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PubMed2003

The incidence of strabismus and refractive error in patients with blepharophimosis, ptosis and epicanthus inversus syndrome (BPES).

A retrospective review was carried out of 204 patients with blepharophimosis, (blepharo) ptosis and epicanthus inversus syndrome (BPES). Of these, 94 (46%) had an autosomal dominant family history of BPES. Forty (20%) had manifest strabismus. Of these, 28 (70%) had esotropia, 10 (25%) had exotropia and 2 (5%) had hypertropia. Twelve (6%) patients had nystagmus. Seventy (34%) patients had a significant refractive error requiring spectacles. Twenty-one (30%) of these patients had anisometropic hypermetropia and 24 (34%) had anisometropic myopia. Forty-three patients had bilateral amblyopia and 40 had unilateral amblyopia, with 26 (65%) of these undergoing occlusion treatment. Of these, 14 had strabismus and refractive error, 7 refractive error only, 2 strabismus only and 3 neither refractive error nor strabismus. We conclude that there is a higher incidence of strabismus and refractive error in patients with BPES than in the normal population.

Blepharophimosis↗

PubMed1999

Botulinum toxin in childhood strabismus.

The use of botulinum toxin A (BTXA) in childhood strabismus is still a matter of debate. This study investigates the indications for and outcome of BTXA therapy in children at our institution. From 1985 to 1995, 237 children up to and including 16 years of age were treated with BTXA for strabismus. We undertook a retrospective study of 163 (69%) children from this group. Factors considered were age; anaesthesia; number of, indication for and outcome of injections; complications and follow-up. There were three major indications for the use of BTXA in children: firstly to improve binocular function, secondly as a post-operative diplopia test or for cosmetic reasons, and thirdly in the investigation or treatment of paralytic and restrictive strabismus. In the first group (54 children), BTXA produced improved binocular function in 54% of all patients treated and in 49% of those with a minimum follow-up of 12 months. In the second group (82 children), 88% showed informative post-operative diplopia tests and 44% had more than one injection to maintain improved cosmetic alignment. The third group comprised 27 children with a range of diagnoses, including 1 third nerve paresis, 12 unilateral or bilateral sixth nerve pareses, 7 unilateral or bilateral Duane's syndromes, 5 lost or fibrosed muscles and 2 others. This group had a range of outcomes which are discussed in the text. BTXA is useful in the treatment of a select group of children with strabismus. If there is evidence of threatened or recently lost binocularity, or risk of creating or worsening diplopia after surgery, it is a useful therapeutic tool. In children with strabismus of unusual cause it has diagnostic value.

Adolescent↗

PubMed2004

Amblyopia & Strabismus Questionnaire: design and initial validation.

Literature on the benefits of screening and treatment of amblyopia emphasizes the costs of insufficiently treated amblyopic patients who lose their better eye. However, patients with insufficiently treated amblyopia and strabismus who do not lose their better eye only experience a slight decrease in their quality of life, and such patients occur more frequently. We designed and validated a questionnaire for amblyopia and strabismus in order to assess the decrease in quality of life of such patients. Complaints were collected from outpatients and reduced to five domains, pertaining to distance estimation, visual disorientation, problems with social contacts and cosmetic problems, diplopia, and fear of losing the better eye. For these domains 26 questions were formulated that constitute the Amblyopia & Strabismus Questionnaire (A&SQ). The A&SQ, the National Eye Institute Visual Function Questionnaire-25 (VFQ-25) and the Short Form-12 Health Survey (SF-12) were presented to 53 healthy controls, 68 outpatients and a cohort of 174 outpatients born between 1962 and 1972 and treated between 1968 and 1974 for amblyopia and strabismus. The quality of life was best in healthy controls and worst in current outpatients, not only on the SF-12 and the VFQ-25 but also on the A&SQ, demonstrating an acceptable construct validity of the A&SQ. The decrease in the quality of life as measured by the A&SQ was most outspoken in our outpatient group of amblyopia and strabismus patients, less in the cohort that had been treated 30 years previously and least in the healthy controls, demonstrating an acceptable discriminatory validity of the A&SQ.

Adult↗

PubMed2005

Incomitance in monkeys with strabismus.

PURPOSE: Rhesus monkeys reared with restricted visual environment during their first few months of life develop large ocular misalignment (strabismus). The purpose of this study was to describe 'A and V' patterns and DVD in these animals during fixation and eye movements and suggest that this form of rearing produces animals that are suitable model to study the mechanisms that might cause 'A/V' pattern incomitant strabismus and dissociated vertical deviation (DVD) in humans. METHODS: Eye movements were recorded during fixation, smooth-pursuit and saccades using binocular search coils in one monkey with esotropia, three monkeys with exotropia and one normal monkey. RESULTS: 1) Monkeys reared with Alternating Monocular Occlusion or Binocular deprivation (tarsal plates intact) showed both horizontal and vertical misalignment during monocular and binocular viewing. 2) Large 'A' patterns were evident in 2 out of 3 exotropes while a 'V' pattern was observed in the esotrope. 3) Similar 'A/V' patterns were observed with either eye viewing and during fixation or eye movements. 4) The vertical misalignment, which consisted of the non-viewing eye being higher than the fixating eye, appeared to constitute a DVD. CONCLUSION: Visual sensory deprivation methods that induce large strabismus also induce 'A/V' patterns and DVD similar to certain types of human strabismus. The source of pattern strabismus could be central, i.e., altered innervation to extraocular muscles from motor nuclei, or peripheral, i.e., altered location of extraocular muscle pulleys.

Animals↗

PubMed2005

Limited protection of the primary visual cortex from the effects of monocular deprivation by strabismus.

Competition between the two eyes for synaptic space is thought to play a crucial role in the developmental plasticity of ocular dominance in the primary visual cortex. This competition should be disrupted if geniculocortical afferents from the two eyes are spatially segregated. In kittens, strabismus was induced in one eye before the onset of the critical period; the effects of a brief period of monocular deprivation (MD) at the height of the critical period and subsequent recovery were assessed in a longitudinal study employing optical imaging of intrinsic signals. Results were compared with those from a control group without strabismus. MD caused a substantial loss of cortical territory dominated by the deprived eye in all animals. However, in the strabismic animals this loss was smaller than in the control group for the hemisphere contralateral to the deprived eye. When the deprived eye was reopened, recovery of cortical territory was remarkably rapid in all kittens, and close to pre-deprivation responses were attained within 3-4 days of reopening. However, kittens without strabismus exhibited a greater rate of recovery from MD. Moreover, recovery of visual acuity, as assessed by visually evoked potential (VEP) measurements, was slower and less complete in animals with strabismus prior to MD. Therefore, strabismus does not provide lasting protection against the effects of MD.

Animals↗

PubMed1987

Further investigation of a strabismus model.

Computer models of strabismus have been available for about ten years. Such models are computer programs which perform a set of calculations based on an interpretation of the oculomotor system as a system of two spheres each with six adjustable springs. The effects of pathology and surgery can be simulated by altering the parameters of the springs. However, such models have not yet met with wide practical acceptance. One reason for this lack of interest is that previous investigators have neglected to apply strabismus models to concomitant strabismus. In this paper the application of a strabismus model to concomitant strabismus is demonstrated and data are generated which should be clinically useful. Another reason for lack of acceptance of computer models results from the expectation that they may be unreliable because of biological variability. The model developed here is tested for its sensitivity to a wide range of biological variations and proves to be very robust. Therefore, information on concomitant squint surgery given by the model should be applicable to most patients.

Computer Simulation↗

PubMed2002

Animal models for visual deprivation-induced strabismus and nystagmus.

The development of gaze-stabilizing systems depends on normal vision during infancy. Monkeys reared with binocular lid suture (BLS) for the first 25-40 days of life have strabismus, optokinetic nystagmus deficits, latent nystagmus, and decreased binocular cells in the visual cortex and nucleus of the optic tract. When BLS is extended to 55 days, pendular and congenital nystagmus also occurs. Eyelids in infant monkeys are hairless and thin, but BLS still degrades sensory fusion, motion, and form perception. To determine to what extent these visual properties are critical in the development of normal gaze stabilization, we examined infant monkeys reared with one opaque contact lens over one eye, alternated to the fellow eye every other day (AMO); and monkeys reared in a 3-Hz strobe environment. Monkeys reared with AMO develop strabismus, but have normal optokinetic nystagmus and no spontaneous nystagmus. Area 17 is monocular, but the medial temporal area and the nucleus of the optic tract are binocular. Monkeys reared in strobe light develop pendular nystagmus but not strabismus. We were puzzled by the results of the AMO monkeys until we examined infant monkeys with BLS that were prevented from seeing form through the lids. This was done by leaving the tarsal plate intact behind the eyelid. They developed similar to the AMO monkeys. These results suggest that disruption of sensory fusion during infancy (BLS, AMO) causes strabismus. If strabismus occurs while the monkeys have some form vision from each eye (BLS without tarsal plate), then the nucleus of the optic tract becomes monocular, which causes optokinetic nystagmus deficits and latent nystagmus. Infant monkeys reared without visual motion develop pendular nystagmus.

Animals↗

PubMed1979

A clinical study on the detection of strabismus, anisometropia or ametropia of children by simultaneous photography of the corneal and the fundus reflexes.

Twenty two strabismus and 106 straight eyed patients with anatomically normal eyes were first photographed with a conventional camera equipped with a weak 100 mm teleobjective and coaxial flashlight and then examined clinically. The possibility of detecting strabismus, anisometropias and ametropias in the photographs by noting the localisation of the corneal reflexes and examining the appearance and lightness of the fundus reflexes and their possible asymmetry were tested in a double blind study. Even small angled strabismus cases could be found because of the asymmetrical localisation of the corneal reflexes. In 18 of the 22 strabismus cases (82%) there was asymmetrical lightness of the fundus reflexes and the fundus reflex of the deviating eye was lighter than that of the fixating eye. All the straight eyed anisometropias of 3.0 diopters or more (five cases) were observed in the photographs because of the asymmetrical appearance of the fundus reflexes. In straight eyed anisometropias of under 3.0 diopters, the fundus reflexes were symmetrical in 90 cases and asymmetrical in 11 cases (11%). Only three out of eight hyperopias of fomr +4.5 to +6.0 diopters were found because of the light crescent in the low part of the pupil. All myopias of over -4.0 diopters (14 cases) were observed because of the light crescent appearance in the upper part of the pupil. No pupillary crescents appeared with refractions of less than -1.75 diopters myopia or less than +4.5 diopters hyperopia; 172 eyes came within this range. Even a technician can perform, without premedication, the method tested here for rapid and simple screening to detect strabismus and straight eyed anisometropias of 3.0 diopters or more in small children or other patients who do not co-operate well in normal clinical examination. Over -4.0 diopters myopias can also be found. The method was rather unreliable for finding hyperopias, presumably because no cycloplegic drops were used.

Astigmatism↗

PubMed2005

Decreasing strabismus surgery.

AIM: To determine whether there has been a consistent change across countries and healthcare systems in the frequency of strabismus surgery in children over the past decade. METHODS: Retrospective analysis of data on all strabismus surgery performed in NHS hospitals in England and Wales, on children aged 0-16 years between 1989 and 2000, and between 1994 and 2000 in Ontario (Canada) hospitals. These were compared with published data for Scotland, 1989-2000. RESULTS: Between 1989 and 1999-2000 the number of strabismus procedures performed on children, 0-16 years, in England decreased by 41.2% from 15 083 to 8869. Combined medial rectus recession with lateral rectus resection decreased from 5538 to 3013 (45.6%) in the same period. Bimedial recessions increased from 489 to 762, oblique tenotomies from 43 to 121, and the use of adjustable sutures from 29 to 44, in 2000. In Ontario, operations for squint decreased from 2280 to 1685 (26.1%) among 0-16 year olds between 1994 and 2000. CONCLUSION: The clinical impression of decrease in the frequency of paediatric strabismus surgery is confirmed. In the authors' opinion this cannot be fully explained by a decrease in births or by the method of healthcare funding. Two factors that might have contributed are better conservative strabismus management and increased subspecialisation that has improved the quality of surgery and the need for re-operation. This finding has a significant impact upon surgical services and also on the training of ophthalmologists.

Adolescent↗

PubMed2004

The genetics of strabismus.

Strabismus (misalignment of the eyes; also known as "squint") comprises a common heterogeneous group of disorders characterised by a constant or intermittent ocular deviation often associated with amblyopia (uniocular failure of normal visual development) and reduced or absent binocular vision. The associated poor cosmetic appearance may also interfere with social and psychological development. Extensive twin and family studies suggest a significant genetic component to the aetiology of strabismus. The complexity of the molecular basis of strabismus is now beginning to be elucidated with the identification of genetic loci and disease causing genes. Currently greater insights have been gained into the incomitant subtype (differing magnitude of ocular misalignment according to direction of gaze), whereas less is known about the pathogenesis of the more common childhood concomitant strabismus. It is hoped that a greater understanding of the molecular genetics of these disorders will lead to improved knowledge of disease mechanisms and ultimately to more effective treatment. The aim of this paper is to review current knowledge of the molecular genetics of both incomitant and concomitant strabismus.

Cranial Nerves↗

PubMed1994

The heritability of strabismus.

The etiology of strabismus has long been observed to have a genetic component. Recent advances in genetic methodology may provide insight into the genetic basis for several types of inherited strabismus, including those associated with genetic multisystem disorders such as Moebius syndrome, Prader-Willi syndrome, craniofacial dysostoses, and mitochondrial myopathies. Inheritance of primary forms of strabismus, such as congenital ocular fibrosis, Brown syndrome and Duane syndrome, has been reported, but less is known of the defective genetic sites. The genetic basis for isolated strabismus that clusters in families, such as infantile esotropia syndrome, is also not yet known, but new techniques of molecular biology may now permit linkage detection in these families. By identifying affected families, clinicians will take part in unraveling the genetic basis of hereditary strabismus syndromes.

Female↗

PubMedDate not supplied

Amniotic band syndrome and strabismus.

Three patients with various manifestations of the amniotic band syndrome associated with strabismus are presented and discussed. All three cases demonstrate a paralytic strabismus due to a unilateral paresis-paralysis of the medial rectus in one case and of the superior rectus in another. The third case showed a bilateral lateral rectus paralysis. In two cases, the strabismus was accompanied by other ocular manifestations, while in one patient strabismus and amblyopia were the sole ophthalmological findings. In two of the cases, a direct association between the mesodermal bands and the strabismus could be established, while in one case this association might have been incidental. Careful ophthalmological followup and treatment of these cases prevented needless loss of vision while appropriate muscle surgery restored acceptable cosmetic appearance in one case.

Abnormalities, Multiple↗

PubMedDate not supplied

Effect of botulinum toxin A chemodenervation in sensory strabismus.

PURPOSE: To study the effect of botulinum toxin type A chemodenervation in sensory strabismus. METHODS: Twelve patients with sensory strabismus were treated with an injection of botulinum toxin type A (Botox; Allergan, Irvine, Calif). Botulinum toxin type A was diluted with 0.9% sodium chloride without preservative at a dose that ranged from 1.25-5 U. A Teflon-coated needle electrode was inserted into the medial rectus muscle in cases of esotropia and into the lateral rectus muscle in cases of exotropia. Four patients were treated with > or =2 injections of botulinum toxin type A. Changes in the angle of strabismus and related complications were followed for >6 months postinjection. RESULTS: The mean deviation before injection was 33.8 prism diopters (delta) and the mean corrective effect on the deviation was 72.8% after injection in patients with sensory strabismus. The final deviation in 9 patients was <10 delta. Complications were hypertropia in 3 (25%) patients and conjunctival hemorrhage in 1 (8.3%) patient. CONCLUSION: Botulinum toxin type A is likely to prevent muscle contracture and affect muscle and neuronal tissues. This study on the effects of sensory strabismus with botulinum toxin type A injection suggests it has the potential to replace surgery or be used as an adjuvant therapy.

Adult↗

PubMedDate not supplied

Strabismus in Down syndrome.

PURPOSE: To determine the distribution of refractive errors and clinical characteristics of strabismus in patients with Down syndrome. PATIENTS AND METHODS: Patients with Down syndrome attending the Izmir Association for Supporting Patients With Down Syndrome in Izmir, Turkey, were screened for strabismus and refractive errors. All patients underwent a complete eye examination including cycloplegic refraction and dilated fundus examination. Ocular alignment was evaluated using the cover test and either the Krimsky or the Hirschberg corneal reflex test depending on the cooperation of the patient. Strabismic and nonstrabismic patients were compared for refractive errors, anisometropia, and amblyopia. RESULTS: Fifty-seven patients with an average (+/- standard deviation) age of 9.30 years (+/- 6.14 years; range, 1 to 31 years) were screened. Twenty-five (44%) were female and 32 (56%) were male. Eleven patients (19%) had strabismus. Ten (18%) had esotropia and 1 (2%) had exotropia. Infantile esotropia was observed in 3 patients who had no significant refractive errors. Seven patients had acquired esotropia; they had clinically significant refractive errors and anisometropia. A higher frequency of hypermetropia was noted in patients with strabismus (P < .05). CONCLUSIONS: Esotropia and hypermetropia are common in patients with Down syndrome. Early diagnosis and treatment of strabismus and associated ocular conditions such as refractive errors and amblyopia may improve the quality of life for these patients.

Adolescent↗

PubMed1999

Aniseikonia in relation to strabismus, anisometropia and amblyopia.

PURPOSE: To study the interrelationships among these four entities which are critical to binocular vision and its precision. SUBJECTS AND METHODS: 102 selected patients (for their ability to have stereoscopic depth perception, a requisite for space eikonometry) were evaluated. Patient testing included stereoscopic testing, Essilor Projection Space Eikonometry, ultrasonic echographic axial length measurements and orthoptic evaluation. Aniseikonia was measured on the Essilor Projection Space Eikonometer. RESULTS: 1. Anisometropia alone was correlated with a marked increase in amblyopia, a moderate increase in aniseikonia and no noteworthy increase in strabismus. Statistical analysis (chi square ratio) showed that persons with elevated anisometropic values had a 4.4 fold increased risk of aniseikonia (p=.003). 2. Aniseikonia alone was not responsible for marked variations in strabismus. 3. Amblyopia was correlated with increases in anisometropia and aniseikonia. 4. Adding aniseikonia to anisometropia produced a possible increase in strabismus and a great increase in amblyopia (using Fisher's Exact Test, 2-tailed). 5. Spearman correlations of the "absolute values" (the mean of the mathematical difference between the two eyes of anisometropia and amblyopia) were as follows: anisometropia (abs) vs. aniseikonia r=.294, p=.006; anisometropia (abs) vs. amblyopia (abs) 4=.555, p=<.001; amblyopia (abs) vs. aniseikonia r=.234, p=.02. CONCLUSIONS: Aniseikonia per se does not appear to have a major causal role in amblyopia or strabismus, but anisometropia does for amblyopia. This role is greatly augmented by aniseikonia and this combination may then produce strabismus.

Amblyopia↗

PubMed2000

Suitability of the lang II random dot stereotest for detecting manifest strabismus in 3-year-old children at child health centres in Sweden.

The aim of the study is to examine the suitability of the Lang II Random Dot Stereotest for use by district nurses in primary healthcare centres. The Lang Stereotest is an inexpensive method. It is easy to apply, but the child's co-operation is required. Approximately 100 district nurses were given detailed information and instruction by an orthoptist prior to a randomized population-based community trial initiated in 1993. In the county of Uppsala in Sweden, all 4293 children born in 1990 were randomized to one of the following four study groups: intervention, control, reliability or validity. All children were followed from birth to 6.5 y of age with respect to the occurrence of strabismus. The kappa statistic for test-retest reliability among district nurses was 0.65 (95% CI, 0.51-0.80). A validation of the outcomes of district nurses' against orthoptists' examinations using the Lang Stereotest showed a sensitivity of 0.33 (95% CI, 0.09-0.65) and a specificity of 0.85 (0.80-0.89). Of 113 cases of strabismus, 53% were detected within the first 3 y of life. Examination of 1132 3-y-old children using the Lang Stereotest enabled the district nurses to detect 11 new cases of strabismus. Only one of these cases was referred to an orthoptist as a direct consequence of the screening. The Lang Stereotest showed low reliability and low validity in this community trial. It is concluded that the Lang II Random Dot Stereotest is not suitable for the screening of manifest strabismus in unselected populations of 3-y-old children in Sweden, where a large proportion of cases of strabismus is detected during the first 3 y of life.

Age Factors↗

PubMed2000

BVAT distance vs. near stereopsis screening of strabismus, strabismic amblyopia and refractive amblyopia; a prospective study of 68 patients.

PURPOSE: Although there have been studies in the past of the difference between distance and near stereopsis in intermittent exotropia, no such comparisons have been studied and/or reported for other forms of strabismus, nor for strabismic functional amblyopia, or for refractive functional amblyopia. METHODS: The study was prospective: Sixty-eight consecutive patients, ages 6-76 years, with either childhood onset strabismus and no amblyopia, childhood onset strabismus and amblyopia, or refractive amblyopia and no strabismus, had their stereopsis measured. Distance stereopsis was determined on the Mentor BVAT with Random Dot E Test (global stereopsis) and the Circle Test (contour stereopsis). Near stereopsis was determined with the Circle Test of the Randot Stereotest. The data were tabulated and analyzed statistically. RESULTS: Of the 26 strabismus/no amblyopia cases, 14 (54%) appreciated distance stereopsis. Of these, 12/14 were intermittent, and other 2 who were constant had deviations of 8 PD or less. Only 4 of the 14 appreciated global stereopsis at distance (mean = 90 sec. of arc), but all 14 appreciated contour stereopsis at distance (mean = 125 sec. of arc). Of all 26, 21 (81%) had near stereopsis (mean = 137 sec. of arc). For the 21 strabismic amblyopes, only one appreciated global stereopsis at distance (120 sec of arc), and 2 (10%) contour stereopsis at distance (mean = 210 sec. of arc). These two and 4 others (total 29%) had near stereopsis (mean = 162 sec. of arc). For the 21 refractive amblyopes, 3 appreciated global stereopsis at distance (mean = 220 sec. of arc), 11 in all, (52%) contour stereopsis at distance (mean = 121 sec. of arc) and 20 (95%) had near stereopsis (mean = 78 sec. of arc). The percentages of patients in all categories capable of appreciating distance stereopsis were "statistically significantly" (P<.05) or clinically/medically significantly different from (less than) the percentages having near stereopsis. CONCLUSIONS: distance stereopsis is more likely to be reduced or absent than near stereopsis in strabismus, strabismic amblyopia and refractive amblyopia and thus appears to be more sensitive to, and better screening for, binocular vision disorders and a stronger and better outcome standard for treatment of binocular vision disorders than near stereopsis.

Adolescent↗

PubMed2001

Strabismus due to flap tear of a rectus muscle.

PURPOSE: To present a previously unreported avulsion-type injury of the rectus muscle, usually the inferior rectus, and detail its diagnosis and operative repair. METHODS: Thirty-five patients underwent repair of flap tears of 42 rectus muscles. The muscle abnormality was often subtle, with narrowing or thinning of the remaining attached global layer of muscle. The detached flap of external (orbital) muscle was found embedded in surrounding orbital fat and connective tissue. Retrieval and repair were performed in each case. RESULTS: Fourteen patients had orbital fractures, 7 had blunt trauma with no fracture, and 9 had suspected trauma but did not undergo computed tomographic scan. Five patients experienced this phenomenon following retinal detachment repair. Diagnostically, the predominant motility defect in 25 muscles was limitation toward the field of action of the muscle, presumably as a result of a tether created by the torn flap. These tethers simulated muscle palsy. Seventeen muscles were restricted away from their field of action, simulating entrapment. The direction taken by the flap during healing determined the resultant strabismus pattern. All patients presenting with gaze limitation toward an orbital fracture had flap tears. The worst results following flap tear repair were seen in patients who had undergone orbital fracture repair before presentation, patients who had undergone previous attempts at strabismus repair, and patients who experienced the longest intervals between the precipitating event and the repair. The best results were obtained in patients who underwent simultaneous fracture and strabismus repair or early strabismus repair alone. CONCLUSIONS: Avulsion-type flap tears of the extraocular muscles are a common cause of strabismus after trauma, and after repair for retinal detachment. Early repair produces the best results, but improvement is possible despite long delay.

Adolescent↗