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At least 163 records · Page 9Linked to original sources
PubMed1980

Structure and electrical properties of eye muscles in cave- and surface-dwelling crayfishes.

The morphologies and passive electrical parameters of fibres in two eye muscles of a surface- and a cave-dwelling crayfish were compared. In the cave-dwelling form the muscles contained fewer fibres, of less diameter, and hence had a smaller cross-sectional area. Current-voltage relationships were similar in both species. Input resistance was higher in the cave-dweller, but the difference was not as great as would be expected on the basis of geometry alone. Accordingly, the specific membrane resistance of muscle fibres in the cave-dweller is 50-60% smaller than that in the surface-dweller. This may account partially for the observation that identified excitatory junctional potentials in muscles of cave- and surface dwellers have similar amplitudes. We conclude that a functional oculomotor system is maintained in cave-dwelling crayfish, and that this system confers some positive selective advantage.

Adaptation, Physiological↗
PubMed1977

Response of oculomotor neurons to eye muscle stretch.

Neurons within the ventral portion of the oculomotor nucleus respond to stretch of extraocular muscles. Response latencies range from 30 to 170 ms. Antidromically identified extraocular motoneurons with this input have slowly conducting axons in the range of 30 to 50 m/s. Only responses to stretch of muscles other than those innervated by these motoneurons were recorded. Responses to stretch of several muscles from both eyes are common.

Action Potentials↗
PubMed1977

[Synthetic, absorbable suture in eye-muscle surgery (author's transl)].

A synthetic, absorbable suture (Vicryl), was investigated for its usability in eye-muscle surgery. In experimental investigations on animals and strabismus surgery in humans, properties of the suture were compared with those of plain catgut. Histological investigations after modified strabismus surgery on rabbits clearly showed a smaller degree of tissue reaction around the hydrolytically dissolvable synthetic suture than around plain catgut. After implantation of Vicryl or catgut into the anterior chamber of rabbit eyes, within the first eight days both cause infective reactions which were somewhat stronger with Vicryl, which caused more scarring over the iris, than with catgut. One-hundred and eighty strabismus operations on man showed that the synthetic suture handles better and rips less markedly than plain catgut, whereas duration and amount of postoperative irritations are similar. Overreactions and granuloma were rare.

Absorption↗
PubMed1991

[Hemorrhage in external eye muscles].

Of 91 unselected forensic autopsy cases then lateral muscles of both eyes were prepared in stepped sections and examined for microscopical haemorrhages. During autopsy we payed attention to macroscopical haemorrhages. Microscopical haemorrhages were found in 12 cases mainly in suffication processes as in two cases of fulminant pulmonary embolism. In five of the examined cases we also found macroscopical hemorrhage, mainly with strangulation. According to our results till now, haemorrhage in ocular muscles are seen in the process of aspyxia; if this is protracted as in manual strangulation or strangulation by ligature, macroscopical haemorrhage may occur.

Asphyxia↗
PubMed2002

[Adjustment of eye muscle surgery dosage under drop anaesthesia in patients with Grave's orbitopathy].

BACKGROUND: Motility restrictions of the eye muscles represent a common and serious impairment for patients with Grave's orbitopathy. Various surgical approaches have been developed for the rehabilitation of these patients. In this study 64 patients in which only one of the rectus inferior muscles was recessed are presented. METHOD: The recession was performed using drop anaesthesia. The active cooperation of the patients was necessary for adjustment of the dosage so that undercorrections or more important overcorrections could be prevented. Indications for this recession were a constant diplopia, an abnormal head posture, a pseudoretraction of the upper eyelid or corneal scarring complications. RESULTS: In all patients the squint angle was significantly reduced. A statistical mathematical correlation between the intraoperatively chosen recession length and the reduction of squint angle was found. On the other hand, the variance of the effect of the operation was so large that no dosage recommendations could be made. This operation technique seems to be able to avoid overcorrections (9.3%) for the majority of patients and only a small group of them presented diplopia postoperatively (10.9%). CONCLUSIONS: These results show a good functional rehabilitation of our patients. Performing the operation under drop anaesthesia, while taking into account the motility situation, seems to be a good method in order to manage the dosage problems presenting in this clinical entity.

Anesthesia, Local↗
PubMedDate not supplied

Clinical, genetic and histopathologic findings in two siblings with muscle-eye-brain disease.

PURPOSE: We present the clinical, genetic and histopathologic findings in two siblings with Muscle-Eye-Brain Disease (MEB-D), an autosomal recessive disease characterized by mental retardation, muscular dystrophy, retinal hypoplasia and brain abnormalities. METHODS: Clinical, histopathologic and gene mapping studies of a family with two normal and two children with MEB-D. RESULTS: Two siblings presented in the first few months of life with developmental delay, hypotonia, and strabismus. MRI of the brain showed colpocephaly, pontine and cerebellar atrophy, and diffuse white matter disease. Both patients were blind and had high myopia, strabismus, and retinal and optic nerve abnormalities. The older boy had glaucoma. Both children died from uncontrolled seizures. There was retinal, choroidal and RPE atrophy and optic nerve hypoplasia on ocular histopathology. Both patients shared the same parental haplotypes at the MEB locus on chromosome 1p, while an unaffected sibling did not, indicating possible linkage to the MEB locus. CONCLUSIONS: Patients with MEB-D have severe visual impairment from retinal and optic nerve hypoplasia. High myopia appears to be a consistent finding. The ocular manifestations of MEB-D appear to be distinct from those of patients with Walker-Warburg syndrome.

Abnormalities, Multiple↗
PubMed2001

Virtual eye muscle surgery based upon biomechanical models.

Within our research project "SEE-KID", a Software Engineering Environment for Knowledge-based Interactive Eye Motility Diagnostics, we focus on virtual reality training for the surgery of human eye muscles of--mostly--children age 1 to 3. Our report gives details on the sound integration of biomechanical muscle data into our virtual reality models in order to evaluate the quality of specific techniques for eye motility surgery regarding real-world pathologies. We illustrate the usefulness of our software system describing some of the possible medical applications, like optimized transposition surgery of the musculus obliquus superior.

Artificial Intelligence↗
PubMed2003

Enzymatic diagnostic test for Muscle-Eye-Brain type congenital muscular dystrophy using commercially available reagents.

OBJECTIVES: Mutations disrupting the interaction of extra-cellular ligands and alpha-dystroglycan are responsible for an etiologically heterogeneous group of autosomal recessive congenital muscular dystrophies (CMD) that can have associated brain and eye abnormalities. The objective is to develop a diagnostic test for one of these CMDs, Muscle-Eye-Brain disease (MEB), due to mutations in the gene encoding Protein O-Mannosyl beta-1,2-N-acetylglucosaminyltransferase 1 (POMGnT1). DESIGN AND METHODS: POMGnT1 enzyme activity was determined in extracts of muscle biopsies from four MEB patients and various controls using commercially available reagents. RESULTS: All four MEB muscle samples showed a highly significant decrease in POMGnT1 activity relative to controls. CONCLUSIONS: The assay of POMGnT1 activity in MEB muscle provides a rapid and relatively simple diagnostic test for this disease. CMDs associated with brain malformations such as MEB, WWS and FCMD are heterogenous in clinical presentation and on radiologic examination, suggesting that POMGnT1 assays of muscle biopsies should be used as a screening procedure for MEB in all CMD patients associated with brain malformations.

Brain↗
PubMed1977

Neuronal responses to eye muscle stretch in cerebellar lobule VI of the cat.

Extraocular proprioceptive input to cerebellar vermis, lobule VI, was investigated in cats under N2O analgesia by recording neuronal responses to eye muscle stretch. Both optic tracts were transected and the periorbital skin and conjunctiva were locally anaesthetized. Eye rotation within the physiological range was achieved by applying a pull of predetermined length and tension to each of the eight musculi recti at their insertion to the globe. Within lobule VI, only small patches of cortex receive stretch receptor afferents. The information made available by these afferents corresponds to a change of eye position. Minimal responses were dependent upon angular deflections of a few degrees. Maximal response amplitudes were obtained within the physiological range of angular deflections and angular velocities for the units tested. Most cells responded to stretch of more than one muscle. Three types of convergence were found: 1) neurons responding according to a certain direction of a conjugated movement of both eyes, 2) neurons responding to movements in either direction of one plane, 3) more complicated response patterns.

Animals↗
PubMed1987

Complications in eye muscle surgery.

Strabologists consider postoperative loss of visual function as a severe and extremely rare complication. Other complications in eye muscle surgery are demonstrated.

Adult↗
PubMed1987

The oculomotor system of Daphnia magna. The eye muscles and their motor neurons.

The highly mobile cyclopic compound eye of Daphnia magna is rotated by six muscles arranged as three bilateral pairs. The three muscles on each side of the head share a common origin on the carapace and insert dorsally, laterally and ventrally on the eye. The dorsal and ventral muscles are each composed of two muscle fibers and the lateral muscle is composed of from two to five fibers, with three the most common number. Individual muscle fibers are spindle-shaped mononucleated cells with organized bundles of myofilaments. Lateral eye-muscle fibers are thinner than those of the other muscles but are otherwise similar in ultrastructure. Two motor neurons innervate each dorsal and each ventral muscle and one motor neuron innervates each lateral muscle. The cell bodies of the motor neurons are situated dorsally in the supraesophageal ganglion (SEG) and are ipsilateral to the muscles they innervate. The dendritic fields of the dorsal-muscle motor neurons are ipsilateral to their cell bodies; those of the ventral-muscle motor neurons are bilateral though predominantly contralateral. The central projections of the lateral-muscle motor neurons are unknown. In the dorsal and ventral muscles one motor axon synapses principally with one muscle fiber; in each lateral muscle the single motor axon branches to, and forms synapses with, all the fibers. The neuromuscular junctions, characterized by pre- and postsynaptic densities and clear vesicles, are similar in all the eye muscles.

Animals↗
PubMed1995

Upper eyelid retraction in the absence of other evidence for progressive ophthalmopathy is associated with eye muscle autoantibodies.

We have studied 25 clinically euthyroid patients with eyelid lag and retraction referred to thyroid/eye clinic for clinical and orbital imaging evidence of extraocular eye muscle (EM) involvement, evidence of progressive ophthalmopathy and serum antibodies reactive with EM membrane antigens in immunoblotting. Fourteen patients had Graves' hyperthyroidism, 5 had Hashimoto's thyroiditis, and 6 had euthyroid Graves' disease. By carrying out orbital imaging we showed EM abnormalities in 10 of 23 patients (43%). Serum antibodies reactive with EM membrane antigens were detected in 96% of patients. Antibodies reactive with a 64-kDa antigen were detected in 66% of patients, while those reactive with 35-, 55-, and 95-kDa antigens were found in 21, 33, and 25% of patients, respectively. Antibody prevalences compared to normals were significantly different (P < 0.005) only for the 64-kDa protein. The prevalence and the degree of reactivity of 64-kDa antibodies were significantly different in patients with abnormal EM compared to those with normal EM at orbital imaging (P < 0.04 and P < 0.01, respectively). The results of this work suggest that in some patients inflammation of the eyelid muscles may be an isolated feature of ophthalmopathy and remains as the only sign of a "subclinical" eye disease in patients with thyroid autoimmunity.

Adult↗
PubMed1997

Muscle-eye-brain disease: a neuropathological study.

A combination of congenital central nervous, ocular and muscular abnormalities is characteristic of muscle-eye-brain disease (MEB), of Fukuyama congenital muscular dystrophy (FCMD), and of Walker-Warburg syndrome (WWS). The nosological relationship of these inherited malformative disorders is still unestablished, although the genetic locus for FCMD has been excluded in MEB. We present the first postmortem neuropathological study of MEB based on 2 male patients. Apart from sharply limited occipital agyric areas, their brains showed coarse gyri with an abnormally nodular surface ("cobblestone cortex"). Both the cerebral and cerebellar cortices showed a total disorganization without horizontal lamination. The haphazardly oriented cortical neurons formed irregular clusters or islands, separated by gliovascular strands extending from the pia. The ocular abnormalities included a pronounced glial preretinal membrane. Although MEB shares the cobblestone cortex-type malformation with FCMD and WWS, the cerebral and ocular manifestations are less severe than in WWS. Furthermore, a consistently weak staining for laminin alpha2 chain (merosin) was found in muscle biopsy specimens from 4 MEB patients, while normal immunoreactivity was observed for the laminin beta2 chain, reported to be severely deficient in WWS. These findings support nosological independence of MEB.

Adult↗
PubMedDate not supplied

Ocular findings in muscle-eye-brain (MEB) disease: a follow-up study.

We present ocular findings of 20 patients with the recessively inherited muscle-eye-brain (MEB) disease, characterised by severe visual failure, mental retardation, a pachygyria-polymicrogyria type neuronal migration disorder and congenital muscular dystrophy. The ocular findings consisted of myopia ranging from -6 to -27 D, retinal degeneration and optic atrophy. Five infants had congenital glaucoma, and juvenile cataracts developed in 9 children. The visual evoked potentials were abnormally high (> 50 microV) and delayed in 70% of patients. The electroretinogram was abolished in 12 patients. The changes were progressive during the follow-up time, which was up to 20 years.

Adolescent↗