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PubMed1998

A muscle-clamping system with an absorbable jaw clip to reduce suturing in strabismus surgery.

Most of the ocular complications of strabismus surgery are related to needle trauma during the suturing of muscles. The authors have developed a muscle-clamping system with an absorbable jaw clip to facilitate exact techniques of eye muscle surgery and to reduce the risk of complications. The absorbable jaw clip is composed of a lower fixing body with three jaws and an upper supporting body. The clip is used to tie an extraocular muscle (which is moved and reattached with the membrane) with a single scleral bite. Using the absorbable jaw clip, the authors performed superior rectus recession on 16 eyes of eight rabbits. The authors examined the conjunctival injection, muscle adhesion power, and light microscopic findings at 1, 2, 4, and 8 weeks postoperatively. The conjunctival injection diminished with time. Bond strengths ranged from 380 to 620 gram gravity, which is sufficient to withstand the normal pull of human extraocular muscles. Some inflammatory cells were found microscopically, and fibrosis increased with time. The muscle-clamping method with the newly invented clip was technically easy, fast, and exact, and it may reduce suturing and complications during strabismus surgery.

Animals↗

PubMed1982

Restricting eye movements in the anesthetized rat: a comparison of four techniques.

Four techniques for the immobilization of rodent eyes were compared. Eye movements were plotted over a three hour period by reflecting a laser beam off a small mirror affixed to the cornea. Surgical techniques for producing local paralysis of the extra-ocular eye muscles were inconsistently successful. Physical stabilization techniques reliably reduced eye movements to an extent compatible with certain neurophysiological tests. None of the techniques was as efficacious as the use of neuromuscular blocking agents combined with physical restraint.

Animals↗

PubMed2004

Dynamic reconstruction of eye closure by muscle transposition or functional muscle transplantation in facial palsy.

For patients with facial palsy, lagophthalmus is often a more serious problem than the inability to smile. Dynamic reconstruction of eye closure by muscle transposition or by free functional muscle transplantation offers a good solution for regaining near-normal eye protection without the need for implants. This is the first quantitative study of three-dimensional preoperative and postoperative lid movements in patients treated for facial paralysis. Between February of 1998 and April of 2002, 44 patients were treated for facial palsy, including reconstruction of eye closure. Temporalis muscle transposition to the eye was used in 34 cases, and a regionally differentiated part of a free gracilis muscle transplant after double cross-face nerve grafting was used in 10 cases. Patients' facial movements were documented by a three-dimensional video analysis system preoperatively and 6, 12, 18, and 24 months postoperatively. For this comparative study, only the data of patients with preoperative and 12-month postoperative measurements were included. In the 27 patients with a final result after temporalis muscle transposition for eye closure, the distance between the upper and lower eyelid points during eye closing (as for sleep) was reduced from 10.33 +/- 2.43 mm (mean +/- SD) preoperatively to 5.84 +/- 4.34 mm postoperatively on the paralyzed side, compared with 0.0 +/- 0.0 mm preoperatively and postoperatively on the contralateral healthy side. In the resting position, preoperative values for the paralyzed side changed from 15.11 +/- 1.92 mm preoperatively to 13.46 +/- 1.94 mm postoperatively, compared with 12.17 +/- 2.02 mm preoperatively and 12.05 +/- 1.95 mm postoperatively on the healthy side. In the nine patients with a final result after surgery using a part of the free gracilis muscle transplant reinnervated by a zygomatic branch of the contralateral healthy side through a cross-face nerve graft, eyelid closure changed from 10.21 +/- 2.72 mm to 1.68 +/- 1.35 mm, compared with 13.70 +/- 1.56 mm to 6.63 +/- 1.51 mm preoperatively. The average closure for the healthy side was from 11.20 +/- 3.11 mm to 0.0 +/- 0.0 mm preoperatively and from 12.70 +/- 1.95 mm to 0.0 +/- 0.0 mm postoperatively. In three cases, the resting tonus of the part of the gracilis muscle transplant around the eye had increased to an extent that muscle weakening became necessary. Temporalis muscle transposition and free functional muscle transplantation for reanimation of the eye and mouth at the same time are reliable methods for reconstructing eye closure, with clinically adequate results. Detailed analysis of the resulting facial movements led to an important improvement of the authors' operative techniques within the last few years. Thus, the number of secondary operative corrections could be significantly reduced. These qualitative and quantitative studies of the reconstructed lid movements by three-dimensional video analysis support the authors' clinical concept of temporalis muscle transposition being the first-choice method in adult patients with facial palsy. In children, free muscle transplantation is preferred for eye closure, so as not to interfere with the growth of the face by transposition of a masticatory muscle. In addition, a higher degree of central plasticity in children might be expected.

Adolescent↗

PubMed2005

Localized, extreme scleral thinning causing globe rupture during strabismus surgery.

Eye muscle surgery in strabismus patients usually is without serious, vision-threatening complications. The risk of scleral perforation during strabismus surgery has been reported to approximately 1% but usually without serious sequelae. Inadvertent perforation may occur during muscle disinsertion or during muscle reattachment. The risk of perforation is increased in myopic eyes, and the risk is higher in recessions than in other strabismus procedures. We report a case of sudden rupture of the globe during a recession procedure on the superior rectus muscle caused by a localized area of extreme scleral thinning adjacent to the muscle insertion. To our knowledge, this serious complication has not previously been reported.

Aged↗

PubMed1979

[Ct-criteria of orbital hemangiomas and their importance in differential diagnosis of intraconal tumors (author's transl)].

CT-scans of 29 histologically proven cavernous hemangiomas were evaluated with respect to their location, shape, delineation from surrounding tissue, contrast-enhancement, and secondary changes of the bony orbit. Whenever a round or oval tumor, located in the outer upper muscle cone, sharply delineated from surrounding tissue, unattached to optic nerve and ocular muscles, spares a small triangular space in the orbital apex, it is in all probability a cavernous hemangioma. Evaluation of the tumors shape and its separation from surrounding tissues requires imaging in multiple sections in two planes oriented, if possible, at right angles. -- Changes in position of the optic nerve and eye muscles in different directions of gaze demonstrated by CT rule out significant tumor-attachments. The portion of the intraconal space least affected by optic nerve shifts and muscle contractions during eye movements, as demonstrated by CT, is the upper outer quadrant, the site preferred by the mobile tumor. -- Tumors which cannot be differentiated from cavernous hemangiomas by CT-criteria are rare usually benign. Reports of rare examples of well delineated or encapsulated malignant intraconal lesions indicate the possibility -- however remote -- of mistaking a malignant tumor for a cavernous hemangioma by CT.

Diagnosis, Differential↗

PubMed2006

[Surgical options in retraction syndrome].

BACKGROUND: A causative therapy for Duane's retraction syndrome, which is the most prominent example of connatal ocular misinnervation, does not exist. Eye muscle surgery is indicated in cases with manifest strabismus in primary position and an annoying compensatory head posture to maintain binocular single vision. Different surgical approaches to the different types of Duane's retraction syndrome, mostly on the affected eye but also on the fellow eye, are described in the literature. METHOD: We retrospectively analyzed the pre- and postoperative findings of 55 patients in whom we performed surgery because of Duane's retraction syndrome during the years 1999 to 2004. The type of retraction syndrome, the angle reduction in primary position and the reduction of head posture were evaluated in regard to the surgical procedure chosen. RESULTS: In 37 cases surgery was primary. In 25 cases a single recession of the medial rectus (16 cases) or the lateral rectus (9 cases) muscle of the affected eye was performed. For a dose-response relationship of the one-muscle recessions, the mean angle reduction in the primary position was 2 pdpt (cm/m) per mm recession. The mean reduction of head posture was 1.5 degrees per mm recession. In 10 cases combined surgery on the affected eye was performed. The correlation between the mean angle reduction and the recession was 3 pdpt (cm/m) per 1 mm. CONCLUSION: Depending on the type of retraction syndrome, the angle in primary position, the head posture and the globe retraction, different surgical options exist which aim at rehabilitation of the patient suffering from Duane's retraction syndrome.

Adolescent↗

PubMed2000

Diplopia after cataract surgery.

PURPOSE: To evaluate the cause of diplopia after cataract surgery. SETTING: Cataract surgery at 7 hospitals and examination of diplopia at a central eye hospital. METHODS: This study comprised 18 eyes of 17 patients with diplopia that developed after cataract surgery in which retrobulbar anesthesia was used. The Hess screen test was done to diagnose oculomotor dysfunction. RESULTS: Several cases showed superior or inferior deviation of the globe, but most patients had nonuniform disturbances of eye movement. Examination of 3 patients by the Hess chart within 1 week after surgery showed paralysis of eye muscles but an overaction at a later stage, evident by reversal of eye position 1 month later. Surgery for strabismus was performed in 6 cases. One case with diplopia improved spontaneously 3 months after cataract surgery and achieved good alignment. CONCLUSIONS: The Hess screen test was useful for comparing changes in oculomotor function before and after surgery. Oculomotor dysfunction after cataract surgery may be caused directly by traumatic injury during administration of anesthesia or surgery using bridle sutures or indirectly from sensitivity to anesthetic agents.

Aged↗

PubMed2000

Observations on the muscles of the eye of the bowhead whale, Balaena mysticetus.

The muscles of the eyelids and the extraocular muscles of mysticete whales are poorly described for a variety of reasons, including considerable difficulty in obtaining specimens. Our objective is to provide such a description for the bowhead whale, Balaena mysticetus. This study has examined the gross anatomy of the region in six specimens (five adults, one fetus) of the bowhead whale. Results show that the muscles associated with the eye are well developed and possess several distinctive features. For example, precise limits of each extraocular muscle are difficult to determine along their entire length because these muscles intermingle with one another near their insertion. Furthermore, some fibers from these muscles (except the retractor bulbi) also insert into the eyelids. Pulling on these muscles to simulate contraction results in movement of the eyelids and suggests a role for these muscles in palpebral retraction. Insertion of a large levator palpebrae superioris muscle into the upper eyelid further enhances opening of the palpebral fissure. Another unusual feature is the presence of tunnel-like structures that redirect the dorsal and ventral oblique muscles. The dorsal oblique muscle is redirected caudally about 90 degrees, then directed medially by another 90 degrees. These directional changes are accomplished via a connective tissue tunnel derived in part from the fibrous connective tissue of the dorsal rectus and the levator palpebrae superioris muscles. In most terrestrial mammals, a similar change in direction is accomplished by a cartilaginous trochlea. The ventral oblique muscle originates via a slender tendon from the frontal bone and undergoes a similar radical change in direction. Its tendon of insertion undergoes about a 90-degree change in direction that is accomplished through a tunnel-like structure derived from fibrous connective tissue of the ventral rectus muscle. Based on the morphology of the musculature presented, it is likely that the eyeballs and eyelids of the bowhead whale are quite mobile and appear capable of complex movement. The possibility of retraction and protrusion of the eyeball is discussed.

Age Factors↗

PubMed2006

[Diagnosis of supranuclear eye movement disorders. Part II: Vertical and torsional oculomotoricity].

The hallmark of a supranuclear eye movement disorder is functional impairment of one or several types of different eye movements while other types of eye movement remain unchanged. All eye movement information is conveyed via the nuclei of the eye muscle nerves. However, the information for a specific type of eye movement is generated in prenuclear cortical and subcortical areas which are activated depending on the type of eye movement performed. The structures responsible for vertical and torsional oculomotoricity are described as well as the functional relationship between them. A summary of the development of saccades and movements arising from them is also given and the influence of the cerebellum on oculomotor processes is dealt with. In many neurological conditions knowledge about the areas of the brain relevant for eye movement enables a clinical diagnosis to be made or the pathological process to be localized to a specific anatomical area. Examination of eye movements is thus a valuable clinical tool in many neurological and neuro-ophthalmological diseases.

Brain Stem↗

PubMed2006

The phiC31 integrase system for gene therapy.

The phiC31 integrase system represents a novel technology that opens up new possibilities for gene therapy. The phiC31 integrase can integrate introduced plasmid DNA into preferred locations in unmodified mammalian genomes, resulting in robust, long-term expression of the integrated transgene. This review describes the nature of the integration reaction and the genomic integration sites used by the enzyme in human cells. Preclinical applications of the system to gene therapy to date are summarized, including in vivo use in liver, muscle, eye, and joint and ex vivo use in skin keratinocytes, muscle precursor cells, and T cell lines. The safety of this phage integrase system for gene therapy is evaluated, and its strengths and limitations are compared to other gene therapy approaches. Ongoing and planned improvements to the phage integrase system are discussed. We conclude that gene therapy strategies using phiC31 integrase and its derivatives offer great promise for success in the near term.

Animals↗

PubMed1987

[Biologic artefacts in the EEG of neurotic patients].

Biological artefacts caused by tension of head and neck muscles, eye movements and blinking, swallowing and perspiration represent part of the patient's mimic expression and psychophysiological state. Therefore the artefact patterns in the EEG of 53 patients with different types of neuroses were analysed, quantified and statistically compared to artefact patterns in 53 EEG of an age- and sex matched control group. None of the patients and controls were receiving psychopharmacological medication. Patients with hysterical neurosis produced the highest rate of blinking and/or eye movements and displayed the most EMG-artefacts (significance level as compared to the control group 2 alpha less than or equal to 0.001 by the Wilcoxon test). The lowest artefact rate was found in patients suffering from depressive neurosis with the exception of swallowing, which occurred more frequently than in any other type of neurosis and than in the control group (2 alpha less than or equal to 0.001). The artefact pattern of patients with obsessional neurosis was instead predominated by EMG and perspiration artefacts.

Adolescent↗

PubMed1996

Motor unit recruitment in a distributed model of extraocular muscle.

1. Eye position commands frequently are treated as a lumped, single-valued variable that is related linearly to eye position. As a step toward investigating how system-level linearity might be achieved despite nonlinear components, a distributed model of motor units in the abducens nucleus and lateral rectus muscle was constructed. 2. Parameters in the model were estimated using data from three main sources: measurement of length-tension curves for eye muscle in people, electrophysiological recording of ocular motoneuron properties in monkeys, and investigations of oculomotor unit properties in cat. Units (n = 100) in the distributed model were assigned equal strengths and for a given fixation command, the force developed by each unit was calculated, and the sum of unit forces compared with the active force in the entire muscle as measured experimentally. 3. The properties of the active units then were adjusted to reduce the size of any resultant error in a manner related to gradient descent methods for neural-net training. Distributed models were "trained" in this fashion for a series of eye positions drawn at random from the oculomotor range until performance stabilized. The goal of the training procedure was to obtain a good match between the output of the model and the experimental data on muscle force as a function of eye position. 4. Plots of trained motor-unit strength against ocular motoneuron threshold revealed a U-shaped pattern with the strongest units being recruited at both extremes of the oculomotor range and the weakest units recruited in the middle. The pattern remained unaltered qualitatively over a range of assumptions about the distribution of ocular motoneuron parameters and the relation between motoneuron firing rate and unit force. 5. The right-hand limb of the U-shaped pattern is similar to that observed in spinal motoneurons, where stronger units tend to have higher recruitment thresholds. The left-hand limb may reflect the two specializations of eye muscle: the functional need for very precise control of eye position in the middle of the oculomotor range and the use of multiply innervated muscle fibers to provide ripple-free control of eye position at low firing frequencies.

Abducens Nerve↗

PubMed1992

[Study on mechanical properties of extraocular muscles. I. Passive length-tension curves in rabbits].

Length-tension curves of detached eye muscles were continuously measured in albino rabbits with a length and tension measuring device developed by the author. The device consists of a strain gauge for measuring passive length-tension, and a position encoder equipped with an eddy current motor. In extending vertical rectus and oblique muscles, an exponential relation was found between length and tension. There was no significant difference between the passive load and extending velocity. The load of the superior rectus muscle was significantly greater than those of the other 3 vertical muscles, and that of the inferior oblique muscle was significantly greater than that of inferior rectus muscle. Each compliance of the inferior rectus muscle or the inferior oblique muscle was significantly greater than that of the superior rectus muscle or the superior oblique muscle.

Animals↗

PubMed2002

The neuroanatomical basis of oculomotor disorders: the dual motor control of extraocular muscles and its possible role in proprioception.

Current investigations show that two separate sets of motoneurons control the extraocular eye muscles, and that is there is a dual final common pathway. We propose that one set of motoneurons are the major source of tension generating eye movements, whereas the other may participate in a proprioceptive system concerned more with the exact alignment and stabilization of the eyes. In this article we discuss the structures that may participate in the proprioceptive circuits; and consider several recent publications in the light of this sensory feedback hypothesis, emphasizing the relevance to eye movement disorders.

Animals↗

PubMed1991

Length-tension recording system for strabismus surgery.

To meet the need for both scientific information and a clinical means for measurement of the mechanical parameters of the most difficult individual strabismus cases we present a technique for directly measuring and plotting the length-tension characteristics of the tissues supporting the eye. Semiconductor strain gauges mounted on the shanks of a custom machined eye forceps and an ultrasonic method of making continuous duction measurements of the eye have proved feasible. When the forceps are interfaced with a dedicated microcomputer, the system provides a permanent, quantitative, length-tension record displayed in real-time. The instrumented length-tension forceps system has provided a noninvasive means for quickly and simply assessing the mechanical underlying determinants of strabismus pathology in the office, the laboratory or in the operating room, and can aid in the planning and immediate intraoperative alteration of strabismus surgery. Under operator coordination, measurements can be made which precisely define the mechanical load which the eye muscles must move. The resulting objectively determined tissue stiffness asymmetries and muscle restrictions limiting ocular motion indicate the purely mechanical contributions to a patient's strabismus. Measurements of active force indicate the magnitudes and patterns of innervation over the entire range of gaze. By comparison of these active force and passive stiffness records, nerve signal imbalances may be quantitatively distinguished from mechanical imbalances in strabismus. It is the detailed interaction of these nonlinear muscle forces and mechanical elements which determines the position of each eye in strabismus and therefore the proper surgical treatment. A brief description of actual use and a few examples of clinical results are included from over 200 human records.

Calibration↗

PubMed1994

Vertical saccadic velocity and force development in superior oblique palsy.

Vertical saccadic movements recorded with electrooculography (EOG) and force development measured by means of a contact lens-strain gauge technique were investigated in 13 patients with a clinical diagnosis of unilateral superior oblique palsy (SOP) and 10 normal subjects. Upward and downward movements from the horizontal level to 5, 10 and 20 deg of deviation with monocular fixation were made in the 20 deg abduction and adduction fields of gaze. Peak velocity (Vp) and the ratio of downward over upward movement (VpD/U) of the paretic eye (PE) and the sound eye (SE) of the patients were compared with the values of the covered, non-fixating eye (CE) and the fixating eye (FE) of the normals respectively. Peak tension (Fp), steady-state tension (Fs) and the ratios of downward over upward movement (Fp D/U, Fs D/U) of PE were compared with the values of CE. Comparisons were done (a) between normals and the whole group of 13 patients, (b) between normals and two subgroups of five patients with acquired and five with congenital SOP, (c) and between the subgroups. Mean Vp for the whole group of SOP showed reduced values from normals in many directions of gaze. However, mean Fp and ratios of Vp D/U and Fp D/U were not different in SOP and normals, and such measures could not be used to differentiate SOP from normal eye muscles in the sample of patients studied. Clear differences were seen in the comparisons between normals and the subtypes of SOP. Vp was significantly reduced in PE for the downward movements in the adduction field of gaze, more marked in acquired than in congenital SOP. Slowing of upward saccades was also found in the congenital group. This may be due to adaptational changes in concomitization of congenital paretic strabismus. Fp for downward saccade, and Vp D/U and Fp D/U were lower for PE in the acquired than in congenital SOP and normals in the lower adduction field of gaze, where the superior oblique has its main action. A linear relation was found between Vp and Fp of downward saccades for the congenital group in the lower adduction of gaze, but the slope was steeper than in normals. However, in acquired SOP the relationship was non-linear, which indicates a force production different from that of a normal muscle. Vertical saccadic velocity and force development measured at 20 deg adduction could reveal weakness of the superior oblique muscle and the imbalance of agonist-antagonist actions in the paretic eye.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed2002

Optimization of laser-solder repair technique for possible application in strabismus surgeries.

Strabismus is the lack of binocular vision due to an inability to control one of the eye muscles. Corrective surgery is the most common recourse and consists of adjusting and reattaching the extraocular muscle to the sclera. In approximately 10% of cases involving re-insertment of the extraocular muscle via suture techniques, the needle is inserted too deeply into the eye resulting in perforation of the retina. Fibrin glues and cyanoacrylates have been substituted with unsatisfactory mechanical results. The goal of this study was to maximize the tensile strength of rabbit extraocular muscles repaired using a laser-solder technique developed by McNally et al., Biodegradable polymer membranes of controlled porosity were fabricated with poly(L-lactic-co-glycolic acid) (PLGA) and salt particles using a solvent-casting and particulate-leaching technique. The porous membranes were doped with protein solder composed of 25% and 50% (w/v) serum albumin and 0.5 mg/ml indocyanine green (ICG) dye mixed in deionized water. In vitro tissue specimens were repaired using the solder-doped polymer membranes in conjunction with an 805 nm diode laser. The tensile strength was tested on an MTS machine and results were analyzed with the Student's T-test.

Albumins↗

PubMed1978

Pursuit eye movements and their neural control in the monkey.

1. Single units in the 3. and 6. nerve nuclei were recorded, together with the stimulus and eye movements in trained macaques during pursuit eye movements. 2. The relationship between the impulse rate of an oculomotor motoneuron and the corresponding eye movements can be described by a first order differential equation only, if distinctions are made between the modes of the oculomotor system (e.g., fixation or pursuit) and between the agonist phase and the antagonist phase of the corresponding eye muscle. 3. The trained monkeys showed a frequency response during pursuit eye movements, which was comparable to that of humans and which clearly indicates the existence of a predictor mechanism. 4. After sudden stimulus disappearance in the pursuit mode, both the neural impulse rate and the eye movement performed smooth changes for more than 1s. These slow post-pursuit eye movements were related to the time course before stimulus disappearance. 5. Our findings lead to the hypothesis, that pursuit eye movements in primates, if elicited by small moving visual stimuli, are generated by means of a feedback system consisting of a predictor mechanism, the parameters of which are continuously corrected by an updating process in the afferent visual system.

Animals↗