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PubMed2002

Genetics of isolated and syndromic strabismus: facts and perspectives.

Family studies have demonstrated the genetic etiology of concomitant strabismus (prevalence in different populations 1-5%, positive family history in 37% on average), as have twin studies (mean concordance in monozygous twins 73% compared to 35% in dizygous twins). In Duane's syndrome, three chromosomal loci have been identified to date: 2q31, 8q13, and 22q11; loci have also been identified in Moebius syndrome (various inheritance patterns): 13q12.2-q13, 3q21-q22, and 10q21.3-q22, as well as in congenital fibrosis of the extraocular muscles (CFEOM; 3 loci, 1 gene).(1) Already identified are the genes for a number of rarer muscular dystrophy syndromes with ocular involvement, various forms of congenital myasthenia, and mitochondrial diseases (with the primary defect located either in the mtDNA, resulting in a mitochondrial inheritance pattern, or in the nuclear DNA with Mendelian inheritance). A number of hereditary retinal diseases (Mendelian inheritance) may also be associated with strabismus. More than one gene is likely to be involved in the frequently occurring concomitant strabismus, making the analysis more difficult. Patients with chromosomal rearrangements, large families and isolated populations (see also the contributions by Preising and Zitzlsperger et al. in this issue)(2,3) will be instrumental in gene identification. In view of the high prevalence of concomitant strabismus, the disclosure of its etiology will have considerable medical, psychosocial and health-cost impact.

Child↗

PubMed2004

Scleral perforations in strabismus surgery: incidence and role of prophylactic cryotherapy--a clinical and experimental study.

PURPOSE: To determine the incidence of scleral perforations in strabismus surgery in a tertiary centre setting in India and to evaluate the risk or benefit, if any, of prophylactic cryotherapy following experimental scleral perforations in rabbits. METHODS: Seven hundred eyes of patients that had undergone strabismus surgery (1121 procedures) were examined postoperatively by indirect ophthalmoscopy. In the experimental component, 20 rabbit eyes were perforated with a 6-0 polyglactin suture. In each rabbit, one eye acted as a control while the other eye received a 20 seconds application of prophylactic cryo at the perforation site. They were then monitored for 6 weeks before subjecting some to histopathological examination by light and electron microscopy. RESULTS: Ten scleral perforations were detected in 9 of the patients (incidence of 1.42% of the eyes and 0.89% of the strabismus procedures). In the rabbits, a chorioretinal scar was seen in all perforated eyes. A mild cryo reaction was observed in the cryoed eyes. No other sequelae were seen. Histopathologic studies showed changes consistent with the normal healing process. CONCLUSIONS: Of the human eyes screened, 1.42% showed evidence of scleral perforation following strabismus surgery. In no case were sequelae leading to visual loss observed. In the rabbits no sequelae were observed at 6 weeks of follow-up apart from a chorioretinal scar and a cryoreaction in those eyes in which cryoprophylaxis had been given. Mild cryoprophylaxis did not exert any positive or negative influence on the natural course of scleral perforation in our short-term animal study.

Adolescent↗

PubMed1991

Occupational lead exposure and strabismus in offspring: a case-control study.

The authors conducted a population-based case-control study to investigate the association between strabismus and parental occupational lead exposure. Cases were children diagnosed with nonrestrictive strabismus between 1985 and 1986 at Baltimore, Maryland-area pediatric ophthalmology practices and clinics (n = 377). Controls were matched for age and hospital of birth (n = 377). Jobs held by parents were assessed for lead exposure by industrial hygienists. The time window for lead exposure was defined as the period from conception through age 9 months. The unadjusted odds ratio for maternal lead exposure and the esotropic form of strabismus was 2.6 (95% confidence interval (CI) 0.4-27). Unadjusted odds ratios for paternal occupational lead exposure and esotropia were 1.0 (95% CI 0.5-2.1) for low exposure, 2.1 (95% CI 0.9-5.3) for moderate exposure, and 1.2 (95% CI 0.4-3.3) for high exposure. The study results suggest the possibility of a weak association between paternal lead exposure and strabismus in offspring.

Amblyopia↗

PubMed1995

The effects of ketorolac and fentanyl on postoperative vomiting and analgesic requirements in children undergoing strabismus surgery.

Fifty-four ASA I and II children 1 to 10 yr of age undergoing strabismus surgery were randomized to receive in a double-blind fashion intravenous ketorolac (0.9 mg/kg), fentanyl (1 microgram/kg), or saline placebo (2 mL) during a standardized general anesthetic. Patients received no analgesic or antiemetics intraoperatively except for the study drug. Patients receiving ketorolac or placebo compared to fentanyl had a significantly lower incidence of postoperative vomiting in the day surgery unit (DSU) (P = 0.03) and overall (DSU plus home) (P = 0.005). The severity (number of episodes) of post-operative vomiting was significantly lower in the DSU, at home (first 24 h after hospital discharge), and overall for patients receiving ketorolac or placebo compared to fentanyl (P < 0.01). Postoperative pain scores and frequency of acetaminophen administration did not differ among the study groups, suggesting that the intraoperative use of ketorolac or fentanyl during pediatric strabismus surgery is unnecessary. No patients required fentanyl postoperatively, indicating that rectal acetaminophen administered in the postanesthesia recovery room provides sufficient analgesia for pediatric strabismus surgery. In conclusion, neither ketorolac nor fentanyl was associated with less postoperative vomiting or analgesic requirements compared to saline placebo administered during pediatric strabismus surgery. Fentanyl should be avoided, as it was associated with a significantly greater incidence of postoperative vomiting compared to ketorolac or placebo.

Acetaminophen↗

PubMed1996

Dimenhydrinate decreases vomiting after strabismus surgery in children.

Dimenhydrinate, an H1-receptor antagonist, has been used to both prevent and treat postoperative vomiting (POV) in children for several decades. However, its effectiveness for POV after strabismus surgery remains anecdotal. This study was designed to determine the effectiveness and side effects of dimenhydrinate for the prevention of POV in children after strabismus surgery. Eighty ASA physical status I or II children, ages 1-12 yr inclusive, who were undergoing strabismus surgery, were prospectively and randomly allocated to receive either dimenhydrinate 0.5 mg/kg intravenously (n = 40) or placebo (n = 40) at induction of anesthesia. The incidence of POV and the times to arousal (and discharge from the recovery room and hospital) were recorded postoperatively in a double blinded manner. For 24 h after discharge from the hospital, all emetic episodes and medications given were recorded by the parents. Demographic data did not differ between the groups. Children who received dimenhydrinate had significantly less POV both inhospital (10%) and overall (30%) than those who received placebo (in-hospital 38%, P < 0.008; overall 65%, P < 0.003). The times to arousal and discharge from the hospital did not differ between the two groups. Dimenhydrinate (0.5 mg/kg) is an effective, safe, and inexpensive antiemetic in children undergoing strabismus surgery. It significantly reduces the incidence of vomiting for 24 h postoperatively and is not associated with prolonged sedation or other adverse effects.

Antiemetics↗

PubMed2002

The effect of remifentanil or fentanyl on postoperative vomiting and pain in children undergoing strabismus surgery.

UNLABELLED: Postoperative vomiting (POV) after strabismus surgery in children results in discomfort and prolonged hospital stays. Opioids increase the incidence of POV. Remifentanil has a context-sensitive half-life of 3 to 4 min, and how this short half-life influences POV in those patients is unknown. We conducted a prospective, double-blinded study in 81 ASA status I or II children from 2 to 12 yr of age undergoing elective strabismus surgery under general anesthesia. Patients were randomized to receive either remifentanil (bolus 1 microg/kg; infusion 0.1-0.2 microg x kg(-1) x min(-1)) or fentanyl (2 microg/kg, and 1 microg/kg every 45 min). POV episodes were recorded for 25 h. Pain scores were obtained by using an objective pain scale for 60 min during recovery. The number of patients who experienced POV did not differ significantly between groups (49% vs 48%). However, in the Remifentanil group, POV episodes were significantly less frequent (0.95 vs 2.2 episodes). In contrast, fentanyl was associated with lower pain scores during the first 30 min of recovery. We conclude that children undergoing strabismus surgery under balanced anesthesia with remifentanil, compared with fentanyl, showed less frequent POV. However, early postoperative analgesia was better with fentanyl. IMPLICATIONS: Opioids increase the incidence of postoperative vomiting (POV). Remifentanil is characterized by the shortest half-life of all opioids used in anesthetic practice. Therefore, we studied the effect of remifentanil on POV compared with the longer-acting opioid fentanyl in children undergoing strabismus surgery.

Analgesics, Opioid↗

PubMed1980

An unexpected role for normal accommodative vergence in strabismus and amblyopia.

Accommodative vergence was measured using the Müller experimental paradigm in which target movement along the line of sight of the viewing eye results in large movement of the fellow (covered) eye. Our paper demonstrates an unexpected predominance of accommodative vergence over disparity vergence in patients with constant strabismus amblyopia, intermittent strabismus, and amblyopia without strabismus. Comparison of accommodative vergence responses in these patients with responses from normal subjects using symmetrical and asymmetrical targets under binocular and monocular conditions established the normal character of the patients' accommodative vergence and the absence of disparity vergence in most of them. The intermittent absence of disparity vergence in certain of our patients--some with surgically corrected strabismus, some with moderate amblyopia, and some with amblyopia treated with orthoptics--raises questions of clinical and neurophysiological interest. Preliminary results on the effects of amblyopia on accommodative responses are also presented.

Accommodation, Ocular↗

PubMed1993

Surgical techniques of strabismus.

Improvements in the management of strabismus are largely dependent on making the specific diagnosis and differentiating patterns of strabismus. This finding is especially true in the management of superior oblique paresis because there are various types. Recent observation suggests that superior oblique paresis may be associated with a lax superior oblique tendon and that the cause of the paresis is not always neurogenic. Some authorities have suggested using the traction test of the superior oblique to determine whether the superior oblique tendon is lax. If it is lax, the treatment of choice would be a tightening procedure of the superior oblique such as the superior oblique tuck. Adjustable-suture strabismus surgery has reduced the incidence of repeat operations; however, adapting the procedure to the fornix incision has been difficult. The use of a scleral traction suture that retracts the conjunctiva to expose the muscle suture area has been useful for fornix surgery. The rectus muscles supply circulation to the anterior segment via the anterior ciliary vessels, which are routinely interrupted during strabismus surgery. Various procedures have recently been described to preserve the anterior ciliary vessels, and these procedures will be useful in patients who are predisposed to anterior segment ischemia. In the 1950s, inferior oblique weakening procedures were deemed dangerous and unpredictable. Recent advances in the understanding of inferior oblique physiology and fascial relationships have inspired the development of a new inferior oblique weakening strategy--the anteriorization procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior Eye Segment↗

PubMed1997

Comitant strabismus.

This article reviews 14 of the past year's important published works on comitant strabismus, referring to the most interesting developments related to subjects such as epidemiology of comitant strabismus and prevalence of esotropia and exotropia in pathologic conditions like cerebral palsy, Down syndrome, and prematurity-factors influencing the surgical success in strabismus and functional outcomes of early surgery in essential infantile esotropia. Relevant anatomic and physiologic findings on extraocular muscle function are also discussed, which may contribute to our knowledge on the pathophysiology of congenital strabismus.

Humans↗

PubMed2005

Adjustable suture use in strabismus surgery.

PURPOSE OF REVIEW: This review includes updated information regarding adjustable suture strabismus surgery for children and adults. RECENT FINDINGS: Main themes in the literature reviewed in this article include the appropriate timing for the adjustment technique, appropriate anesthesia, recent modifications in adjustable strabismus surgery techniques, and future developments. SUMMARY: Improved timing of adjustment, improved anesthesia, and newer surgical techniques allow strabismus surgeons to offer treatment options better suited to the needs of each strabismus patient.

Adult↗

PubMed2006

Strabismus in craniosynostosis.

PURPOSE OF REVIEW: To present peer-reviewed articles related to strabismus in craniosynostosis. RECENT FINDINGS: Improved neurosurgical treatment has resulted in amblyopia replacing optic atrophy as the main cause of visual impairment in Apert's and Crouzon syndromes. Patients with nonsyndromic craniosynostosis have an increased incidence of significant refractive error and horizontal strabismus similar to syndromic craniosynostosis. Imaging of the orbit and extraocular muscles continues to be recommended as helpful for presurgical planning. Surgical techniques continue to be explored in order to improve outcomes for craniosynostosis patients. SUMMARY: Attention to diagnosis and treatment of amblyopia and strabismus is necessary to preserve vision in craniosynostosis patients. Orbital imaging may aid in planning for these patients whose strabismus surgery remains a challenge.

Amblyopia↗

PubMed1981

Dynamic vergence eye movements in strabismus and amblyopia: asymmetric vergence.

This report investigates line-of-sight asymmetric disparity vergence in patients having either intermittent strabismus, constant strabismus with amblyopia, or amblyopia without strabismus. We find an absence of disparity vergence in all patients with strabismus and in some with amblyopia only. Accommodative vergence and saccades place the dominant eye on the targets moving in depth. These accommodative vergence responses have normal dynamic characteristics, thus indicating a properly functioning vergence motor system. We purpose there is a higher-level central defect in which incoming information of one eye is suppressed, so that the disparity vergence system is rendered inoperable.

Adolescent↗

PubMed1990

Incidence of inadvertent globe perforation during strabismus surgery.

Visual loss following strabismus is rare and usually follows inadvertent perforation of the globe at the time of surgery. Previous studies have reported that the incidence of this complication occurs in 8% to 12.1% of patients undergoing conventional strabismus surgery, and higher incidences have been reported for posterior fixation sutures. We conducted a prospective study to determine the incidence of this complication in our patients. We identified one case of globe perforation in 67 patients (100 eyes). Twenty-two patients (44 eyes) had undergone previous strabismus surgery, and there was no evidence of previous scleral perforation in this group. We discuss the recent advances in strabismus surgery which may account for this difference in the incidence of scleral perforation.

Adolescent↗

PubMed1995

Prospective multicentre study of the accuracy of surgery for horizontal strabismus.

Eight centres throughout the United Kingdom cooperated with a prospective evaluation of the accuracy of surgery for horizontal strabismus. The eight centres were divided into four with a specialist interest in strabismus and four offering a general ophthalmic service. Each participating surgeon was asked to indicate the anticipated outcome of surgery and, thereafter, orthoptic examinations were made post-operatively to determine the actual outcome. Two hundred and five cases were included in the study and it is hoped the results will serve as useful guidelines for those departments wishing to undertake audit of their own strabismus surgery. There was no statistically significant difference in the accuracy of surgical alignment achieved by strabismus specialists and general ophthalmologists.

Clinical Competence↗

PubMed2000

Effect of spectacles on changes of spherical hypermetropia in infants who did, and did not, have strabismus.

AIM: To explore why emmetropisation fails in children who have strabismus. METHODS: 289 hypermetropic infants were randomly allocated spectacles and followed. Changes in spherical hypermetropia were compared in those who had strabismus and those who did not. The effect of wearing glasses on these changes was assessed using t tests and regression analysis. RESULTS: Mean spherical hypermetropia decreased in both eyes of "normal" children (p<0.001). The consistent wearing of glasses impeded this process in both eyes (p<0.007). In the children with strabismus, there were no significant changes in either eye, irrespective of treatment (p>0. 05). CONCLUSIONS: In contrast with normal infants, neither eye of those who had strabismus emmetropised, irrespective of whether the incoming vision was clear or blurred. It is suggested that these eyes did not "recognise" the signal of blurred vision, and that they remained long sighted because they were destined to squint. Hence, the children did not squint because they were long sighted, and glasses did not prevent them squinting.

Eyeglasses↗

PubMed2000

Long term follow up of premature infants: detection of strabismus, amblyopia, and refractive errors.

AIM: To establish recommendations for long term ophthalmological follow up of prematurely born infants. METHODS: 130 infants with a gestational age (GA) <37 weeks and born between 1 November 1989 and 31 October 1990 were enrolled in a prospective study about the development of strabismus, amblyopia, and refractive errors. Infants were subdivided in three groups according to GA: A <28 weeks (n=32), B >/=28-</=32 weeks (n=64), C >32-<37 weeks (n=34). Ophthalmological assessment took place at the postconceptional age of 32 weeks, at term and at 3, 6, 12, and 30 months post term. At the age of 5 years parents received a questionnaire and a majority of the children was examined again (n=99). RESULTS: At the age of 5 years 46 infants were known to have strabismus (n=29) and/or amblyopia (n=22) and/or refractive errors (n=22). Statistical analysis showed that gestational age, duration of supplementary oxygen, and duration of hospitalisation were important predictive variables for the development of strabismus, amblyopia, or refractive errors (SAR) at the age of 5 years (p<0.05). Infants with a GA </=32 weeks had a significantly higher risk of developing SAR than infants with a GA >32 weeks, who developed an incidence comparable with the normal population. Strabismus developed mainly in the first year of life and at the age of 5 years. Most infants with amblyopia were detected at the age of 2-3 years. Refractive errors were found in the first year of life and at the age of 2.5 and 5 years. CONCLUSION: Infants with a GA <32 weeks should be selected for long term ophthalmological follow up. These infants should be screened at the age of 1 year, in the third year of life (preferably at 30 months), and just before school age (including testing of visual acuity with optotypes).

Amblyopia↗

PubMed2001

Ramosetron compared with granisetron for the prevention of vomiting following strabismus surgery in children.

BACKGROUND/AIMS: Postoperative vomiting occurs frequently after strabismus surgery in children. Granisetron, a selective 5-hydroxytryptamine type 3 receptor antagonist, is effective for the prevention of vomiting following paediatric strabismus surgery. Ramosetron, another new antagonist of 5-hydroxytryptamine type 3 receptor, has more potent and longer acting properties than granisetron against cisplatin induced emesis. This study was undertaken to compare the efficacy and safety of granisetron and ramosetron for the prevention of vomiting following strabismus surgery in children. METHODS: In a randomised, double blinded manner 80 children, aged 4-10 years, received intravenously granisetron 40 microg/kg or ramosetron 6 microg/kg (n=40 each) at the end of surgery. A standard general anaesthetic technique and postoperative analgesia were used. Emetic episodes and safety assessment were performed during the first 24 hours and the next 24 hours after anaesthesia. RESULTS: The percentage of patients who were emesis free during 0-24 hours after anaesthesia was 85% with granisetron and 90% with ramosetron, respectively (p = 0.369); the corresponding rate during 24-48 hours after anaesthesia was 70% and 95% (p = 0.003). No clinically serious adverse events caused by the study drug were observed in any of the groups. CONCLUSION: Prophylactic antiemetic therapy with ramosetron is comparable with granisetron for the prevention of vomiting during 0-24 hours after anaesthesia in children undergoing strabismus surgery. During 24-48 hours after anaesthesia, ramosetron is more effective than granisetron for prophylaxis against postoperative vomiting.

Analysis of Variance↗

PubMed2002

Changing patterns of strabismus: a decade of experience in Hong Kong.

BACKGROUND/AIMS: Racial variation in the pattern of strabismus is known, but few large scale studies on non-white populations are available. Furthermore, longitudinal change in this pattern within a local setting has not been well documented in the past. This study aims to support the clinical impression that exotropia is more common in Chinese patients, and that the proportion of patients with exotropia has been increasing in the past decade. METHODS: A total of 2704 consecutive patients with the diagnosis of primary horizontal strabismus, seen in the strabismus clinic of the Hong Kong Eye Hospital, were retrospectively analysed to determine the relative prevalence of esotropia and exotropia. Characteristics recorded include patient demographics, type of strabismus, and whether the nature of the squint was constant or intermittent. RESULTS: 742 (27.4%) patients were found to have esotropia, 548 (20.3%) had constant exotropia, 1213 (44.9%) had intermittent exotropia, and 201 (7.4%) had microtropia. The proportion of exotropic to esotropic patients was shown to increase steadily throughout the past decade (p<0.0001). This was mainly accounted for by an increase in the number of patients with intermittent exotropia, and a corresponding decrease in the number of patients with esotropia. CONCLUSION: Exotropia was shown to be more prevalent than esotropia in a Hong Kong Chinese population. Furthermore, the proportion of patients with intermittent exotropia appears to be increasing, in contrast with esotropic patients. The exact nature of this trend, and possible aetiological factors will require further study.

Esotropia↗