Factors Associated with Childhood Strabismus

Prevalence And Associated Factors Of Visual Impairment Among School-Age Children In Bahir Dar City, Northwest Ethiopia

INTRODUCTION

Visual impairment (VI) is one of the major public health problems in the world. It is highly prevalent among children in sub-Saharan countries, including Ethiopia. Worldwide, the magnitude of VI among school-age children is 1%-10%. However, there was limited information regarding the prevalence and associated factors of VI among school-age children in the study area, which is essential to plan and implement appropriate interventions.

OBJECTIVE

The aim of this study was to determine the prevalence and associated factors of VI among school-age children livin g in Bahir Dar city, northwest Ethiopia.

METHODS

A community-based cross-sectional study was done on a sample of 632 school-age children selected by multistage sampling in Bahir Dar from April 30 to May 15, 2018. Data were collected through interviews and physical examinations. Face-to-face interviews were done with a pretested semistructured questionnaire. Physical examinations were done with visual acuity measures and assessment of ocular pathology by optometrists. Data were entered into Epi Info 7 and exported to and analyzed with SPSS 20. Binary logistic regression was fitted, and variables with P<0.05 in the multivariate model were considered statistically significant.

RESULTS

A total of 601 study subjects were included in this study, giving a response rate of 95.2%. The median age was 13 (IQR 11-16) years, and 303 (50.3%) were male. Prevalence of VI was 52 (8.7%, 95% CI 6.2%-10.7%). In multivariate analysis, prematurity [AOR 2.8 (95% CI 1.19-6.83)], admission to a neonatal intensive-care unit (AOR 5.5, 95% CI 2.01-15.15), having a parent with VI (AOR 1.8, 95% CI 0.13-0.97), watching television from <2 m (AOR 8.7, 95% CI 1.49-18.24), and mobile-phone exposure >4 hours per day (AOR 1.6, 95% CI 1.32-4.45) were factors significantly associated with VI.

CONCLUSION

The prevalence of VI among school-age children in Bahir Dar was significant. Premature birth, admission to a neonatal intensive-care unit, having a parent with VI, watching television from <2 m, and mobile exposure >4 hours per day were significantly associated.

Utility of Magnetic Resonance Imaging (MRI) in Children With Strabismus

PURPOSE

Magnetic resonance imaging (MRI) of the brain can provide valuable information about structural abnormalities in strabismus. The aim of this study was to evaluate the utility of MRI in this regard and to identify risk factors for abnormal MRI results in children with strabismus.

METHODS

A retrospective analysis of children <18 years of age presenting with strabismus, who underwent brain MRI at Pusan National University Hospital (Busan, Korea) between January 2012 and March 2017, was performed. Clinical characteristics, MRI results, and ophthalmologic findings were reviewed. Findings were classified as normal or abnormal according to MRI results. Additionally, patients were divided according to age to compare characteristics of infantile and childhood strabismus.

RESULTS

A total of 90 patients (47 [52.2%] male, 43 [47.8%] female; mean age, 2.19 ± 0.53 years) were enrolled. Of those, 64 (71.1%) presented with normal and 26 (28.9%) with abnormal MRI results. The age at presentation was lower and abnormal findings on fundus examination were more common in the abnormal MRI group (P = .002 and P = .008, respectively). Among the patients, 46 (51.1%) had infantile strabismus and 44 (48.9%) had childhood strabismus. Global developmental delays, speech delays, and MRI abnormalities were more common in patients with infantile than in those with childhood strabismus. Ptosis and headaches were more common in patients with childhood strabismus (P = .025, P = .025, respectively).

CONCLUSION

Brain MRI was helpful for accurate diagnosis and treatment of strabismus in younger children, those with abnormal findings on fundus examination, and infants with developmental, especially speech, delays.

A commonly occurring genetic variant within the NPLOC4-TSPAN10-PDE6G gene cluster is associated with the risk of strabismus

Strabismus refers to an abnormal alignment of the eyes leading to the loss of central binocular vision. Concomitant strabismus occurs when the angle of deviation is constant in all positions of gaze and often manifests in early childhood when it is considered to be a neurodevelopmental disorder of the visual system. As such, it is inherited as a complex genetic trait, affecting 2-4% of the population. A genome-wide association study (GWAS) for self-reported strabismus (1345 cases and 65,349 controls from UK Biobank) revealed a single genome-wide significant locus on chromosome 17q25. Approximately 20 variants across the NPLOC4-TSPAN10-PDE6G gene cluster and in almost perfect linkage disequilibrium (LD) were most strongly associated (lead variant: rs75078292, OR = 1.26, p = 2.24E-08). A recessive model provided a better fit to the data than an additive model. Association with strabismus was independent of refractive error, and the degree of association with strabismus was minimally attenuated after adjustment for amblyopia. The association with strabismus was replicated in an independent cohort of clinician-diagnosed children aged 7 years old (116 cases and 5084 controls; OR = 1.85, p = 0.009). The associated variants included 2 strong candidate causal variants predicted to have functional effects: rs6420484, which substitutes tyrosine for a conserved cysteine (C177Y) in the TSPAN10 gene, and a 4-bp deletion variant, rs397693108, predicted to cause a frameshift in TSPAN10. The population-attributable risk for the locus was approximately 8.4%, indicating an important role in conferring susceptibility to strabismus.

Ophthalmic outcomes following neonatal hypoxic ischaemic encephalopathy; oculomotor, biometric and refractive data in early childhood

OBJECTIVES

To investigate the functional and structural impact of neonatal hypoxic ischaemic encephalopathy (HIE) on childhood visual development.

METHODS

In a prospective study, the neurocognitive outcomes of 42 children with a history of neonatal HIE were assessed serially up to 5 years. For the ophthalmic component of the study, visual, refractive, orthoptic and ocular biometry measurements were obtained in 32 children, with axial length measurements estimated using the IOLMaster.

RESULTS

For the 32 children who completed the ophthalmic component of the study, severity of HIE grade was determined to be mild, moderate, or severe in 18 (56.3%), 13 (40.6%), and 1 (3.1%) cases, respectively. One (3.1%) child was classed as visually impaired. Twelve (37.5%) were found to have ametropia. Mean (±SD) axial length was 22.09 (±0.81) mm, within the normal range for the age of this cohort. Seven of the 42 (16.7%) children who were involved in the larger neurodevelopmental arm of the study had clinical evidence of a squint. There was no correlation between the severity of HIE grade at birth and axial length or occurrence of squint.

CONCLUSIONS

Neonatal HIE is associated with a higher incidence of squint compared with the general paediatric population. This occurred irrespective of severity of HIE grade. The ocular biometry measurements were consistent with published normative data, and no significant difference in ocular biometry was demonstrated between HIE severity groups.

Amblyopia risk factors in congenital nasolacrimal duct obstruction: A longitudinal case-control study

Purpose

To investigate longitudinal changes in risk factors for amblyopia in children treated with congenital nasolacrimal duct obstruction (CNLDO).

Methods

Retrospective observational case control study. A total of 446 children under 4 years of age who underwent probing and/or intubation for CNLDO between January 2004 and January 2018, and 446 age-matched controls were included. Cycloplegic refraction and ocular alignment were investigated at the time of treatment and after at least one year of symptom improvement. Children were classified as having amblyopia risk factors on the basis of the American Association for Pediatric Ophthalmology and Strabismus guideline in 2013.

Main outcome measures

The prevalence of amblyogenic refractive errors, and determinants associated with the presence of amblyogenic refractive errors in CNLDO patients.

Results

The prevalence of amblyogenic refractive errors in CNLDO patients (5.4%) was similar to that of the control group (6.5%) (P = 0.571). After one year of symptom improvement in CNLDO patients, the prevalence of amblyogenic refractive errors was 4.7%. There was no difference in the prevalence of amblyogenic refractive errors between unilateral and bilateral CNLDO patients. Multivariate analysis revealed that manifest strabismus was the only risk factor related with the presence of amblyogenic refractive errors (odds ratio = 6.383, confidence interval = 1.205–33.826, P = 0.029).

Conclusions

This study found no evidence to suggest that the prevalence of amblyopia risk factors is higher in CNLDO patients compared with normal controls. Manifest strabismus was the only determinant associated with the presence of amblyogenic refractive errors.

Maternal smoking during pregnancy and the risk of strabismus in offspring: a meta-analysis

The effect of maternal smoking during pregnancy on strabismus in offspring remains unclear. We conducted a meta-analysis to summarize epidemiological evidences on the association between maternal smoking during pregnancy and the risk of offspring strabismus. Eligible studies were searched from the PubMed, Ovid, Embase and CNKI databases up to May 2018. The qualities of included articles were assessed with the Newcastle-Ottawa Scale and the assessment scale recommended by the Agency for Healthcare Research and Quality. Odds ratios (ORs) corresponding with its 95% confidence intervals (CIs) were pooled to estimate the effects of maternal cigarette smoking on the risk of offspring strabismus. Subgroup analyses and meta-regression were performed to explore the potential sources of heterogeneity. The Begg's test and Egger's test were used to assess the publication bias. Eleven articles involving 4,833 patients with strabismus were included. The pooled OR showed that maternal smoking during pregnancy was significantly associated with strabismus in offspring (OR = 1.46, 95% CI = 1.32-1.60). Compared with less than 10 cigarettes per day (OR = 1.17, 95% CI = 1.06-1.29), maternal smoking 10 cigarettes or more per day during pregnancy significantly increased the risk of offspring strabismus (OR = 1.79, 95% CI = 1.39-2.31). The risk of developing esotropia and exotropia for smoking pregnant women, respectively, increased by 65% (OR = 1.65, 95% CI = 1.31-2.09 and OR = 1.65, 95% CI = 1.24-2.19) than those who did not smoke during pregnancy. Additionally, the increased risk of maternity smoking associated with offspring strabismus was stable across all subgroup analyses. Overall, maternal smoking during pregnancy was associated with a significantly increased risk of offspring strabismus and the result was persistent in subgroup analyses, suggesting the importance in changing smoking habit or smoking cessation for women who are pregnant or preparing to.

Global and regional prevalence of strabismus: a comprehensive systematic review and meta-analysis

Purpose: Despite the importance of information on the prevalence of strabismus, which can be effective in planning preventive and curative services, no study has addressed its prevalence comprehensively. In this study, a systematic search was done to estimate the regional and global prevalence of strabismus in different age and sex groups and factors affecting prevalence heterogeneity. Methods: A comprehensive and systematic search was done in different international databases, including Web of Science, Scopus, PubMed, Embase, etc. to find published articles on the total prevalence of strabismus and the prevalence of exotropia and esotropia. A binomial distribution was used to calculate the prevalence and 95% confidence interval (CI). The Cochran's Q-test and I² were applied to evaluate heterogeneity and a random-effects model was used to assess the pooled prevalence. The Begg's test was administered to investigate publication bias and finally, a meta-regression method was applied to determine the factors affecting the heterogeneity among studies. Results: Of 7980 articles, 56 articles with a total sample size of 229,396 were analyzed. Many of these articles (n = 14) were from the Regional Office for the Americas. The estimated of pooled prevalence (95% CI) of any strabismus, exotropia, and esotropia was 1.93% (1.64-2.21), 1.23% (1.00-1.46), and 0.77% (0.59-0.95), respectively. The heterogeneity in prevalence of strabismus and its subtypes according to I² was above 95% (p value <.001 for all). Age had a direct effect on heterogeneity in the prevalence of exotropia (b: 3.491; p: 0.002). Moreover, WHO region had a significant direct effect on heterogeneity in the prevalence of strabismus (b: 0.482; p < .001) and esotropia (b: 0.168; p: 0.027), and publication year had a significant direct effect on heterogeneity in the prevalence of exotropia (b: 0.059; p: 0.045). Sample size and publication year did not have any association with strabismus nor with other variables. There was no publication bias according to the Begg's test. Conclusion: The prevalence of strabismus varies widely in the world. As for factors affecting heterogeneity in the prevalence of strabismus, the results showed that age affected heterogeneity in the prevalence of exotropia, WHO region affected heterogeneity in the prevalence of strabismus and esotropia, and publication year affected heterogeneity in the prevalence of exotropia. Information about the global prevalence of strabismus can help health care planners design interventions and prioritize resource allocation.

Validity of the +1.50 plus lens screening test as a predictor of uncorrected moderate hyperopia

PURPOSE

Screening for uncorrected hyperopia in school children is important given its association with poorer visual function and academic performance. However, standard distance visual acuity screening may not detect low to moderate hyperopia. The plus lens test is used to screen for hyperopia in many school screening protocols, but has not been well validated. The current study investigated the effectiveness of the plus lens test to identify hyperopia in school children.

METHODS

Participants included Grade 2 school children. Monocular distance visual acuity (logMAR letter chart) was measured unaided, and then through a +1.50D lens, known as the plus lens test. Cycloplegic refraction was undertaken to classify moderate hyperopia (≥+2.00D). Sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were calculated for commonly used cut-offs for the plus lens test: 6/6, 6/9 and less than two lines difference between unaided acuity and acuity through the plus lens test.

RESULTS

The sample included 59 children (mean age 7.2 ± 0.4 years). Fourteen (24%) children were classified as having uncorrected hyperopia. The sensitivity and specificity of the +1.50 plus lens test for identifying hyperopia were 0% and 98% respectively for a 6/6 cut-off, 29% and 91% for 6/9 cut-off, and 50% and 76% for a <2 line reduction between unaided acuity and acuity through the plus lens test. Receiver Operating Curve (ROC) analysis revealed area under curves of 0.69 based on acuity through the plus lens test, and 0.65 for a reduction in acuity through the plus lens test.

CONCLUSIONS

The plus lens test has low sensitivity for detecting uncorrected hyperopia using traditional cut-offs of 6/9 or better. This raises questions about the role of the plus lens test in school screening batteries.

Development and Preliminary Evaluation of a Smartphone App for Measuring Eye Alignment

Purpose

We evaluate a smartphone application (app) performing an automated photographic Hirschberg test for measurement of eye deviations.

Methods

Three evaluation studies were conducted to measure eye deviations in the horizontal direction. First, gaze angles were measured with respect to the ground truth in nonstrabismic subjects (n = 25) as they fixated monocularly on targets of known eccentricity covering an angular range of approximately ±13°. Second, phoria measurements with the app at near fixation (distance = 40 cm) were compared with the modified Thorington (MT) test in normally-sighted subjects (n = 14). Third, eye deviations using the app were compared to a cover test with prism neutralization (CTPN; n = 66) and Synoptophore (n = 34) in strabismic subjects. Regression analyses were used to compare the app and clinical measurements of the magnitude and direction of eye deviations (prism diopters, Δ).

Results

The gaze angles measured by the app closely followed the ground truth (slope = 1.007, R² = 0.97, P < 0.001), with a root mean squared error (RMSE) of 2.4Δ. Phoria measurements with the app were consistent with MT (slope = 0.94, R² = 0.97, P < 0.001, RMSE = 1.7Δ). Overall, the strabismus measurements with the app were higher than with Synoptophore (slope = 1.15, R² = 0.91, P < 0.001), but consistent with CTPN (slope = 0.95, R² = 0.95, P < 0.001). After correction of CTPN values for near fixation, the consistency of the app measurements with CTPN was improved further (slope = 1.01).

Conclusions

The app measurements of manifest and latent eye deviations were consistent with the comparator clinical methods.

Translational Relevance

A smartphone app for measurement of eye alignment can be a convenient clinical tool and has potential to be beneficial in telemedicine.

Altered Functional Connectivity of the Primary Visual Cortex in Adult Comitant Strabismus: A Resting-State Functional MRI Study

PURPOSE

The aim of this study was to examine the functional connectivity between the primary visual cortex and other cortical areas during rest in normal subjects and patients with comitant strabismus using functional magnetic resonance imaging (fMRI).

METHODS

A prospective, observational study was conducted. Ten patients with comitant exotropia and eleven matched healthy subjects underwent resting-state fMRI with their eyes closed. Resting-state fMRI was performed using a 3.0 T MR scanner. The primary visual cortex was subdivided into anterior and posterior subdivisions. The resting-state functional connectivities within the primary visual cortex and between the primary visual cortex and other cortical areas were calculated for each group and compared between the strabismic and normal control groups. fMRI data were analyzed using Statistical Parametric Mapping software and Analysis of Functional NeuroImages software.

RESULTS

Compared with the normal controls, patients with comitant strabismus had increased functional connectivity between the posterior primary visual cortex and other cortical areas, especially the visual cortex [Brodmann area 19 (BA19)] and other oculomotor regions, such as the frontal eye field (BA6).

CONCLUSIONS

The fMRI results suggest that ongoing and permanent cortical changes occur in patients with comitant strabismus. Disrupted brain functional connectivities are associated with abnormal eye movement and loss of stereopsis. Our study provides a neurological basis for understanding the pathophysiology of comitant strabismus, which may prompt new areas of research to more precisely define this basis and extend these findings to enhance diagnosis and treatment.

Botulinum toxin chemodenervation for childhood strabismus in England: National and local patterns of practice

Background

Botulinum toxin injection chemodenervation is a well-established intervention for adult strabismus, and has also been recognised as an effective alternative to routine incisional surgery for paediatric disease. We aimed to investigate the temporal patterns of practice, indications and outcomes of chemodenervation for paediatric strabismus at national and tertiary centre level.

Methods

Retrospective study using routinely collected patient data: Hospital Episode Statistics (HES) data were used to identify children undergoing non-incisional strabismus procedures in England from 2007 to 2016. Single–centre retrospective data on children undergoing botulinum toxin injections (Dysport^® 2.5 units/ 0.1ml) as an isolated intervention (not involving incisional procedures) was undertaken to identify indications and outcomes. Successful outcome was defined as deviation <11 prism dioptres (PD).

Results

Between 2007 and 2016, there was no increase in the proportion of childhood strabismus involving non-incisional procedures. Amongst 150 children undergoing chemodenervation for strabismus within the tertiary centre, the most common diagnoses were acute onset esotropia (n = 34), infantile esotropia (n = 16) and consecutive exotropia (n = 15). Median age at injection was 8.5 years (range 0.9–15 years), and median follow up 12 months (6 months—11 years). Success rates differed by diagnosis, from 66% (non or partially accommodative esotropia) to 0% (congenital cranial disorders). Adverse events were seen in 62/150, 41%, most commonly transient ptosis (39%, n = 58). Overcorrection was seen in 14/119, 13%. Mild subconjunctival haemorrhage (n = 2) was the only other adverse event.

Conclusions

Botulinum toxin for childhood strabismus has an acceptable safety profile, and considerable potential therapeutic benefit. However, nationally there has been no increased uptake of chemodenervation non-incisional procedures. Further prospective studies are necessary to understand the predictors of outcome within the separate clinical subgroups, to guide clinical decision making.

Prevalence and Risk Factors of Amblyopia among Refractive Errors in an Eastern European Population

Background and objective: Amblyopia is the leading cause of visual impairment in children and adults and is very common during childhood. The aim of this study was to identify the prevalence and the risk factors of amblyopia in a pediatric population with refractive errors from an Eastern European country. Materials and methods: A total of 1231 children aged 5–16 years, who had refractive errors and were examined from January to August 2017, were enrolled in a cross-sectional population-based study. Every child underwent a complete ophthalmological exam. Amblyopia was defined as a visual acuity (VA) of less than 0.63. The study respected the Multi-Ethnic Pediatric Eye Disease Study (MEPEDS) criteria for defining amblyopia (MEPEDS, 2008). Parents participated in a face-to-face interview. The questionnaire contained details about their family history of amblyopia; the child’s maternal nutritional status in the preconception period; their history of maternal smoking or work in a toxic environment; the child’s birth, and the child’s history of congenital naso-lacrimal duct obstruction (CNLDO). Results: Amblyopia was identified in 2.8% of the participants. The ocular conditions hyperopia (p = 0.0079), astigmatism (p = 0.046), anisometropia (p < 0.001), esotropia (p < 0.001), exotropia (p = 0.0195), and CNLDO (p < 0.001), as well as a family history of amblyopia (p < 0.001), were associated with amblyopia. The non-ocular risk factors for amblyopia that were found in the study included low birth weight (p < 0.0009), prematurity (p < 0.001), an Apgar score under 7 (p = 0.0008), maternal age, maternal smoking history or work in toxic environment (p < 0.001), and maternal body mass index in the preconception period (p < 0.003). Conclusions: Some of the risk factors we identified for amblyopia are modifiable factors. This is an important observation as an adequate health education program can provide the relevant information for future mothers that will allow for a better management of the condition. We also wanted to highlight the need for amblyopia screening starting from the age of 3 years in case of significant parental refractive errors, strabismus, prematurity, and maternal risk factors.

Time and Factors Affecting the Direction of Re-drift in Essential Infantile Esotropia

PURPOSE

To investigate the development pattern and related factors of postoperative re-drift in infantile esotropia.

METHODS

A total of 112 patients with infantile esotropia who underwent surgery before 3 years of age were included. Surgical outcomes were divided into (1) consecutive exotropia: more than 8 prism diopters (PD) of exodeviation; (2) recurrent esotropia: more than 8 PD of esodeviation; and (3) monofixation syndrome: maintenance of deviations within 8 PD. The occurrence rate, time of onset, and associated factors of the re-drift were evaluated.

RESULTS

At a mean follow-up of 9.5 years, consecutive exotropia developed in 37 patients (33.0%) and recurrent esotropia in 43 patients (38.4%). Whereas 76.7% of total recurrent esotropia cases were identified within postoperative 1 year, consecutive exotropia occurred constantly over 10 years postoperatively. The mean time to consecutive exotropia development from surgery was 78.6 months, greater than that of recurrent esotropia development (8.9 months) (P < 0.001). In multinomial logistic regression using monofixation syndrome as the reference category, fixation preference before surgery (odds ratio [OR]: 6.64, 95% confidence interval [CI]: 2.07 to 21.32) and the rate of myopic progression (OR: 15.07 per -1.00 D/year, 95% CI: 1.23 to 184.86) were associated with consecutive exotropia, whereas increase in the angle of esodeviation on postoperative day 1 (OR: 1.15, 95% CI: 1.04 to 1.26) was correlated with recurrent esotropia.

CONCLUSIONS

This study demonstrates a difference between the development pattern of exotropic and esotropic drift after infantile esotropia surgery. Detailed preoperative assessment and close postoperative observation of deviations and refractive status will help to determine surgical outcomes of infantile esotropia. [J Pediatr Ophthalmol Strabismus. 2018;55(2):128-134.].

Association between mode of delivery and astigmatism in preschool children

PURPOSE

To determine whether mode of delivery has any impact on astigmatism.

METHODS

This case-control study was performed in the Department of Ophthalmology in 2015. Exposure was mode of delivery [vaginal delivery (VD) or caesarean section (CS), which here included both elective and emergency CS]. Outcome was astigmatism (≥2.5 D), which was determined by cycloplegic refraction. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were computed to assess the associations between mode of delivery and astigmatism from logistic regression models.

RESULTS

Of the 659 children studied here (341 boys; mean age, 4.37 years), 440 were born by CS and 219 by VD. The incidence of severe astigmatism (≥2.5 D) in the CS and VD groups was 22.06% and 13.24%, respectively. Children delivered by CS had a 77.9% higher risk of severe astigmatism compared with vaginally delivered children (OR = 1.779; 95% CI, 1.121 to 2.824). After dividing CS into elective CS and emergency CS, children delivered by elective CS had an 87.3% increased risk of severe astigmatism (OR = 1.873; 95% CI, 1.157 to 3.032), but children delivered by emergency CS did not differ from vaginally delivered children. In addition, the children whose mothers had histories of breastfeeding had a 44.6% lower risk of severe astigmatism than children whose mother did not breastfeed them (OR = 0.554, 95% CI, 0.335-0.914).

CONCLUSION

Birth by CS, especially elective CS, increases the risk of severe astigmatism (≥2.50 D) in childhood.

Prevalence and risk factors of strabismus in children and adolescents in South Korea: Korea National Health and Nutrition Examination Survey, 2008-2011

Purpose

To evaluate the prevalence and risk factors associated with horizontal strabismus in children and adolescents in South Korea.

Methods

A total of 5,935 children and adolescents 5–18 years of age who participated in the fourth and fifth Korean National Health and Nutrition Examination Survey (KNHANES IV-V) from July 2008 to December 2011 were evaluated and the prevalence of horizontal strabismus was estimated. Univariate and multivariate logistic regression analyses were conducted to determine the association between demographic, socioeconomic and clinical risk factors and clinically significant exodeviation (≥15 prism diopters [PD]) and esodeviation (≥10 PD).

Results

Among 5,935 eligible subjects, 84 subjects had clinically significant exodeviation and 13 had clinically significant esodeviation. The overall prevalence of clinically significant horizontal strabismus was 1.6% (95% confidence interval [CI], 1.2–2.1): 1.3% (95% CI, 1.0–1.7) for clinically significant exodeviation and 0.3% (95% CI, 0.1–0.6) for clinically significant esodeviation. Clinically significant exodeviation was associated with amblyopia (adjusted odds ratio [aOR], 6.45; 95% CI, 2.14–19.44), family history of strabismus (aOR, 4.91; 95% CI, 1.71–14.08) and astigmatism ≥1.0 D (aOR, 1.84; 95% CI, 1.13–2.98). Clinically significant esodeviation was associated with hyperopia (aOR, 12.16; 95% CI, 1.31–113.04) and amblyopia (aOR, 4.70; 95% CI, 1.12–19.81). Other demographic, socioeconomic, and clinical variables were not associated with strabismus.

Conclusion

This study provides data on the prevalence and independent risk factors for clinically significant exodeviation and esodeviation in a representative population of children and adolescents in South Korea.

Prevalence and associated factors of strabismus in former preterm and full-term infants between 4 and 10 Years of age

Background

Limited data exist collating most of the associated factors for strabismus in one analysis. The aim of this study was to assess the prevalence of strabismus and to analyse associated factors in former preterm and full-term infants.

Methods

In this cross-sectional study, 239 former preterm infants with gestational age (GA) ≤ 32 weeks and 264 former full-term born infants with GA ≥ 37 weeks underwent detailed ophthalmologic examination in the age of 4–10 years and perinatal data assessment for risk factor analysis. Ophthalmologic examinations included cover testing, best corrected visual acuity, cycloplegic objective refraction, slit lamp as well as fundus examinations. For association analysis with strabismus, the following data was collected and included in multivariable analysis: sex, age at examination, anisometropia, myopic and hyperopic refractive error (≥ 3 dioptres), astigmatism, birth weight percentile, gestational age, retinopathy of prematurity occurrence, maternal age at childbirth, mother smoking, breastfeeding < 3 months, artificial ventilation, intraventricular bleeding, and other perinatal adverse events.

Results

Overall, 4/264 (2%) full-term infants, 15/125 (12%) preterm-infants with GA 29–32 weeks without ROP, 13/59 (22%) preterm infants with GA ≤ 28 weeks without ROP and 14/55 (26%) with GA ≤ 32 weeks with retinopathy of prematurity were affected by strabismus. In the multivariable regression model strabismus was associated with GA (OR = 0.84 per week; p = 0.001), hyperopic refractive error (OR = 4.22; p = 0.002) and astigmatism (OR = 1.68; p = 0.02).

Conclusion

This investigation highlights that low gestational age and refraction of the eye are independent risk factors for strabismus, while the other factors show less independent influence.

To assess knowledge and attitude of parents toward children suffering from strabismus in Indian subcontinent

Purpose:

Strabismus and anisometropia are the most common causes of amblyopia. It can be easily prevented or treated if detected early. With the changing socio-cultural-economic milieu of the society, the perspectives of strabismus in society are gradually changing but still adequate knowledge, awareness, and attitude of parents toward strabismus will help in preventing amblyopia and aid in the proper psychosocial adaptation of such children. This study aimed to assess knowledge and attitude of parents toward children suffering from strabismus.

Methods:

A prospective study was carried out from January 1 to February 29, 2016, through a structured questionnaire to assess the level of knowledge and attitude of parents of children suffering from strabismus.

Results:

One hundred and twenty parents of children with strabismus were interviewed through a questionnaire. Education level of 78 parents was less than graduation (60%) and of 42 parents (40%) was graduation or higher. The majority of the parents, i.e., 116 (96.67%) were bothered due to strabismus. One hundred and one (84.17%) parents felt that their child's strabismus was noticed by others during interaction. Seventy-four (61.67%) parents felt that their children will have difficulty in making friends. Ninety (75%) parents felt uncomfortable if someone asked something about their child's strabismus. One hundred and ten (91.67%) parents considered strabismus as cosmetic stigma.

Conclusion:

Some parents, especially from the lower educated segment, had poor understanding of strabismus, thus resulting in late presentation and ineffective countermeasures. The key to prevent strabismic amblyopia and its psychosocial impacts is to provide health education regarding strabismus.

Endophthalmitis Following Strabismus Surgery: IPOSC Global Study

PURPOSE

To examine the characteristics of patients with endophthalmitis after strabismus surgery (PSSE), the characteristics of the strabismus surgery, treatment, and prognosis as reported by pediatric ophthalmologists who are members of the American Association for Pediatric Ophthalmology and Strabismus (AAOPS) around the world.

METHODS

An email communication was sent to all members of AAPOS. The email included a web link to a survey that included 34 questions that examined the characteristics of patients with endophthalmitis after strabismus surgery.

RESULTS

Three hundred forty-nine ophthalmologists responded to the questionnaire. Two hundred sixty four (76%) had practiced pediatric ophthalmology for over 10 years. Twenty-seven cases of endophthalmitis were reported. The medial rectus muscle (MR) was the most common muscle undergoing surgery (55%). In 5 patients (21%), perforation was observed at the time of surgery. In all cases, endophthalmitis was diagnosed 3-7 days after surgery. The final visual acuity of 34% was no light perception (NLP).

DISCUSSION

This series is the largest existing series on PSSE. Our data suggest that PSSE can occur also in healthy patients and in patients without a visualized scleral perforation. The majority of PSSE occurs during the first week after surgery. Therefore, we believe that all patients that underwent strabismus surgery should be examined in this time frame. The prognosis was poor with 48% demonstrating a visual acuity of LP or NLP at the final follow-up.

Clinical characteristics of sibling patients with comitant strabismus

AIM

To investigate the clinical characteristics of sibling patients with comitant strabismus.

METHODS

Sibling patients who were diagnosed with comitant strabismus from January 2005 to December 2014 were retrospectively reviewed. Factors including age, sex, types of strabismus, refractive errors, angle of deviation, and coexistence of other strabismus were analyzed.

RESULTS

A total of 62 patients (31 pairs of siblings) were included. Of these, 26 pairs had intermittent exotropia, 3 had accommodative esotropia, and 2 had infantile esotropia. There were no pairs with different subtypes of strabismus. The age at first visit was 3.7±2.6y and the mean follow-up period was 30.5±24.1mo. In siblings with intermittent exotropia, there was no difference in age of onset, age at operation, or refractive errors between the first and second-born children. The 20 (77%) pairs of siblings with exotropia showed more than 80% concordance of maximum angle of deviation during follow-up. In the 9 pairs in which both siblings had an operation, the final angle of deviation after the operation was 8.2±8.1 prism diopters (PD) in first-born children and 8.6±6.5 PD in second-born children.

CONCLUSION

The subtypes of strabismus are the same in all pairs of siblings and clinical characteristics of strabismus are similar between the first and second-born children. This similarity could be an indicator for the diagnosis of second-born children. Further prospective study including a larger number of sibling patients is needed.

Refractive Errors and Concomitant Strabismus: A Systematic Review and Meta-analysis

This systematic review and meta-analysis is to evaluate the risk of development of concomitant strabismus due to refractive errors. Eligible studies published from 1946 to April 1, 2016 were identified from MEDLINE and EMBASE that evaluated any kinds of refractive errors (myopia, hyperopia, astigmatism and anisometropia) as an independent factor for concomitant exotropia and concomitant esotropia. Totally 5065 published records were retrieved for screening, 157 of them eligible for detailed evaluation. Finally 7 population-based studies involving 23,541 study subjects met our criteria for meta-analysis. The combined OR showed that myopia was a risk factor for exotropia (OR: 5.23, P = 0.0001). We found hyperopia had a dose-related effect for esotropia (OR for a spherical equivalent [SE] of 2–3 diopters [D]: 10.16, P = 0.01; OR for an SE of 3-4D: 17.83, P < 0.0001; OR for an SE of 4-5D: 41.01, P < 0.0001; OR for an SE of ≥5D: 162.68, P < 0.0001). Sensitivity analysis indicated our results were robust. Results of this study confirmed myopia as a risk for concomitant exotropia and identified a dose-related effect for hyperopia as a risk of concomitant esotropia.

Visual Function of Moderately Hyperopic 4- and 5-Year-Old Children in the Vision in Preschoolers - Hyperopia in Preschoolers Study

PURPOSE

To compare visual performance between emmetropic and uncorrected moderately hyperopic preschool-age children without strabismus or amblyopia.

DESIGN

Cross-sectional study.

METHODS

setting: Multicenter, institutional. patient or study population: Children aged 4 or 5 years. intervention or observation procedures: Visual functions were classified as normal or reduced for each child based on the 95% confidence interval for emmetropic individuals. Hyperopic (≥3.0 diopters [D] to ≤6.0 D in the most hyperopic meridian; astigmatism ≤1.50 D; anisometropia ≤1.0 D) and emmetropic status were determined by cycloplegic autorefraction.

MAIN OUTCOME MEASURES

Uncorrected monocular distance and binocular near visual acuity (VA); accommodative response; and near random dot stereoacuity.

RESULTS

Mean (± standard deviation) logMAR distance visual acuity (VA) among 248 emmetropic children was better than among 244 hyperopic children for the better (0.05 ± 0.10 vs 0.14 ± 0.11, P < .001) and worse eyes (0.10 ± 0.11 vs 0.19 ± 0.10, P < .001). Mean binocular logMAR near VA was better in emmetropic than in hyperopic children (0.13 ± 0.11 vs 0.21 ± 0.11, P < .001). Mean accommodative response for emmetropic children was lower than for hyperopic subjects for both Monocular Estimation Method (1.03 ± 0.51 D vs 2.03 ± 1.03 D, P < .001) and Grand Seiko (0.46 ± 0.45 D vs 0.99 ± 1.0 D, P < .001). Median near stereoacuity was better in emmetropic than in than hyperopic children (40 sec arc vs 120 sec arc, P < .001). The average number of reduced visual functions was lower in emmetropic than in hyperopic children (0.19 vs 1.0, P < .001).

CONCLUSIONS

VA, accommodative response, and stereoacuity were significantly reduced in moderate uncorrected hyperopic preschool children compared to emmetropic subjects. Those with higher hyperopia (≥4 D to ≤6 D) were at greatest risk, although more than half of children with lower magnitudes (≥3 D to <4 D) demonstrated 1 or more reductions in function.

The Effect of Achieving Immediate Target Angle on Success of Strabismus Surgery in Children

PURPOSE

To determine if achieving the ideal postoperative target range increases the long-term success of pediatric strabismus surgery.

DESIGN

Interventional case series.

METHODS

Children below 12 years old with horizontal strabismus who underwent surgical correction by recession, resection, advancement, or a combination of both between 1996 and 2011 were included. Alignment was measured within 1 week and at a minimum of 6 months after surgery. The ideal postoperative target range was defined as 0-8 prism diopters (PD) of esotropia in exotropic patients and within 4 PD of orthotropia in esotropic patients measured within 1 week after the surgery. Success was defined as a measurement within 10 PD of orthotropia at the latest postoperative visit. The main outcome measures were surgical success rate and the factors affecting it.

RESULTS

We included 352 patients with mean follow-up of 18 months. Overall, patients within the target range had a higher success rate than those outside it (75.6% vs 57% P = .0004). This was highly significant for exotropia (P = .0002) but not for esotropia (P = .4). Multiple regression analysis revealed that being within target range was the strongest predictor of long-term success (odds ratio [OR] = 2.3, range 1.4-3.7). Overall, surgeries on patients with esotropia were more likely to be successful than on those with exotropia (OR = 1.9, range 1.2-3), and premature patients had poorer outcomes (OR = 0.2, range 0.1-0.8).

CONCLUSION

Achieving the ideal target range within 1 week after surgery is associated with a high rate of long-term success in exotropia surgery in children.

Association between childhood strabismus and refractive error in Chinese preschool children

PURPOSE

To investigate the association between concomitant esotropia or concomitant exotropia and refractive error in preschool children.

METHODS

A population-based sample of 5831 children aged 3 to 6 years was selected from all kindergartens in a representative county (Yuhuatai District, Nanjing, Jiangsu Province) of Nanjing, China. Clinical examinations including ocular alignment, ocular motility, visual acuity, optometry, stereopsis screening, slit lamp examination and fundus examination were performed by trained ophthalmologists and optometrists. Odd ratios (OR) and 95% confidence intervals (95% CI) were calculated to evaluate the association of refractive error with concomitant esotropia and concomitant exotropia.

RESULTS

In multivariate logistic regression analysis, concomitant esotropia was associated independently with spherical equivalent anisometropia (OR, 3.15 for 0.50 to <1.00 diopter (D) of anisometropia, and 7.41 for > = 1.00 D of anisometropia) and hyperopia. There was a severity-dependent association of hyperopia with the development of concomitant esotropia, with ORs increasing from 9.3 for 2.00 to <3.00 D of hyperopia, to 180.82 for > = 5.00 D of hyperopia. Concomitant exotropia was associated with astigmatism (OR, 3.56 for 0.50 to 1.00 D of astigmatism, and 1.9 for <0.00 D of astigmatism), myopia (OR, 40.54 for -1.00 to <0.00 D of myopia, and 18.93 for <-1.00 D of myopia), and hyperopia (OR, 67.78 for 1.00 to <2.00 D of hyperopia, 23.13 for 2.00 to <3.00 D of hyperopia, 25.57 for 3.00 to <4.00 D of hyperopia, and 8.36 for 4.00 to <5.00 D of hyperopia).

CONCLUSIONS

This study highlights the close associations between refractive error and the prevalence of concomitant esotropia and concomitant exotropia, which should be considered when managing childhood refractive error.

Effect of gestational age and birth weight on the risk of strabismus among premature infants

IMPORTANCE

Strabismus causes irreversible vision loss if not detected and treated early. It is unclear whether birth weight (BW) and gestational age (GA) are risk factors for strabismus.

OBJECTIVE

To estimate the effect of BW and GA on the likelihood of premature infants developing strabismus.

DESIGN, SETTING, AND PARTICIPANTS

In this longitudinal cohort analysis, we monitored a group of premature children from birth to determine the proportion that developed strabismus and the timing of the first strabismus diagnosis. Multivariable Cox regression analyses assessed the relationships of BW and GA with the development of strabismus. Regression models were adjusted for other risk factors for strabismus, sociodemographic factors, and ocular comorbidities. The analysis included 38,055 otherwise healthy children born prematurely who were enrolled for more than 6 months in a nationwide US managed care network between 2001 and 2011 in communities throughout the United States.

EXPOSURES

Birth weight less than 2000 g or GA of 32 weeks or less.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) for strabismus with 95% CIs.

RESULTS

Of 38,055 otherwise healthy children who were born prematurely, 583 received a diagnosis of strabismus later in life. The cumulative incidence of strabismus was 3.0% at 5 years. Controlling for GA and other covariates, infants born with BW less than 2000 g had a 61% increased hazard (HR, 1.61; 95% CI, 1.22-2.13) of developing strabismus. Controlling for BW and other covariates, there was no significant association between strabismus and GA (HR, 0.98; 95% CI, 0.69-1.38). Among premature infants with BW of less than 2000 g, a GA of 32 weeks or less conveyed no additional increased risk for developing strabismus relative to infants born after 32 weeks (HR, 1.27; 95% CI, 0.86-1.88). In contrast, among infants with a GA of 32 weeks or less, BW of less than 2000 g conveyed a 14-fold increase in the risk of strabismus relative to BW of 2000 g or more (HR, 14.39; 95% CI, 1.99-104.14).

CONCLUSIONS AND RELEVANCE

Independent of GA, very low BW conferred a large increase in strabismus risk among premature infants. In contrast, independent of BW, GA did not significantly affect the risk of strabismus. Updates to existing guidelines in the pediatric and ophthalmic literature should be considered, highlighting the importance of BW rather than GA and alerting clinicians about the need for careful monitoring of premature infants with low BW for strabismus.

Associations between hyperopia and other vision and refractive error characteristics

PURPOSE

To investigate the association of hyperopia greater than +3.25 diopters (D) with amblyopia, strabismus, anisometropia, astigmatism, and reduced stereoacuity in preschoolers.

METHODS

Three- to five-year-old Head Start preschoolers (N = 4040) underwent vision examination including monocular visual acuity (VA), cover testing, and cycloplegic refraction during the Vision in Preschoolers Study. Visual acuity was tested with habitual correction and was retested with full cycloplegic correction when VA was reduced below age norms in the presence of significant refractive error. Stereoacuity testing (Stereo Smile II) was performed on 2898 children during study years 2 and 3. Hyperopia was classified into three levels of severity (based on the most positive meridian on cycloplegic refraction): group 1: greater than or equal to +5.00 D, group 2: greater than +3.25 D to less than +5.00 D with interocular difference in spherical equivalent greater than or equal to 0.50 D, and group 3: greater than +3.25 D to less than +5.00 D with interocular difference in spherical equivalent less than 0.50 D. "Without" hyperopia was defined as refractive error of +3.25 D or less in the most positive meridian in both eyes. Standard definitions were applied for amblyopia, strabismus, anisometropia, and astigmatism.

RESULTS

Relative to children without hyperopia, children with hyperopia greater than +3.25 D (n = 472, groups 1, 2, and 3) had a higher proportion of amblyopia (34.5 vs. 2.8%, p < 0.0001) and strabismus (17.0 vs. 2.2%, p < 0.0001). More severe levels of hyperopia were associated with higher proportions of amblyopia (51.5% in group 1 vs. 13.2% in group 3) and strabismus (32.9% in group 1 vs. 8.4% in group 3; trend p < 0.0001 for both). The presence of hyperopia greater than +3.25 D was also associated with a higher proportion of anisometropia (26.9 vs. 5.1%, p < 0.0001) and astigmatism (29.4 vs. 10.3%, p < 0.0001). Median stereoacuity of nonstrabismic, nonamblyopic children with hyperopia (n = 206) (120 arcsec) was worse than that of children without hyperopia (60 arcsec) (p < 0.0001), and more severe levels of hyperopia were associated with worse stereoacuity (480 arcsec for group 1 and 120 arcsec for groups 2 and 3, p < 0.0001).

CONCLUSIONS

The presence and magnitude of hyperopia among preschoolers were associated with higher proportions of amblyopia, strabismus, anisometropia, and astigmatism and with worse stereoacuity even among nonstrabismic, nonamblyopic children.

Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES)

PURPOSE

To determine the prevalence of amblyopia and strabismus in 7th-grade junior high school students in central China.

METHODS

Using stratified cluster sampling, 2363 7th-grade students were recruited from four junior high schools in Anyang city into the cross-sectional Anyang Childhood Eye Study (ACES). All students underwent visual acuity (VA), cycloplegic autorefraction, cover test, and ocular movement examinations. Uncorrected VA and best-corrected VA (BCVA) were measured with a logarithm of the minimum angle of resolution (logMAR) chart. Cycloplegic autorefraction was performed after administration of 1.0% cyclopentolate and Mydrin-P. Strabismus was defined as heterotropia at near or distance fixation. Amblyopia was defined as BCVA ≤ 0.1 logMAR units in one or both eyes, without ocular pathology in either eye.

RESULTS

Of the 2363 eligible students, 2260 (95.6%) completed all examinations. The mean age of the students was 12.4 ± 0.6 years. Amblyopia was present in 52 students (2.5%), of whom 33 (63.5%) had unilateral and 19 (36.6%) had bilateral amblyopia. Of those with unilateral amblyopia, 18 (54.5 %) had anisometropia and 7 (21.2%) had strabismus. Of those with bilateral amblyopia, 6 (31.6%) had significant refractive error. Strabismus was present in 108 students (5.0%), of whom 2 (1.9%) had esotropia, 102 (94.4%) had exotropia, 3 (2.8%) had vertical strabismus, and 1 (0.9%) had microstrabismus. Of the 108 students with strabismus, 9 (8.3%) had amblyopia.

CONCLUSION

The cross-sectional ACES which examined the prevalence of amblyopia and strabismus in 7th-grade students in central China revealed the prevalence of strabismus, particularly the proportion of exotropia, to be higher than previously reported.

Alcohol use and positive screening results for depression and anxiety are highly prevalent among Chinese children with strabismus

PURPOSE

To study associations between strabismus and alcohol use, anxiety, and depression among 10- to 17-year-old children in Guangdong, southern China.

DESIGN

Cross-sectional, population-based study.

METHODS

Among 7537 children aged 6-17 years from 9 randomly selected primary and middle schools, ocular alignment was assessed with the Hirschberg light reflex, cover-uncover testing, and alternate cover testing at distance (6 m) and near (40 cm). Additionally, 4000 children (53.1%) aged 10+ years received self-administered questionnaires containing screening questions on alcohol use, anxiety, and depression.

RESULTS

Examinations were completed on 7464 of 7537 subjects (99.0%), including 3928 boys (52.6%), with a mean age of 11.1 ± 1.8 years. The prevalence of any strabismus, including exotropia (2.7%), esotropia (0.2%), and intermittent exotropia (3.9%), was 6.8%. Strabismus was more prevalent in urban students (7.3%) and female subjects (7.4%) compared to rural students (6.0%) and male subjects (6.2%) (all P < .05). In multivariate regression models, any strabismus was associated with older age and rural vs urban residence. Among 3903 children (97.6%) answering questionnaires, history of alcohol use (62.3% vs 36.3%) and positive screening responses for depression (26.0% vs 11.6%) and anxiety (10.3% vs 4.9%) were significantly (P < .01 for all) more common among children with strabismus.

CONCLUSION

These Chinese children with strabismus had a significantly higher prevalence of alcohol use and possible markers of emotional problems than children without strabismus. Further research should focus on the appropriateness of classifying surgical treatment for strabismus as "cosmetic" (ineligible for reimbursement) under China's rural health insurance.

Incidence, types, and lifetime risk of adult-onset strabismus

OBJECTIVE

To describe the incidence and types of adult-onset strabismus in a geographically defined population.

DESIGN

Retrospectively reviewed population-based cohort.

PARTICIPANTS

All adult (≥19 years of age) residents of Olmsted County, Minnesota, diagnosed with new-onset adult strabismus from January 1, 1985, through December 31, 2004.

METHODS

The medical records of all potential cases identified by the resources of the Rochester Epidemiology Project were reviewed.

MAIN OUTCOME MEASURES

Incidence rates for adult-onset strabismus and its types.

RESULTS

Seven hundred fifty-three cases of new-onset adult strabismus were identified during the 20-year period, yielding an annual age- and gender-adjusted incidence rate of 54.1 cases (95% confidence interval, 50.2-58.0) per 100 000 individuals 19 years of age and older. The 4 most common types of new-onset strabismus were paralytic (44.2% of cases), convergence insufficiency (15.7%), small-angle hypertropia (13.3%), and divergence insufficiency (10.6%). The incidence of adult-onset strabismus overall and its 4 most common forms significantly increased with age (P <0.001 for all), with a peak incidence in the eighth decade of life. The lifetime risk of being diagnosed with adult-onset strabismus was 4.0% in women and 3.9% in men.

CONCLUSIONS

Paralytic strabismus was the most common subtype of new-onset adult strabismus in this population-based cohort. All of the most common forms of adult-onset strabismus increased with age, especially after the sixth decade of life. Further characterization of strabismus types found in this study is warranted to better define this disorder.

Accuracy of noncycloplegic retinoscopy, retinomax autorefractor, and SureSight vision screener for detecting significant refractive errors

PURPOSE

To evaluate, by receiver operating characteristic (ROC) analysis, the ability of noncycloplegic retinoscopy (NCR), Retinomax Autorefractor (Retinomax), and SureSight Vision Screener (SureSight) to detect significant refractive errors (RE) among preschoolers.

METHODS

Refraction results of eye care professionals using NCR, Retinomax, and SureSight (n = 2588) and of nurse and lay screeners using Retinomax and SureSight (n = 1452) were compared with masked cycloplegic retinoscopy results. Significant RE was defined as hyperopia greater than +3.25 diopters (D), myopia greater than 2.00 D, astigmatism greater than 1.50 D, and anisometropia greater than 1.00 D interocular difference in hyperopia, greater than 3.00 D interocular difference in myopia, or greater than 1.50 D interocular difference in astigmatism. The ability of each screening test to identify presence, type, and/or severity of significant RE was summarized by the area under the ROC curve (AUC) and calculated from weighted logistic regression models.

RESULTS

For detection of each type of significant RE, AUC of each test was high; AUC was better for detecting the most severe levels of RE than for all REs considered important to detect (AUC 0.97-1.00 vs. 0.92-0.93). The area under the curve of each screening test was high for myopia (AUC 0.97-0.99). Noncycloplegic retinoscopy and Retinomax performed better than SureSight for hyperopia (AUC 0.92-0.99 and 0.90-0.98 vs. 0.85-0.94, P ≤ 0.02), Retinomax performed better than NCR for astigmatism greater than 1.50 D (AUC 0.95 vs. 0.90, P = 0.01), and SureSight performed better than Retinomax for anisometropia (AUC 0.85-1.00 vs. 0.76-0.96, P ≤ 0.07). Performance was similar for nurse and lay screeners in detecting any significant RE (AUC 0.92-1.00 vs. 0.92-0.99).

CONCLUSIONS

Each test had a very high discriminatory power for detecting children with any significant RE.

Risk factors for strabismus and amblyopia in young Singapore Chinese children

PURPOSE

To determine the risk factors for strabismus and amblyopia in young Singapore Chinese children.

METHODS

A total of 3009 children were recruited for the population-based cross-sectional Strabismus, Amblyopia and Refractive Error in Singaporean Preschoolers Study (STARS). Strabismus was defined as any tropia identified on cover test. Visual acuity was measured in children aged 30-72 months with a logMAR chart where possible and the Sheridan-Gardiner test if not. Amblyopia was defined based on visual acuity and refractive error or presence of strabismus or past/present visual axis obstruction. Parents completed questionnaires on family, prenatal and birth histories.

RESULTS

Our study showed that 24 children aged 6-72 months (1.2%) had strabismus (20 with exotropia), and 20 children aged 30-72 months (0.8%) were amblyopic. After multivariate analysis, strabismus was associated with astigmatism ≥1.00 diopter (D; p = 0.03), amblyopia (p = 0.003), a sibling with strabismus (p < 0.001), and families with lower parental education (p = 0.04). In addition to strabismus, amblyopia was associated with anisometropia ≥1.00 D (p < 0.001) and astigmatism ≥1.00 D (p < 0.001). No association was noted between either strabismus or amblyopia and prematurity, maternal age or smoking.

CONCLUSION

This study highlights the importance of family history in strabismus, and the close associations between refractive error and strabismus with amblyopia. These factors play a more important role in young Singapore Chinese children.

Preterm-associated visual impairment and estimates of retinopathy of prematurity at regional and global levels for 2010

BACKGROUND

Retinopathy of prematurity (ROP) is a leading cause of potentially avoidable childhood blindness worldwide. We estimated ROP burden at the global and regional levels to inform screening and treatment programs, research, and data priorities.

METHODS

Systematic reviews and meta-analyses were undertaken to estimate the risk of ROP and subsequent visual impairment for surviving preterm babies by level of neonatal care, access to ROP screening, and treatment. A compartmental model was used to estimate ROP cases and numbers of visually impaired survivors.

RESULTS

In 2010, an estimated 184,700 (uncertainty range: 169,600-214,500) preterm babies developed any stage of ROP, 20,000 (15,500-27,200) of whom became blind or severely visually impaired from ROP, and a further 12,300 (8,300-18,400) developed mild/moderate visual impairment. Sixty-five percent of those visually impaired from ROP were born in middle-income regions; 6.2% (4.3-8.9%) of all ROP visually impaired infants were born at >32-wk gestation. Visual impairment from other conditions associated with preterm birth will affect larger numbers of survivors.

CONCLUSION

Improved care, including oxygen delivery and monitoring, for preterm babies in all facility settings would reduce the number of babies affected with ROP. Improved data tracking and coverage of locally adapted screening/treatment programs are urgently required.

Prevalence, causes and associations of amblyopia in year 1 students in Central China : The Anyang childhood eye study (ACES)

BACKGROUND

Earlier diagnosis and treatment of amblyopia are associated with improved visual outcomes. This study reports the prevalence of amblyopia and associated factors in year 1 primary school students in central China.

METHODS

The school-based, cross-sectional study involved 3,112 year 1 primary school students . All the participants underwent a comprehensive eye examinations including cycloplegic refraction, cover test and ocular movement examinations. The unaided and best corrected visual acuity (BCVA) was recorded. Unilateral amblyopia was defined as a 2-line interocular difference with BCVA ≤ 20/32 (≥ logMar 0.2) in the worse eye and with coexisting anisometropia (≥ 1.00 D SE for hyperopia, ≥ 3.00 D SE for myopia, or ≥ 1.50 D for astigmatism), strabismus or past or present visual axis obstruction. Bilateral amblyopia was defined as BCVA in both eyes<20/40 (> logMar 0.3), with coexisting hyperopia ≥ 4 D SE, myopia ≤ -6 D SE, or astigmatism ≥ 2.5 D, or past or present visual axis obstruction.

RESULTS

Out of the 3,112 eligible students, 2,893 (93.0 %) students completed the examinations. The average age of the students was 7.1 ± 0.4 (mean ± standard deviation SD) years old. The prevalence of amblyopia was 1.0 % (95 % confidence interval [CI], 0.6 %-1.3 %) with no difference between the sexes (P = 0.88). Of the 27 amblyopic students, unilateral amblyopia was found in 18 (66.7 %) students, and bilateral amblyopia in 9 (33.3 %) students. Of 18 unilateral amblyopia, 13 were anisometropic amblyopia, 4 were strabismus amblyopia, 1 was mixed amblyopia. Of 9 bilateral amblyopia, 7 were isoametropic amblyopia, 2 were stimulus deprivation. The mean corrected VA of the amblyopic eyes was 30.50 logMAR letters (Snellen VA equivalent 4/12.6), and the range was 5 to 45 logMAR letters (Snellen VA equivalent 4/40-4/6.3). Most amblyopic eyes (38.9 %) were significantly hyperopic (spherical equivalent ≥ +3.00 D); 25.0 % were myopic. In addition, 58 (2.1 %) students had a previous amblyopia history of amblyopia that was not corroborated in this study.

CONCLUSIONS

The study shows a relatively low prevalence of amblyopia (1.0 %) in year 1 students in central China. Amblyopia is usually caused by abnormal refractive error.

Abnormal expression of seven myogenesis-related genes in extraocular muscles of patients with concomitant strabismus

Hyperplasia or hypoplasia of muscles gradually leads to strabismus. Myogenesis-related genes are involved in extraocular muscle development, including myogenic differentiation 1 (MYOD1), myogenin (MYOG), retinoblastoma 1 (RB1), cyclin-dependent kinase inhibitor 1A (P21), cyclin‑dependent kinase inhibitor 1C (P57), insulin-like growth factor 1 (IGF1) and muscle creatine kinase (MCK). This study evaluated the expression of the above seven myogenesis-related genes by real-time quantitative RT-PCR in 18 resected extrocular muscles of patients with concomitant strabismus and 12 normal control muscle samples from one presumably healthy male 6 h after sudden mortality. We found that although there was a great divergence among the expression levels of 6 myogenesis-related regulatory factors, the relative expression patterns were similar in all the normal muscles, including the synergistic, antagonistic and yoke muscles. However, their expression levels in the 18 diseased extraocular muscles were abnormal; the expression levels of all the genes, with the exception of P57, were reduced in most of the diseased muscle tissues. These results imply that the abnormal expression of these myogenesis-related genes may contribute to concomitant strabismus.

Horizontal strabismus worldwide--what are the risk factors?

Horizontal strabismus has constant risk factors of ethnicity, family history, genetic conditions and potentially modifiable risk factors of maternal smoking, prematurity, low birth weight, refractive errors and neurodisability.

Parent-reported symptoms of attention deficit hyperactivity disorder in children with intermittent exotropia before and after strabismus surgery

PURPOSE

To investigate the symptoms of attention deficit hyperactivity disorder (ADHD) as reported by parents in children with intermittent exotropia [X(T)] and to determine whether strabismus surgery for X(T) affects ADHD symptoms.

MATERIALS AND METHODS

Fifty-one consecutive children undergoing muscle surgery for X(T) were prospectively recruited. One parent of each child completed the ADHD rating scale IV (ADHD RS-IV) assessment consecutively before and one year after surgery. Patients whose preoperative scores were above the cut-off point, the 90th percentile based on a Korean sample, were regarded as demonstrating the ADHD trait. The impact of muscle surgery on ADHD symptoms was assessed by comparing the preoperative scores with the post-operative scores.

RESULTS

Eight (15.7%) of the 51 patients demonstrated the ADHD trait. ADHD RS-IV scores following strabismus surgery significantly decreased in patients with the ADHD trait (p=0.014), while they did not differ in patients without the ADHD trait. Seven (87.5%) of the 8 patients with the ADHD trait showed improvement in their ADHD RS-IV scores after surgery. There was no difference in surgical success rates between X(T) patients with and without the ADHD trait.

CONCLUSION

The ADHD trait was relatively common in children with X(T), and the parent-reported symptoms of the children with the ADHD trait improved after strabismus surgery. These results suggest that childhood X(T) may be one contributing factor to ADHD- related symptoms.

Heritability of strabismus: genetic influence is specific to eso-deviation and independent of refractive error

Strabismus represents a complex oculomotor disorder characterized by the deviation of one or both eyes and poor vision. A more sophisticated understanding of the genetic liability of strabismus is required to guide searches for associated molecular variants. In this classical twin study of 1,462 twin pairs, we examined the relative influence of genes and environment in comitant strabismus, and the degree to which these influences can be explained by factors in common with refractive error. Participants were examined for the presence of latent ('phoria') and manifest ('tropia') strabismus using cover-uncover and alternate cover tests. Two phenotypes were distinguished: eso-deviation (esophoria and esotropia) and exo-deviation (exophoria and exotropia). Structural equation modeling was subsequently employed to partition the observed phenotypic variation in the twin data into specific variance components. The prevalence of eso-deviation and exo-deviation was 8.6% and 20.7%, respectively. For eso-deviation, the polychoric correlation was significantly greater in monozygotic (MZ) (r = 0.65) compared to dizygotic (DZ) twin pairs (r = 0.33), suggesting a genetic role (p = .003). There was no significant difference in polychoric correlation between MZ (r = 0.55) and DZ twin pairs (r = 0.53) for exo-deviation (p = .86), implying that genetic factors do not play a significant role in the etiology of exo-deviation. The heritability of an eso-deviation was 0.64 (95% CI 0.50-0.75). The additive genetic correlation for eso-deviation and refractive error was 0.13 and the bivariate heritability (i.e., shared variance) was less than 1%, suggesting negligible shared genetic effect. This study documents a substantial heritability of 64% for eso-deviation, yet no corresponding heritability for exo-deviation, suggesting that the genetic contribution to strabismus may be specific to eso-deviation. Future studies are now needed to identify the genes associated with eso-deviation and unravel their mechanisms of action.

Ocular motor function in relation to gross motor function in congenital and childhood myotonic dystrophy type 1

PURPOSE

To assess ocular motor function in congenital and childhood myotonic dystrophy type 1 (DM1) and correlate the results with cytosine-thymine-guanine (CTG) repeat size, severity of the disease, myotonia and skeletal muscle function.

METHODS

A cross-sectional investigation into strabismus, versions/ductions, saccades, smooth pursuit movements and ptosis was performed on 49 individuals with a confirmed diagnosis of DM1, all diagnosed at <18 years of age and with >40 CTG expansion repeats. The results were correlated with myotonia as well as Hammersmith motor ability scale (HMA). In addition, the ocular results were compared to results from an age and- sex-matched control group.

RESULTS

Ocular motor abnormalities were seen in 82%; the most frequent findings were altered conjugate eye movements and 'pseudoptosis' while blepharoptosis was rare. Strabismus was most common in the severe congenital subgroup, with a frequency 14 times higher than in the control group. Positive correlations were seen between CTG repeat size and affected eyelids, and between myotonia and affected eyelids; both these findings were most prominent in the mild congenital group. CTG repeat size was also correlated with version/duction defects, and most obviously in the childhood group. Low HMA scores were associated with high occurrence of strabismus and version/duction defects.

CONCLUSION

Abnormalities of ocular motor function are frequently present. CTG repeat size correlates positively with altered versions/ductions and eyelid pathology. Gross motor dysfunction correlates with strabismus and defect versions/ductions, and eyelid pathology indicates involvement of myotonia.

What are the effects of metopic synostosis on visual function?

Metopic synostosis is a premature fusion of the metopic cranial suture. Small case studies into the effects on vision have suggested that there is a raised incidence of astigmatic refractive error with increased risk of failure to develop normal vision if reconstructive surgery is delayed beyond 7 months of age. The aim of this study was to look at a much larger group of patients to give more statistical significance on the incidence of significant refractive error and strabismus in cases of metopic synostosis and compare this with that known for the general population of children at a similar age. A secondary objective was to look at the age at surgery and the visual outcome. A retrospective analysis of case notes was carried out for 64 children with a confirmed diagnosis of metopic synostosis attending the Oxford Craniofacial Unit. Twenty children (31%) were found to have a visual problem, with 18 needing glasses to correct a refractive error and 10 having strabismus. The nature of refractive error was generally hypermetropia, in some cases combined with low astigmatism (1.5 diopters [D] or less). Only 1 child was recorded as having more than 1.5 D of astigmatism. The age at surgery did not seem to influence visual outcome. The incidence of significant refractive error requiring correction and strabismus across the metopic group (31%) was higher than that found in the general population of children at a similar age (5%-11%). This reinforces the importance of orthoptic/ophthalmic surveillance in metopic synostosis.

Prevalence of eye diseases in South Korea: data from the Korea National Health and Nutrition Examination Survey 2008-2009

PURPOSE

The aim of this study is to report on preliminary data regarding the prevalence of major eye diseases in Korea.

METHODS

We obtained data from the Korea National Health and Nutrition Examination Survey, a nation-wide cross-sectional survey and examinations of the non-institutionalized civilian population in South Korea (n = 14,606), conducted from July 2008 to December 2009. Field survey teams included an ophthalmologist, nurses, and interviewers, traveled with a mobile examination unit and performed interviews and ophthalmologic examinations.

RESULTS

The prevalence of visual impairment, myopia, hyperopia and astigmatism in participants over 5 years of age was 0.4 ± 0.1%, 53.7 ± 0.6%, 10.7 ± 0.4%, and 58.0 ± 0.6%, respectively. The prevalence of strabismus and blepharoptosis in participants over 3 years of age was 1.5 ± 0.1% and 11.0 ± 0.8%, respectively. In participants over 40 years of age, the prevalence of cataract, pterygium, early and late age-related macular degeneration, diabetic retinopathy and glaucoma was 40.2 ± 1.3%, 8.9 ± 0.5%, 5.1 ± 0.3%, 0.5 ± 0.1%, 13.4 ± 1.5%, and 2.1 ± 0.2%, respectively.

CONCLUSIONS

This is the first nation-wide epidemiologic study conducted in South Korea for assessment of the prevalence of eye diseases by both the Korean Ophthalmologic Society and the Korea Center for Disease Control and Prevention. This study will provide preliminary information for use in further investigation, prevention, and management of eye diseases in Korea.