Latency of saccades, vergence, and combined movements in children with early onset convergent or divergent strabismus.
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The goal of this study was to examine latency of horizontal eye movements in the natural space (saccades, vergence, and combined saccade-vergence movements) in children with early onset convergent or divergent strabismus. Ten children were tested (8-11 years old): three with divergent strabismus, seven with convergent strabismus. A paradigm was used to elicit pure lateral saccades at far and near distance, pure vergence (convergence and divergence) and saccades combined with vergence movements. Horizontal eye movements from both eyes were recorded simultaneously by a photoelectric device (Oculometer, Dr. Bouis). The latency of saccades (at far and near distance), of vergence (convergence and divergence), and of combined movements greatly varies among subjects and has tendency to be longer than that observed in normal children of matched age, however, these differences reach significance in only a few cases. Children with divergent strabismus and residual gross binocular vision show abnormally longer vergence latencies than children with convergent strabismus without binocular vision. The initiation of combined movements does not show a dominant pattern, such as preceding vergence, as is found in normal children. Finally, strabismus surgery has no major effect on latencies. We conclude that there is no overall deficiency in latencies of eye movements in 3D space in children with early onset strabismus. Most likely, monocular visual input can be efficient as normal binocular vision for vergence movements. In a few subjects with divergent strabismus and fragile, intermittent binocular vision, latencies can be abnormally long, just because of the fragile binocular input and/or attention effort needs to use it. The absence of a pattern of initiation similar to normal children could be due to attention and fixation capabilities. (+info)
Intermittent exotropia increasing with near fixation: a "soft" sign of neurological disease.
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AIM: To examine the association of distance-near disparity with neurological disease in children with intermittent exotropia. METHODS: A retrospective analysis was performed of the medical records of all children with intermittent exotropia examined at the Arkansas Children's Hospital between 1989 and 2002. The study group consisted of children with intermittent exotropia who had a near deviation that exceeded the deviation at distance by at least 10 prism dioptres. The control group consisted of children with intermittent exotropia who had a distance deviation greater than or equal to the deviation at near. The main outcome measures were the prevalence of neurological abnormalities in the study and control groups. RESULTS: Among the 29 patients in the study group, 19 (66%) had a history of concurrent neurological abnormalities. Associated neurological conditions included developmental delay (10 patients), attention deficit disorder (four patients), cerebral palsy (four patients), history of intracranial haemorrhage (four patients), periventricular leucomalacia (three patients), seizures (two patients), cortical visual impairment (two patients), hydrocephalus (one patient), history of anoxic brain damage (one patient), history of encephalitis (one patient), and autism (one patient). Among the 37 patients in the control group, seven (19%) had a history of concurrent neurological abnormalities. The difference in the prevalence of neurological disease between the study group and the control group was significant (p = 0.0002). CONCLUSION: Intermittent exotropia increasing with near fixation is associated with neurological disease in children. (+info)
Sensory exotropia subsequent to senile cataract.
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To evaluate the phacoemulsification and intraocular lens implantation in patients with sensory exotropia subsequent to senile cataract. The authors prospectively studied the role of phacoemulsification and intraocular lens implantation on 25 patients by observing visual acuity, ocular alignment, binocular vision and diplopia pre-, 1 month post- and 3 months post-operation. The patients underwent follow-up for three months. Postoperatively, one patient had a corrected visual acuity of 20/50, and 24 patients had 20/40 or better. The ocular alignment, binocular vision and diplopia were resolved spontaneously. Phacoemulsification and intraocular lens implantation performed together is effective on sensory exotropia subsequent to senile cataract. (+info)
Magnetic resonance imaging of the effects of horizontal rectus extraocular muscle surgery on pulley and globe positions and stability.
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PURPOSE: Magnetic resonance imaging (MRI) was used to determine the effect of recessions and resections on horizontal extraocular muscle (EOM) paths and globe position. METHODS: Four adults with horizontal strabismus underwent contrast-enhanced, surface-coil MRI in central, secondary, and tertiary gazes, before and after horizontal EOM recessions and/or resections. EOM paths were determined from 2-mm thickness, quasicoronal MRI by analysis of cross-sectional area centroids in a normalized, oculocentric coordinate system. Globe displacement was determined by measuring the apparent shift of the bony orbit in eccentric gaze. RESULTS: In all subjects, the anteroposterior positions of the horizontal rectus pulleys shifted by less than 2 mm after surgery, indistinguishable from zero within measurement precision. In three subjects who underwent medial rectus (MR) recession or resection, postoperative globe position was similar in central gaze, but globe translation during vertical gaze shift changed markedly. There was no effect on globe translation in the subject who underwent only lateral rectus (LR) resection. CONCLUSIONS: Recessions and resections of horizontal EOMs have minimal effect on anteroposterior EOM pulley positions. Because the pulley does not shift appreciably despite large alterations in the EOM insertion, the proximity of a recessed EOM to its pulley would be expected to introduce torsional and vertical actions in tertiary gazes. Connective tissue dissection during MR surgery may destabilize the globe's vertical translational stability within the orbit, potentially changing the effective pulling directions of the rectus EOMs in vertical gazes. These changes may mimic oblique muscle dysfunction. LR surgery may avoid globe destabilization. (+info)
Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children.
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AIM: To study the distribution of anisometropia and aniso-astigmatism in young Australian children, together with clinical and ocular biometry relations. METHOD: The Sydney Myopia Study examined 1765 predominantly 6 year old children from 34 randomly selected Sydney schools during 2003-4. Keratometry, cycloplegic autorefraction, and questionnaire data were collected. RESULTS: Spherical equivalent (SE) anisometropia (> or =1 dioptre) prevalence was 1.6% (95% confidence interval (CI) 1.1% to 2.4%). Aniso-astigmatism (>or =1D) prevalence was 1.0% (CI: 0.6% to 1.6%). Both conditions were significantly more prevalent among moderately hyperopic (SE > or =2.0D) than mildly hyperopic (SE 0.5-1.9D) children. Myopic children (SE < or =-0.5D) had higher anisometropia prevalence. Neither condition varied by age, sex, or ethnicity. In multivariate analyses, anisometropia was significantly associated with amblyopia, odds ratio (OR) 29, (CI: 8.7 to 99), exotropia (OR 7.7, CI: 1.2 to 50), and neonatal intensive care unit (NICU) admission (OR 3.6, CI: 1.1 to 12.6). Aniso-astigmatism was significantly associated with amblyopia (OR 8.2, CI: 1.4 to 47), maternal age >35 years (OR 4.0, CI: 1.3 to 11.9), and NICU admission (OR 4.6, CI: 1.2 to 17.2). Anisometropia resulted from relatively large interocular differences in axial length (p<0.0001) and anterior chamber depth (p = 0.0009). Aniso-astigmatism resulted from differences in corneal astigmatism (p<0.0001). CONCLUSION: In this predominantly 6 year old population, anisometropia and aniso-astigmatism were uncommon, had important birth and biometry associations, and were strongly related to amblyopia and strabismus. (+info)
Neurological features of congenital fibrosis of the extraocular muscles type 2 with mutations in PHOX2A.
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Congenital fibrosis of the extraocular muscles type 2 (CFEOM2) is a complex strabismus syndrome that results from mutations in the homeodomain transcription factor PHOX2A. To define the clinical and neuroimaging features of patients with this autosomal recessive syndrome, we studied 15 patients with genetically defined CFEOM2. All patients underwent full neurological, neuro-ophthalmological and orthoptic assessments. Twelve patients had pupillary pharmacological testing and nine had 3.0 tesla MRI of the brain, brainstem and orbits. Patients were born with severe bilateral ptosis and exotropia with almost complete bilateral absence of adduction, elevation, depression and intorsion. Variable abduction was present prior to strabismus surgery in 14 patients, and central ocular motility reflexes (smooth pursuit, saccades, vestibulo-ocular reflex and optokinetic reflex) were intact except for convergence. Pupillary light and near reflexes were not present, but irises were anatomically normal and responded to pupillary pharmacology. Neuroimaging of brain and brainstem was remarkable for the anatomical absence of cranial nerve (CN) 3 and probably CN 4 bilaterally. Therefore, the CFEOM2 phenotype and neuroimaging are both consistent with the congenital absence of CNs 3 and 4. Additional features included presence of most central ocular motility reflexes, a central lack of pupillary responsiveness of uncertain aetiology and modest phenotypic variability that does not correlate with specific PHOX2A mutations. Clinical presentation, neuroimaging and Phox2a-/- animal models all support the concept that CFEOM2 is a primary neurogenic abnormality with secondary myopathic changes. (+info)
Distance stereoacuity in intermittent exotropia.
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BACKGROUND: Studies of distance stereoacuity in intermittent exotropia suggest that normal stereoacuity corresponds to good control of the deviation and that reduced or negative stereoacuity signifies poorer control. AIM: : To evaluate distance stereoacuity in intermittent exotropia using the Frisby Davis Distance stereo test (FD2). METHODS: Children with intermittent exotropia where the near angle was less than or equal to distance were eligible for recruitment. Standardised prospective data collection included FD2 distance stereoacuity. This was a longitudinal study in which outcomes are reported for baseline, last follow-up (> or =6 months before any surgery) or preoperative and last postoperative visits for those undergoing surgery. RESULTS: 110 children with intermittent exotropia had FD2 stereoacuity tested at baseline: 70 comprehended the test. Mean (standard deviation (SD)) age was 4.6 (1.7) years (range 2-10 years). 41/70 (59%) showed positive responses: mean (SD) stereoacuity 30 (12) s of arc. The mean follow-up period before any surgery was 13 months (range 6-27 months). At follow-up, mean (SD) stereoacuity was 24 (11) s of arc. Preoperative and postoperative stereoacuity were not significantly different from those not undergoing surgery. CONCLUSION: This study was the first to report distance stereoacuity in intermittent exotropia using the FD2 stereo test: patients with intermittent exotropia can achieve normal levels of distance stereoacuity, but a considerable proportion, despite comprehending, showed a negative response. This suggests that using the FD2, distance stereoacuity in intermittent exotropia is either absent or normal rather than reduced. Possible reasons for this and its implications are discussed. (+info)
Antielevation syndrome after unilateral anteriorization of the inferior oblique muscle.
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PURPOSE: To report antielevation syndrome with restriction of elevation on abduction in the operated eye and overaction (OA) of the inferior oblique muscle (IO) of the contralateral eye after unilateral IO anteriorization (AT). METHODS: Medical records were reviewed retrospectively in 8 of 24 patients who underwent unilateral IOAT. Four patients were referred from other hospitals after the same surgery. RESULTS: Four patients had infantile esotropes. The rest showed accommodative esotropia, superior oblique palsy, exotropia, and consecutive exotropia. The mean amount of hyperdeviation was 16.3 PD (10 approximately 30). The mean restriction of elevation on abduction in the operated eye was -1.6 (-1 approximately -4) and IOOA of the contralateral eye was +2.7 (+2 approximately +3). IOAT of nonoperated eyes in 4 patients, IO weakening procedure of anteriorized eyes in 2 patients, and IO myectomy on an eye with IOAT in 1 patient were performed. Ocular motility was improved after surgery in all patients. CONCLUSIONS: Unilateral IOAT may result in antielevation syndrome. Therefore bilateral IOAT is recommended to balance antielevation in both eyes. A meticulous caution is needed when performing unilateral IOAT. (+info)