene to progeny, and one line was bred to homozygosity. The line of mice homozygous for the transgene expressed E1A-specific RNA at a low level in their eyes; no expression could be detected in other tissues that were tested. Either the founder animals or their progeny exhibited developmental abnormalities of their eyes, including a small eye phenotype, retinal dysplasia, anterior cleavage syndrome, and retinal pigment epithelium dysplasia. Individuals from the same line of mice exhibited subsets of the abnormalities, e.g., many animals had one normal size eye and one small eye, even though both eyes contained E1A-specific RNA. No tumors resulted from E1A expression in animals monitored for 22 months.

Adenovirus E1A Proteins↗
PubMed1998

Fast eye movement initiation of ocular torsion in mesodiencephalic lesions.

Three patients with episodic ocular torsion and skew deviation due to mesodiencephalic lesions were studied by using binocular three-dimensional scleral search coils. The conjugate ocular torsion (upper pole of each eye rotating toward the side of the brainstem lesion) was initiated by a torsional fast eye movement. During prolonged episodes, torsional nystagmus was also present. Cessation of the ocular torsion and skew deviation occurred by slow eye movements with exponentially decreasing velocities in 2 patients, and by multiple fast torsional movements in 1 patient. In 1 patient, the abnormal eye movements were temporally linked to dystonic movements in the limbs on the side opposite the brainstem lesion. The occurrence of skew deviation with conjugate ocular torsion in brainstem lesions has been attributed to functional asymmetry in vestibular pathways responsible for the slow-phase compensatory eye movement response to roll. In comparison, the findings in our patients show that in mesodiencephalic lesions conjugate ocular torsion with skew deviation may be generated by torsional fast eye movements, indicating activation of the burst cells of the rostral interstitial nucleus of the medial longitudinal fasciculus.

Adult↗
PubMed1995

Targeted mutation in the col5a2 gene reveals a regulatory role for type V collagen during matrix assembly.

The tissue-specific organization of collagen molecules into tridimensional macroaggregates determines the physiomechanical properties of most connective tissues, but the factors and mechanisms controlling this process are unknown. It has been postulated that quantitatively minor types V and XI collagen regulate the growth of type I and II collagen fibrils, respectively. To test this hypothesis, we created mice that produce a structurally abnormal alpha 2(V) collagen chain. Homozygous mutant mice survive poorly, possibly because of complications from spinal deformities, and exhibit skin and eye abnormalities caused by disorganized type I collagen fibrils. Our results demonstrate that type V collagen is a key determinant in the assembly of tissue-specific matrices, and provide an animal model for human connective tissue disorders.

Animals↗
PubMed2005

Mitochondrial dysfunction in a patient with Joubert syndrome.

Joubert syndrome is a genetically heterogeneous disorder. The diagnostic criteria include episodic hyperventilation, abnormal eye movements, psychomotor retardation, hypotonia, ataxia, and the characteristic neuro-imaging findings (molar-tooth sign). Many of these clinical features have been observed in new-borns with mitochondrial disorders as well. Congenital brain malformations, including cerebellar hypoplasia, have been described in pyruvate dehydrogenase deficiency. Malformations of the vermis and the cerebellar peduncles, with the lack of axonal decussations, however, are characteristic for Joubert syndrome but unique in patients with mitochondrial disorders. Here, we describe a child with Joubert syndrome presenting with primary lactic acidemia, decreased pyruvate oxidation rates, decreased ATP production, and a mildly decreased pyruvate dehydrogenase complex activity measured in a fresh muscle biopsy. Sequence analysis of the PDHc E1 alpha gene and the PDHX genes revealed no mutations. The patient received continuous feeding through a feeding tube for two years and showed a significant clinical improvement with a complete resolution of the chronic lactic acidemia. A second muscle biopsy revealed significantly decreased pyruvate oxidation rates and ATP production, but a normal pyruvate dehydrogenase complex activity. We suggest that the described mitochondrial dysfunction in our patient is secondary to an underlying mutation leading to Joubert syndrome.

Abnormalities, Multiple↗
PubMed1999

Ocular motor abnormalities in ataxia telangiectasia.

Although abnormal eye movements are a prominent feature of ataxia telangiectasia, the characteristics of the oculomotor dysfunction in the disease have been reported only in small groups of patients. We have examined eye movements clinically in 56 patients with ataxia telangiectasia, and obtained electrooculographic recordings of eye movements in 33 subjects. Deficits were observed in the eye movement systems that stabilize images on the retina, including pursuit, gaze holding, convergence, vestibular and optokinetic slow phases, and cancellation of vestibular slow phases. Abnormalities in the systems that maintain fixation and shift gaze were also prominent, including abnormal reflexive and voluntary saccades (characterized by prolonged latency, hypometric amplitude, and the use of head movements to initiate gaze shifts), impaired fixation, and a reduction in vestibular and optokinetic quick phases. The abnormalities in image stabilization most likely result from dysfunction in the cerebellar flocculus and paraflocculus. The basis of the saccadic and fixation disturbance is less certain but may be the result of abnormal supranuclear control of the superior colliculus resulting from dysfunction in the cerebellar vermis or the basal ganglia.

Adolescent↗
PubMed2005

A girl with abnormal head and eye movements: Joubert syndrome (2005:3b).

We describe a mentally retarded patient with developmental delay, abnormal head and eye movements with suspected blindness and episodes of abnormal breathing. Subsequent CT and MRI were performed to reach to the final diagnosis. The clinical history and the imaging findings were classical for Joubert syndrome.

Abnormalities, Multiple↗
PubMed1992

Possible new type of oral-facial-digital syndrome with retinal abnormalities: OFDS type (VIII)

The most recent classification of the oral-facial-digital syndromes (OFDS) includes 7 types distinguishable by different clinical signs. We describe 2 brothers presenting oral, facial, and digital anomalies and an additional manifestation consisting of specific retinal abnormalities, i.e., retinochoroideal lacunae of colobomatous origin. Our patients may be affected with a new type of OFDS, i.e., OFDS type VIII, characterized by eye abnormalities in addition to other manifestations that partially overlap with those of OFDS type II. Given that there are 2 affected brothers, we cannot distinguish between autosomal and X-linked recessive inheritance.

Adult↗
PubMed1994

Acceleration by NMDA treatment of visually induced map reorganization in juvenile Xenopus after larval eye rotation.

Each tectal lobe of Xenopus frogs receives two topographic maps, one via the ipsilateral eye and one via the contralateral eye. The alignment of the ipsilateral map with the contralateral map depends upon binocular visual input during a critical period that extends from late tadpole to early juvenile stages. Rotation of one eye during the critical period leads to reorganization of the ipsilateral map, which eventually comes back into alignment with the contralateral map despite the abnormal eye position. The ipsilateral eye's map initially develops as if there had been no alteration in eye position; there is a delay of 4-6 weeks before reorganization can be detected by electrophysiological mapping. In this paper, the possible role of the NMDA receptor in the delay in reorganization is addressed. The degree of NMDA receptor activation may need to be above some threshold level to trigger reorganization. If NMDA receptor activation normally is below that level until after the first month postmetamorphosis, then exogenous NMDA might boost the process sufficiently to start the reorganization process sooner than usual. In order to test this possibility, the left eye of tadpoles was rotated and NMDA was applied to the right tectal lobe for 3-5 weeks, starting at 1 week postmetamorphosis. Electrophysiological mapping demonstrated that reorganization takes place more rapidly than in untreated frogs or frogs treated with vehicle only. This result is consistent with the interpretation that the activation of the NMDA receptor is a rate-limiting step in the activity-dependent matching of binocular maps in Xenopus tectum.

Animals↗
PubMed2005

Orbital complications of functional endoscopic sinus surgery: MR and CT findings.

AIM: To describe the radiological findings of ophthalmic complications during functional endoscopic sinus surgery (FESS) and correlate them with the clinical manifestations and mechanisms of injury. METHODS: This was a retrospective review of the clinical and cross-sectional imaging findings of 9 patients with orbital complications during FESS. RESULTS: The most common site of entry into the orbit during FESS was the lower medial orbital wall (7 of 9), followed by the inferior orbital wall, resulting in injury to the medial rectus (4 of 9) and, less frequently, the inferior rectus (2 of 9) or superior oblique muscles (1 of 9). Extensive scarring on imaging (3 of 9) was associated with global ocular motility dysfunction. In contrast, localized scarring (3 of 9) or extraocular muscle trauma (6 of 9) resulted in disturbance of eye movement in the direction of gaze from the injured site. CONCLUSIONS: Orbital magnetic resonance and computed tomography findings correlate very well with the abnormal eye movements clinically observed, and can assist in clarifying the cause of injury and guide surgical corrective management of patients suffering orbital complications from FESS. Radiologists should be familiar with the recent developments in FESS instrumentation as well as with the most commonly injured structures within the orbit.

Adolescent↗
PubMed1989

Fused binocular vision is required for development of proper eye alignment in barn owls.

The eyes of adult barn owls (Tyto alba) are virtually fixed in the head in positions that are highly consistent from one individual to the next. However, early in development the eyes are exodeviated; the eyes achieve their adult positions during the owl's second month of life. Disruption of binocular vision in baby owls leads to permanent, highly abnormal eye positions and interocular alignment. Of three owls raised with both eyelids sutured closed, two developed exotropic strabismus and one developed esotropic strabismus. Two owls reared with monocular vision developed esotropic strabismus, whereas three owls reared with fused, but optically deviated binocular vision developed normal eye positions. Thus, the alignment of the eyes in adults results from an active process that depends on fused binocular vision during early life. Extracellular microelectrode recordings from the optic tecta of strabismic owls reveal that many units retain binocular inputs from corresponding points of the two eyes: the left-eye and right-eye receptive fields of individual units are misaligned by an amount predicted by the direction and magnitude of the strabismus. These results indicate that an innately determined pattern of connections in the brain anticipates the eye positions necessary to achieve binocular fusion. The hypothesis is put forth that the powerful activation of such binocular neurons by strong, synchronous inputs from the two eyes is the signal required by the optimotor system that proper eye alignment has been attained.

Animals↗