A Method for Rehabilitating Vision after Stroke

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 28-28
Author(s):  
V Virsu ◽  
P Koskela
Keyword(s):  
Eye Movements ◽  
Rectus Muscle ◽  
Eye Position ◽  
Central Vision ◽  
Binocular Fusion ◽  
Primary Position ◽  
Lateral Rectus Muscle ◽  
Correct Function ◽  
One Year ◽  
Voluntary Saccades

We developed a method for rehabilitating eye movements and binocular fusion, and tested the method in one patient. An infarct of the pons caused the paresis of the lateral rectus muscle of the left eye. Beginning from the third week in hospital, the patient was trained in eye movements and binocular fusion. Fusion was made possible by means of prisms that moved the images of targets in central vision to the threshold of fusion in the primary eye position. During practice sessions lasting 0.5 to 2 h daily the patient kept the images fused by making a horizontal head movement when necessary. Several eye-movement sessions were held daily, consisting of voluntary saccades and fixations as far to the left as possible. The strength of the prismatic correction required for fusion decreased, and four months after the onset of stroke the patient could fuse without prisms in the primary position. His binocular vision became practically normal in one year. The plasticity of the visual system can be utilised in rehabilitation by a practice that uses minimal remedial means necessary for correct function at each level of performance.

Recruitment Order of Cat Abducens Motoneurons and Internuclear Neurons

2003 ◽  
Vol 90 (4) ◽  
pp. 2240-2252 ◽  
Author(s):  
Ángel M. Pastor ◽  
David González-Forero
Keyword(s):  
Rectus Muscle ◽  
Neuronal Firing ◽  
Eye Position ◽  
High Dose ◽  
Recruitment Threshold ◽  
Ocular Reflex ◽  
Lateral Rectus Muscle ◽  
Vestibulo Ocular Reflex ◽  
Recruitment Order ◽  
Eye Velocity

Abducens neurons undergo a dose-dependent synaptic blockade (either disinhibition or complete blockade) when tetanus neurotoxin (TeNT) is injected into the lateral rectus muscle at either a low (0.5) or a high dose (5 ng/kg). We studied the firing pattern and recruitment order in abducens neurons both in control and after TeNT injection. The eye position threshold for recruitment of control abducens neurons was exponentially related to the eye position and velocity sensitivities. We also found a constancy of recruitment threshold for different eye movement modalities (spontaneous, optokinetic, and vestibular). Exponential relationships were found, as well, for eye velocity sensitivity during saccades and for position and velocity sensitivities during the vestibulo-ocular reflex. Likewise, inverse relationships were found between recruitment threshold or position sensitivity with the antidromic latency in control abducens neurons. These relationships, however, did not apply following TeNT treatment. Neuronal firing after TeNT appeared either disinhibited (low dose) or depressed (high dose), but the relationships between neuronal sensitivities and recruitment still applied. However, the pattern of recruitment shifted toward the treated side as more inputs were blocked by the low- and high-dose treatments, respectively. Nonetheless, although the recruitment-to-sensitivity relationships persisted under the TeNT synaptic blockade, we conclude that synaptic inputs are determinant for establishing the recruitment threshold and recruitment spacing of abducens motoneurons and internuclear neurons.

scholarly journals Surgical Management of Complex Anomalous Head Posture in Idiopathic Infantile Nystagmus

2020 ◽  
pp. 1-4
Author(s):  
Sandra C Ganesh ◽  
Sandra C Ganesh ◽  
Ashwini S Raut ◽  
Shilpa G Rao
Keyword(s):  
Anterior Segment ◽  
Head Tilt ◽  
Rectus Muscle ◽  
Primary Position ◽  
Second Child ◽  
Head Posture ◽  
Infantile Nystagmus ◽  
One Year ◽  
Second Procedure ◽  
Anomalous Head Posture

Idiopathic infantile nystagmus (IIN) is usually associated with a null zone, which is the zone of minimal nystagmus intensity. An anomalous head posture (AHP) is adopted to shift the null zone from an eccentric position to primary position. A complex AHP may include head position involvement in different ocular axes-namely face turn, chin elevation or depression and head tilt or a combination of these. Surgically, various procedures have been described for correction of this condition. We evaluated 2 children aged six and ten years, who presented with shaking of eyes along with presence of a complex AHP. First child had 20 degrees right face turn, 20 degrees right head tilt and 10 degrees of chin elevation. She underwent a combination of 2 procedures-augmented Anderson’s procedure for correction of right face turn and modification of Kestenbaum procedure for right head tilt along with bilateral IR recession, for correction of chin elevation. Postoperatively, AHP was satisfactorily corrected to 5 degrees face turn and minimal head tilt, and it remained stable for one year. The second child had left face turn 15 degrees, with right head tilt of 20 degrees and chin depression 10 degrees. He underwent a combination of 2 procedures-augmented Anderson’s procedure for correction of left face turn and modification of Kestenbaum procedure for right head tilt along with bilateral SR recession, for correction of chin depression. Postoperatively, AHP was satisfactorily corrected to 5 degrees face turn and minimal head tilt, which remained stable over a period of one year. In both cases, AHP was corrected by operating on only 2 muscles in each eye (one horizontal and one vertical) at a time. As both cases presented with combination of both torsional and vertical components of AHP, we decided to treat them both by surgery on a single vertical rectus muscle bilaterally to correct the chin position (elevation or depression), as well as torticollis (transposition of vertical recti, either nasally or temporally as needed). Since a third rectus muscle was not operated upon, there was a lesser possibility of developing anterior segment ischaemia. Additionally, as all components of AHP were corrected in one session, need for a second procedure under general anaesthesia to correct residual AHP was avoided in both cases.

Abnormal fixational eye movements in strabismus

2017 ◽  
Vol 102 (2) ◽  
pp. 253-259 ◽  
Author(s):  
Fatema F Ghasia ◽  
Jorge Otero-Millan ◽  
Aasef G Shaikh
Keyword(s):  
Eye Movements ◽  
Large Angle ◽  
Fine Tuning ◽  
Eye Position ◽  
Visually Guided ◽  
Binocular Fusion ◽  
The Gaze ◽  
Fixational Eye Movements ◽  
The Stability ◽  
Fixational Saccades

IntroductionFixational saccades are miniature eye movements that constantly change the gaze during attempted visual fixation. Visually guided saccades and fixational saccades represent an oculomotor continuum and are produced by common neural machinery. Patients with strabismus have disconjugate binocular horizontal saccades. We examined the stability and variability of eye position during fixation in patients with strabismus and correlated the severity of fixational instability with strabismus angle and binocular vision.MethodsEye movements were measured in 13 patients with strabismus and 16 controls during fixation and visually guided saccades under monocular viewing conditions. Fixational saccades and intersaccadic drifts were analysed in the viewing and non-viewing eye of patients with strabismus and controls.ResultsWe found an increase in fixational instability in patients with strabismus compared with controls. We also found an increase in the disconjugacy of fixational saccades and intrasaccadic ocular drift in patients with strabismus compared with controls. The disconjugacy was worse in patients with large-angle strabismus and absent stereopsis. There was an increase in eye position variance during drifts in patients with strabismus. Our findings suggest that both fixational saccades and intersaccadic drifts are abnormal and likely contribute to the fixational instability in patients with strabismus.DiscussionFixational instability could be a useful tool for mass screenings of children to diagnose strabismus in the absence of amblyopia and latent nystagmus. The increased disconjugacy of fixational eye movements and visually guided saccades in patients with strabismus reflects the disruption of the fine-tuning of the motor and visual systems responsible for achieving binocular fusion in these patients.

Stimulation-Evoked Eye Movements With and Without the Lateral Rectus Muscle Pulley

2003 ◽  
Vol 90 (6) ◽  
pp. 3809-3815 ◽  
Author(s):  
Diana M. Dimitrova ◽  
Mary S. Shall ◽  
Stephen J. Goldberg
Keyword(s):  
Eye Movements ◽  
Eye Movement ◽  
Rectus Muscle ◽  
Lateral Rectus ◽  
Physiological Data ◽  
Movement Amplitude ◽  
Lateral Rectus Muscle ◽  
Before And After ◽  
Orbital Tissue ◽  
Orbital Layer

Recent studies have suggested that extraocular muscle (EOM) pulleys, composed of collagen, elastin, and smooth muscle, are among the tissues surrounding the eye. High-resolution magnetic-resonance imaging appears to indicate that the pulleys serve to both constrain and alter the pulling paths of the EOMs. The active pulley hypothesis suggests that the orbital layer of the EOMs inserts on the pulley and serves to control it. Based on anatomical data, the active pulley hypothesis also suggests that the orbital layer does not rotate the eye within the orbit; this is done by the global layer of the muscle. However, no physiological data exist to confirm this hypothesis. Here we used stimulation-evoked eye movements in anesthetized monkeys and cats before and after destruction of the lateral rectus muscle pulley by removal of the lateral bony orbit and adjacent orbital tissue. The absence of these structures resulted in increased lateral, in the primate, and medial, in the cat, eye-movement amplitude and velocity. Vertical eye movements in the cat were not significantly affected. The results indicate that these increases, confined to horizontal eye-movement amplitude and velocity, may be attributed to passive properties within the orbit. In relation to the active pulley hypothesis, we could discern no clear impact (in terms of amplitude or velocity profile of the movements) of lateral eye exposure that could be directly attributable to the active lateral pulley system.

scholarly journals Surgical treatment of a patient with congenital nystagmus with compensatory head posture: A case report

2020 ◽  
Vol 89 (9-10) ◽  
pp. 515-520
Author(s):  
Alma Kurent ◽  
Dragica Kosec
Keyword(s):  
Visual Acuity ◽  
Surgical Treatment ◽  
Rectus Muscle ◽  
Congenital Nystagmus ◽  
Head Turn ◽  
Primary Position ◽  
Head Posture ◽  
Straight Position ◽  
Lateral Rectus Muscle ◽  
The Right

The correction of compensatory head posture in a congenital nystagmus involves surgical treatment that includes recession and resection of extraocular muscles to move the eccentric null zone to a primary position. A 39-year-old patient presented with an impaired visual acuity and nystagmus that was present since childhood. She had a left head turn with permanent neck pain. At the examination, best corrected visual acuity was 0.4 in both eyes with her glasses. Correction in the right eye was -6.50-1.50/180° and in the left eye -5.50-2.50/180°. Measured objective and subjective angles of squint were +4°, fusion from -3° to +29°, with the presence of stereo vision. During the cover test the nystagmus was present and it enhanced while covering the eye. Ocular motility was not limited. Fundus examination revealed myopic changes in both eyes. Prisms were prescribed, which were well tolerated by the patient. Also, no apparent head turn was noticed while wearing the prisms. Nine months later, the patient underwent a Kestenbaum procedure. Retroposition of the lateral rectus muscle with resection of the medial rectus muscle in the right eye and retroposition of the medial rectus muscle with resection of the lateral rectus muscle in the left eye were performed. After the procedure nystagmus dampened the most in the minimal left position, the head was in a straight position. Two years after the procedure nystagmus dampened the most in the primary position, the head was in a straight position. Nine years after surgery and refractive correction with contact lenses, the visual acuity was 0.8-0.9p in both eyes. The presented case showed that adequate functional and surgical treatment led to a good morphological outcome with improved visual acuity in a patient with congenital nystagmus and a compensatory head posture even in adulthood.

scholarly journals Task Dependent Variations of Ocular Lateropulsion in Wallenberg’s Syndrome

1981 ◽  
Vol 8 (1) ◽  
pp. 21-26 ◽  
Author(s):  
T.H. Kirkham ◽  
D. Guitton ◽  
M. Gans
Keyword(s):  
Magnetic Field ◽  
Eye Movements ◽  
Eye Position ◽  
Position Information ◽  
Wallenberg’S Syndrome ◽  
Wallenberg's Syndrome ◽  
Vertical Saccades ◽  
The Right ◽  
Voluntary Saccades ◽  
Multiple Step

SUMMARYThe eye movements of a patient with a left lateral medullary infarct (Wallenberg’s syndrome) were recorded using the scleral search coil in magnetic field technique. When asked to look at spontaneously appearing targets, saccades to the left were generally accurate hut those to the right reached the target by multiple step refixation saccades. Large amplitude rightward saccades were possible between two continuously visible targets or when making voluntary saccades in the dark.Vertical saccades, up or down, between spontaneously appearing targets were always associated with a leftward eye movement (lateropulsion). Voluntary vertical saccades between continuously visible targets showed that upward movements had left lateropulsion but downward movements were normal. Vertical voluntary saccades in the dark were oblique, upward saccades showing left lateropulsion and downward saccades showing rightward deviation. The aberrant horizontal components of vertical saccades had amplitude and velocity characteristics for components of normal oblique saccades. Possibly impaired assessment of vertically with incorrect eye position information produced by the infarct accounts for the lateropulsion of saccades in Wallenberg’s syndrome.

Worldwide outcomes of nasal transposition of the split lateral rectus muscle for strabismus associated with 3rd-nerve palsy

2021 ◽  
pp. bjophthalmol-2021-319667
Author(s):  
Ankoor S Shah ◽  
Mary-Magdalene Ugo Dodd ◽  
Birsen Gokyigit ◽  
Birgit Lorenz ◽  
Erick Laurent ◽  
...  
Keyword(s):  
Success Rate ◽  
Nerve Palsy ◽  
Rectus Muscle ◽  
Strabismus Surgery ◽  
Lateral Rectus ◽  
Oblique Muscle ◽  
Primary Position ◽  
Lateral Rectus Muscle ◽  
Muscle Insertion ◽  
Contralateral Eye

Background/aimsTo determine success rate and complications associated with nasal transposition of the split lateral rectus muscle (NTSLR) for treating strabismus from 3rd-nerve palsy.MethodsAn international, multicentre, registry of patients with unilateral 3rd-nerve palsy treated with NTSLR was created. Patients with concurrent surgery on the contralateral eye were excluded. Primary outcome was horizontal alignment within 15 prism dioptres (PD) of orthotropia. Incidence of technical difficulties and vision-threatening complications by 6 months post-procedure were reported.ResultsNinety-eight patients met inclusion criteria. Median age was 33.5 years (IQR 10.75–46). Aetiologies included congenital (31%), neoplastic (16%) and traumatic (15%). Twenty-five per cent of patients had prior ipsilateral strabismus surgery. Median exotropia decreased from 70PD preoperatively (IQR 50–90) to 1PD postoperatively (IQR 0–15.5), with a success rate of 69%. Performing concurrent superior oblique muscle tenotomy (SOT) was independently associated with success (p=0.001). Technical challenges occurred in 30% of cases, independently associated with a history of ipsilateral strabismus surgery (p=0.01). Eleven per cent of patients had vision-threatening complications, independently associated with more posterior placement of the split lateral rectus (LR) muscle (p<0.001), and most commonly transient serous choroidal effusion. Surgical placement of the split LR muscle within 4.25 mm of the medial rectus (MR) muscle insertion reduced this risk.ConclusionNTSLR significantly improved primary position alignment altered by 3rd-nerve palsy. Concurrent SOT and placement of the split LR muscle ≤4.25 mm posterior to the MR muscle insertion optimised outcomes. NTSLR proved technically challenging when prior ipsilateral strabismus surgery had been performed.

scholarly journals Lateral rectus muscle differentiation potential in paralytic esotropia patients

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Qing Xia ◽  
Xiangtian Ling ◽  
Zhonghao Wang ◽  
Tao Shen ◽  
Minghao Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Rectus Muscle ◽  
Lateral Rectus ◽  
Control Group ◽  
Differentiation Potential ◽  
Partial Restoration ◽  
Reverse Transcription Pcr ◽  
Lateral Rectus Muscle

Abstract Purpose and background Recently, we found that maximal medial rectus recession and lateral rectus resection in patients with complete lateral rectus paralysis resulted in a partial restoration of abduction. In an attempt to understand some of the mechanisms involved with this effect we examined gene expression profiles of lateral recti from these patients, with our focus being directed to genes related to myogenesis. Materials and methods Lateral recti resected from patients with complete lateral rectus paralysis and those from concomitant esotropia (controls) were collected. Differences in gene expression profiles between these two groups were examined using microarray analysis and quantitative Reverse-transcription PCR (qRT-PCR). Results A total of 3056 differentially expressed genes (DEGs) were identified between these two groups. Within the paralytic esotropia group, 2081 genes were up-regulated and 975 down-regulated. The results of RT-PCR revealed that PAX7, MYOG, PITX1, SIX1 and SIX4 showed higher levels of expression, while that of MYOD a lower level of expression within the paralytic esotropia group as compared with that in the control group (p < 0.05). Conclusion The decreased expression of MYOD in the paralytic esotropia group suggested that extraocular muscle satellite cell (EOMSCs) differentiation processes were inhibited. Whereas the high expression levels of PAX7, SIX1/4 and MYOG, suggested that the EOMSCs were showing an effective potential for differentiation. The stimulation resulting from muscle surgery may induce EOMSCs to differentiate and thus restore abduction function.

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