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PubMed1999

Paralytic strabismus.

In the past 12 months there have been many interesting publications on paralytic strabismus. Many investigators have reported on various imaging techniques helping both the clinician and the basic scientist better evaluate the causes and effects of paralytic strabismus on the extraocular muscle environment. Some interesting cases of neurologic and systemic associations have also been reported, including a unilateral pupil-sparing third nerve paralysis developing after the use of sildenafil citrate (Viagra; Pfizer, New York, New York). Advances in genetics are now helping us further understand complex entities such as progressive external ophthalmoparesis and congenital fibrosis syndrome. At the other end of the spectrum, colleagues are reporting clinical findings to help specify the diagnosis of conditions as diverse as degenerative ataxic disorders and masked bilateral superior oblique muscle paresis. Unfortunately, there were very few papers on proven new effective surgical techniques for the treatment of paralytic strabismus this year. Finally, to help clarify terminology, and when at all possible depending on the reports reviewed, the following nomenclature will be used in this paper: paralysis--complete loss of function of a muscle or group of muscles innervated by a specified (when applicable) cranial nerve or branch; paresis--incomplete loss of function; and palsy--when the authors failed to specify the degree of weakness.

Diagnosis, Differential↗

PubMed2000

Development of refraction and strabismus.

Research on the etiology and causes of refractive errors has become a very active field of study during the past few years. Most of this research has focused on myopia. But hyperopia and astigmatism are also being examined both in comparison to myopia and in their own right. Animal models have also been developed for the study of experimentally induced myopia and hyperopia. These studies demonstrate the chain of neural and molecular events that occurs in induced myopia and hyperopia with increasing precision. In the future, these results may elucidate the mechanisms that underlie the refractive errors seen in human populations. Research into the development of strabismus has not progressed with the same vigor. The links among hyperopia, accommodative convergence, and strabismus are well established. Numerous neural, oculomotor, and subjective correlates of strabismus are now well established, but there has been a failure to develop the experimental paradigms needed to demonstrate the causal relations among these different factors.

Adaptation, Ocular↗

PubMed1997

Does propofol reduce vomiting after strabismus surgery in children?

BACKGROUND: Previous studies have indicated that propofol anaesthesia may reduce the incidence of postoperative nausea and vomiting after strabismus surgery in children. This study was designed to investigate the incidence of vomiting after strabismus surgery at two different levels of propofol anaesthesia compared to thiopental/isoflurane anaesthesia. METHODS: Ninety ASA class I or II children, aged 5-14 yrs were randomly assigned to one of three groups: Group T/I (n = 30) induction with 5 mg kg-1 of thiopental and maintenance with isoflurane, group P5 (n = 31) induction with propofol 2 mg kg-1, maintenance with propofol infusion 5 mg kg-1 h-1 or group P10 (n = 29) induction with propofol 2 mg kg-1, maintenance with propofol 10 mg kg-1 h-1. All received glycopyrrolate, vecuronium, fentanyl and controlled ventilation with O2/N2O 30/70. Ketorolac i.v. was given to prevent postoperative pain. If additional analgesia was needed, ibuprofen/acetaminophen or buprenorphine was given according to clinical need. RESULTS: There were no differences between study groups with respect to age, weight, history of previous anaesthesia or emesis after previous anaesthesia, duration of anaesthesia, surgery or sleep after anaesthesia, or number of muscles operated. The incidence of vomiting was 37%, 29% and 28% in groups T/I, P5 and P10, respectively. There were no statistically significant differences between the three groups in the incidence of vomiting. The median age of patients who vomited was 7.5 (range 5.0-13.7) yrs while the median age of the patients who did not vomit was 9.1 (range 5.0-14.0) yrs (P < 0.01). CONCLUSION: In the present study, propofol anaesthesia compared to thiopental/isoflurane anaesthesia did not reduce the incidence of vomiting following strabismus surgery in children.

Adolescent↗

PubMed1988

Complicated strabismus and adjustable sutures.

Clinical experience in performing over 500 adjustable strabismus operations is mentioned in this paper particularly as it relates to complicated strabismus. A maximum hang-loose recession of a rectus muscle has a limited effect, which is tabulated and the implications discussed. Aids in finding the lost medial rectus muscle are mentioned. Adjustable sutures are then exploited in managing the found "lost" medial rectus. Adjustable recession of both vertical recti in the affected eye were used in some cases of blow-out fracture to manage limitations of upward and downward gaze. Adjustable recession of both yoke medial recti are used in some unilateral superior oblique palsies where the main sequela is hypertropia in downward gaze only. A previously paralysed lateral rectus muscle, which has completely recovered function but has left the patient with a concomitant esotropia with full ductions and normal versions, responds excessively to resection. This should be taken into consideration when planning adjustable strabismus surgery in such a case.

Abducens Nerve↗

PubMed2000

Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery.

The oculocardiac reflex (OCR) is induced by mechanical stimulation and therefore is frequently encountered during strabismus surgery. This study was designed to determine how various anaesthetic regimes modulate the haemodynamic effects of the OCR during paediatric strabismus surgery. Thirty-nine patients (4-14 years, ASA I) were randomized to one of four anaesthetic regimes: group P: propofol (12 mg.kg(-1).h(-1)) and alfentanil (0.04 mg.kg(-1).h(-1)); group S: sevoflurane 1-1.2 MAC in 30% O(2)/70% N(2)O; group K: ketamine racemate (10-12 mg. kg(-1).h(-1)) and midazolam (0.3-0.6 mg.kg(-1).h(-1); group H: halothane 1-1. 2 MAC in 30% O(2)/70% N(2)O. Electrocardiogram (ECG), beat-to-beat heart rate (HR) and blood pressure (BP) changes were measured during and after a standardized traction was applied to an external eye muscle (4-6 Newton, 90 s). OCR was defined as a 10% change in HR induced by traction. OCR occurred in 77% of patients. Whereas virtually all patients in the P, H and S groups developed OCR, only 22% developed it in group K. Median HR change in group P (-37 bpm) was significantly greater (P < 0.05) than in group H (-17 bpm) or group K (-7 bpm). Median BP change in group K (+10 mmHg) was significantly different (P < 0.05) from group H (-5 mmHg), group S (-3 mmHg) and group P (-8 mmHg). Atrioventricular rhythm disorders were significantly more frequent in group P compared with group K (P < 0.02). Respiration-induced sinus dysrhythmia was significantly less frequent (P < 0.001) in group K (0%), compared with group P (100%), group H (56%) and group S (55%). Of the anaesthetic techniques studied, ketamine anaesthesia is associated with the least haemodynamic changes induced by OCR during strabismus surgery in paediatric patients.

Adolescent↗

PubMed1996

Biases of motion perception revealed by reversing gratings in humans who had infantile-onset strabismus.

Motion perception was tested by requiring adult subjects to view gratings that remained stationary but reversed in contrast several times per second. Subjects viewed monocularly and judged whether the gratings were stationary, or moving in one direction, in successive 3s trials. Subjects who had early-onset strabismus most frequently perceived vertically oriented gratings to be moving nasalward, and horizontally oriented gratings to be moving up or down. Normal subjects and subjects who had late-onset strabismus most frequently perceived the gratings to be stationary. The asymmetries of motion perception in early-onset strabismus imply that the visual motion neurons of cerebral cortex develop properly only if they receive normal binocular input during infancy.

Adolescent↗

PubMed2006

Polytetrafluoroethylene (Goretex) for muscle elongation in the surgical treatment of strabismus with restricted motility.

PURPOSE: Repeated strabismus surgery as well as eye muscle fibrosis in various forms of strabismus, can be followed by restriction of the motility of the eye. Tendon elongation may be necessary if further improvement of the deviation and duction of the eye muscle is to be achieved. We used polytetrafluoroethylene (Goretex) and looked at its user comfort, compatibility and dose-rate relationship. METHOD: Three patients with consecutive exotropia after repeated operations for congenital esotropia, two patients with VI nerve palsy and residual head turn after combined convergence operation and one child with congenital fibrosis syndrome underwent muscle tendon elongation with Goretex (7-15 mm) of either the medial or the lateral rectus muscle, which had already been resected and/or recessed in former surgeries. Forced duction under general anaesthesia was restricted in all patients. RESULTS: The correction of the deviation in primary position (deviation at distance + 3 degrees to - 4 degrees and at near - 1 degrees to - 8 degrees ) and in side gaze was satisfactory and motility was clearly improved. There were no postoperative complications (infection, shrinkage, scarring) and the postoperative results in terms of the angle of deviation and the improvement in motility remained stable for 1-6 years. CONCLUSION: Polytetrafluoroethylene (Goretex) is a good material with which to resolve complicated cases of strabismus in which muscle tendon elongation for bulbus restriction is necessary.

Adult↗

PubMed1986

Photorefraction: a useful tool to detect small angle strabismus.

Forty patients with small angle strabismus and 30 straight eyed controls were examined by photorefraction in order to establish the validity of this method to detect strabismus. The sensitivity of the method was based on detection of asymmetry of the corneal light and/or fundus reflexes. All cases with a deviation of 2 degrees or more were detected, and 2 controls were falsely considered to be strabismic patients. The sensitivity of the method decreased when the patient wore optimal correction. Photorefraction therefore is considered to be a reliable, simple, and cheap tool with high sensitivity and specificity in screening for strabismus as well as refractive errors.

Adolescent↗

PubMed2006

Effect of refractive surgery on binocular vision and ocular alignment in patients with manifest or intermittent strabismus.

OBJECTIVE: To evaluate the effect of refractive surgery on binocular vision and ocular alignment in patients with manifest or intermittent strabismus, with or without vertical component. SETTING: University Hospital Antwerp, Edegem, Belgium. PATIENTS AND METHODS: 13 patients (22 eyes) with strabismus underwent refractive surgery. Five of these patients presented with an esotropia and four of them with a small vertical deviation. Five patients had a manifest exotropia, of whom two presented with a small vertical deviation. Two patients had an intermittent exotropia with binocular vision, of whom one patient had a vertical deviation. One patient had a hypertropia with a dissociated vertical deviation. RESULTS: Ocular alignment and binocular function remained unchanged postoperatively in all except two patients with high anisometropia who experienced an improvement in binocular function. In these patients, the preoperative manifest deviation became intermittent or latent after surgery, allowing fusion and stereopsis. Vertical deviation was found preoperatively in 8 of the 13 patients. This vertical deviation remained unchanged postoperatively, but improved in one patient with anisometropia. CONCLUSION: Preoperative intermittent or manifest strabismus is not a contraindication for refractive surgery provided some specific recommendations are taken into account, such as an adequate preoperative orthoptic examination and aiming at emmetropia for both eyes.

Adult↗

PubMed1997

Comparison of the efficacy of diclofenac and betamethasone following strabismus surgery.

AIMS: To compare the relative antiinflammatory potency and safety of topical diclofenac-gentamicin with betamethasone-neomycin following strabismus surgery. METHODS: A single centre, single observer, prospective, randomised, and double masked clinical trial of 25 children undergoing bilateral symmetrical horizontal strabismus surgery was carried out. One eye received diclofenac-gentamicin and the contralateral eye received betamethasone-neomycin; both treatments were instilled four times a day for 4 weeks postoperatively. Ocular inflammation was assessed at 1 and 4 weeks postoperatively, objectively by comparison with a photographic chart and subjectively by questionnaire. RESULTS: There was no statistically significant difference in the rate of resolution of the inflammatory response between each group at both visits. CONCLUSION: Diclofenac appears to be as effective as betamethasone in controlling postoperative inflammation following strabismus surgery and may offer a safer alternative to the use of topical steroids.

Anti-Bacterial Agents↗

PubMed2001

Indocyanine green angiography of the anterior segment in patients undergoing strabismus surgery.

BACKGROUND: Anterior segment imaging using fluorescein angiography is only suitable in lightly pigmented irides as the brown pigmentation of the iris masks fluorescein transmission. Indocyanine green (ICG) angiography has excellent penetration of pigment epithelium and, therefore, has potential application in detecting perfusion changes of dark irides after strabismus surgery. METHODS: A prospective study was conducted on patients older than 15 years undergoing strabismus surgery. A fundus camera was focused on the arteriolar tufts of the pupillary margin and 50 mg of ICG (concentration of 12.5 mg/ml) was given intravenously. Images were then obtained at 1 minute intervals of 5 minutes' duration. RESULTS: 45 patients with a mean age of 54.6 years and a mean follow up period of 8.6 weeks were studied. There were 23 patients in the primary surgery group, 11 in the secondary surgery group, and 11 in the staged group. Iris ICG angiograms were successfully performed in all patients. No persistent filling defect was detected in the primary and secondary horizontal recti surgery groups or in the secondary or staged vertical and combined vertical rectus groups 6-8 weeks postoperatively. 57% of both primary vertical and combined vertical and horizontal groups showed defects in the early postoperative phase. Only three cases demonstrated late perfusion defects in this series. CONCLUSION: ICG can detect iris perfusion changes in dark irides after strabismus surgery. Iris reperfusion was achieved in the majority of the cases.

Adolescent↗

PubMed1980

Spatial localization in cats reared with strabismus.

1. The capacity for judging the location of an object relative to the body (egocentric localization) was assessed in cats by measuring the landing position attained when the cat jumped toward a platform viewed from a known distance. 2. Normal cats and kittens land at center of the platform when using one eye or both. In contrast, nine animals tested immediately after tenotomy of the medial rectus muscle of one eye all landed consistently off-center when using the operated eye. The direction of the error was predictable from the assumption that the cat was unaware of the eye's deviation from its natural position. Thus, proprioceptive reafference is not capable, under these conditions, of supporting an accurate awareness of eye position. 3. After initial testing, all cats were maintained in a normal environment with both eyes open and were tested intermittently. Jumps guided by the deviated eye became accurate over a period of weeks in kittens younger than 4 mo. In contrast, behavioral adjustment in older kittens required many months. An adult cat displayed almost no adjustment over a period of 9 mo. 4. Five additional kittens were first tested several months after the onset of strabismus. These animals manifested accurate use of the operated eye from the first trial onward. Therefore, acquisition of accurate use of the deviated eye is not dependent on repeated testing. 5. Two kittens subjected to early exodeviation of one eye displayed a reduced capacity for adjustment when subjected to late exodeviation of the second eye. Thus, changes in neural function resulting from early strabismus (for instance, the loss of binocular connectivity in striate cortex) do not produce persistent behavioral flexibility. 6. In two strabismic kittens with a fully developed compensatory adjustment of monocular egocentric localization, the capacity for judging the relative location of two objects viewed simultaneously through separate eyes was assessed through use of a two-choice visual discrimination paradigm. One animal made predictable systematic errors, while the other exhibited correct judgments. Thus, it appears that a compensatory shift of retinal correspondence may occur in some strabismic kittens, but that such a change is not necessary for accurate use of the deviated eye in monocular visual guidance. 7. A number of observations are described that tend to indicate that cats reared with strabismus continue to use both the deviated and the nondeviated eye for visual guidance under binocular viewing conditions, unlike many human strabismics.

Adaptation, Physiological↗

PubMed1999

Comparison of halothane/thiopental and propofol anesthesia for strabismus surgery.

Day case surgery has become a widely accepted practice for many ophthalmological procedures including strabismus surgery. Prompt recovery from anesthesia and minimal postoperative morbidity are especially requested to the anesthesiologists to deal with the high day case surgery burden. The purpose of this study was to compare two anesthesia techniques, halothane/thiopental anesthesia and propofol anesthesia, for patients undergoing monocular strabismus surgery. We studied the level of postoperative consciousness, nausea and vomiting, ocular pain, starting oral intake and activity in 43 patients, ranging from 7 to 41 years of age. A scoring system was used to assess these parameters in the first postoperative 48 h. Although there was not a significant difference in the level of ocular pain, the propofol group had less morbidity in terms of having a better level of consciousness and appetite, less nausea and vomiting and enhanced activity than the halothane/thiopental group. We conclude that propofol anesthesia has significant advantages over halothane/thiopental anesthesia on an outpatient basis for strabismus surgery.

Adolescent↗

PubMed1992

Extraocular muscles in congenital strabismus: muscle fiber and nerve ending ultrastructure according to different regions.

The ultrastructure of the extraocular muscles of patients affected by congenital strabismus is not completely known, and the structures responsible of the pathogenesis of this condition are still to be determined. Specimens obtained from patients suffering from congenital strabismus were studied and compared with specimens obtained from patients enucleated for various pathologies and not affected by any disorder in the oculomotor system. The scleral myotendinous junction, where the occurrence of an altered proprioceptive innervation was already reported, was examined, and findings obtained were compared with those observed in the muscle body (venter), where motor innervation is prominent and usually described as normal. Only a small number of damaged muscle fibers was found everywhere. The damage consisted in alterations of both contractile structures and mitochondria and resulted in severer lesions in the scleral myotendinous junction rather than in the muscle body. The normal muscle fibers were innervated by motor nerve endings with normal features and by few altered proprioceptors. The less damaged muscle fibers were innervated by normal motor nerve endings and severely damaged proprioceptors. The most severely damaged muscle fibers did not receive any type of innervation. These data seem to imply that the most important functional alteration in strabismus regards the scleral myotendinous junction. It is the authors' opinion that these findings might have a clinical importance in choosing the treatment to be pursued in patients with a squint.

Adolescent↗

PubMed2003

Development of refractive error and strabismus in children with Down syndrome.

PURPOSE: To investigate the development of refractive errors and strabismus in a cohort of children with Down syndrome. METHOD: Data for 55 children with Down syndrome who are participating in this longitudinal study of visual development, first examined by us when aged less than 2 years and on at least two other occasions, were analyzed. Mohindra retinoscopy was used to measure refractive error. Ocular alignment was assessed using the Hirschberg test and, when possible, the cover test. RESULTS: Despite the high prevalence of large refractive errors in children with Down syndrome, longitudinal data showed that these are not always present in early infancy. Twenty-one (38%) of the children were emmetropic throughout the study. Of the 24 children with a significant refractive error at the outset, only 6 (25%) showed emmetropization. The others retained or increased their refractive errors. The remaining 10 children were emmetropic at the outset, but then had a significant refractive error develop. There is a high prevalence of strabismus in children with Down syndrome (29% of the total group), which cannot be attributed to the presence of hypermetropia or anisometropia. CONCLUSIONS: The retention or development of infantile refractive errors in many children with Down syndrome indicates a failure of emmetropization. All children were at risk of strabismus whatever the refractive error. The findings have implications for timing of screening programs.

Down Syndrome↗

PubMed2003

Optokinetic nystagmus in strabismus: are asymmetries related to binocularity?

PURPOSE: Strabismus may be associated with an asymmetry of monocular horizontal optokinetic nystagmus (OKN). It is unclear whether OKN asymmetries are associated with deficiency in binocular and/or stereovision. In the current study, patients with different degrees of binocularity were investigated. METHODS: OKN was examined in the dominant and nondominant eyes of four groups of patients: (1) no measurable binocularity (NB), (2) poor binocularity (PB)-that is, showing binocularity on the Bagolini Test and/or rudimentary stereovision, (3) good binocularity (GB) with good stereoacuity after squint surgery, and (4) a control group. Monocular OKN was elicited with black-and-white stripes moving temporally to nasally (TN) or nasally to temporally (NT) at velocities of 15, 30, 45, and 60 deg/s. Eye movements were recorded with infrared oculography. RESULTS: Only subjects in the NB group showed a significant OKN asymmetry, with preference for TN stimulation in dominant and nondominant eyes. Subjects with PB did not have significant OKN asymmetries but reduced OKN gains in both stimulus directions. Subjects with GB had normal mean OKN gains without asymmetry. Larger OKN asymmetries were correlated with younger age at detection of strabismus if NB and GB were grouped together, but not if each group was analyzed separately. CONCLUSIONS: For the first time, a large groups of patients classified by level of binocular vision has been investigated. The results show that OKN gain and asymmetry are associated with the development of binocular vision. OKN investigation may be helpful to identify patients with binocularity or binocular potential in strabismus.

Adolescent↗

PubMed1986

Rapid strabismus screening for the pediatrician.

"I thought I saw my child's eyes turning" is a frequent observation of parents. The Brueckner test is a simple method, easily learned, to determine the presence or absence of true strabismus. With some practice, an observer can uncover strabismus and amblyopia. This test makes use of a direct ophthalmoscope and the same corneal reflexes one is familiar with in pen light testing. The position of the corneal light reflex is an important portion of the Brueckner test, but the additional, definitive information is derived from the red reflex that fills the entire pupil and gives an excellent backdrop to the bright white dot that is the corneal light reflex. The eye that is turned in or out will have a brighter, more orange-red reflex and the appearance of increased pupil size. Even with pseudostrabismus or unusual angle kappas, the equality or inequality of the red reflex determines the absence or presence of true strabismus. With practice, the Brueckner test can yield the doctor an answer to one of the most common parental concerns.

Amblyopia↗

PubMedDate not supplied

[New surgical approach in the treatment of incomitant strabismus: case report].

The authors report the utilization of the surgical technique proposed by Scott, in 1994, of recess and resection of the same extraocular muscle in the treatment of incomitant horizontal strabismus. A 22-year-old female presented with incomitant strabismus, with an esotropia of 9delta for distant and 30delta for near. She was submitted to a recess and resection of the right medial rectus. She presented satisfactory results in the long-term, showing that this technique could be part of the therapeutic arsenal for correction of incomitant strabismus.

Adult↗