Associations between unilateral amblyopia in childhood and cardiometabolic disorders in adult life: a cross-sectional and longitudinal analysis of the UK Biobank

Background

Amblyopia is a common neurodevelopmental condition and leading cause of childhood visual impairment. Given the known association between neurodevelopmental impairment and cardiometabolic dysfunction in later life, we investigated whether children with amblyopia have increased risk of cardiometabolic disorders in adult life.

Methods

This was a cross-sectional and longitudinal analysis of 126,399 United Kingdom Biobank cohort participants who underwent ocular examination. A subset of 67,321 of these received retinal imaging. Data analysis was conducted between November 1st 2021 and October 15th 2022. Our primary objective was to investigate the association between amblyopia and a number of components of metabolic syndrome and individual cardiometabolic diseases. Childhood amblyopia, dichotomised as resolved or persisting by adulthood, cardiometabolic disease and mortality were defined using ophthalmic assessment, self-reported, hospital admissions and death records. Morphological features of the optic nerve and retinal vasculature and sublayers were extracted from retinal photography and optical coherence tomography. Associations between amblyopia and cardiometabolic disorders as well as retinal markers were investigated in multivariable-adjusted regression models.

Findings

Individuals with persisting amblyopia (n = 2647) were more likely to be obese (adjusted odds ratio (95% confidence interval): 1.16 (1.05; 1.28)), hypertensive (1.25 (1.13; 1.38)) and diabetic (1.29 (1.04; 1.59)) than individuals without amblyopia (controls, (n = 18,481)). Amblyopia was also associated with an increased risk of myocardial infarction (adjusted hazard ratio: 1.38 (1.11; 1.72)) and death (1.36 (1.15; 1.60)). On retinal imaging, amblyopic eyes had significantly increased venular caliber (0.29 units (0.21; 0.36)), increased tortuosity (0.11 units (0.03; 0.19)), but lower fractal dimension (-0.23 units (-0.30; -0.16)) and thinner ganglion cell-inner plexiform layer (mGC-IPL, -2.85 microns (-3.47; -2.22)). Unaffected fellow eyes of individuals with amblyopia also had significantly lower retinal fractal dimension (-0.08 units (-0.15; -0.01)) and thinner mGC-IPL (-1.14 microns (-1.74; -0.54)). Amblyopic eyes with a persisting visual deficit had smaller optic nerve disc height (-0.17 units (-0.25; -0.08)) and width (-0.13 units (-0.21; -0.04)) compared to control eyes.

Interpretation

Although further research is needed to understand the basis of the observed associations, healthcare professionals should be cognisant of greater cardiometabolic dysfunction in adults who had childhood amblyopia. Differences in retinal features in both the amblyopic eye and the unaffected non-amblyopic suggest generalised versus local processes.

Funding

Medical Research Council (MR/T000953/1) and the National Institute for Health and Care Research.

Prevalence of strabismus and risk factors in adults born preterm with and without retinopathy of prematurity: results from the Gutenberg Prematurity Eye study

AIM

The purpose of this study was to assess the prevalence of strabismus and nystagmus and to analyse associated factors in preterm and full-term infants in adulthood.

METHODS

The Gutenberg Prematurity Eye Study is a retrospective cohort study with a prospective ophthalmological examination of participants born preterm and full-term (aged 18-52 years). Perinatal data were carefully assessed for risk factors and comprehensive ophthalmological examinations were conducted. The association between strabismus and nystagmus was assessed by analysing 16 different perinatal and actual risk factors in multivariable analysis. Participants were grouped into full-term controls (gestational age (GA) at birth ≥37 weeks), preterm participants without retinopathy of prematurity (ROP) and GA 33-36 weeks (group 2), GA 29-32 weeks (group 3), GA ≤28 weeks (group 4), non-treated ROP (group 5) and treated ROP (group 6).

RESULTS

In total, 892 eyes of 450 preterm and full-term individuals (mean age: 28.6 years, SD: ± 8.6 years, 251 females) were included. Strabismus was observed in 2.1% (3/140), 6.6% (9/137), 17.4% (16/92), 11.1% (2/18), 27.1% (13/48) and 60% (9/15) of participants and nystagmus in 0.7% (1/140), 1.5% (2/137), 4.3% (4/92), 5.6% (1/18), 10.4% (5/48) and 26.7% (4/15) of participants in the respective groups. In the multivariable regression model, strabismus was associated with GA (OR=0.90; p=0.046), anisometropia ≥1.5 diopter (OR=3.87; p=0.003), hypermetropia ≥2 diopter (OR=9.89; p<0.001) and astigmatism ≥1.5 diopter (OR=2.73; p=0.017). Esotropia was more frequent than exotropia and hypermetropia/hypometropia. Most strabismus cases occurred within the first 10 years of life. The strongest predictor associated with nystagmus was perinatal adverse events (OR=15.8; p=0.002).

CONCLUSION

Low GA and refraction of the eye are independent risk factors for strabismus, which typically occurs in the first 10 years of life. Perinatal adverse events are the most important factors for the presence of nystagmus in adulthood.

Early childhood eye diseases and perinatal risk factors: potential of record linkage between current information flows

BACKGROUND

The aim of this study was to analyze the occurrence of specific maternal, obstetric or neonatal factors, by performing a comparison between children with refractive error, strabismus and/or amblyopia (cases) and unaffected children (controls) in the province of Trento (North-East Italy).

METHODS

In 2012-2014, 14,346 children attending the second year of nursery school were assessed through the preschool orthoptic screening scheme (covering 91% of the preschool population). Record linkage was performed between the orthoptic screening database and birth records (birth confirmation certificate database) for the corresponding birth cohorts (2008-2010), to examine specific maternal factors (age, smoking, nationality/race), obstetric factors (type of delivery) and neonatal factors (gestational age, weight at birth, Apgar Score, congenital birth defects, hospitalization at birth). The correlations were investigated using univariate and multivariate analysis in accordance with the logistic regression method.

RESULTS

During orthoptic screening, 6.4% of children were found to have at least one refractive error, with astigmatism being the most common condition (5.1%). 1.9% of children were found to have strabismus and 1.8% amblyopia. Multivariate logistic regression analysis showed that the risk of developing a refractive error is associated with: maternal age ≥45 years, foreign nationality, vacuum-assisted delivery and neonatal weight <1500 grams. An excessive risk of strabismus was observed in children whose mother had smoked during pregnancy (adjusted OR=1.64).

CONCLUSIONS

Preschool orthoptic screening is a well-consolidated practice in the province of Trento, with adhesion values consistently over 90%. Studies of this type show the potential of record linkage between current information flows.

Divergence excess and basic exotropia types of intermittent exotropia: a major review. Part 1: prevalence, classification, risk factors, natural history and clinical characteristics

INTRODUCTION

Intermittent exotropia (IXT) is a common form of strabismus. It is an outward deviation of one eye typically when viewing at distance. Symptoms include, but are not limited to double vision, eyes feeling tired, excessive blinking, and reduced quality of life. Its clinical characteristics are distinctive from other types of strabismus. This paper provides a comprehensive review of prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT.

METHODS

Search strategies involving combination of keywords including intermittent exotropia, exotropia, divergences excess, basic exotropia, prevalence, incidence, classification, terminology, risk factor, natural history, observation, angle of deviation, control, control score, symptom, quality of life, suppression, anomalous retinal correspondence, AC/A, accommodative convergence/accommodation, accommodative convergence, convergence, accommodation, vergence, incomitance and vertical were used in Medline. All English articles from 1900/01/01 to 2020/09/01 were reviewed. The reference list of the identified article was also checked for additional relevant article. Studies focused on animal model or strabismus associated with neurologic disorder or injury were excluded.

RESULTS

The estimated prevalence of IXT in children ranges from 0.1% to 3.7%. Hypoxia at birth and being female are potential risk factors of IXT. Using validated measures of control, multicenter prospective studies showed that the rate of conversion from IXT to constant exotropia is low. The angle of deviation is the most reported outcome measure in studies of IXT. It is often used to represent the severity of the condition and has been suggested as one of the four core outcomes for studies of the surgical management of IXT. Control of exodeviation is one of the four suggested core outcomes for study of surgery of IXT and is considered the main parameter of disease severity. Several validated tools for quality of life score are available to evaluate the subjective severity of IXT.

DISCUSSION

We reviewed the prevalence, classification, risk factors, natural history and clinical characteristics of the divergence excess and basic exotropia types of IXT. Further research into these areas, especially its clinical characteristics (e.g. suppression, dual retinal correspondence), will increase our understanding of this condition and potentially lead to better management of this common form of strabismus.

Association between Gestational Age, Birth Weight, Parental Age at Childbirth, Mode of Delivery, and Infantile Esotropia

SIGNIFICANCE

This study investigated the potential perinatal risk factors associated with infantile esotropia in a Chinese population, including advanced parental age at childbirth and mode of delivery. The findings may be significant in developing better intervention strategies for infantile esotropia.

PURPOSE

This study aimed to investigate the associations between gestational age, birth weight, parental age at childbirth, mode of delivery, family history of strabismus, and infantile esotropia in the Chinese population.

METHODS

Ninety-nine patients with infantile esotropia and 117 control subjects were enrolled between March 2018 and March 2021. Detailed questionnaires were administered to parents to collect relevant information. Univariate and multivariate logistic regression models were used to identify possible risk factors of infantile esotropia. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated.

RESULTS

Infantile esotropia was associated with low birth weight (<2500 g; OR, 4.235; 95% CI, 1.460 to 12.287; P = .008) and emergency cesarean delivery (OR, 2.230; 95% CI, 1.127 to 4.413; P = .02).

CONCLUSIONS

The findings suggest that low birth weight and emergency cesarean deliveries are risk factors for infantile esotropia, highlighting a need for collaborative care between obstetricians, pediatricians, and vision care providers.

Profile of infantile strabismus at a tertiary eye care center in India

Purpose

To study the profile, risk factors, and management outcomes of infantile strabismus at a tertiary eye care center.

Methods

We prospectively analyzed the data of infants (children less than 1 year of age) who presented at our institute from August 2018 to December 2019. We excluded infants who did not complete a minimum follow-up of 6 months. Detailed meticulous history based on a set of standardized questionnaires was obtained and a comprehensive ophthalmological examination of the child was performed. Data were collected regarding refractive error (astigmatism; myopia; hyperopia; anisometropia [<1.0 DS or >1.0 DS]; astigmatism [<1.0 DS or >1.0 DS]) and the type of strabismus.

Results

During this period, we saw 4,773 infants, out of which 123 infants were diagnosed to have infantile-onset strabismus (hospital prevalence of 2.6%). Boys and girls were equally affected. Sixty-two patients had esotropia, 37 had exotropia, 2 had hypotropia, and 22 had pseudo strabismus. Prematurity, hypermetropia, and anisometropia had increased odds of developing esotropia, whereas delivery by cesarean section, delayed cry at birth, infantile seizures, parental consanguinity, delayed development of milestones, and myopia had increased odds of developing exotropia. Twenty-nine patients underwent a surgical correction. The mean deviation at the first visit was 42.59 ± 15.40 PD and 8.25 ± 12.70 PD at the last visit. For all patients who underwent a squint surgery, the change in ocular deviation was clinically and statistically significant (P-value <0.0001, paired t-test).

Conclusion

The hospital prevalence of infantile strabismus in our cohort was found to be 2.6%. Our study suggests that esotropia is two-fold more common in our cohort as compared to exotropia. Further, our study highlights risk factors for the development of strabismus in infancy, which must be kept in mind and awareness must be created among pediatricians. Surgical correction should be considered early during the infantile period, because it may lead to promote the development of good binocular vision.

Subclinical markers of strabismus in children 5-18 years of age

PURPOSE

To report the prevalence of subclinical markers of strabismus from a community-based screening of children.

METHODS

A family history and ophthalmic examination (including six markers of strabismus: oblique muscle dysfunction, stereopsis <60 arcsec, monofixation, nasal-temporal pursuit asymmetry, dissociated strabismus, and anisometropia) were obtained from consecutive children, aged 5-18 years, in the local school system and the pediatric outpatient clinic of Mayo Clinic, Rochester, Minnesota.

RESULTS

A total of 1,000 children (498 males [49.8%]) were examined at a mean age of 10.6 years (range, 5-18.98). Of the 1,000, 57 (5.7%) had strabismus, and 130 (13%) had some form of phoria. Of the 943 children without strabismus, 103 (10.9%) had one or more of the six subclinical markers, including 43 (4.5%) with inferior oblique dysfunction, 37 (3.9%) with anisometropia, 34 (3.6%) with subnormal stereopsis, 6 (0.6%) with nasal-temporal pursuit asymmetry, 3 (0.3%) with monofixation, and none with dissociated strabismus. A subclinical marker of strabismus occurred in 20 (12.7%) of the 157 nontropic subjects who had a family history of either strabismus, amblyopia, or both and in 83 (10.6%) of the 786 nontropic children without a family history.

CONCLUSIONS

In this community-based screening of children, subclinical disorders of binocular vision occurred in 10%-13% of children without strabismus, of which inferior oblique muscle dysfunction, anisometropia, and subnormal stereopsis were most prevalent. Identifying these disorders among strabismic families may be useful in elucidating the genetic puzzle of childhood strabismus.

Prevalence of Strabismus and Its Associated Factors Among School-Age Children Living in Bahir Dar City: A Community-Based Cross-Sectional Study

INTRODUCTION

Strabismus is a manifest deviation of the eye that exceeds the control of the fusional mechanism so that the eyes are misaligned under binocular conditions. Its prevalence reaches from 0.7% to 5% globally and 1.5% to 17.9% in Ethiopia.

OBJECTIVE

This study aimed to assess the prevalence of strabismus and its associated factors among school-age children living in Bahir Dar city.

METHODS

A community-based cross-sectional study was conducted from April 15 to May 25, 2019, in Bahir Dar city and a total of 632 participants were recruited using a multistage sampling technique. The data were collected with a face-to-face interview, Snellen acuity, prisms, pen torch, portable slit lamp, and ophthalmoscope. The collected data were entered into Epi Info version 7 and transposed to statistical package for social science version 20 for formal statistical analysis. Frequency (percentage), mean (standard deviation), tables and graphs were used to present the summary statistics. All variables with a p-value of less than 0.2 in bi-variable logistic regression were entered into multiple logistic regression and variables with a p-value of less than 0.05 were taken as significantly associated with strabismus. The strength of association between variables was shown with an odds ratio and a 95% confidence interval.

RESULTS

A total of 611 children participated with a response rate of 96.7% and a mean age of 12.3 (±3.25). The prevalence of strabismus was 31 (5.0%), 95% CI: (3.45, 6.97). Family history of strabismus (AOR= 3.9 (95% CI: 1.71, 11.22)), hyperopia ≥ +3.00 diopters sphere (AOR=5.3 (95% CI: 2.01, 10.77)), and not with exclusive breastfeeding (AOR= 2.9 (95% CI: 1.14, 4.71)) were the only risk factors found for strabismus.

CONCLUSION

The prevalence of strabismus was 5% among children living in Bahr Dar city. A family history of strabismus, not with exclusive breastfeeding, and hyperopia ≥ +3.00 diopters sphere were associated with strabismus.

Prevalence, incidence and risk factors of strabismus in a Chinese population-based cohort of preschool children: the Nanjing Eye Study

AIMS

To evaluate the prevalence, incidence and their related risk factors of strabismus among preschool children in China.

METHODS

Children born between September 2011 and August 2012 in Yuhuatai District of Nanjing were invited to participate in the Nanjing Eye Study for a comprehensive eye examination annually since 2015. The data presented in this paper were obtained from 2015 to 2017, when these children grew from the age of 3 to 5 years. Eye examinations included visual acuity, anterior segment, posterior segment, refraction, and ocular alignment and motility. Risk factors were evaluated using univariable and multivariable logistic regression models for prevalent and incident strabismus.

RESULTS

In 2015, a total of 2018 children (87.7% response rate) of 2300 eligible preschoolers completed the baseline eye examination when they were 3 years old. Among the 2018 participants, 50 had strabismus (prevalence rate, 2.48%). In multivariable analysis, prevalent strabismus was independently associated with parental strabismus history (OR=11.60, p<0.001), hyperopia (OR=6.22, p<0.001), prematurity (OR=3.07, p=0.01) and astigmatism (OR=2.15, p=0.04). Among 1766 children followed up for 2 years, 63 developed strabismus (annual incidence rate, 1.78%), of whom 57 had exotropia and 6 had esotropia. In multivariable analysis, incident strabismus was significantly associated with parental strabismus history (OR=5.55, p=0.04) and prematurity (OR=3.77, p<0.001).

CONCLUSIONS

In this population-based cohort study, we found a higher incidence of strabismus and a higher exotropia:esotropia ratio than previous studies in preschool children. Parental strabismus history and prematurity were associated with a higher risk for both prevalent and incident strabismus.

Influence of prenatal environment and birth parameters on amblyopia, strabismus, and anisometropia

PURPOSE

To report the prevalence of amblyopia, strabismus, and anisometropia in a young adult population at a single center in Australia and to investigate the underlying prenatal and early-life risk factors.

METHODS

Participants in the Raine Study have been followed from mid-gestation (n = 2,868 newborns) to young adulthood. At age 20 years, 1,344 participants had a comprehensive eye examination, including visual acuity and a detailed orthoptic assessment. Risk factors were determined from medical records and questionnaires completed by the mothers at 18 weeks' gestation. The main outcome measures were the proportions of participants with amblyopia, esotropia, exotropia, or anisometropia (defined as >1 D difference).

RESULTS

Of the 1,125 white participants, 12 (1.1%) had amblyopia, 39 (3.5%) had strabismus, and 33 (2.9%) had anisometropia. In multivariable logistic regression, amblyopia was associated with a maternal history of pregnancy-induced hypertension (OR = 3.80; 95% CI, 1.19-12.13); esotropia, with lower gestational age (OR = 0.97; 95% CI, 0.95-0.97) and a heavier placenta (OR = 1.02; 95% CI, 1.00-1.04); exotropia, with a maternal history of previously treated hypertension (OR = 4.00; 95% CI, 1.06-15.03) and maternal use of recreational drugs during early pregnancy (OR = 3.61; 95% CI, 1.06-15.03); and anisometropia, with older maternal age (OR = 1.07; 95% CI, 1.01-1.14) and an abnormal umbilical cord (OR = 2.39; 95% CI, 1.04-5.47).

CONCLUSIONS

The prevalence of amblyopia, strabismus, and anisometropia in this cohort was similar to that in other studies. Preterm birth and maternal health may have adverse effects on eye development.

Virtual reality-based measurement of ocular deviation in strabismus

BACKGROUND AND OBJECTIVE

Strabismus is an eye movement disorder in which shows the abnormal ocular deviation. Cover tests have mainly been used in the clinical diagnosis of strabismus for treatment. However, the whole process depends on the doctor's level of experience, which could be subjected to several factors. In this study, an automated technique for measurement of ocular deviation using a virtual reality (VR) device is developed.

METHODS

A VR display system in which the screens that have the fixation target are changed alternately between on and off stages is used to simulate the normal strabismus diagnosis steps. Patients watch special-designed 3D scenes, and their eye motions are recorded by two infrared (IR) cameras. An image-processing-based pupil tracking technique is then applied to track their eye movement. After recording eye motion, two strategies for strabismus angle estimation are implemented: direct measurement and stepwise approximation. The direct measurement converts the eye movement to a strabismus angle after considering the eyeball diameter, while the stepwise approximation measures the ocular deviation through the feedback calibration process.

RESULTS

Experiments are carried out with various strabismus patients. The results are compared to those of their doctors' measurement, which shows good agreement.

CONCLUSIONS

The results clearly indicate that these techniques could identify ocular deviation with high accuracy and efficiency. The proposed system can be applied in small space and has high tolerance for the unexpected head movements compared with other camera-based system.

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.

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.

A comparison of surgical outcomes between pre-and full-term patients with exotropia

PURPOSE

To compare the surgical outcomes between pre- and full-term patients with exotropia and to examine the factors associated with surgical outcomes.

METHODS

This retrospective study included 48 pre- and 432 full-term patients with basic-type exotropia who underwent unilateral or bilateral lateral rectus muscle (ULR or BLR) recession. Preoperative characteristics and surgical outcomes were compared between the pre- and full-term infants. Additionally, factors affecting the surgical outcomes were evaluated in all patients.

RESULTS

The preoperative characteristics were significantly different between the pre- and full-term groups in terms of neurodevelopmental disabilities (p = 0.020). There were no significant differences between the pre- and full-term groups in terms of the success, overcorrection, and recurrence rates after the mean follow-up period of 34.6 ± 13.9 months (p = 0.697). The major cause of surgical failure was recurrence in both groups. Pre-term birth was not a risk factor for overcorrection and recurrence. However, regardless of the pre- or full-term birth status, the presence of neurodevelopmental disabilities significantly affected final overcorrection (p = 0.004).

CONCLUSIONS

Pre-term patients with exotropia showed similar surgical outcomes to full-term controls. The presence of neurodevelopmental disabilities was a risk factor for final overcorrection.

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.

Ophthalmologic Features of Lennox-Gastaut Syndrome

PURPOSE

To describe the characteristics and frequency of ophthalmologic findings in patients with Lennox-Gastaut syndrome (LGS).

METHODS

The medical records of patients diagnosed with LGS at Seoul National University Children's Hospital from January 2004 to August 2014 were retrospectively reviewed. The records of 34 patients (mean age ± standard deviation, 2.66 ± 3.51 years; male, 58.8%) were reviewed. The primary measure was the incidence of ophthalmologic manifestations.

RESULTS

Of the 34 patients, 88.2% had at least one ocular abnormality. Refractive error (52.9%) was the most frequently observed ophthalmologic manifestation in patients with LGS, followed by strabismus (32.4%), cortical visual impairment (23.5%), and retinopathy of prematurity (8.8%). Among these cases, seven patients had exotropia and three had esotropia.

CONCLUSIONS

LGS is a childhood-onset epileptic encephalopathy with variable ophthalmologic manifestations, the most frequent being refractive errors. Patients with suspected LGS should be examined regularly because ophthalmological features can change during their disease course.

Epidemiology of Intermittent Exotropia in Preschool Children in China

PURPOSE

To determine the prevalence, subtypes, and associated risk factors for intermittent exotropia (IXT) in preschool children aged 3 to 6 years in eastern China.

METHODS

A population-based study including 5831 preschool children aged 3 to 6 years was conducted from 2011 to 2012 in Yuhua District, Nanjing, China, using an age-stratified random sampling procedure. Clinical examinations including ocular alignment, ocular motility, visual acuity, prism cover test, cycloplegia refraction, stereopsis screening, slitlamp examination, and fundus examination were performed by trained ophthalmologists and optometrists. Intermittent exotropia was defined as an acquired intermittent exodeviation of at least 10 prism diopters in an otherwise healthy child following the classification recommended by the National Eye Institute.

RESULTS

The overall prevalence of IXT in this population was 3.24% (95% confidence interval, 2.79 to 3.69%), with no age (p = 0.19) and sex (p = 0.89) differences. Among 166 children with IXT, the "basic type" was the most common type of IXT (74.7%), the "divergence excess" was the second (19.9%), whereas the "convergence weakness" was the rarest (5.4%). In multivariate analysis adjusting for age, sex, and other confounders, the presence of IXT was only associated with a history of hypoxia at birth (odds ratio, 4.41; 95% confidence interval, 2.47 to 7.86).

CONCLUSIONS

Intermittent exotropia affected approximately 1 in 30 Chinese preschool-aged children in eastern China, indicating a relatively higher burden of this pediatric eye condition in the world's most populous country. The presence of IXT was strongly associated with a history of hypoxia at birth.

Strabismus at Age 2 Years in Children Born Before 28 Weeks' Gestation: Antecedents and Correlates

Children born very preterm are at greater risk of ophthalmic morbidities, including strabismus, than children born at term. We evaluated perinatal factors associated with strabismus at age 2 years in a large population of infants delivered before 28 weeks' gestation. A total of 996 infants in the multicenter ELGAN (Extremely Low Gestational Age Newborn) study who had a retinal exam in infancy and a developmental assessment at 2 years corrected age are included. Their mothers were interviewed about the pregnancy, and both mother and newborn charts were reviewed. Certified examiners administered the Bayley Scales of Infant Development-II and performed an examination of ocular alignment. Time-oriented logistic regression risk models were created to evaluate the associations of characteristics and exposures with the development of strabismus. Overall, 14% (n = 141) of the children had strabismus at 2 years, and 80% of strabismic children had esotropia. Characteristics associated with strabismus were birth before 26 weeks' gestation, severe fetal growth restriction, and maternal history of aspirin ingestion. Associated postnatal factors included a SNAP-II (Score for Neonatal Acute Physiology) illness severity value ≥ 30, brain ventriculomegaly, type I retinopathy of prematurity, and ventilator-dependent severe bronchopulmonary dysplasia. Strabismus in very preterm populations is associated with a number of antenatal and postnatal antecedents as well as clinical and imaging correlates indicative of brain damage in these children. Routine ophthalmologic assessments in the early years can allow appropriate and timely interventions.

Vision and hearing deficits and associations with parent-reported behavioral and developmental problems in international adoptees

To determine the occurrence of vision and hearing deficits in international adoptees and their associations with emotional, behavioral and cognitive problems. The Minnesota International Adoption Project (MnIAP) was a 556-item survey that was mailed to 2,969 parents who finalized an international adoption in Minnesota (MN) between January 1990 and December 1998 and whose children were between 4 and 18 years-old at the time of the survey. Families returned surveys for 1,906 children (64%); 1,005 had complete data for analyses. The survey included questions about the child's pre-adoption experiences and post-placement medical diagnoses, and the Child Behavior Checklist (CBCL). Multivariate logistic regression assessed associations between hearing and vision problems and problems identified by the CBCL. Information on hearing and vision screening and specific vision and hearing problems was also collected via a telephone survey (HVS) from 96/184 children (52%) seen between June 1999 and December 2000 at the University of Minnesota International Adoption Clinic. In both cohorts, 61% of children had been screened for vision problems and 59% for hearing problems. Among those children screened, vision (MnIAP = 25%, HVS = 31%) and hearing (MnIAP = 12%, HVS = 13%) problems were common. For MnIAP children, such problems were significant independent predictors for T scores >67 for the CBCL social problems and attention subscales and parent-reported, practitioner-diagnosed developmental delay, learning and speech/language problems, and cognitive impairment. Hearing and vision problems are common in international adoptees and screening and correction are available in the immediate post-arrival period. The importance of identifying vision and hearing problems cannot be overstated as they are risk factors for development and behavior problems.

Origins of strabismus and loss of binocular vision

Strabismus is a frequent ocular disorder that develops early in life in humans. As a general rule, it is characterized by a misalignment of the visual axes which most often appears during the critical period of visual development. However other characteristics of strabismus may vary greatly among subjects, for example, being convergent or divergent, horizontal or vertical, with variable angles of deviation. Binocular vision may also vary greatly. Our main goal here is to develop the idea that such “polymorphy” reflects a wide variety in the possible origins of strabismus. We propose that strabismus must be considered as possibly resulting from abnormal genetic and/or acquired factors, anatomical and/or functional abnormalities, in the sensory and/or the motor systems, both peripherally and/or in the brain itself. We shall particularly develop the possible “central” origins of strabismus. Indeed, we are convinced that it is time now to open this “black box” in order to move forward. All of this will be developed on the basis of both presently available data in literature (including most recent data) and our own experience. Both data in biology and medicine will be referred to. Our conclusions will hopefully help ophthalmologists to better understand strabismus and to develop new therapeutic strategies in the future. Presently, physicians eliminate or limit the negative effects of such pathology both on the development of the visual system and visual perception through the use of optical correction and, in some cases, extraocular muscle surgery. To better circumscribe the problem of the origins of strabismus, including at a cerebral level, may improve its management, in particular with respect to binocular vision, through innovating tools by treating the pathology at the source.

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.

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.

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.

Prevalence and course of strabismus through age 6 years in participants of the Early Treatment for Retinopathy of Prematurity randomized trial

PURPOSE

To present strabismus data for children who participated in the Early Treatment for Retinopathy of Prematurity (ETROP) randomized trial.

METHODS

The prevalence of strabismus, categorized as present or absent, was tabulated for all children with history of high-risk prethreshold retinopathy of prematurity (ROP) who participated in the ETROP randomized trial and were examined at 9 months to 6 years of age. Relationships among strabismus and demographic measures, eye characteristics, and neurodevelopmental factors were analyzed.

RESULTS

Among the 342 children evaluated at 6 years, the prevalence of strabismus was 42.2%. Even with favorable acuity scores in both eyes, the prevalence of strabismus was 25.4%, and with favorable structural outcomes in both eyes the prevalence of strabismus was 34.2%. Of children categorized as visually impaired as the result of either ocular or cerebral causes, 80% were strabismic at the 6-year examination. Of 103 study participants who were strabismic at 9 months, 77 (74.8%) remained so at 6 years. Most strabismus was constant at both the 9-month (62.7%) and the 6-year examination (72.3%). After multiple logistic regression analysis, risk factors for strabismus were abnormal fixation behavior in one or both eyes (P < 0.001), history of amblyopia (P < 0.003), unfavorable structural outcome in one or both eyes (P = 0.025), and history of anisometropia (P = 0.04). Strabismus surgery was performed for 53 children. By 6 years, the cumulative prevalence of strabismus was 59.4%.

CONCLUSIONS

Most children with a history of high-risk prethreshold ROP develop strabismus at some time during the first 6 years of life.