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PubMed2004

Neuroanatomy of adult strabismus: a voxel-based morphometric analysis of magnetic resonance structural scans.

Cerebral deficit has been implicated in the genesis of strabismus and in the mechanisms adopted to compensate for the visual disorder. Voxel-based morphometry (VBM) was applied to magnetic resonance images of strabismic adults to detect any abnormal brain anatomy, which could not be easily identified by simple inspection. The gray matter volume in strabismic adults was smaller than that in normal subjects at the areas consistent with the occipital eye field (OEF) and parietal eye field (PEF). However, greater gray matter volume was found in strabismic adults relative to normal controls at the areas consistent with the frontal eye field (FEF), the supplementary eye field (SEF), the prefrontal cortex (PFC), and subcortical regions such as the thalamus and the basal ganglia. These opposite gray matter changes in the visual and the oculomotor processing areas are compatible with a hypothesis of plasticity in the oculomotor regions to compensate for the cortical deficits in the visual processing areas.

Adult↗

PubMed2004

Strabismus following posterior segment surgery.

Persistent diplopia following posterior segment surgery is not uncommon. There are several causes of postoperative strabismus, some of which are preventable. Knowledge of the possible causes, proper evaluation, and appropriate treatment can eliminate or at least reduce the morbidity from this unwelcome postoperative surprise.

Humans↗

PubMed2006

Strabismus after deep lateral wall orbital decompression in thyroid-related orbitopathy patients using automated hess screen.

PURPOSE: To evaluate the effect of deep lateral wall orbital decompression with intraconal fat debulking on strabismus in thyroid-related orbitopathy (TRO) patients using automated Hess screen (AHS). DESIGN: Prospective nonrandomized clinical study. PARTICIPANTS: Eleven TRO patients (19 surgeries) operated on at the Jules Stein Eye Institute from January, 2004, through December, 2004. METHODS: Automated Hess screen testing was performed in all patients before surgery and 3 months after surgery; all patients received surgery in the nonactive phase of the disease. MAIN OUTCOME MEASURES: Amplitude of horizontal and vertical deviations (prism diopters) in all standard positions of gaze. RESULTS: Eleven TRO patients (7 females; mean age, 47 years) were included in the study; 8 patients underwent bilateral surgery. After surgery, exophthalmos decreased an average (+/-standard deviation) of 2.7 mm (+/-2.5 mm; P = 0.003). Before surgery, 7 patients (63%) reported primary gaze diplopia, whereas only 2 patients (18%) showed diplopia in primary gaze after surgery (P = 0.03, chi-square analysis). Orbital decompression had no statistically significant effect on horizontal and vertical ocular deviations measured by AHS. Mean amplitude of deviation in primary gaze was 1.2 prism diopters (PD) esotropia and 0.07 PD hypotropia before surgery, and 2.5 PD exotropia with 0.6 PD hypertropia after surgery (delta = 3.7 PD for horizontal deviation and -0.7 for vertical deviation; P = 0.051, paired samples t test for horizontal difference and P not significant for vertical difference). Nonsignificant P values were obtained in all 9 positions of gaze. Most patients had periocular numbness that resolved spontaneously 2 to 6 months after surgery. CONCLUSIONS: Deep lateral wall orbital decompression with intraconal fat debulking had no statistically significant effect on horizontal and vertical deviations measured by the AHS. Patients may demonstrate small angle exotropia shift, but this finding was not clinically significant.

Adipose Tissue↗

PubMed1998

Unilateral peripapillary myelinated retinal nerve fibers associated with strabismus, amblyopia, and myopia.

PURPOSE: To describe the association of unilateral peripapillary myelinated retinal nerve fibers with myopia, strabismus, and amblyopia and to propose a possible pathologic mechanism. METHODS: Four patients who have the findings associated with unilateral peripapillary myelinated nerve fibers are described and reviewed. RESULT: All patients had poor visual outcomes despite treatment with full cycloplegic refraction and appropriate patching. CONCLUSIONS: Although the origin of this association is unknown, we believe that peripapillary myelinated nerve fibers in a unilateral myopic eye may be secondary to an imbalance between the process of myelination and the formation of the lamina cribrosa. Good results have been reported with amblyopic therapy; however, it is our experience that these patients are somewhat refractory to amblyopia therapy.

Amblyopia↗

PubMed1987

Botulinum toxin chemodenervation in infants and children: an alternative to incisional strabismus surgery.

Eighty-two children aged 13 years or younger were given injections of botulinum toxin for horizontal strabismus. Improvement was achieved in all but one patient. Children younger than 1 year or older than 6 years of age received only topical drop anesthesia and no sedation. Young children generally required low-dose ketamine sedation. The technique typically undercorrects, so reinjection was necessary in 85% of the patients. There were no systemic complications. Side effects, lasting up to a few weeks, included transient ptosis and hypertropia caused by involvement of other extraocular muscles.

Botulinum Toxins↗

PubMed2003

Strabismus.

The various forms of strabismus present clinicians with interesting diagnostic and treatment dilemmas. The importance in distinguishing the various structural, neurosensory, and developmental forces at work in the interplay between visual acuity, binocularity, and oculomotor function keeps even experienced strabismologists occupied. It is hoped that this article may help pediatricians approach their strabismic patients with a fuller understanding of the subject.

Child↗

PubMed1983

Diagnosis and management of strabismus and amblyopia.

Strabismus and amblyopia are among the most common eye problems encountered in children. Proper assessment and management require a knowledge of the various types, methods of detection, and principles of treatment. The role of the pediatrician is emphasized because of the importance of early detection.

Abducens Nerve↗

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↗

PubMed1997

Visual responses of neurons from areas V1 and MT in a monkey with late onset strabismus: a case study.

One adult monkey (Macaca fascicularis) was investigated psychophysically and electrophysiologically after at least 5 years of late onset esotropic macrostrabismus (squint angle 52 deg). Behavioural tests revealed normal monocular visual and visuomotor functions. No indications of deep amblyopia or oculomotor asymmetry were found. The monkey used the left or right eye alternately at about equal frequencies. Single unit recordings from area VI disclosed a normal ocular dominance distribution. Most VI neurons from both hemispheres received binocular input. Thus, discordant visual information from corresponding retinal locations of the two eyes converged onto the cortical neurons. No evidence for anomalous retinal correspondence was found. Diplopia and confusion must therefore be avoided by suppression of vision through one eye to allow stable, unambiguous perception. Possible suppression was investigated by stimulating a neuron through the same eye when it was actively used for fixation in one set of trials, and when it was not used for fixation in another set of trials. Significant differences in these two stimulus conditions were found in 20/39 neurons from area VI and in 11/34 motion sensitive neurons recorded in the middle superior temporal area (MT). The normalized population activity in VI and MT was higher if cells were stimulated through the fixating eye. The data are discussed with respect to possible suppressive mechanisms helping to prevent double vision in strabismus and in binocular rivalry.

Action Potentials↗

PubMed1997

Listing's plane dependence on alternating fixation in a strabismus patient.

Listing's law of the eye is one of the best studied findings in motor control, but its functional meaning is still incompletely understood and its status in neurological disorders and in strabismus is almost entirely unknown. We investigated the mechanisms underlying Listing's law and its possible clinical relevance. The dual magnetic search coil technique was used to record three-dimensional binocular eye movements in a stereoblind strabismic patient with good visual acuity in both eyes and capable of voluntarily alternating fixation. This technique yielded an accurate, objective and simultaneous measure of ocular misalignment in three dimensions and showed that the squint angle depended on which eye was fixating. Saccadic eye movement data throughout the oculomotor range were used to fit Listing's plane. Listing's primary position and the thickness of the plane for each eye were calculated for three different fixation conditions. For comparison, control measurements were taken from four normals. In the patient, no large deviations from normal values for the thickness of Listing's plane and the confidence limits of the Listing primary position were found. The most remarkable abnormality was that the orientation of Listing's plane depended on which eye was fixating. Both the change in ocular misalignment and the shift of Listing's primary positions observed when changing fixation are probably linked to accommodation-related vergence. Despite repeated surgery at early age, the patient had well-defined Listing planes for both eyes, but their alignment during left-eye fixation was abnormal. The obedience to Listing's law may reflect a strategy which minimizes muscular effort in each eye separately. The abnormal fixation-condition dependence is probably due to an aberrant coupling with vergence.

Adult↗

PubMed2002

Use of augmented rectus muscle transposition surgery for complex strabismus.

PURPOSE: Full tendon rectus muscle transposition surgery augmented with posterior fixation sutures has been shown to be effective in the treatment of abducens palsy and Duane's syndrome. The purpose of this study is to summarize our experience with the use of this procedure and a three fourths partial tendon transposition modification of this procedure for a variety of complex vertical and horizontal paralytic eye movement disorders. DESIGN: Retrospective noncomparative interventional consecutive case series. PARTICIPANTS: Eighteen patients with paralytic strabismus. INTERVENTION: Full tendon rectus muscle transposition procedure augmented with posterior fixation sutures (13 patients) or a three fourths partial tendon transposition augmented with posterior fixation sutures (5 patients). MAIN OUTCOME MEASURES: Resolution of diplopia in the primary position and improved ocular alignment. RESULTS: Comparing preoperative to postoperative status, presence of primary position diplopia decreased from 64% to 14%, anomalous head posture decreased from 56% to 6%, and primary position alignment improved in all patients. CONCLUSIONS: Full tendon rectus muscle transposition surgery augmented with posterior fixation sutures and the vessel-sparing three fourths partial tendon transposition modification of this technique are effective for the treatment of a variety of complex vertical and horizontal paralytic ocular motility disorders.

Adolescent↗

PubMed1979

Strabismus in the aphakic patient.

Fifty patients with aphakia and strabismus were studied. The chief complaint was diplopia following full optical correction. Prism therapy was recommended if the diplopia persisted after 3 to 4 months. When prism therapy was ineffective or impractical, surgery was recommended. The result of therapy was not influenced by the cause of the cataract treatment was considered successful in approximately 80% of patients. Patients who had convergence insufficiency did well with prism therapy alone. Half of the patients who had divergence excess needed extraocular-muscle surgery. One fourth of the patients had esotropia, nearly half associated with lateral rectus palsy. While prism therapy resulted in fusion, a reduction in prism power was not tolerated in this group. For this reason, surgery was suggested for all patients who had esotropia.

Adolescent↗

PubMed1979

The four-step test for diagnosis of paralytic and/or restrictive strabismus.

By placing four diagnostic steps in a logical sequential manner, the diagnosis of a paralytic or restrictive deviation is made somewhat easier. Each time an incomitant strabismus is presented to an ophthalmologist, the four-step procedure should be used. Versions, ductions, and the cover test will reveal the eye to be investigated. Saccades, forced ductions, and/or forced generations will determine the problem and direct a surgical approach if needed.

Duane Retraction Syndrome↗

PubMed1980

Paralytic strabismus in children. Etiologic incidence and management of the third, fourth, and sixth nerve palsies.

The results of a retrospective study of the etiologic incidence of all cases of third fourth, and sixth nerve palsies in patients at Wills Eye Hospital and St Christopher's Hospital are reported. A total of 121 patients ranging in age from birth to sixteen were studied. Thirty-two cases of third nerve palsy, eighteen cases of fourth nerve palsy, and sixty-two cases of sixth nerve palsy were identified in this series. Nine additional cases illustrated combinations of multiple nerve involvement. With few exceptions, acquired third nerve palsy in children is an ominous sign whereas the congenital form is generally indicative of developmental anomaly or birth trauma. Acquired sixth nerve palsy in a child is always a matter of concern since it may represent the first sign of a brain-stem glioma. Active force studies may be carried out periodically to assess the speed of recovery and indicate when it is time to initiate a more aggressive role in the surgical management. The surgical results in children with paralytic strabismus that have been carefully evaluated offer a favorable prognosis.

Adolescent↗

PubMed1982

Strabismus surgery and its effect upon infant development in congenital esotropia.

Parents of children with congenital esotropia have reported improvements in their child's fine motor development and visual functions after surgery. Eighteen patients with congenital esotropia were tested pre- and post-operatively with The Bayley Scales of Infant Development to determine if these observations were valid. A three-point increase in the Bayley raw score of strabismus patients was noted after operation that is significant at the 0.01 level, as compared to the performance of age-matched controls. An improvement in fine motor skills was observed in 35% of the children, and visually directed reaching and grasping increased in 41%. Item #87 on the Bayley, which requires the child to recognize depressions without monocular clues, appears to be related specifically to depth perception. On this item, the study population showed the greatest improvement.

Child Development↗

PubMed1983

The role of funduscopy and fundus photography in strabismus diagnosis.

Fundus photographs taken in 66 patients with vertical strabismus were analyzed in a blind study with respect to ocular torsion. The objective presence or absence of ocular torsion was then correlated with the patient's clinical diagnosis. The presence or absence of objective ocular torsion as seen in fundus photographs had a sensitivity of 0.86 and a specificity of 0.96 for diagnosing the presence of oblique dysfunction, and a sensitivity of 0.96 and specificity of 0.83 for diagnosing the presence of normal oblique function.

Double-Blind Method↗

PubMed1989

Strabismus in infancy.

In order to prospectively study the development of strabismus in infancy, the ocular alignment of a large population of normal neonates was studied and follow-up examinations were obtained in a subset of these infants. The characteristic findings of congenital esotropia subsequently developed in three infants who were either orthotropic or exotropic at birth. Pathologic exotropia developed in two infants; both were exotropic at birth, but no more so than most normal neonates. In infants with congenital esotropia or pathologic exotropia, the characteristic deviation appears to develop between 2 and 4 months of age, a period during which normal infants are becoming increasingly orthotropic.

Abducens Nerve↗

PubMed1990

A primate model of anterior segment ischemia after strabismus surgery. The role of the conjunctival circulation.

Fornix conjunctival incisions in strabismus surgery may provide partial protection against anterior segment ischemia by preserving the perilimbal conjunctival-Tenon's circulation, which is disrupted with limbal conjunctival incisions. Six adult cynomolgus monkeys underwent tenotomies of three or four rectus muscles by making limbal conjunctival incisions in one eye and fornix incisions in the other. Iris fluorescein angiography and slit-lamp biomicroscopy were used to monitor changes. The eyes that had limbal incisions exhibited more severe anterior segment ischemic changes than the eyes that had fornix incisions in every instance of four rectus muscle surgery.

Animals↗