Prevalence of amblyopia and other vision disorders in young Newfoundland and Labrador children

Comparing paediatric optometric vision care in Canada over a 14-year period

PURPOSE

In Canada, teaching in paediatric eye care has increased in the past decade both within the optometry curriculum and as continuing education to optometrists. Paediatric vision care guidelines have also been established by North American optometric associations. This study examined whether this exposure was associated with changes in paediatric eye care in Canada over a 14-year period.

METHODS

Canadian optometrists were invited to participate in an anonymous 35-item survey in 2007 and 2021. The surveys sought to investigate optometrist's recommendations for first eye examinations, the number of paediatric patients seen in a typical week and preparedness to provide eye examinations to children. Response frequencies were determined for each survey item.

RESULTS

Across Canada, 133/1000 (13.3%) and 261/~6419 (~4.1%) optometrists responded to the survey in 2007 and 2021, respectively. No significant difference was found in the number of years practicing, days per week in practice and total number of patients seen per week. The modal age optometrists recommended children be seen for their first eye examination changed from 3-4 years in 2007 (53%) to 6-12 months in 2021 (61%). In 2007, 87% of respondents provided eye examinations to children <2 years, increasing to 94% in 2021 (p = 0.02). Despite a reduction in the recommended age between the two survey years, the most frequent age children were seen for their first eye examination was 3-4 years (30% in both surveys) and the most common age seen in a typical week remained unchanged (4-6 years-56% 2007; 66% 2021).

CONCLUSION

Although optometrists' willingness to provide paediatric eye care increased over the past 14 years, the number of children seen in a typical week did not change. Barriers to determine why more children are not being seen at an earlier age need to be investigated.

Continued care and provision of glasses are necessary to improve visual and academic outcomes in children: Experience from a cluster-randomized controlled trial of school-based vision screening

OBJECTIVE

To assess the effectiveness of a kindergarten vision screening program by randomly assigning schools to receive or not receive vision screening, then following up 1.5 years later.

METHODS

Fifty high-needs elementary schools were randomly assigned to participate or not in a vision screening program for children in senior kindergarten (SK; age 5‒6 years). When the children were in Grade 2 (age 6‒7 years), vision screening was conducted at all 50 schools.

RESULTS

Contrary to expectations, screened and non-screened schools did not differ in the prevalence of suspected amblyopia in Grade 2 (8.6% vs. 7.5%, p = 0.10), nor prevalence of other visual problems such as astigmatism (45.1% vs. 47.1%, p = 0.51). There was also no difference between screened and non-screened schools in academic outcomes such as the proportion of children below grade level in reading (33% vs. 29%) or math (44% vs. 38%) (p = 0.86). However, more children were wearing glasses in screened than in non-screened schools (10.2% vs. 7.8%, p = 0.05), and more children reported their glasses as missing or broken (8.3% vs. 4.7%, p = 0.01), suggesting that SK screening had identified successfully those in need of glasses. Examination of individual results revealed that 72% of children diagnosed and treated for amblyopia in SK no longer had amblyopia in Grade 2.

CONCLUSION

The prevalence of amblyopia and other visual problems was not reduced in Grade 2 by our SK vision screening program, perhaps because of poor treatment compliance and high attrition. The results suggest that a single screening intervention is insufficient to reduce visual problems among young children. However, the data from individuals with amblyopia suggest that continuing vision care and access to glasses benefits children, especially children from lower socioeconomic class.

Cost-effectiveness of Universal School- and Community-Based Vision Testing Strategies to Detect Amblyopia in Children in Ontario, Canada

IMPORTANCE

Screening for amblyopia in primary care visits is recommended for young children, yet screening rates are poor. Although the prevalence of amblyopia is low (3%-5%) among young children, universal screening in schools and mandatory optometric examinations may improve vision care, but the cost-effectiveness of these vision testing strategies compared with the standard in primary care is unknown.

OBJECTIVE

To evaluate the relative cost-effectiveness of universal school screening and mandated optometric examinations compared with standard care vision screening in primary care visits in Toronto, Canada, with the aim of detecting and facilitating treatment of amblyopia and amblyopia risk factors from the Ontario government's perspective.

DESIGN, SETTING, AND PARTICIPANTS

An economic evaluation was conducted from July 2019 to May 2021 using a Markov model to compare 15-year costs and quality-adjusted life-years (QALYs) between school screening and optometric examination compared with primary care screening in Toronto, Canada. Parameters were derived from published literature, the Ontario Schedule of Benefits and Fees, and the Kindergarten Vision Testing Program. A hypothetical cohort of 25 000 children aged 3 to 5 years was simulated. It was assumed that children in the cohort had irreversible vision impairment if not diagnosed by an optometrist. In addition, incremental costs and outcomes of 0 were adjusted to favor the reference strategy. Vision testing programs were designed to detect amblyopia and amblyopia risk factors.

MAIN OUTCOMES AND MEASURES

For each strategy, the mean costs per child included the costs of screening, optometric examinations, and treatment. The mean health benefits (QALYs) gained were informed by the presence of vision impairment and the benefits of treatment. Incremental cost-effectiveness ratios were calculated for each alternative strategy relative to the standard primary care screening strategy as the additional cost required to achieve an additional QALY at a willingness-to-pay threshold of $50 000 Canadian dollars (CAD) ($37 690) per QALY gained.

RESULTS

School screening relative to primary care screening yielded cost savings of CAD $84.09 (95% CI, CAD $82.22-$85.95) (US $63.38 [95% CI, US $61.97-$64.78]) per child and an incremental gain of 0.0004 (95% CI, -0.0047 to 0.0055) QALYs per child. Optometric examinations relative to primary care screening yielded cost savings of CAD $74.47 (95% CI, CAD $72.90-$76.03) (US $56.13 [95% CI, $54.95-$57.30]) per child and an incremental gain of 0.0508 (95% CI, 0.0455-0.0561) QALYs per child. At a willingness-to-pay threshold of CAD $50 000 (US $37 690) per QALY gained, school screening and optometric examinations were cost-effective relative to primary care screening in only 20% and 29% of iterations, respectively.

CONCLUSIONS AND RELEVANCE

In this study, because amblyopia prevalence is low among young children and most children in the hypothetical cohort had healthy vision, universal school screening and optometric examinations were not cost-effective relative to primary care screening for detecting amblyopia in young children in Toronto, Canada. The mean added health benefits of school screening and optometric examinations compared with primary care screening did not warrant the resources used.

Description of Audiologic, Developmental, Ophthalmologic, and Neurologic Diagnoses at a Primary Care Clinic for Children in Foster Care

OBJECTIVES

This study aimed to describe the prevalence of medically diagnosed audiologic, developmental, ophthalmologic, and neurologic conditions in a foster care primary care clinic and to identify any associations among these diagnoses and patient characteristics, placement type, and maltreatment type.

METHODS

This study used the electronic medical records for patients (n = 4977), aged 0 to 20 years, with at least 1 visit to an academic-affiliated medical center primary care clinic exclusively serving children in foster care between January 1, 2017, and December 31, 2020. This study was a retrospective chart review. Descriptive statistics were calculated. Bivariate logistic regression analysis was used to determine associations between the outcome variables and each independent variable. Multivariable logistic regression analysis was performed using only significant independent variables from the bivariate analysis.

RESULTS

Overall, 3.5% of children had an audiologic diagnosis, 42% had a developmental diagnosis, 9.0% had an ophthalmologic diagnosis, and 4.5% had a neurologic diagnosis. There were increased odds of developmental delay with child neglect and medical complexity and decreased odds with Hispanic ethnicity, Black race, female sex, obesity, and shelter placement.

CONCLUSION

These findings add to the limited data regarding medically diagnosed audiologic, developmental, ophthalmologic, and neurologic conditions for children in foster care in a primary care setting. A medical home may help children in foster care, who experience many barriers to comprehensive health care, to better identify and address these health conditions. Future studies are needed that examine health outcomes of children in foster care with these health conditions followed in a medical home.

Profile of Amblyopia Among Children Aged from 5 to 15 Years at Hawassa University Comprehensive Specialized Hospital Pediatric Eye Clinic, South Ethiopia, 2020/21

PURPOSE

Functional visual impairment in children is mostly caused by amblyopia. Permanent visual impairment is caused by belated treatment of amblyopia and underlying causes, mostly due to the lack of awareness. Amblyopia affects children's school performance, social interaction and motor skills. This study was aimed to assess the profile of amblyopia among children aged from 5 to 15 years.

METHODS AND MATERIALS

A hospital-based, cross-sectional study was done from November to April 2020/21. Data were collected from all children who came to Hawassa university comprehensive specialized hospital pediatric eye out patient department in the data collection period. Visual acuity measurement, slit lamp examination, cycloplegic refraction, cover test and dilated fundus examination were conducted. Data was entered in Epi-info version 7 and analyzed by Statistical Package for Social Science version 20. Descriptive statistics were conducted to estimate the proportion of amblyopia and its causes.

RESULTS

The proportion of amblyopia was 23.8% (18.3-29.7). Most of the participants were within the age range of 5-9 years (55.4%) and males (51.5%). Anisometropia was the commonest cause of amblyopia (31.25%), followed by meridional (20.83), mixed (16.67%), isometropia (12.50%), sensory deprivation (10.42%) and strabismus (8.33%).

CONCLUSION

The proportion of amblyopia was 23.8%. Anisometropia, meridional, sensory deprivation, isometropia, mixed type and strabismus were the identified causes of amblyopia.

Socioeconomic Status and Vision Care Services in Ontario, Canada: A Population-Based Cohort Study

OBJECTIVE

To test the association of material deprivation and the utilization of vision care services for young children.

STUDY DESIGN

We conducted a population-based, repeated measures cohort study using linked health and administrative datasets. All children born in Ontario in 2010 eligible for provincial health insurance were followed from birth until their seventh birthday. The main exposure was neighborhood-level material deprivation quintile, a proxy for socioeconomic status. The primary outcome was receipt of a comprehensive eye examination (not to include a vision screening) by age 7 years from an eye care professional, or family physician.

RESULTS

Of 128 091 children included, female children represented 48.7% of the cohort, 74.4% lived in major urban areas, and 16.2% lived in families receiving income assistance. Only 65% (n = 82 833) had at least 1 comprehensive eye examination, with the lowest uptake (56.9%; n = 31 911) in the most deprived and the highest uptake (70.5%; n =19 860) in the least deprived quintiles. After adjusting for clinical and demographic variables, children living in the least materially deprived quintile had a higher odds of receiving a comprehensive eye examination (aOR 1.43; 95% CI 1.36, 1.51) compared with children in the most materially deprived areas.

CONCLUSIONS

Uptake of comprehensive eye examinations is poor, especially for children living in the most materially deprived neighborhoods. Strategies to improve uptake and reduce inequities are warranted.

The Global Prevalence of Amblyopia in Children: A Systematic Review and Meta-Analysis

Epidemiological data about the prevalence of amblyopia around the world vary widely among regions and periods. This meta-analysis aimed to determine the global prevalence of amblyopia in children. PubMed, Embase, and the Cochrane Library were searched for prevalence studies published up to 5 November 2021. The outcome was the prevalence of amblyopia, analyzed as pooled estimates with 95% confidence intervals (CI). A total of 97 studies were included, including 4,645,274 children and 7,706 patients with amblyopia. The overall worldwide pooled prevalence of amblyopia was 1.36% (95%CI: 1.27-1.46%). The prevalence of amblyopia was higher in males (1.40%, 95%CI: 1.10-1.70%) than in females (1.24%, 95%CI: 0.94-1.54%) (OR = 0.885, 95%CI: 0.795-0.985, P = 0.025). The results of the meta-regression analysis showed that there were no significant associations between the prevalence of amblyopia and geographical area, publication year, age, sample size, and whether it was carried out in a developed or developing country (all P > 0.05). Begg's test (P = 0.065) and Egger's test (P < 0.001) showed that there was a significant publication bias in the prevalence of amblyopia. In conclusion, amblyopia is a significant vision problem worldwide, and public health strategies of early screening, treatment, and management are important.

Economic evaluations of vision screening to detect amblyopia and refractive errors in children: a systematic review

OBJECTIVE

To synthesize and appraise economic evaluations of vision screening to detect vision impairment in children.

METHODS

Literature searches were conducted on seven electronic databases, grey literature, and websites of agencies conducting health technology assessments. Studies were included if they (1) were full, comparative economic evaluations that used cost-utility, cost-benefit, cost-effectiveness, cost-consequence, or cost-analysis methods; (2) described screening services designed to detect amblyopia, strabismus, or uncorrected refractive errors in children under 6 years of age; and (3) published after 1994. High-quality studies were synthesized descriptively. Currencies were reported in 2019 Canadian dollars. Quality was assessed with the Pediatric Quality Appraisal Questionnaire (PQAQ).

RESULTS

Vision screening services were conducted by paid staff, volunteers, or health care professionals in schools or clinics. Thirteen studies were published from five countries: China (n = 1), United States (n = 4), United Kingdom (n = 1), Canada (n = 1), and Germany (n = 6). Analytical techniques included cost-utility/cost-effectiveness combination (n = 2), cost-effectiveness analysis (n = 7), cost-utility analysis (n = 1), cost-benefit analysis (n = 1), cost-consequence analysis (n = 1), and cost analysis (n = 1). Incremental cost-effectiveness ratios ranged from C$1,056 to C$151,274 per additional case detected/prevented and from C$9,429 to C$30,254,703 per additional QALY gained, depending on the type of screening service and comparator. Six studies were determined to be of high quality.

CONCLUSION

Vision screening to detect amblyopia for young children may be cost-effective compared with no screening if amblyopia reduced quality of life. Studies varied significantly in the type of screening services and comparators used. Methodological limitations were common. Future studies would be aided immensely by prospective studies on the impact of amblyopia on the health-related quality of life of young children and guidelines on the effective conduct of vision screening.

Successes and shortfalls of community Plusoptix photoscreening: results from the iSee study in Southwestern Ontario

OBJECTIVE

The purpose of this work is to provide the final results from a community-wide photoscreening program in Southwestern Ontario for children aged 18 to 72 months, and to estimate the prevalence of amblyogenic risk factors in this population.

STUDY DESIGN

Prospective, multisite photoscreening program.

PARTICIPANTS

5959 children aged 18-72 months were recruited and screened in Southwestern Ontario at 210 locations over a period of 3 years and 4 months.

METHODS

Ophthalmic screening examinations were performed with the Plusoptix S12 photoscreener. The threshold for the referral criteria used was the manufacturer's criteria on receiver operating characteristics 4.

RESULTS

The screening was negative in 5386 children (90.4%), positive in 403 (6.8%), and unreadable in 170 (2.9%); 42% of all screened children were ≤36 months old. The estimated amblyogenic risk factor prevalence of anisometropia was 4.0%, astigmatism was 3.1%, hyperopia was 1.1%, myopia was 0.4%, and strabismus was 0.4%. Of the 403 referred children, 99 (24.5%) completed a formal eye examination based on the responses returned to the study site.

CONCLUSIONS

This is the first Canadian study that provides data on amblyogenic risk factors based on a volunteer-led photoscreening program. Photoscreening is an effective screening tool, particularly for pre-school-aged children; however, the lack of mandatory follow-up to ensure that children receive proper treatment based on cycloplegic refraction reduces the efficacy of screening.

Feasibility of a school-based vision screening program to detect undiagnosed visual problems in kindergarten children in Ontario

BACKGROUND

Visual problems can negatively affect visual development and learning but often go undetected. We assessed the feasibility of scaling up a school-based screening program to identify and treat kindergarten children with visual problems.

METHODS

We conducted a prospective cohort study offering vision screening to junior (JK) and senior kindergarten (SK) children attending 43 schools in 15 Ontario communities. Screening comprised photoscreeners and tests of visual acuity, stereoacuity and eye alignment. Children who failed any test were referred for a comprehensive eye examination, with treatment as needed (e.g., glasses).

RESULTS

Using a passive consent model, 89% of children were screened compared with 62% using an active consent model (p < 0.001). Referral rates to an optometrist varied across schools (mean referral rate for children in JK 53%, range 25%-83%; mean referral rate for children in SK 34%, range 12%-61%). Among 4811 children who were screened, a visual problem was detected in 516 (10.7%), including 164 (3.4%) with amblyopia and 324 (6.7%) with clinically significant refractive errors. For 347 (67.2%) of the children with a visual problem, this was their first eye examination. Rescreening in Year 2 did not lead to detection of additional problems among children who passed screening in Year 1. Regardless of location (child's school or optometrist's office), 1563 (68.9%) of children attended the follow-up optometry examination. Most of the children who were surveyed (291 of 322, 90.4%) indicated that they enjoyed vision screening.

INTERPRETATION

Many children in Ontario with a visual problem were not being identified by the status quo in 2015-2017. We found that in-school vision screening with follow-up eye examinations is an effective strategy for identifying at-risk children and placing them in eye care before grade 1.

Distorted optical input affects human perception

Collinear facilitation, the mechanism for grouping contour elements, is a process involving lateral interactions that improve the detectability of a target by the presence of collinear flankers. It was shown that the development of collinear facilitation is experience dependent and that it may be impaired when the visual input is distorted in one meridian (meridional amblyopia). In oblique astigmatism, the blurring is on the opposite oblique meridian in both eyes, resulting in two conflicting images, which may affect the development of binocular vision. We hypothesized that the collinear facilitation of adults with oblique astigmatism is reminiscent of the abnormal development of the lateral facilitation of meridional amblyopia. We explored the perception of binocular vision and collinear facilitation in cases of both distorted and non-distorted vision. Fully corrected participants that tested for the target contrast detection of Gabor patches and two collinear flankers, presented for 80 ms, were positioned at different orientations (0° (180°), 45°, 90°, and 135°) and for different eyes (monocular, binocular). The results show a significant anisotropy for monocular collinear facilitation between the blured and the clear meridians, being lower in the blurriest meridian than in the clearest meridian, resembling the meridional amblyopia results. Collinear facilitation results in poor binocular summation between the monocular channels. Our results indicate that the perceptual behavior was similar to that of meridional amblyopic subjects having an anisotropy of collinear facilitation between cardinal meridians in oblique astigmatic subjects.

Video games as rich environments to foster brain plasticity

This chapter highlights the key role of two main factors, attentional control and reward processing, in unlocking brain plasticity. We first review the evidence for the role that each of these mechanisms plays in neuroplasticity, and then make the case that tools and technologies that combine these two are likely to result in maximal and broad, generalized benefits. In this context, we review the evidence concerning the impact of video game play on brain plasticity, with an eye toward plasticity-driving methods such as the seamless integration of neurofeedback into the video game platforms.

Guide de pratique clinique fondé sur des données probantes pour l'examen périodique de la vue chez les enfants de 0 à 5 ans au Canada

CONTEXTE

Étant donné que les maladies oculaires avant l'âge de 5 ans sont courantes, une certaine forme de dépistage des troubles de la vision devrait être effectuée chez les enfants avant qu'ils ne fréquentent l'école primaire. Cependant, l'absence de recommandations nationales cohérentes crée de la confusion chez les patients, les professionnels des soins oculovisuels et les gouvernements. MéTHODES: L'objectif de ce document est de fournir des recommandations quant aux types d'examens oculaires à pratiquer chez les enfants en bonne santé de 0 à 5 ans ainsi que sur le moment et la périodicité de tels examens. Une recension des écrits a produit 403 articles. Un comité d'experts multidisciplinaire (composé de deux optométristes, d'un ophtalmologiste effectuant des examens complets de la vue, d'un ophtalmologiste pratiquant en pédiatrie, d'un médecin de famille et d'un pédiatre) a établi de façon indépendante les articles jugés essentiels à la question clinique. Les articles se prêtant à un classement [n = 16] ont ensuite été soumis à une évaluation critique indépendante par un groupe externe, lequel a fourni un profil « GRADE » des articles à utiliser et leur a attribué une cote.

RECOMMANDATIONS

En plus du dépistage de routine effectué par les professionnels de première ligne, un examen complet de la vue mené par un professionnel possédant l'expertise nécessaire à la détection des facteurs de risque de l'amblyopie (comme un ophtalmologiste ou un optométriste) est requis durant la petite enfance. Les conclusions confirment l'importance de la détection précoce de l'amblyopie avant 36 mois et au plus tard 48 mois par le dépistage assorti d'au moins un examen complet de la vue avant l'âge de 5 ans.

CONCLUSIONS

Le dépistage de la vue effectué chez les bébés et les enfants par les fournisseurs de soins de première ligne au cours des consultations de routine et des vaccinations périodiques est un élément essentiel de la détection des maladies oculaires. Toutefois, le potentiel de détection précoce est limité et un examen oculovisuel complet est également recommandé avant que l'enfant n'entre à l'école. Si l'amblyopie, le strabisme ou une autre pathologie oculaire est détecté ou soupçonné, et que le problème dépasse le champ de compétences du professionnel qui examine le patient, celui-ci peut être dirigé vers le spécialiste approprié, ce qui permet d'amorcer le traitement en temps opportun.

Evidence-based clinical practice guidelines for the periodic eye examination in children aged 0-5 years in Canada

BACKGROUND

As eye disease before age 5 years is common, some form of vision screening should be performed on children before attending primary school. However, the lack of consistent national recommendations creates confusion for patients, eye care professionals, and governments alike.

METHODS

The objective of this document is to provide guidance on the recommended timing, intervals, and types of ocular assessments for healthy children aged 0-5 years. A literature search yielded 403 articles. A multidisciplinary expert committee (comprising 2 optometrists, a comprehensive ophthalmologist, a pediatric ophthalmologist, a family physician, and a pediatrician) independently determined those articles deemed to be key to the clinical question. Articles that were gradable (n = 16) were then submitted for independent critical appraisal by an external review group, which provided a Grading of Recommendations Assessment, Development and Evaluation profile of the reviewed articles to use for assigning a grade of evidence.

RECOMMENDATIONS

In addition to routine screening by a primary health care professional, a comprehensive eye examination by an individual with the expertise to detect risk factors for amblyopia-such as an ophthalmologist or optometrist-is required in early childhood. The findings support the importance of early detection of amblyopia before 36 months and no later than 48 months of age via screening with at least 1 comprehensive eye examination before age 5 years.

CONCLUSIONS

Vision screening performed by primary health care providers during routine well-baby/child visits and scheduled vaccinations is an essential part of the detection of ocular disease. However, this early detection potential is limited, and a full oculovisual assessment is also recommended before the child entering the school system. If amblyopia, strabismus, or other eye pathology is detected or suspected that is beyond the scope of the eye care professional examining the patient, a referral to the appropriate specialist can be made, allowing treatment to be initiated in a timely fashion.

Choosing appropriate tools and referral criteria for vision screening of children aged 4-5 years in Canada: a quantitative analysis

OBJECTIVES

To assess the diagnostic accuracy of five vision screening tools used in a school setting using sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

DESIGN

We compared the results of the five best evidence-based screening tools available in 2014 to the results of a comprehensive eye exam with cycloplegic refraction by a licenced optometrist. Screening included Cambridge Crowded Acuity Cards, Plusoptix S12 and Spot photoscreeners, Preschool Randot Stereoacuity Test and the Pediatric Vision Scanner (PVS). Referral criteria followed AAPOS (2013) guidelines and published norms.

SETTING

A large school in Toronto, Canada, with 25 split classrooms of junior kindergarten (JK: 4 year olds) and senior kindergarten (SK: 5 year olds) children.

PARTICIPANTS

Over 2 years, 1132 eligible children were enrolled at the school. After obtaining parental consent, 832 children were screened. Subsequently, 709 children had complete screening and optometry exam data.

MAIN OUTCOME MEASURES

The presence/absence of a visual problem based on optometrist's assessment: amblyopia, amblyopia risk factors (reduced stereoacuity, strabismus and clinically significant refractive errors) and any other ocular problem (eg, nystagmus).

RESULTS

Overall, 26.5% of the screened children had a visual problem, including 5.9% with amblyopia. Using all five tools, screening sensitivity=84% (95% CI 78 to 89), specificity=49% (95% CI 44 to 53), PPV=37% (95% CI 33 to 42), and NPV=90% (95% CI 86 to 93). The odds of having a correct screening result in SK (mean age=68.2 months) was 1.5 times those in JK (mean age=55.6 months; 95% CI 1.1 to 2.1), with sensitivity improved to 89% (95% CI 80 to 96) and specificity improved to 57% (95% CI 50 to 64) among SK children.

CONCLUSIONS

A school-based screening programme correctly identified 84% of those kindergarten children who were found to have a visual problem by a cyclopleged optometry exam. Additional analyses revealed how accuracy varies with different combinations of screening tools and referral criteria.

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.

Comparative study of visual dysfunctions in 6-10-year-old very preterm- and full-term-born children

PURPOSE

To compare visual dysfunction between very preterm-born (VPB) children with no retinopathy of prematurity (no-ROP) at 6-10 years of age and age- and sex-matched full-term-born controls.

METHODS

This is an observational, prospective study that included 30 children, 6-10 years of age, born ≤ 32 weeks of gestation, with no-ROP, and 30 age- and sex-matched full-term-born controls, conducted from January 2015 until August 2015. All children underwent complete ophthalmic evaluation. Main outcome measures include visual functions (best corrected visual acuity (BCVA), color vision, and stereoacuity), ocular alignment, refractive errors, and the presence of amblyopia and nystagmus.

RESULTS

Mean BCVA of the right eyes was 0.04 ± 0.08 logMAR for VPB children and 0.02 ± 0.05 logMAR for the full-term children (P = 0.075). Mean BCVA for the left eyes was 0.07 ± 0.09 logMAR for VPB children and 0.02 ± 0.05 logMAR for the full-term children (P = 0.014). Refractive errors were slightly higher though not statistically significant in VPB children compared to full-term children (P = 0.125). The incidence of myopia and hypermetropia was 16.7 and 40%, respectively, in VPB children and 10 and 23.3%, respectively, in full-term children. Anisometropia found only in VPB children with an incidence of 16.7%. Amblyopia found in 10% of VPB children compared to 3.3% in full-term children. Strabismus was found equally in 10% of each group.

CONCLUSION

VPB children with no-ROP are at an increased risk of developing decreased BCVA at least in one eye and anisometropia compared to age-matched full-term controls.

The visual status of adolescents in Riyadh, Saudi Arabia: a population study

Purpose

The visual status of adolescents in Saudi Arabia (SA) has not been well reported. To date, the prevalence and types of refractive errors (REs), amblyopia, strabismus, and correctable visual impairments have not been quantified. The aim of the study was to investigate the visual status in adolescents in Riyadh, SA.

Methods

This study was based on a population cross-sectional and random cluster design. After design and the sample calculations, 1,007 participants, 12–20 years of age, were screened during the study. Nine participants were excluded due to ocular disorders. The participants were assessed for REs, distance visual acuity logarithm of the minimum angle of resolution, contrast sensitivity, stereoacuity, pinhole test findings, and cover–uncover test findings.

Results

The results showed that 55.5% of the participants had some form of REs, while correctable visual impairment was found in one-fifth of the screened participants. Myopia was the dominant type (53.3%, ranged from −0.50 DS to −14.00 DS), whereas hyperopia was found in 2.2% (+2.00 DS to +5.50 DS) and astigmatism was present in 15% (−0.75 DC to −5.25 DC). Only 43% of the participants had corrected REs; however, the noncompliance for spectacle use was 20.25%.

Conclusion

This study was the first attempt to investigate the visual status in adolescents in SA. It provided estimations of the REs, amblyopia, and strabismus. The high prevalence of REs emphasizes the need to identify the best proactive strategies to detect and manage REs to reduce the incidence of visual impairment in SA. Increasing awareness about eye health and employing efficient screening programs could help to address the need for REs corrections.

Paediatric vision screening in the primary care setting in Ontario

Objectives

Early intervention is critical to prevent treatable causes of vision loss in children. The objectives of the current study are: (1) to assess how well primary care physicians in Ontario follow the vision screening guidelines for children as recommended by the Canadian Paediatric Society and the Rourke Baby Record and (2) to identify barriers to vision screening in the primary care setting.

Design

Cross-sectional survey.

Methods

A 19-question survey was mailed out to 1000 randomly selected family physicians (family MDs), 1000 general practitioners (GPs) and 1000 paediatricians in Ontario as listed in the 2013 Canadian Medical Directory.

Results

A total of 719 completed surveys were included in the analysis (449 from family MDs/GPs and 270 from paediatricians). Vision screening was reported to be performed by 65% of family MDs/GPs and 52% of general paediatricians at every well child visit. While red reflex was reported to be checked by 94% of all physicians in children under 3, it was only performed by 25% of respondents for children over 3. Thirty seven percent of all physicians reported never performing a visual acuity test in any age group. When asked about the obstacles preventing them from performing vision screening, lack of training (family MDs/GPs: 50%, paediatricians: 42%), time constraints (family MDs/GPs: 42%; paediatricians: 40%) and inadequate reimbursement (family MDs/GPs: 17%; paediatricians: 15%) were the most commonly cited reasons.

Conclusions

Strategies to improve vision screening are necessary given that early intervention is crucial to prevent treatable causes of vision loss in children.

Protocol for a scoping review to map evidence from randomised controlled trials on paediatric eye disease to disease burden

BACKGROUND

Currently, about 2 per 1000 children in the industrialised world are severely visually impaired or blind (SVI/BL) due to diverse uncommon conditions that are usually present from early infancy. The impact of SVI/BL is lifelong and life-changing. Thus, children are a priority in the WHO-led global initiative against avoidable blindness. The aim of this scoping review is to assess the current evidence base on interventions to prevent or treat the major causes of childhood SVI/BL, specifically the degree of alignment between robust interventional research (RCTs) and the burden (relative frequency) of the key causative disorders, identifying gaps in the evidence base for tackling childhood blindness.

METHODS/DESIGN

We will perform a scoping review of the published literature of randomised controlled trials (RCTs) for clinical interventions that prevent or treat eye and vision diseases in children (<18 years old). Major electronic databases MEDLINE (PUBMED), EMBASE and the Cochrane CENTRAL will be searched to identify published trials using a comprehensive paediatric specific strategy informed by previous searches. The outcome of our study, randomised clinical trial activity, will be measured by the total number of RCTs and total paediatric participants randomised. The quantity and distribution of activity across diseases will be classified in the broad categories of anatomical site affected (per WHO taxonomy). The degree of alignment between paediatric trial activity and burden of SVI/BL disease (relative proportion) will be measured using a test of association (Spearman's correlation coefficient).

DISCUSSION

Despite the global public health importance of childhood blindness, there has been no assessment of the completeness of the evidence base regarding clinical interventions to prevent or treat the causative disorders. This scoping review will measure the degree of alignment between the published evidence and the burden of disease to identify gaps in current knowledge and consider the underlying reasons, informing clinicians, policy makers and funders about research priorities.

A dichoptic custom-made action video game as a treatment for adult amblyopia

Previous studies have employed different experimental approaches to enhance visual function in adults with amblyopia including perceptual learning, videogame play, and dichoptic training. Here, we evaluated the efficacy of a novel dichoptic action videogame combining all three approaches. This experimental intervention was compared to a conventional, yet unstudied method of supervised occlusion while watching movies. Adults with unilateral amblyopia were assigned to either play the dichoptic action game (n=23; 'game' group), or to watch movies monocularly while the fellow eye was patched (n=15; 'movies' group) for a total of 40hours. Following training, visual acuity (VA) improved on average by ≈0.14logMAR (≈28%) in the game group, with improvements noted in both anisometropic and strabismic patients. This improvement is similar to that obtained following perceptual learning, video game play or dichoptic training. Surprisingly, patients with anisometropic amblyopia in the movies group showed similar improvement, revealing a greater impact of supervised occlusion in adults than typically thought. Stereoacuity, reading speed, and contrast sensitivity improved more for game group participants compared with movies group participants. Most improvements were largely retained following a 2-month no-contact period. This novel video game, which combines action gaming, perceptual learning and dichoptic presentation, results in VA improvements equivalent to those previously documented with each of these techniques alone. Our game intervention led to greater improvement than control training in a variety of visual functions, thus suggesting that this approach has promise for the treatment of adult amblyopia.

Prevalence of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia

PURPOSE

To determine the prevalence and causes of amblyopia in primary school children in Qassim province, Kingdom of Saudi Arabia (KSA).

MATERIALS AND METHODS

In this cross sectional study, 5176 children, aged 6 to 13 years (mean - 9.53 ± 1.88 years) were evaluated. There were 2573 (49.71%) males and 2603 (50.29%) females. Distance visual acuity (V/A) was tested monocularly using a logMAR chart with and without correction. Cycloplegic refraction was performed in children with reduced vision. To determine the etiology of amblyopia, children were enrolled if there was a difference in V/A of two or more lines between eyes or an absolute reduction in acuity <20/30 in either eye, that could not be corrected by refraction. P ≤ 0.05 was considered statistically significant.

RESULTS

There 202 out of 5176 (3.90%) with ambylopia. There are 98 (1.88%) amblyopic females. There was no statistical difference in gender for amblyopes (P > 0.05). The prevalence of amblyopia was statistically significant higher in the older age group (10-13 year) compared to younger age group (6 to 9 years) (P < 0.05). Unilateral amblyopia (3.24%) was more frequent than bilateral amblyopia (0.66%). The most frequent causes of amblyopia were refractive error (94.56%), of which anisometropic amblyopia was present in 77.72%, isoametropic amblyopia in 16.84% and strabismus in 5.44%.

CONCLUSION

The prevalence of amblyopia in Qassim province, KSA, is 3.9% which is similar or higher than other published studies on amblyopia. Anisometropic refractive errors are the most common underlying cause for this population. We recommend implementation of visual screening programs for children with appropriate clinical and social settings for early detection and proper management of amblyopia.

Ten-Year Results of Home Vision-Screening Test in Children Aged 3-6 Years in Seoul, Korea

PURPOSE

To characterize the prevalence of refractive error and amblyopia among three- to six-year-old children during the period from 2002 to 2011.

METHODS

About 31,400 children annually (from 16,592 to 40,816) during the period from 2002 to 2011 were enrolled. The preschool vision screening was performed by the Korean Foundation for the Prevention of Blindness (KFPB) annually during a period that extended from March to September. We reviewed the KFPB annual report about the home vision-screening test as performed during the period from 2002 to 2011. Changes in the prevalence and types of refractive error, strabismus, and amblyopia that manifested throughout this period were analyzed.

RESULTS

The prevalence of refractive errors ranged from 1.10% in 2002 to 0.42% in 2011. The prevalence of hyperopia and myopia changed little throughout the 10-year study period. Myopia and hyperopia were equally common among the population examined (χ(2)-test, p = 0.137). The prevalence of anisometropia decreased over time. The annual prevalence of amblyopia ranged from 0.39% to 0.06%, while the overall prevalence of amblyopia dropped from 0.25% in 2002 to 0.06% in 2011. The prevalence of strabismus was highest in 2006 (0.30%) and had decreased by 0.06% in 2011. The type of strabismus showed no significant difference over time (χ(2)-test, p = 0.579).

CONCLUSIONS

The prevalence of amblyopia, refractive error, anisometropia, and strabismus was lower in 2011 than in early 2000. The prevalence of hyperopia and myopia as well as strabismus remained similar throughout the study period.

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.

Prevalence of amblyopia in children undergoing nasolacrimal duct irrigation and probing

Purpose:

To investigate ambylopia and amblyopia risk factors of children who underwent nasolacrimal duct (NLD) irrigation and probing for congenital nasolacrimal duct obstruction (CNLDO).

Materials and Methods:

The medical records of patients who had undergone NLD irrigation and probing for CNLDO at an age of 3 years or younger were reviewed, and 51 of the patients were recalled between October 1 and December 31, 2011 for a detailed ophthalmic examination to determinate amblyopia or amblyopia risk factors. Amblyopia was accepted as difference in visual acuity of two or more Snellen lines between the two eyes or visual acuity of 20/30 or worse in either eye.

Results:

The median age of the 51 patients to whom NLD irrigation and probing were attempted for CNLDO was 23 months. CNLDO affected a total of 70 eyes. All patients were reviewed for best-corrected visual acuity, refractive errors, and strabismus at a median age of 70.5 months (range 31-95 months). Amblyopia or amblyopia risk factors were identified in 14 patients (27.5%). One child (7.15%) had only strabismus, six children (42.8%) had only amblyogenic refractive errors, two (14.3%) had a combination of two, one child (7.15%) had a family history for amblyopia, but four children (28.6%) had no amblyopia risk factors but had amblyopia.

Conclusion:

Amblyogenic risk factors are found higher in patients with CNLDO and patients undergoing NLD irrigation and probing in comparison to normal population. Therefore, we recommend these children to routinely undergo cycloplegic refractions and full ophthalmic examinations.

Uncorrected refractive errors

Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC), were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR) Development, Service Development and Social Entrepreneurship.

Children with fetal alcohol spectrum disorder show an amblyopia-like pattern of vision deficit

AIM

The aim of the study was to assess and characterize visual functioning in children with fetal alcohol spectrum disorder (FASD) using a broader and more inclusive range of measures than has been reported previously.

METHOD

Standard tests of visual functioning were used to assess 21 children (11 females, 10 males) with FASD and 21 sex- and age-matched comparison children without FASD. The age of the children ranged from 6 years 9 months to 11 years 11 months (mean 9y 6mo). Children were tested individually under standardized conditions for visual acuity, stereoacuity, contrast sensitivity, ocular alignment/motility, color vision, and refractive error.

RESULTS

Compared with non-affected children, children with FASD showed deficits in visual acuity, contrast sensitivity, and stereoacuity. Ocular alignment/motility, refractive error, and color vision measures were normal. Among children with FASD, 62% met the criteria for referral to an eye specialist, compared with 20% of children without FASD.

INTERPRETATION

Children with FASD showed an amblyopia-like pattern of vision deficit in the absence of the optical and oculomotor disruptions of early experience that usually precede this condition. Evidence from animal models suggests that the deficits in spatial vision may be due to alterations in the functional architecture of the neocortex that occurs following prenatal alcohol exposure.

Childhood vision screening in Canada: public health evidence and practice

OBJECTIVES

Best practice guidelines recommend vision testing in children 3 to 5 years of age for the prevention of amblyopia; however, universal vision screening is controversial. In Canada, amblyopia screening can be the responsibility of physicians, optometrists, and/or Public Health. We review the evidence underlying preschool vision screening for amblyopia using an Evidence-based Public Health (EBPH) approach, and consider implications for the Public Health provision of universal screening programs for amblyopia in Canadian jurisdictions in light of present practices.

METHODS

We searched the literature to address each major screening criterion (disease, test, treatment, program requirements) necessary to support preschool vision screening for amblyopia. We also reappraised papers cited in two systematic reviews related to the impact of vision screening. The Chief Medical Officer of Health of each province/territory was sent a short survey asking whether there currently was a Public Health preschool vision screening program in place and if so, for specifics about the program.

RESULTS

An EBPH approach to the literature with respect to the criteria for screening and available intervention studies support amblyopia screening by Public Health. There is a public health divide in amblyopia screening practice in Canada; while some provinces maintain organized programs, others have chosen to delegate the task to other professionals, without a concurrent surveillance function to monitor disparities in uptake.

CONCLUSIONS

Amblyopia deserves attention from Public Health. Efforts should be made to maintain existing programs, and provinces without organized screening programs should reconsider their role in the prevention of inequities with regard to preventable blindness in Canadian children.

Video-game play induces plasticity in the visual system of adults with amblyopia

A pilot study suggests that playing video games may enhance a range of spatial vision functions in adults with amblyopia.

Abnormal visual experience during a sensitive period of development disrupts neuronal circuitry in the visual cortex and results in abnormal spatial vision or amblyopia. Here we examined whether playing video games can induce plasticity in the visual system of adults with amblyopia. Specifically 20 adults with amblyopia (age 15–61 y; visual acuity: 20/25–20/480, with no manifest ocular disease or nystagmus) were recruited and allocated into three intervention groups: action videogame group (n = 10), non-action videogame group (n = 3), and crossover control group (n = 7). Our experiments show that playing video games (both action and non-action games) for a short period of time (40–80 h, 2 h/d) using the amblyopic eye results in a substantial improvement in a wide range of fundamental visual functions, from low-level to high-level, including visual acuity (33%), positional acuity (16%), spatial attention (37%), and stereopsis (54%). Using a cross-over experimental design (first 20 h: occlusion therapy, and the next 40 h: videogame therapy), we can conclude that the improvement cannot be explained simply by eye patching alone. We quantified the limits and the time course of visual plasticity induced by video-game experience. The recovery in visual acuity that we observed is at least 5-fold faster than would be expected from occlusion therapy in childhood amblyopia. We used positional noise and modelling to reveal the neural mechanisms underlying the visual improvements in terms of decreased spatial distortion (7%) and increased processing efficiency (33%). Our study had several limitations: small sample size, lack of randomization, and differences in numbers between groups. A large-scale randomized clinical study is needed to confirm the therapeutic value of video-game treatment in clinical situations. Nonetheless, taken as a pilot study, this work suggests that video-game play may provide important principles for treating amblyopia, and perhaps other cortical dysfunctions.

Early abnormal visual experience disrupts neuronal circuitry in the brain and results in reduced vision, known as amblyopia or “lazy eye,” the most frequent cause of permanent visual loss in childhood. It is generally believed that adult amblyopia is irreversible beyond the sensitive period of brain development during childhood. In this study, we examine whether playing video games, both action and non-action, has an effect on the vision of adults with amblyopia. We assessed visual acuity (visual resolution), positional acuity (the ability to localize object's relative position), spatial attention (the ability to direct visual attention to various locations in the visual field), and stereoacuity (stereo-vision / 3-D depth perception) in a small group of teenagers and adults. We found that they tended to recover vision much faster than we would have expected from the results of conventional occlusion therapy in childhood amblyopia. Additional experiments and modelling suggest that the improvements are a result of decreasing spatial distortion and increasing information processing efficiency in the amblyopic brain. Thus, video games may include essential elements for active vision training to boost visual performance. Most importantly, our findings suggest that video-game play may provide important principles for treating amblyopia, a suggestion that we are pursuing with larger scale clinical trials.

Assessment of a modification of Brückner's test as a screening modality for anisometropia and strabismus

BACKGROUND

Current amblyopia screening methods are not cost effective.

AIM

To evaluate the diagnostic capability of a modified Brückner test (MBT) for amblyopiogenic risk factors.

MATERIALS AND METHODS

We applied the MBT using the streak retinoscope to identify anisometropia and strabismus by noting an inter-ocular difference in movement and glow, from children who failed 6/9 Snellen on community vision screening, followed by comprehensive eye examination. STATISITICS: Data were analyzed by 2 × 2 tables for diagnostic test parameters (95% CI).

RESULTS

From 7998 children vision-screened, 392 failed 6/9 VA and were referred. Since 34 failed to reach the centers, and 15 were excluded due to poor/ no glow, data from 343 was analyzed. The prevalence of anisometropia of 0.5D was 17%, of 1D was 11% and of strabismus 5%. For the MBT the accuracy was ≥ 90% (95%CI 89% to 97%) over the three outcomes. The sensitivity, specificity, NPV and +LR for anisometropia of 0.5D were: 0.57 (0.48, 0.64), 0.97 (0.95, 0.98), 0.92 (0.90, 0.93) and 18 (9.7, 35); for 1D: 0.74(0.60, 0.82), 0.95 (0.94, 0.97), 0.97 (0.95, 0.98) and 16 (9.3, 28); and for strabismus: 0.5 (0.32, 0.66), 0.98 (0.97, 0.98), 0.97 (0.96, 0.98) and 20 (9.1, 42).

CONCLUSION

Our data suggests that the MBT is highly accurate and useful for ruling in anisometropia and strabismus in children who fail 6/9 Snellen. The MBT needs further validation, both by different care givers and on differing populations. It offers an affordable, portable, and clinically useful tool to detect anisometropia and strabismus. We suggest that performing an MBT prior to uniocular retinosocpy should be a routine practice.

Visual development in infants: physiological and pathological mechanisms

PURPOSE OF REVIEW

This review summarizes current knowledge on ocular conditions related to abnormal visual development in infants, including prevalence, risk factors, causes, and mechanisms involved. We discuss the role of eyeball growth with pathologic mechanism of visual deprivation and development of amblyopia in infants, particular developmental issues in preterm neonates, methods of visual assessment and screening, diagnosis, treatment, and nutritional issues.

RECENT FINDINGS

Visual development is incomplete at birth, particularly in premature infants; maturation of the visual system--including neurological and ocular components--is influenced by many factors including prenatal and postnatal nutrition and postnatal visual stimulation. In early life, particularly during sensitive periods of development, abnormal visual input, for example caused by visual deprivation mechanism, amblyopia, or ocular misalignment, leads to abnormalities in visual development, including abnormal eyeball growth and neurological changes. Untreated anomalies or abnormal visual development can result in long-term or even permanent visual impairment. Nutrition plays a key role in visual development: infant formulas containing nutrients essential for normal visual development (specifically omega-3 fatty acid docosahexaenoic acid and omega-6 fatty acid arachidonic acid) may protect nonbreast-fed infants against visual development abnormalities.

SUMMARY

Problems related to visual anomalies are common among young children, particularly in preterm neonates. Screening to enable early diagnosis and correction of visual deficiency is important as abnormal visual input can lead to abnormalities in visual development, which can become permanent visual impairment if left untreated. Optimized nutrition can help to reduce the risk of abnormal visual development and prevent long-term or permanent visual deficits.

The prevalence of anisometropia, amblyopia and strabismus in schoolchildren of Shiraz, Iran

PURPOSE

To determine the prevalence of amblyopia, anisometropia, and strabismus in schoolchildren of Shiraz, Iran.

MATERIALS AND METHODS

A random cluster sampling was used in a cross-sectional study on schoolchildren in Shiraz. Cycloplegic refraction was performed in elementary and middle school children and high school students had non-cylcoplegic refraction. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were recorded for each participant. Anisometropia was defined as spherical equivalent (SE) refraction difference 1.00D or more between two eyes. Amblyopia was distinguished as a reduction of BCVA to 20/30 or less in one eye or 2-line interocular optotype acuity differences in the absence of pathological causes. Cover test was performed for investigating of strabismus.

RESULTS

Mean age of 2638 schoolchildren was 12.5 years (response rate = 86.06%). Prevalence of anisometropia was 2.31% (95% confidence interval [CI], 1.45 to 3.16). 2.29% of schoolchildren (95% CI, 1.46 to 3.14) were amblyopic. The prevalence of amblyopia in boys and girls was 2.32% and 2.26%, respectively (p = 0.945). Anisometropic amblyopia was found in 58.1% of the amblyopic subjects. The strabismus prevalence was 2.02% (95% CI, 1.18 to 2.85). The prevalence of exotropia and esotropia was 1.30% and 0.59%, respectively.

CONCLUSIONS

Results of this study showed that the prevalence of anisometropia, amblyopia, and strabismus are in the mid range. The etiology of amblyopia was often refractive, mostly astigmatic, and non-strabismic. Exotropia prevalence increased with age and was the most common strabismus type.

A review of the evidence on the effectiveness of children's vision screening

Screening programmes enable health conditions to be identified so that effective interventions can be offered. The aim of this review was to determine: (1) the effectiveness of children's vision screening programmes; (2) at what age children should attend vision screening; and (3) what form vision screening programmes should take to be most effective. A literature review on the effectiveness of vision screening programmes in children aged 0-16 years was undertaken. Eligible studies/reviews were identified through clinical databases, hand searches and consultation with expert reviewers. The methodological quality of papers was rated using National Health and Medical Research Council (NHMRC) guidelines. Screening of children 18 months to 5 years, and subsequent early treatment, led to improved visual outcomes. The benefit was primarily through treatment of amblyopia, with improved visual acuity of the amblyopic eye. However, the overall quality of the evidence was low. The implication of improved visual acuity (e.g. any potential impact on quality of life) was not considered. Without consideration of 'quality of life' values, such as loss of vision in one eye or possibility of future bilateral vision loss, the cost-effectiveness of screening is questionable. Screening and treating children with uncorrected refractive error can improve educational outcomes. Evidence suggested that screening occur in the preschool years. Orthoptists were favoured as screening personnel; however, nurses could achieve high sensitivity and specificity with appropriate training. Further research is required to assess the effectiveness of neonatal screening. Most studies suggested that children's vision screening was beneficial, although programme components varied widely (e.g. tests used, screening personnel and age at testing). Research is required to clearly define any improvements to quality of life and any related economic benefits resulting from childhood vision screening. The evidence could be used to guide optimization of existing programmes.

Ethnic differences in the prevalence of myopia and ocular biometry in 10- and 11-year-old children: the Child Heart and Health Study in England (CHASE)

PURPOSE

Ethnic differences in childhood prevalence of myopia have not been well characterized in the United Kingdom. In this study, ethnic differences in refractive status and ocular biometry were examined in a multiethnic sample of British children.

METHODS

This was a cross-sectional study of 10- and 11-year-old school children of South Asian, black African Caribbean, and white European ethnic origin. Vision, open-field autorefraction (without cycloplegia), and ocular biometry were measured in each eye. Myopia was defined as spherical equivalent refraction of -0.50 D with unaided vision of 20/30 or worse (in one or both eyes). Ethnic differences in the prevalence of myopia were examined by using logistic regression, and multiple linear regression was used for ethnic differences in ocular biometry. All models were adjusted for age, sex, and clustering within school.

RESULTS

Data were available for 1179 children. The prevalence of myopia was 25.2%, 10.0%, and 3.4%, respectively, in the South Asian, black African Caribbean, and white European children. Adjusted odds ratios (ORs) of myopia compared with the white European children were 8.9 (95% confidence interval [CI] 4.0 to 19.4) in the South Asian and 3.2 (95% CI, 1.4 to 7.2) in black African Caribbean children. Ethnic differences in the prevalence of myopia were largely accounted for by ethnic differences in axial length. The South Asian and black African Caribbean children had longer axial lengths (0.44 mm; 95% CI, 0.30 to 0.57 mm and 0.30 mm; 95% CI, 0.16 to 0.44 mm, respectively).

CONCLUSIONS

Among British children exposed to the same schooling environment, the South Asians had the highest prevalence of myopia, followed by the black African Caribbeans compared with the white Europeans. A quarter of British South Asian children were myopic, which is strongly related to increased axial length.

Prevalence of amblyopia and strabismus in young singaporean chinese children

PURPOSE. To determine the prevalence of amblyopia and strabismus in young Singaporean Chinese children. METHODS. Enrolled in the study were 3009 Singaporean children, aged 6 to 72 months. All underwent complete eye examinations and cycloplegic refraction. Visual acuity (VA) was measured with a logMAR chart when possible and the Sheridan-Gardner test when not. Strabismus was defined as any manifest tropia. Unilateral amblyopia was defined as a 2-line difference between eyes with VA < 20/30 in the worse eye and with coexisting anisometropia (> or =1.00 D for hyperopia, > or =3.00 D for myopia, and > or =1.50 D for astigmatism), strabismus, or past or present visual axis obstruction. Bilateral amblyopia was defined as VA in both eyes <20/40 (in children 48-72 months) and <20/50 (<48 months), with coexisting hyperopia > or =4.00 D, myopia < or = -6.00 D, and astigmatism > or =2.50 D, or past or present visual axis obstruction. RESULTS. The amblyopia prevalence in children aged 30 to 72 months was 1.19% (95% confidence interval [CI], 0.73-1.83) with no age (P = 0.37) or sex (P = 0.22) differences. Unilateral amblyopia (0.83%) was twice as frequent as bilateral amblyopia (0.36%). The most frequent causes of amblyopia were refractive error (85%) and strabismus (15%); anisometropic astigmatism >1.50 D (42%) and isometropic astigmatism >2.50 D (29%) were frequent refractive errors. The prevalence of strabismus in children aged 6 to 72 months was 0.80% (95% CI, 0.51-1.19), with no sex (P = 0.52) or age (P = 0.08) effects. The exotropia-esotropia ratio was 7:1, with most exotropia being intermittent (63%). Of children with amblyopia, 15.0% had strabismus, whereas 12.5% of children with strabismus had amblyopia. CONCLUSIONS. The prevalence of amblyopia was similar, whereas the prevalence of strabismus was lower than in other populations.

Ocular growth and morbidity in preterm children without retinopathy of prematurity

PURPOSE

To investigate ocular growth and morbidity in both preschool and school-aged children born prematurely without retinopathy of prematurity (ROP).

METHODS

This population-based study was carried out in 26 children, 5-7 years of age, born prematurely without ROP. All children underwent a full ocular examination, including corrected visual acuity, cycloplegic refractive errors, color vision, ocular alignment, and anterior and posterior segment examinations. Anterior chamber depth, lens thickness, vitreous length, and total axial length were measured.

RESULTS

There was no correlation between the degree of prematurity and visual acuity or refractive state. Two (7.7%) subjects had strabismus, two (7.7%) had amblyopia, and four (15%) had anisometropia. Total axial length was significantly correlated with both gestational age at birth (r=0.822, P<0.001) and birth weight (r=0.569, P=0.003). Similarly, vitreous length was also significantly correlated with gestational age (r=0.744, P<0.001) and birth weight (r=0.553, P=0.004).

CONCLUSIONS

This study showed that although the globe gets longer as gestational age approaches term and as birth weight increases, this condition does not result in any significant refractive error. According to the literature, the prevalence of strabismus, amblyopia, and anisometropia may be higher in preterm children without ROP than in age-matched, normally delivered children.

The NEI VFQ-25 vision-related quality of life and prevalence of eye disease in a working population

PURPOSE

To apply the National Eye Institute 25-item Visual Function Questionnaire (VFQ-25) to a large group of working people and assess the prevalence of eye disease.

METHODS

In this cross-sectional study, 619 employees of two large enterprises in Munich, Germany, underwent complete ophthalmological examination and assessment of the vision-related quality of life by the Visual Function Questionnaire (VFQ-25, German translation). Statistical analysis including binary logistic regression to investigate predictive factors of eye disease was performed.

RESULTS

The age of the participants was mean 42 years. In 108 patients (17.4%) an ophthalmological disease was present. The mean VFQ-25 composite score was 91.1, and was not significantly different between the group with (88.8) or without (91.6) eye disease. A clear age dependency of VFQ-25 scores was seen. Most reduced subscales in eye disease were ocular pain and role difficulties. Patients with amblyopia did not show any reduction in visual quality of life (composite score 93.4). In the binary regression model, considering the clinical parameters intraocular pressure (IOP), cup/disc ratio (CDR), and spherical equivalent, as well as some of the VFQ-25 subscales, the presence of eye disease could be predicted with a high specificity of 98.7% but a low sensitivity of 12.2%.

CONCLUSIONS

Normal values of the VFQ-25 performance in a large number of working people in Germany are given with a clear age dependency. A combination of refraction, IOP, CDR and some VFQ subscales could reasonably well exclude any prevalent eye disease. For screening purposes, neither variable nor combination was sufficiently sensitive and specific.

Field testing of the plusoptiX S04 photoscreener

PURPOSE

To evaluate the diagnostic accuracy of the plusoptiX S04 digital photoscreener in a school screening program.

METHODS

Between 2006 and 2007, 1343 information pamphlets/consent forms were sent to all junior kindergarten students in a local school district. Assistants from a local public health unit photographed 307 children. Of these, 271 children received an independent ophthalmic examination by a physician. Photographic results were compared with the those of the ophthalmic examination. Amblyopia risk factors were defined as anisometropia >1 D (sphere or cylinder), astigmatism >1.25 D, myopia >3 D, hyperopia >3.5 D, any manifest strabismus, and any media opacity.

RESULTS

Photographic and examination results agreed in 94% of cases. Sensitivity in detecting amblyopia risk factors was 83%; specificity was 95%. The positive and negative predictive values were 73% and 97%, respectively. The untestable/unusable rate was 1%.

CONCLUSIONS

These results compare favorably with a previously reported (but no longer available) digital photoscreening camera and are superior to results obtained with other off-axis photoscreening devices that require human interpretation. On the basis of these results, in a real-world screening program, the camera would falsely refer 4% of those screened and would fail to correctly refer 2%. The accuracy of the plusoptiX S04 camera in detecting amblyopia risk factors appears sufficiently high to consider its further deployment in a widespread school screening program.