Refractive Errors In School-age Children Research Articles

Assessing the relationship between anthropometric factors and refractive errors in school-age children: height, weight, or BMI?

Assessing the relationship between anthropometric factors and refractive errors in school-age children: height, weight, or BMI?

Magnitude of Prevelance of Refractive Errors in School-age Children: A Cross-sectional Study

Aim: To determine the frequency of refractive errors in school-age children.
 Study Design: Cross-sectional study.
 Place and duration: Two Government and two Private schools of Hyderabad Sindh, screened by the institute of ophthalmology at Liaquat University of Medical and Health Sciences Jamshoro, from January 2021 to June 2021.
 Methodology: Schools and students were selected by stratified random method; a total of four hundred students were screened in four schools. From class one to class ten, 10 students were selected from each class. Prior written permission was obtained from parents. External ocular examination, visual acuity, pinhole test, autorefraction, and fundus examination were done and recorded on proforma along with the information regarding age, sex, family history, and parent’s education. The data was entered and analyzed by SPSS version 22.
 Results: In government schools 27 students out of 200 had refractive errors, myopia was present in 15 (55.55%) students, hypermetropia in 7 (25.93%) students and astigmatism in 5 (18.52%) students, while in private schools 25 students had refractive errors. Myopia was present in 16 (64%) students, hypermetropia in 7 (28%) students and astigmatism in 2 (8%) students. Myopia and astigmatism were more prevalent in female sex being 8.1% and 2% respectively, while in males it was 6.4% and 1.4% cases. In this study, no significant refractive error difference was found between government and private sector schools.
 Conclusion: In our study, the prevalence of refractive errors was 13% (52) out of 400 students. Refractive errors are the most common and easily treatable causes of decreased vision in school-aged children. It is recommended that visual acuity be checked prior to admission to school because refractive errors can be easily corrected with glasses. If it is treated in time, the child can be prevented from amblyopia and squint.

The prevalence of refractive error in schoolchildren

ABSTRACT Clinical relevance Information on the refractive error prevalence in school-aged children will result in delivering the optimal eye health service to this group. Background Understanding the prevalence of refractive error in school-aged children is crucial to reduce the consequences of uncorrected refractive error. This study aims to investigate the prevalence of refractive error among school-aged children in Shiraz, Iran. Methods In this cross-sectional population-based study, 2001 schoolchildren aged 6–12 years participated. All participants underwent cycloplegic refraction. Spherical equivalent (SE) of −0.50 dioptre or more was considered as myopia, SE of +2.00 dioptre or more as hyperopia, and astigmatism as cylinder power of 0.75 dioptre or more. The difference of 1.00 dioptre or more between two eyes defined as anisometropia. Results The prevalence of myopia was 11.6% (95% confidence interval [CI]: 10.2–13.1%), hyperopia 6.7% (95%CI: 5.6–7.9%), and astigmatism 28.9% (95%CI: 26.9–31.0%), out of which 82.1% had with the rule astigmatism. Anisometropia was detected in 4.0% (95%CI: 3.2–5.0%) of children. Astigmatism and anisometropia were significantly higher in boys (p < 0.001, p = 0.03 respectively). The SE decreased significantly with increasing age (p < 0.001) indicating an increase in myopia with age. In addition, the rate of myopic astigmatism increased with age (p < 0.001). Among studied schoolchildren 97.0% could achieve the best-corrected visual acuity of 6/6 and 3.0% could not in the better eye. Conclusion Astigmatism was the most common refractive error among primary school children. The prevalence of myopia was relatively higher than other studies conducted in Iran, and it increased with age. These results may highlight the role of lifestyle changes and increased near work activities on the myopic shift in school-aged children. The findings provide information for screening programmes in school-aged children.

Effect of a Randomized Interventional School-Based Vision Program on Academic Performance of Students in Grades 3 to 7

Uncorrected refractive error in school-aged children may affect learning. To assess the effect of a school-based vision program on academic achievement among students in grades 3 to 7. This cluster randomized clinical trial was conducted in Baltimore City Public Schools during school years from 2016 to 2019 among 2304 students in grades 3 to 7 who received eye examinations and eyeglasses. Participating schools were randomized 1:1:1 to receive eye examinations and eyeglasses during 1 of 3 school years (2016-2017, 2017-2018, and 2018-2019). The primary outcome was 1-year intervention impact, measured by effect size (ES), defined as the difference in score on an academic test (i-Ready or Partnership for Assessment of Readiness for College and Careers tests on reading and mathematics) between intervention and control groups measured in SD units, comparing cohort 1 (intervention) with cohorts 2 and 3 (control) at the end of program year 1 and comparing cohort 2 (intervention) with cohort 3 (control) at the end of program year 2. The secondary outcome was 2-year intervention impact, comparing ES in cohort 1 (intervention) with cohort 3 (control) at the end of program year 2. Hierarchical linear modeling was used to assess the impact of the intervention. Analysis was performed on an intention-to-treat basis. Among the 2304 students included in the study, 1260 (54.7%) were girls, with a mean (SD) age of 9.4 (1.4) years. The analysis included 964 students (41 schools) in cohort 1, 775 students (41 schools) in cohort 2, and 565 students (38 schools) in cohort 3. There were 1789 Black students (77.6%), 388 Latinx students (16.8%), and 406 students in special education (17.6%). There was an overall 1-year positive impact (ES, 0.09; P = .02) as assessed by the i-Ready reading test during school year 2016-2017. Positive impact was also observed among female students (ES, 0.15; P < .001), those in special education (ES, 0.25; P < .001), and students who performed in the lowest quartile at baseline (ES, 0.28; P < .001) on i-Ready reading and among students in elementary grades on i-Ready mathematics (ES, 0.03; P < .001) during school year 2016-2017. The intervention did not show a sustained impact at 2 years or on Partnership for Assessment of Readiness for College and Careers testing. Students in grades 3 to 7 who received eyeglasses through a school-based vision program achieved better reading scores. Students had improved academic achievement over 1 year; however, a sustained impact was not observed after 2 years. The Registry of Efficacy and Effectiveness Studies Identifier: 1573.1v1.

Prevalence of Refractive Error and Associated Risk Factors in School-Age Children in Nepal: A Cross-sectional Study

Introduction: The most common visual disorder in school age children is refractive error globally. The present study aimed to know the prevalence of refractive errors and explore the factors associated with the refractive error in school-age children in Palpa district of western part of Nepal. Methods: All the school children were selected between age groups 5 to 18 years from four schools of Palpa by multistage sampling method. After the preliminary examination on visual acuity, the children were referred to the Department of Ophthalmology, Lumbini Medical College, Palpa for confirmation of the refractive errors. Results: In school-age children the prevalence of refractive error was 9% of which myopia was the most common (4.05%). Females (about 12%) were more likely to have refractive errors than males (about 7%). The refractive error of males was 0.106 (right eye) and 0.564 (left eye) times more likely than females. The refractive errors were statistically found more common in Dalit students (14.6%) than Brahmin/Chhetri (about 12%) and Janajati (7.6%). The prevalence of refractive errors among students using smart phone/ laptop (about 12%) was higher than those not using (8.36%). Conclusion: Sex, ethnicity, and near-work activity like using the smart device were the covariates of developing refractive error on the eye. Myopia was more among those students who were using smartphones/laptops. Near activities stress on eyes of the children and might be one of the causes of developing myopia.

Refractive Error and Visual Impairment Among School Children: Result of a South-Eastern Nigerian Regional Survey.

PurposeTo determine the prevalence refractive errors and causes of visual impairment in school children in the south-eastern region of Nigeria.MethodsSchool-based cross-sectional samples of children 5 to 15 of age in both urban and rural areas were profiled through cluster sampling. The main outcome measures were presenting, uncorrected, and best-corrected visual acuity using the Refractive Error in School-age Children (RESC) protocol.ResultsA total of 5723 children were examined during the study period comprising 2686 (46.9%) males and 3037 (53.1%) females; (M:F ratio 0.9:1) and aged 10.49±2.74SD of mean (range, 5 to 15 years). The age group 12 to <13 accounted for the highest 776 (13.6%) number of the study participants. The uncorrected visual acuity (VA) of <20/40 (6/12) was seen in 188 (3.4%) of the study participants while the presenting and best-corrected visual acuity of <20/40 (6/12) were noted in 182 (3.4%) children and 14 (0.2%) children, respectively. Refractive error was the principal cause of visual impairment.ConclusionPrevalence of refractive error is low. Myopia is the principal cause of refractive error occurring more in females and in urban schools. The main cause of visual impairment is refractive error, and most children that need spectacle correction did not have them. Program to identify children with refractive error in addition to providing free or affordable optical services remains the key to preventing visual impairment from refractive error particularly in resource-poor settings.

Prevalence of refractive errors and visual impairment in school children in Enugu South-East Nigeria.

To determine the prevalence of refractive errors and causes of visual impairment in school children in Enugu State, South-eastern Nigeria. A descriptive cross-sectional, school-based survey in children aged 5-15 years from selected primary and junior secondary schools (public and private) in both urban and rural communities of Enugu State was carried out. Ocular examinations were performed on them according to the Refractive Error in School-age Children (RESC) protocol. A total of 1167 children were examined. The mean age (standard deviation) was 10.58 ± 3.0 years. Females were 653 (54.4%) of the study population. The uncorrected, presenting and best-corrected visual acuity of ≤20/40 (6/12) in the better eye of the children in this study were 3.6%. 3.5% and 0.4%. Among the children that had visual impairment, refractive error accounted for 33.3% of reduced vision while the overall prevalence of refractive error was 2.1%. Prevalence of myopia was 1.9% and hyperopia, 0.1%. The most prevalent astigmatism was ≤0.75 dioptre cylinder. The prevalence of refractive error in this study is low, with myopia being more common. Despite the low prevalence of refractive error, school vision screening is still important for African children as it serves as an opportunity to identify other ocular morbidities among the children.

Assesment of the QuickSee wavefront autorefractor for characterizing refractive errors in school-age children.

PurposeTo assess the performance of an open-view binocular handheld aberrometer (QuickSee) for diagnosing refractive errors in children.Methods123 school-age children (9.9 ± 3.3 years) with moderate refractive error underwent autorefraction (AR) with a standard desktop device and subjective refraction (SR), with or without cycloplegia to determine their eyeglass prescription. Measurements with QuickSee (QS) were taken in 62 of these patients without cycloplegia (NC), and in 61 under cycloplegia (C). Differences in refraction values (AR vs SR vs QS) as well as the visual acuity (VA) achieved by the patients with each method (QS vs SR) were used to evaluate the performance of the device in measuring refractive error.ResultsThe spherical equivalent refraction obtained by QS agreed within 0.5 D of the SR in 71% (NC) and 70% (C) of the cases. Agreement between the desktop autorefractor and SR for the same threshold was of 61% (NC) and 77% (C). VA resulting from QS refractions was equal to or better than that achieved by SR procedure in 77% (NC) and 74% (C) of the patients. Average improvement in VA with the QS refractions was of 8.6 and 13.4 optotypes for the NC and C groups respectively, while the SR procedure provided average improvements of 8.9 (NC) and 14.8 (C) optotypes.ConclusionsThe high level of agreement between QuickSee and subjective refraction together with the VA improvement achieved in both study groups using QuickSee refractions suggest that the device is a useful autorefraction tool for school-age children.

Vision problems: A review of prevalence studies on refractive errors in school-age children

Background: Refractive errors are common eye disorders and are leading causes of visual impairment in the general population. Children with uncorrected refractive error may experience reduced visual acuity, transient blurring, headache and persistent ocular discomforts particularly for close work which can impair reading efficiency and school performance.Aim: This article documents the prevalence of refractive errors in school-age children of different ethnic origins. The goal is to identify possible variation in measuring techniques and diagnostic criteria, as well as limitations of studies, to provide a clear direction for future studies.Methods: The review was undertaken through a detailed evaluation of peer-reviewed publications of primary research on this topic. The keywords for the search included ‘refractive error’, ‘hyperopia’, ‘myopia’, ‘astigmatism’ and ‘school children’. Only epidemiological studies with participants between 5 and 18 years of age were included.Results: Although several population and school-based studies have been conducted in various racial groups and populations, their findings were diverse owing to inconsistencies in the methods applied in identifying children in need of refraction, measurement techniques and diagnostic criteria for refractive errors. There are also some limitations associated with the sampling design and characteristics, which may have influenced the outcome measures.Conclusion: Despite the problems inherent in the studies, the review indicates that refractive error in school-age children is a public health concern in those populations and warrants additional research that will provide reliable data for proper planning of intervention strategies.

Prevalence of ocular morbidity among tribal children in Jawadhi hills, southern India: A cross-sectional study

Purpose:Childhood blindness is second to cataract in terms of blind person years; population-based prevalence of ocular morbidity among tribal children has not been studied. We conducted this study to determine the prevalence of ocular morbidity in tribal children age 15 years or younger in Jawadhi hills, southern India.Methods:A population-based cross-sectional study was conducted in four tribal villages where all children below 15 years of age were invited to participate in the study. After appropriate consent/assent, an optometrist assessed uncorrected vision refraction and best-corrected visual acuity using suitable techniques. A comprehensive ophthalmic examination was also done by an ophthalmologist to determine the presence of ocular morbidity. Children requiring cycloplegic refraction or further treatment were referred to the base hospital.Results:Among 260 children examined, the prevalence of ocular morbidity was 10.8% [95% confidence interval (CI): 6.3–13.7]. Vitamin A deficiency (VAD) was the foremost morbidity: 4.6% (95% CI 1.6–6.3) followed by refractive error (2.7%). Three (10.7%) children had more than one ocular morbidity. Nearly 1 in 10 tribal children suffer from ocular morbidity and 1 in 57 had low vision.Conclusion:VAD is a public health problem in this tribal region which requires immediate intervention with prophylaxis and treatment. Uncorrected refractive errors in school-age children also need to be attended.

Efficacy and outcomes of a summer-based pediatric vision screening program

To investigate the prevalence of decreased visual acuity and uncorrected refractive error in school-aged children participating in summer programs. During the summers of 2014-2016, Wills Eye Hospital collaborated with summer programs in Philadelphia to provide vision screenings for underserved children. Parental consent was obtained prior to vision screening. Fail criteria included children in grades K-1 (ages 5-6) with visual acuity worse than 20/40 in either eye, children in grades 2-6 (ages 7-13) with visual acuity worse than 20/30 in either eye, or children with ≥2 lines of interocular difference. If decreased visual acuity was correctable to ≥20/30 by the onsite optometrist, two pairs of free eyeglasses were provided. Children with other ocular abnormalities were referred to pediatric ophthalmology. Of 1,627 children screened, 360 children (22.1%) did not pass vision screening, and 64 (3.9%) were referred. The prevalence of decreased distance visual was 34.1%. Younger children were more likely to have worse visual acuity than older children (OR=0.943; P=0.023; 95% CI, 0.896-0.992). Myopia (73%), astigmatism (56.8%), hyperopia (15.5%), spherical anisometropia (12.5%), and cylindrical anisometropia (11.9%) presented in the 303 children who underwent a manifest refraction. Myopia increased with age (OR=0.818; P=0.001; 95% CI, 0.724-0.922), whereas astigmatism decreased (OR=0.817; P<0.001; 95% CI, 0.728-0.913) with age. Two pairs of glasses were provided to 301 children. Partnership with summer programs and other community initiatives to provide vision screenings facilitates access to eye care ultimately aimed at improving social functioning and academic performance.

Prevalence of uncorrected refractive errors among school-age children in the School District of Philadelphia

To determine the prevalence and severity of uncorrected refractive errors in school-age children attending Philadelphia public schools. The Wills Eye Vision Screening Program for Children is a community-based pediatric vision screening program designed to detect and correct refractive errors and refer those with nonrefractive eye diseases for examination by a pediatric ophthalmologist. Between January 2014 and June 2016 the program screened 18,974 children in grades K-5 in Philadelphia public schools. Children who failed the vision screening were further examined by an on-site ophthalmologist or optometrist; children whose decreased visual acuity was not amenable to spectacle correction were referred to a pediatric ophthalmologist. Of the 18,974 children screened, 2,492 (13.1%) exhibited uncorrected refractive errors: 1,776 (9.4%) children had myopia, 459 (2.4%) had hyperopia, 1,484 (7.8%) had astigmatism, and 846 (4.5%) had anisometropia. Of the 2,492 with uncorrected refractive error, 368 children (14.8%) had more than one refractive error diagnosis. In stratifying refractive error diagnoses by severity, mild myopia (spherical equivalent of -0.50 D to<-3.00 D) was the most common diagnosis, present in 1,573 (8.3%) children. In this urban population 13.1% of school-age children exhibited uncorrected refractive errors. Blurred vision may create challenges for students in the classroom; school-based vision screening programs can provide an avenue to identify and correct refractive errors.

Vision screening for correctable visual acuity deficits in school-age children and adolescents.

Vision screening for correctable visual acuity deficits in school-age children and adolescents.

Identifying Children at Risk of High Myopia Using Population Centile Curves of Refraction.

PurposeTo construct reference centile curves of refraction based on population-based data as an age-specific severity scale to evaluate their efficacy as a tool for identifying children at risk of developing high myopia in a longitudinal study.MethodsData of 4218 children aged 5–15 years from the Guangzhou Refractive Error Study in Children (RESC) study, and 354 first-born twins from the Guangzhou Twin Eye Study (GTES) with annual visit were included in the analysis. Reference centile curves for refraction were constructed using a quantile regression model based on the cycloplegic refraction data from the RESC. The risk of developing high myopia (spherical equivalent ≤ -6 diopters [D]) was evaluated as a diagnostic test using the twin follow-up data.ResultsThe centile curves suggested that the 3rd, 5th, and 10th percentile decreased from -0.25 D, 0.00 D and 0.25 D in 5 year-olds to -6.00 D, -5.65D and -4.63 D in 15 year-olds in the population-based data from RESC. In the GTES cohort, the 5th centile showed the most effective diagnostic value with a sensitivity of 92.9%, a specificity of 97.9% and a positive predictive value (PPV) of 65.0% in predicting high myopia onset (≤-6.00D) before the age of 15 years. The PPV was highest (87.5%) in 3rd centile but with only 50.0% sensitivity. The Mathew’s correlation coefficient of 5th centile in predicting myopia of -6.0D/-5.0D/-4.0D by age of 15 was 0.77/0.51/0.30 respectively.ConclusionsReference centile curves provide an age-specific estimation on a severity scale of refractive error in school-aged children. Children located under lower percentiles at young age were more likely to have high myopia at 15 years or probably in adulthood.

Prevalence of visual impairment and refractive error in school-aged children in South Darfur State of Sudan

Background: Global estimates suggest there are almost 19 million visually impaired children worldwide, the major cause being uncorrected refractive error (RE).Aim: To assess the prevalence of visual impairment (VI) and RE among Sudanese school-aged children.Setting: Eight randomly selected primary schools from 21 districts in South Darfur State of Sudan were involved.Methods: A school-based cross-sectional study of RE and VI in primary schoolchildren from grades 1 to 8 (children aged 6–15 years) was investigated. A Refractive Error Study in Children (RESC) protocol was implemented to determine the prevalence of RE and VI in these schoolaged children. Participants were enrolled through stratified multistage cluster sampling of four all-male and four all-female primary schools from South Darfur State of Sudan. Examination procedures followed the RESC protocol, which included visual acuity (VA) measurements, binocular vision assessments, retinoscopy and autorefraction under cycloplegia, as well as examination of the external eye, anterior-segment, media and fundus.Results: A total of 1775 children were invited to participate in the study and 1678 were examined resulting in a participation rate of 94.5%. The findings indicated that the prevalence of uncorrected, presenting and best-corrected VA of 6/12 or worse was 6.4% (95% confidence interval [CI], 4.9–7.9), 4.4% (95% CI, 2.9–5.9) and 1.2% (95% CI, 0.3–2.7) respectively. RE was the cause of VI in 57% of participants, retinal disorders in 13.1%, amblyopia in 5.6%, corneal opacity in 0.9%, cataract in 3.7%, with the causes of reduced vision undetermined in 10.3% and various other causes contributed 9.3%. External and anterior-segment abnormalities were observed in 10.2% of children. This was mainly allergic conjunctivitis (5.3%) followed by bacterial and viral conjunctivitis (4.2%). The prevalence of myopia (≥|-0.50 D|) in one or both eyes was 6.8% (95% CI, 5.3–8.3), hypermetropia (≥ 2 D) was noted in 1.9% (95% CI, 0.4–3.4) and astigmatism (≥|-0.75 D|) prevailed in 2.5% (95% CI, 1.0–4.0). Prevalence of VI among schoolaged children were associated with the children’s age and grade levels (p = 0.00) but was not correlated with gender (p = 0.224). Prevalence of RE among school-aged children was significantly correlated with age and grade levels (p = 0.00). No significant correlation was found between gender and prevalence of RE (p = 0.833). The prevalence of VI because of myopia was associated with increasing grade levels and also the childhood age (p = 0.023), but there was no significant difference in the prevalence of VI because of myopia between male and female children.Conclusion: Uncorrected RE was a major cause of VI among children in the South Darfur State. There is thus a critical need for developing a comprehensive child eye care plan focusing on the reduction of uncorrected RE through collaboration between key stakeholders and government.

Refractive Errors in School-age Children in Qazvin, Iran

Results: The study was performed on 5641 (47.72%) male and 6180 (52.28%) female students. The prevalence of myopia (from 32.96% at the age of 7 to 79.02% at the age of 18 years) significantly increased (P < 0.001), and hyperopia significantly decreased (from 47.07% in 7-year- old individuals to 8.32% in 18-year- old subjects) with age (P < 0.001). There were significant differences in refractive errors between males and females. Hyperopia and myopia was more common among female in comparison to males (P < 0.001). Astigmatism greater than 0.75 D in one or both eyes was found in 990 children (8.37%). Astigmatism increased from 6.04% in 7-year-old students to 9.86% in 15-year-oldstudents e and then no more difference was found in age group ranged from 15 to 18 years. Conclusions: Based on our study, the prevalence of myopia is more than other types of refractive error, which is similar to that reported in previous studies on other school-age populations in some Asian countries. The high prevalence of refractive error among school-age children indicated that untreated refractive error is one of the most common public health problems.

Population‐based survey of refractive error among school‐aged children in rural northern China: the Heilongjiang eye study

The prevalence of refractive error in the north of China is unknown. The study aimed to estimate the prevalence and associated factors of refractive error in school-aged children in a rural area of northern China. Cross-sectional study. The cluster random sampling method was used to select the sample. A total of 1700 subjects of 5 to 18 years of age were examined. All participants underwent ophthalmic evaluation. Refraction was performed under cycloplegia. Association of refractive errors with age, sex, and education was analysed. The main outcome measure was prevalence rates of refractive error among school-aged children. Of the 1700 responders, 1675 were eligible. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye was 6.3%, 3.0% and 1.2%, respectively. The prevalence of myopia was 5.0% (84/1675, 95% CI, 4.8%-5.4%) and of hyperopia was 1.6% (27/1675, 95% CI, 1.0%-2.2%). Astigmatism was evident in 2.0% of the subjects. Myopia increased with increasing age, whereas hyperopia and astigmatism were associated with younger age. Myopia, hyperopia and astigmatism were more common in females. We also found that prevalence of refractive error were associated with education. Myopia and astigmatism were more common in those with higher degrees of education. This report has provided details of the refractive status in a rural school-aged population. Although the prevalence of refractive errors is lower in the population, the unmet need for spectacle correction remains a significant challenge for refractive eye-care services.

Ametropias in School-Age Children in Fada N′Gourma (Burkina Faso, Africa)

To assess epidemiological aspects of refractive errors in school-age children in Burkina Faso (west-central Africa). A total of 315 school children (ranging from 6 to 16 years of age and belonging to different ethnic groups) taken at random from two urban schools in eastern Burkina Faso were examined to assess their refractive error, which was determined by non-cycloplegic retinoscopy with optical fogging. The standard Refractive Error Study in Children (RESC) definitions of refractive errors were used: myopia ≤-0.5 D spherical equivalent (SE) in at least one eye, hyperopia ≥2 D SE in at least one eye, astigmatism ≤-0.75 D cylinder in at least one eye, and anisometropia ≥1 D SE difference between the two eyes. Unilateral myopia and bilateral myopia were found in 2.5 and 1%, respectively; unilateral hyperopia in 17.1%, bilateral hyperopia in 8.6%; astigmatism in at least one eye in 11.7%. The highest prevalence value (18.4%) of astigmatism (≤-0.75 D) in at least one eye was found in the Gourmantché ethnic group. The low prevalence of large refractive errors makes visual acuity in these children very good (visual acuity logarithm of the minimum angle of resolution -0.073 ± 0.123 SD). There was a low prevalence of myopia in these African school children. Clinically significant high hyperopia (≥+2 D SE) was also uncommon. There were no significant differences between the distributions of refractive errors according to gender or ethnicity. With respect to age groups, the prevalences of hyperopia and astigmatism were significantly higher in the younger age groups.

Refractive Status and Prevalence of Refractive Errors in Suburban School-age Children

This study investigated the distribution pattern of refractive status and prevalence of refractive errors in school-age children in Western China to determine the possible environmental factors. A random sampling strategy in geographically defined clusters was used to identify children aged 6-15 years in Yongchuan, a socio-economically representative area in Western China. We carried out a door-to-door survey and actual eye examinations, including visual acuity measurements, stereopsis examination, anterior segment and eyeball movements, fundus examinations, and cycloplegic retinoscopy with 1% cyclopentolate. A total of 3469 children living in 2552 households were selected, and 3070 were examined. The distributions of refractive status were positively-skewed for 6-8-year-olds, and negatively-skewed for 9-12 and 13-15-year-olds. The prevalence of hyperopia (≥+2.00 D spherical equivalent [SE]), myopia (≤-0.50 D SE), and astigmatism (≥1.00 diopter of cylinder [DC]) were 3.26%, 13.75%, and 3.75%, respectively. As children's ages increased, the prevalence rate of hyperopia decreased (P<0.001) and that of myopia increased significantly (P<0.001). Children in academically challenging schools had a higher risk of myopia (P<0.001) and astigmatism (≥1.00DC, P =0.04) than those in regular schools. The distribution of refractive status changes gradually from positively-skewed to negatively-skewed distributions as age increases, with 9-year-old being the critical age for the changes. Environmental factors and study intensity influence the occurrence and development of myopia.

Prevalence of refractive errors in school‐age children in Morocco

The prevalence of refractive errors in school-age children in Morocco was assessed. A total of 545 children (300 boys and 245 girls, between 6 and 16 years of age) attending school were examined to assess their refractive errors in a field study in Morocco (North Africa). The examination included autorefraction under cycloplegia and visual acuity, stereopsis and anterior corneal-radius measurements . We found a low prevalence of myopia (< or =-0.5 D SE [spherical equivalent] in at least one eye), i.e. only 6.1%. The prevalence of hyperopia (> or =2.0 D SE in at least one eye) was 18.3%. Astigmatism (< or =-0.75 D of cylinder in at least one eye) was found in 23.5% of these children. The low prevalence of large refractive errors makes visual acuity in these children very good. In general, the corneal radii did not significantly vary with age. There were no significant differences between the distribution of refractive errors in these children according to gender but there were with respect to age. There was a low prevalence of myopia in these African children, astigmatism being the most frequent refractive error. The mean refractive errors found were low, and therefore visual acuity was high in these children.