The prevalence of refractive errors among schoolchildren in Dezful, Iran

Characteristics of astigmatism in school-age children aged 5 to 13 years in northeast Sichuan: a cross-sectional school-based study

Background

Astigmatism is closely associated with myopia progression, vision loss, eye fatigue and amblyopia, which seriously endangers children's eye health. This study aims to investigate the prevalence and characteristic distribution of astigmatism in children in Langzhong City, providing valuable insights for allocating resources and develop prevention and control strategies.

Methods

A cross-sectional study and random sampling survey were conducted. Between January and November 2021, 21,415 students aged 5 to 13 years from 14 primary schools in Langzhong City underwent non-cycloplegic refractive testing using autorefraction. The data on myopia were analyzed using SPSS (Statistical Package for the Social Sciences) version 23.0.

Results

The inclusion criterion was set at an absolute astigmatism value of ≥0.50D. Among the 21,415 children studied, 61.70% were found to have astigmatism. The prevalence of astigmatism varied significantly across different grades (χ2=501.414, P<0.001). The predominant types of astigmatism were mild astigmatism (0.50-1.00D) and with-the-rule astigmatism. Mixed astigmatism was primarily observed in children in grades 1 and 2, while compound myopic astigmatism was more common in children in grades 3 to 6. These differences were statistically significant. As the degree of astigmatism increased, the proportions of against-the-rule astigmatism, oblique astigmatism, compound myopic astigmatism, and simple hyperopic astigmatism decreased, whereas the proportions of with-the-rule astigmatism, mixed astigmatism, and compound hyperopic astigmatism increased.

Conclusions

The prevalence of astigmatism among school-age children aged 5 to 13 years in northeast Sichuan is notably high, with compound myopic astigmatism and with-the-rule astigmatism being the most common types. Regular refractive examinations are crucial for the early detection and management of astigmatism.

Prevalence of hyperopia in school-aged children in eastern Mediterranean region: A systematic review and meta-analysis

PURPOSE

This systematic review and meta-analysis aimed to provide the available data on the prevalence of childhood hyperopia in the eastern Mediterranean region (EMR).

METHODS

The study used preferred reporting items for systematic reviews and meta-analyses, 2020. The articles were searched in six online databases (Web of Sciences, Scopus, Index Medicus for the EMR, ProQuest, PubMed, and Medline). For studies published on the prevalence of hyperopia in the EMR from January 2000 to May 2022. The reviewed data were grouped by age, gender, and refractive measurement technique, hyperopia was defined as refractive error ≥2.00 diopter.

RESULTS

The final meta-analysis contained 27 quality-assessed studies from 12 countries, covering 51, 987 children. The overall pooled prevalence of childhood hyperopia from 2000 to 2022 is 6.33% in EMR. The hyperopia prevalence was slightly higher among females at 4.34%, compared to males at 4.21%. The prevalence of hyperopia in younger children (5-10 years) was higher at 5.72%, and lower in older aged (11-17) years at 3.23%; P = 0.001. Furthermore, there was a higher hyperopia prevalence with cycloplegic refraction at 7.35% compared with noncycloplegic refraction at 3.93%. There was highly significant heterogeneity between the studies (P < 0.0001).

CONCLUSION

The prevalence of hyperopia among children in the EMR was high compared to other regions, particularly in younger children. More studies are required using standardized methods in different regions where there is a lack of information on hyperopia prevalence. Early interventions are essential to be implemented in the EMR to protect future adults from the development of strabismus and amblyopia.

Refractive Errors of School Children from Economically Disadvantaged Areas in Northwest México

Background: Refractive errors, including myopia, hyperopia, and astigmatism, are the leading causes of visual impairment in school-aged children and can significantly impact their academic performance and quality of life. This study aimed to assess the prevalence of refractive errors among school children from economically disadvantaged areas in Northwest México, using a consistent methodology to facilitate comparison with global data. Methods: We adopted the Refractive Error Study in Children (RESC) protocol by the World Health Organization to examine the prevalence of myopia, hyperopia, and astigmatism. The study comprised a systematic sampling of children aged 6 to 18 years from diverse schools in Northwest México. Trained optometrists conducted visual acuity testing and autorefraction, while ophthalmologists performed cycloplegic refraction to ensure accuracy. Results: The study found a myopia (SE ≤-1.50 D at least one eye) prevalence of 14.55% (95% CI: 13.27-15.91), with a higher incidence in females (6.92%) compared to males (6.00%) in at least one eye. Hyperopia (SE ≥ +1.00 D at least one eye) was less common, at 3.23% (95% CI: 2.61-3.95), with a slightly higher occurrence in males in at least one eye. Astigmatism (Cylinder ≥ 0.75 D at least one eye) was present in 18.63% (95% CI: 17.21-20.12) of the students in at least one eye, with no significant difference between genders. These findings are consistent with other studies in regions such as Puerto Rico and Iran, indicating widespread refractive error issues among schoolchildren. Conclusions: The high prevalence of refractive errors, particularly myopia and astigmatism, highlights the critical need for regular vision screenings in schools and the implementation of public health interventions to provide corrective eyewear. Our study confirms the importance of utilizing standardized methodologies like the RESC protocol to compare refractive error prevalence across different geographical and socio-economic contexts, thereby informing global public health strategies.

Dental caries as a health risk for visual acuity in relation to salivary transforming growth factor beta-1 among students aged 8-10 years: A cross-sectional study

Background

Dental caries and an impairment in visual acuity (VA) may both be caused by a variety of risk factors. Various conditions of the eye can appear as a consequence of overall inflammation and active dental caries.

Aim

The present study aims to assess dental caries and salivary status by measuring the transforming growth factor beta-1 (TGF-β1) and flow rate between visually impaired students compared with students with normal vision.

Materials and Methods

Research was performed employing a cross-sectional comparative study design conducted among representative 653 students aged 8-10 years at primary schools in Al-Diwaniyah governorate using the Snellen E chart for measuring VA status. Partitioning the students according to the degree of VA into normal students with normal VA of 6/9 or better and students with visual impairment of 6/12 or worse was done. Sub-sample of 180 students was recruited randomly from both groups, age and gender-matched participants for salivary analysis, and dental caries assessment measured by decay, missed, filled index, according to the World Health Organization in 2013.

Results

Out of 653 students, only 70 students suffer from a decrease in VA. Dental caries was more prevalent in those who had a decrease in VA compared with normal groups. For primary teeth decay, missed, filled teeth index (DMFT/dmft), the result was not significant but highly significant for DMFT/dmft. A significant decrease in salivary flow rate and increased salivary TGF-β1 level among visually impaired students was found.

Conclusions

According to the current research, the study population that has impaired VA, dental health status has greatly deteriorated.

Three-year change in refractive error and its risk factors: results from the Shahroud School Children Eye Cohort Study

OBJECTIVES

To determine spherical equivalent (SE) progression among children in the Shahroud School Children Eye Cohort Study.

METHODS

A prospective cohort study recruited children aged 6 to 12 years in 2015 (baseline) with a follow-up in 2018. Cycloplegic autorefraction and axial length (AL) measurements were included. SE progression over 3 years was analysed in non-myopic (SE ≥ + 0.76 D), pre-myopic (PM; SE between +0.75 D and -0.49 D), low myopic (LM; SE between -0.5 D and -5.99 D), and high myopic (HM; SE ≤ - 6 D) eyes. Age, sex, near work, outdoor time, living place, parental myopia, mother's education, and baseline SE were evaluated as risk factors for SE progression (≤ -0.50 D).

RESULTS

Data were available for 3989 children (7945 eyes). At baseline, 40.3% (n = 3205), 3.4% (n = 274) and 0.1% (n = 7) eyes had PM, LM and HM, respectively. At the 3-year follow-up, 40.5% (n = 3216), 7.5% (n = 599) and 0.2% (n = 15) eyes had PM, LM, and HM, respectively. SE progression in eyes with LM and HM was -1.08 ± 0.76 D and -1.60 ± 1.19 D, respectively. SE progression was associated with age at baseline (Odds Ratio [OR] = 1.14; 95% confidence interval [CI], 1.08-1.21), female sex (OR = 1.80; 95% CI: 1.48-2.18), near work (OR = 1.08; 95% CI: 1.02-1.14), parental myopia (OR = 1.20; 95% CI: 1.01-1.42) and baseline SE (OR = 2.28; 95% CI: 1.88-2.78).

CONCLUSION

A myopic shift was associated with older age, female sex, near work, parental myopia and greater myopic baseline SE. These results help identifying children at risk of progression that may benefit from treatment and lifestyle counselling.

Refractive development I: Biometric changes during emmetropisation

PURPOSE

Although there are many reports on ocular growth, these data are often fragmented into separate parameters or for limited age ranges. This work intends to create an overview of normal eye growth (i.e., in absence of myopisation) for the period before birth until 18 years of age.

METHODS

The data for this analysis were taken from a search of six literature databases using keywords such as "[Parameter] & [age group]", with [Parameter] the ocular parameter under study and [age group] an indication of age. This yielded 34,409 references that, after screening of title, abstract and text, left 294 references with usable data. Where possible, additional parameters were calculated, such as the Bennett crystalline lens power, whole eye power and axial power.

RESULTS

There were 3422 average values for 17 parameters, calculated over a combined total of 679,398 individually measured or calculated values. The age-related change in refractive error was best fitted by a sum of four exponentials (r²  = 0.58), while all other biometric parameters could be fitted well by a sum of two exponentials and a linear term ('bi-exponential function'; r² range: 0.64-0.99). The first exponential of the bi-exponential fits typically reached 95% of its end value before 18 months, suggesting that these reached genetically pre-programmed passive growth. The second exponentials reached this point between 4 years of age for the anterior curvature and well past adulthood for most lenticular dimensions, suggesting that this part represents the active control underlying emmetropisation. The ocular components each have different growth rates, but growth rate changes occur simultaneously at first and then act independently after birth.

CONCLUSIONS

Most biometric parameters grow according to a bi-exponential pattern associated with passive and actively modulated eye growth. This may form an interesting reference to understand myopisation.

Refractive Errors and Their Associated Factors in Schoolchildren: A Structural Equation Modeling

PURPOSE

To determine the prevalence of myopia and hyperopia in Shahroud schoolchildren and their risk factors.

METHODS

Optometric examinations including the measurement of uncorrected and corrected visual acuity as well as non-cycloplegic and cycloplegic refraction using retinoscopy were done for students. Generalized Structural Equation Modeling (GSEM) was used to determine direct and indirect effects of independent variables on myopia and hyperopia.

RESULTS

The data of 5581 students with a mean age of 9.24 ± 1.7 years were used in this study. The prevalence of myopia was 5.0% (95%CI: 4.3-5.7) and the prevalence of hyperopia was 4.8% (95%CI: 4.0 - 5.5) in all schoolchildren. According to the GSEM results, the odds of myopia in rural areas were 0.55 compared to urban areas. A one-unit increase in the ocular AL increased the odds of myopia by 4.91 times. The interaction of sex and age on myopia was significant such that in girls, the odds of myopia increased by 20% for every one-year increase in age while no significant change was seen in boys. A one-unit increase in the ocular AL decreased the odds of hyperopia by 0.49 times. Moreover, the interaction of outdoor activity hours and sex on the prevalence of hyperopia was significant such that increased outdoor activity reduced the odds of hyperopia in girls while no significant correlation was found in boys.

CONCLUSION

Myopia and hyperopia had moderate prevalence. Axial Length had the largest direct association on myopia and hyperopia. Age and outdoor activity had weak associations on refractive errors.

Prevalence of refractive errors in children of Puerto Rico

AIM

To determine the prevalence of refractive error in 5- to 17-year-old schoolchildren in Puerto Rico.

METHODS

A quantitative descriptive study of 2867 children aged 5 to 17y from all seven educational regions of Puerto Rico was conducted from 2016-2019. Refractive error was determined via static and subjective refraction. Children with distance acuity ≤20/40 or near visual acuity ≤20/32 had a cycloplegic refraction. Data analysis included descriptive statistics, correlation coefficient, Kruskal-Wallis, Chi-square, and t test calculations.

RESULTS

Twenty percent of the children had a spherical equivalent refractive error ≤ -0.50 D, 3.2% had a spherical equivalent ≥ +2.00 D, and 10.4% had astigmatism ≥1 D. There was a statistically (but non-clinically) significant myopic change in spherical equivalent refractive error with age (P<0.001). The prevalence of myopia increased with age (P<0.001) but not hyperopia (P=0.59) or astigmatism (P=0.51). Males had a significantly higher hyperopic spherical equivalent than females (P<0.001). Females had a higher prevalence of myopia (P<0.001) than males, but there was no difference in the hyperopia (P=0.74) or astigmatism prevalence (P=0.87).

CONCLUSION

The prevalence of a spherical equivalent equal to or less than -0.50 D (myopia, 20.7%) is one of the highest among similar-aged children worldwide. Further studies should explore the rate of myopia progression in children in Puerto Rico. Individual children must be monitored to examine the need for treatment of myopia progression.

The Prevalence and Causes of Low Vision and Visual Impairment in School-Aged Children: The Shiraz Pediatric Eye Study

Purpose

To determine the prevalence and causes of visual impairment (VI) in Shiraz schoolchildren aged between 6 and 12 years.

Methods

In the present population-based study, stratified random sampling was used to select 2400 schoolchildren aged 6-12 years from all four educational districts of Shiraz, Iran. Using the definitions of the World Health Organization, VI was defined as best-corrected visual acuity (BCVA) ≤0.5 logMAR (20/60) in the better eye, and blindness as BCVA worse than 1.3 logMAR (20/400) in the better eye. The low vision was defined as BCVA equal to or worse than 0.5 logMAR (20/60) in either eye. Data were recorded from a detailed interview and ocular examination of each eligible student.

Results

The mean age of the students was 9.1 ± 1.6 years. The prevalence of VI was 3/2001 (0.14%). The cause of VI in all these three patients (100%) was amblyopia due to high refractive errors (high ametropia and astigmatism). Regarding the main refractive errors leading to VI among these three patients, one patient had bilateral high hyperopia (compound hyperopic astigmatism), one of them had bilateral high astigmatism, and the other one had compound myopic astigmatism. According to a visual acuity of less than or equal to 20/60 in at least one eye, 9/2001 (0.4%) of children had low vision.

Conclusions

This study revealed a low prevalence of VI in a sample of 6- to 12-year-old school-aged children. Amblyopia in the setting of high ametropia and astigmatism were the most common causes of VI.

A School Eye Health Rapid Assessment (SEHRA) planning tool: Module to survey the magnitude and nature of local needs

BACKGROUND

Eye conditions in children can have negative consequences on visual functioning and quality of life. There is a lack of data on the magnitude of children with eye conditions who need services for effective planning of school eye health programmes. To address this, the School Eye Health Rapid Assessment (SEHRA) tool is being developed to collect data to support school eye health programme planning.

METHODS

The module, 'the magnitude and nature of local needs in school children' is the first of six modules in the SEHRA tool. The module outlines a school-based cluster survey designed to determine the magnitude of eye health needs in children. This paper outlines the survey sampling strategy, and sample size calculations.

RESULTS

The requirements for the SEHRA survey indicate that in regions where a larger sample size is required, or where fewer schools are recruited to the survey, confidence in the accuracy of the data will be lower.

CONCLUSIONS

The SEHRA survey module 'the magnitude and nature of local needs in school children' can be applied in any context. In certain circumstances, the confidence in the survey data will be reduced.

Rural-urban differences in prevalence of and risk factors for refractive errors among school children and adolescents aged 6-18 years in Dalian, China

Purpose

To assess the prevalence of refractive errors (REs) in school children aged 6-18 years in urban and rural settings in Dalian, Northeast of China.

Methods

This is a school-based cross-sectional survey using multi-stage randomization technique. Six- to eighteen-year-old school children from elementary schools, junior and senior high schools from a rural area and an urban area in Dalian were included in December 2018. All subjects underwent a comprehensive questionnaire and eye examination.

Results

A total of 4,522 school children with 6-18 years of age were investigated. The age, gender-adjusted prevalence of myopia, and anisometropia were 82.71 and 7.27% among the urban students as compared to 71.76% and 5.41% among the rural ones (OR = 1.80, 95 % CI = 1.53 - 2.11, P < 0.001; OR = 1.29, 95 % CI = 1.00-1.67, P = 0.049), respectively. The hyperopia was less common in urban students than in rural ones (5.63 vs. 10.21%; OR = 0.54, 95 % CI: 0.43-0.67, P < 0.001). However, there was no significant difference in prevalence of astigmatism between urban (46.07%) and rural (44.69%) participants (OR = 0.96, 95 % CI: 0.84-1.10, P = 0.559). The differences on prevalence of REs were attributed to different social-demographic and physiologic factors.

Conclusions

The students from urban settings are more likely to have myopia and anisometropia but less likely to have hyperopia than their rural counterparts. Although considerable attention had been paid to controlling REs, it is necessary to further consider the urban-rural differences in REs.

The prevalence and causes of pediatric uncorrected refractive error: Pooled data from population studies for Global Burden of Disease (GBD) sub-regions

BACKGROUND

There are limited systematic reviews on the prevalence of uncorrected refractive errors in children. We aimed to summarize the prevalence and causes of pediatric uncorrected refractive error (URE) from studies in the Global Burden of Disease (GBD) sub-regions.

METHODS

The pooled analysis used the individual participant data (ages less than 20 years old) from population-based studies around the world by regions. URE was defined as presenting VA < 6/18 and improving to ≥ 6/18 or ≥1 line on using a pinhole in either eye, with main causes of myopia, hyperopia or astigmatism. Each study provided data on any URE, myopia, hyperopia or astigmatism by age, gender, and ethnicity. Prevalence rates were directly age and gender standardized to the 2020 world population with all age groups. Estimates were calculated by study and sub-regions after pooling. Summary estimates included studies in which URE was assessed from a pinhole-corrected refraction in the better eye.

RESULTS

The combined pooled data contained 302,513,219 patients including 8 963 URE cases individuals from 57 studies. Prevalence varied by age and GBD sub-regions and differed by gender. The age- and region-standardized prevalence of URE was 3.41 per 1000 (CI, 1.53~7.62) in Western Pacific region (12 studies), 2.26 per 1000 (CI, 0.85~6.01) in South-East Asia region (14 studies), 5.85 per 1000 (CI, 3.75~9.13) in Americans (11 studies) and 4.40 per 1000 (CI, 3.0~6.45) in Eastern Mediterranean region (13 studies). On the basis of these data, myopia was the first-leading cause in female children with 12~17 age group, with the prevalence rate 18.2 per 1000 (CI, 11.52~23.61). Astigmatism was detected in 27.2 per 1000 male children with 6~11 age group (CI: 19.12-30.68).

CONCLUSIONS

Prevalence of URE available data within these sub-regions are widely disparate. Myopia and astigmatism in young age children continue as the leading cause of URE worldwide. Providing appropriate refractive correction to those individuals whose vision can be improved is an important public health endeavor with implications for safety and quality of life.

Prevalence of refractive errors and risk factors for myopia among schoolchildren of Almaty, Kazakhstan: A cross-sectional study

Introduction

Very little is known about the prevalence of refractive errors among children in Kazakhstan. The aim of this study was to investigate the prevalence of refractive errors and risk factors of myopia among schoolchildren in Almaty, Kazakhstan.

Methods

In the cross-sectional study of 2293 secondary school students (age 6–16), we examined cycloplegic autorefraction and offered a questionnaire in three age groups: 1^st grade (N = 769), 5^th grade (N = 768) and 9^th grade (N = 756). The questionnaire covered main risk factors such as parental myopia, screen time, time outdoors, sports activities, near work, gender, grade, and school shift. Adjusted logistic regression analysis was applied to test the association of risk factors with myopia.

Results

The mean spherical equivalent (SER) was -0.54 ± 1.51 diopters (D). The overall prevalence of refractive errors was 31.6% (95% confidence interval (CI) 29.7; 33.5); myopia 28.3% (95% CI 26.5; 30.1); hyperopia 3.4% (95% CI 2.7–4.1) and astigmatism 2.8% (95% CI 2.1; 3.5). In the multivariate adjusted regression analysis, higher class level (5^th grade (odds ratio (OR) 1.78; 95% CI 1.26; 2.52) and 9^th grade (OR 3.34; 95% CI 2.31; 4.82)) were associated with myopia, whereas outdoors activity more than 2 hours a day (OR 0.64; 95% CI 0.46; 0.89) and sports (OR 0.70; 95% CI 0.52; 0.93) were associated with a lower incidence of myopia.

Conclusions

Myopia is a leading refractive error in schoolchildren in Almaty, Kazakhstan. Myopia prevention measures, including more time outdoors, should guide public health interventions in this population.

Trends in Myopia Development Among Primary and Secondary School Students During the COVID-19 Pandemic: A Large-Scale Cross-Sectional Study

Objectives

To evaluate myopia development among primary and secondary school students during the coronavirus 2019 (COVID-19) pandemic.

Methods

A cross-sectional study was conducted to evaluate the development of myopia among students in Shenzhen, China during the COVID-19 outbreak.

Results

The study included 1,472,957 and 1,573,824 students in 2019 and 2020, respectively. The prevalence of myopia was 46.9 and 50.5% in 2019 and 2020, respectively. The prevalence of myopia among students in the former Shenzhen Special Economic Zone (SEZ) was higher than that in areas outside the former Shenzhen SEZ (2019: 47.0 vs. 43.7%; 2020: 50.5 vs. 47.3%). The prevalence of myopia among girls was higher than that among boys (2019: 50.4 vs. 44.0%; 2020: 54.0 vs. 47.6%). The 50th percentile (P50) of spherical equivalent refraction (SER) in the right eye among girls was lower than that in boys. The prevalence of myopia continued to increase as the grade increased, with the greatest annual increase observed in Grades 2–5 (3.4–3.9%). The P50 of SER in the right eye of students decreased as the grade increased.

Conclusions

The prevalence of myopia among students increased during the COVID-19 pandemic, especially in primary school Grades 2–5.

The prevalence of refractive error in schoolchildren

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.

Prevalence of refractive errors among school students in Ethiopia: A systematic review and meta-analysis

Objective:

Refractive errors are most common ocular disorders among children and adolescents. They remain as secondary causes of avoidable blindness in impoverished areas in Africa, most notably in Ethiopia. The problem worsens if it is not managed and addressed early. The aim of this systematic review and meta-analysis was to determine the prevalence of refractive errors among school students in Ethiopia.

Methods:

We searched international databases such as PubMed/Medline, Web of Science, CINAHL, Embase, Scopus, Cochrane Library, Google Scholar, and Science Direct for relevant articles. Data were extracted using Microsoft Excel and exported to Stata version 14.0 software for analysis. The Cochrane Q and I2 tests were used to assess heterogeneity. Funnel plot, Egger’s, and Begg’s tests were used to assess reporting bias. Random effect meta-analysis model was employed to estimate pooled prevalence of refractive errors. A regional subgroup analysis was carried out.

Results:

We reviewed 22 qualified studies with 23,355 study participants. The overall prevalence of refractive errors among school students was 7.36% (95% confidence interval = 6.05, 8.67). The prevalence of myopia, hyperopia, and astigmatism was 5.10% (95% confidence interval = 3.79, 6.40), 0.95% (95% confidence interval = 0.59, 1.31), and 0.01% (95% confidence interval = 0.01, 0.04), respectively. From subgroup analysis, the highest prevalence of refractive errors was reported in Amhara Region (9.18%, 95% confidence interval = 6.63, 11.74), followed by Southern Nations, Nationalities, and Peoples’ region (6.78%, 95% confidence interval = 4.65, 8.92) while the lowest prevalence of refractive errors was reported in Addis Ababa (3.93%, 95% confidence interval = 3.30, 4.56).

Conclusion:

In Ethiopia, the prevalence of refractive errors among school students is higher (7.36%) compared to what it was 5 years (7.05%) ago. Amhara Region has the highest prevalence of refractive errors among school students in Ethiopia with myopia being the most common type of refractive error.

Global Prevalence and Causes of Visual Impairment and Blindness in Children: A Systematic Review and Meta-Analysis

Purpose:

To determine the global prevalence and common causes of visual impairment (VI) and blindness in children.

Methods:

In this meta-analysis, a structured search strategy was applied to search electronic databases including PubMed, Scopus, and Web of Science, as well as the list of references in the selected articles to identify all population-based cross-sectional studies that concerned the prevalence of VI and blindness in populations under 20 years of age up to January 2018, regardless of the publication date and language, gender, region of residence, or race. VI was reported based on presenting visual acuity (PVA), uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA) of equal to 20/60 or worse in the better eye. Blindness was reported as visual acuity worse than 20/400 in the better eye.

Results:

In the present study, 5711 articles were identified, and the final analyses were done on 80 articles including 769,720 people from twenty-eight different countries. The prevalence of VI based on UCVA was 7.26% (95% confidence interval [CI]: 4.34%–10.19%), PVA was 3.82% (95% CI: 2.06%–5.57%), BCVA was 1.67% (95% CI 0.97%–2.37%), and blindness was 0.17% (95% CI: 0.13%–0.21%). Refractive errors were the most common cause of VI in the subjects of selected articles (77.20% [95% CI: 73.40%–81.00%]). The prevalence of amblyopia was 7.60% (95% CI: 05.60%–09.10%) and congenital cataract was 0.60% (95% CI: 0.3%–0.9%).

Conclusion:

Despite differences in the definition of VI and blindness, based on PVA, 3.82%, and based on BCVA, 1.67% of the examined samples suffer from VI.

Is myopia prevalence related to outdoor green space?

PURPOSE

Rapid urbanisation and lifestyle changes have been associated with a huge increase in myopia across many parts of the world. There is strong evidence that environmental factors including time outdoors and urbanisation can influence the development of myopia, particularly in school-aged children. The aim of this study is to determine whether there is a relationship between the prevalence of myopia and the amount of vegetation/green spaces across different regions of the world, as a risk factor for myopia development.

METHODS

The prevalence of myopia in the 15 to 19-year age group in Australia, Brazil, China, Finland, India, Iran, Japan, Oman, Singapore, South Africa and the UK was obtained from a meta-analysis by Holden et al. Normalised Difference Vegetation Index (NDVI) was used to quantify green space exposure based on Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite data. Green space was measured in locations specific to 15 studies that reported myopia prevalence. Simple linear regression was used to analyse yearly data, and a mixed effects model was applied to assess the significance of green space when study was a random effect.

RESULTS

Myopia prevalence increases significantly when green space was <-0.2, but the effect was less apparent for values >-0.1. When a mixed effects model was used, the effect of green space was found to be significantly associated with myopia prevalence (p = 0.05).

CONCLUSIONS

There was evidence of a weak but significant non-linear relationship between myopia and green space, with the effect most apparent at low levels of green space. A larger data sample, along with further investigations into the utilisation of green spaces, are required to understand whether increasing the amount of green space can reduce myopia incidence and progression impact.

Prevalence of amblyopia and its determinants in a rural population: a population-based cross-sectional study

To determine the prevalence of amblyopia and its determinants in underserved rural villages of Iran. This population-based cross-sectional study was conducted in 3850 subjects selected from two underserved districts in the north (Kojur District, Nowshahr County, Mazandaran Province) and southwest (Shahyun District, Dezful County, Khuzestan Province) of Iran using multi-stage cluster sampling. The subjects underwent complete ophthalmic examinations including the measurement of uncorrected (UCVA) and best-corrected (BCVA) visual acuity, objective and subjective refraction, unilateral and alternate cover tests and ocular health examination. Amblyopia was defined as a reduction of BCVA to 20/30 or less in one eye or a 2-line interocular optotype acuity difference in the absence of any pathological factors. Of 3850 selected subjects, 3314 participated in the study (response rate = 86.08%). The mean age of the participants was 36.90 ± 20.21 years (range: 3-93 years). The prevalence and 95% confidence interval of total, bilateral, and unilateral amblyopia were 2.73% (2.17 to 3.38), 0.50% (0.28 to 0.83), and 2.23% (1.73 to 2.83), respectively. The most common type of amblyopia was anisometropic followed by strabismic and mixed. The lowest and highest prevalence was seen in the age group 6-20 years (1.36%; 0.65 to 2.49) and above 70 years (5.97%; 3.02 to 10.44), respectively. According to the results of multiple logistic regression analysis, compared to illiterate subjects, the odds ratio of amblyopia was 0.321 (P = .033) in subjects with High school education, 0.181 (P = .030) in subjects with secondary School education, and 0.486 (P = .041) in subjects with primary school education. The odds ratio of amblyopia for north villages residence vs southwest villages residence was 2.105 (P = .012). The odds ratio of amblyopia was 2.765 for age group>70 years vs. 6-20 years (P = .033). The prevalence of amblyopia was higher in north region, in participants with lower education level and older individuals. The high prevalence of amblyopia in older people may be due to the lack of screening programs in previous generations and consequently the lack of timely diagnosis and treatment.

A systematic review of Amblyopia prevalence among the children of the world

Objective: to assess the prevalence of Amblyopia disease in the children of the world. Methods: In order to perform this systematic review, PICO was considered as the research question. Then, the preferred keywords were searched in Medline (via PubMed), Embase, Scopus, Web of Science, and ProQuest databases. The retrieved citations were reviewed by two independent inspectors in a three-step process in terms of the title, abstract, and full-text, based on the inclusion criteria. The studies included in the review were critically evaluated and then were extracted by two dependent expert reviewers. Finally, the prevalence of Amblyopia disease in the children of the world was pooled by meta-analysis CMA v.2 software. The heterogeneity of the selected studies was evaluated using I2 and chi-square. Also, subgroup-analysis was performed using designs and continents. Results: Out of 952 retrieved citations, 131 studies were included. The total prevalence of Amblyopia in the children of the world was calculated to be 4.3% [Pooled Prevalence: 4.3%, 95% CI: 2.6%-7.00%, P-value 0.0001]. In addition, the heterogeneity of the studies was reported to be high (Q: 48281.18, df: 56, p-value 0.001, I-square: 99.88). The subgroup analysis showed that America had the highest (5.57%, 95% CI: 2.23%-13.94%, P-value 0.0001) prevalence, and the lowest prevalence of Amblyopia in the children of the world was seen in Africa (7.1%, 95% CI: 0.003%-172.53%, P-value 0.05). Conclusion: It can be concluded that the total prevalence of Amblyopia is 3.4%, but this estimate varies in all continents, especially in Africa. The major reason for this variation was reported to be the heterogeneity of studies. These assessments have investigated different populations in terms of severity of illness, age, and gender. Therefore, further worldwide high-quality and valid studies should be carried out to allow the calculation of the real prevalence of Amblyopia among children of the world. Abbreviations: VA = visual acuity, ALSPAC = Avon Longitudinal Study of Parents and Children, JBI = Joanna Briggs Institute, PRISMA = Systematic Review and Meta-analysis, CMA = Comprehensive Meta-analysis Software.

National and sub national prevalence of Amblyopia and its trends from 1990 to 2018 in Iran

PURPOSE

To determine the national and subnational prevalence of amblyopia and the respective provincial distribution and trend during 1990-2018 in Iran.

METHODS

Amblyopia data retrieved from 26 original studies, systematic reviews, Data has been cleaned by STATA and a linear mixed effect spatio-temporal model was used to calculate Gaussian process regression mean functions. Using a Bayesian approach, by pooling empirical data based on the assumed prior, a posterior distribution obtained for age and sex specific prevalence prediction nationally during the study time and provincially.

RESULTS

The overall age-adjusted prevalence of Amblyopia was 0.03 (95% CI, 0.022-0.035). The prevalence was comparable in boys and girls (p = 0.85), highest prevalence was in >30 years old (p = 0.038). Our extrapolation revealed a stable trend of prevalence of Amblyopia in Iran during 1990-2018 (national screening program has been active from 1990 onwards). While Amblyopia prevalence suggested a declining trend in three provinces of Hormozgan, Qom and Tehran and it went up in 13 other provinces.

CONCLUSION

Amblyopia prevalence seems unchanged despite the concurrent screening program. It is noteworthy that the coverage of the program has been improved and has reached more than 85% in 2018. Our finding mandates a formal evaluation on the program.

Prevalence of Refractive Errors in Iranian University Students in Kazerun

Purpose:

To determine the prevalence of refractive errors and visual impairment and the correlation between personal characteristics, including age, sex, weight, and height, with different types of refractive errors in a population of university students in the south of Iran.

Methods:

In this cross-sectional study, a number of university majors were selected as clusters using multi-stage sampling in all universities located in Kazerun (27 clusters of 133 clusters). Then, proportional to size, a number of students in each major were randomly selected to participate in the study. Uncorrected and corrected visual acuity, non-cycloplegic objective refraction and subjective refraction were measured in all participants.

Results:

The prevalence and 95% confidence interval (CI) of presenting visual impairment and blindness was 2.19% (1.48–3.23) and 0.27% (0.12–0.62), respectively. Refractive errors comprised 75% of the causes of visual impairment. The prevalence (95% CI) of myopia [spherical equivalent (SE) ≤ –0.5 D], hyperopia (SE ≥ 0.5 D), and astigmatism (cylinder power < –0.5 D) was 42.71% (39.71–45.77), 3.75% (2.85–4.51), and 29.46% (27.50–31.50), respectively. Totally, 49.03% (46.39–51.68) of the participants had at least one type of refractive error. There was a positive association between weight and myopia (1.01; 95% CI: 1.01–1.02), anisometropia (1.03; 95% CI: 1.01–1.06), and refractive errors (1.01; 95% CI: 1.01–1.02). In comparison with the age group 18–19 years, the odds ratio (OR) of astigmatism in the age group 26–27 years was 1.64 (95% CI: 1.03–2.61), and the OR of anisometropia in the age group ≥ 30 years was 0.21 (95% CI: 0.04–0.98).

Conclusions:

The prevalence of refractive errors, especially myopia, is higher in university students than the general population. Since refractive errors constitute a major part of visual impairment, university students should receive special services for providing corrective lenses and glasses to reduce the burden of these disorders.

The prevalence of refractive errors in the Middle East: a systematic review and meta-analysis

PURPOSE

The purpose of the present study was to evaluate the prevalence of refractive errors in the Middle East region.

METHODS

In this meta-analysis, a structured strategy was applied to search databases PubMed, Web of Science, Scopus, and Google Scholar, databases as well as the reference lists of the selected articles to identify cross-sectional studies assessing the prevalence of refractive errors in the Middle East region until September 2019. The outcome measure was the prevalence of refractive errors, including myopia, hyperopia, and astigmatism, in two age groups of ≤ 15 years and > 15 years. The study results were combined using a random effects model at a confidence level of 95%.

RESULTS

The prevalence of myopia, hyperopia, and astigmatism was 4% (95% CI 4, 5), 8% (95% CI 6, 10), and 15% (95% CI 10, 19) in people less than or equal to 15 years and 30% (95% CI 25, 34), 21% (95% CI 15, 28), and 24% (95% CI 16, 31) in subjects over 15 years, respectively. The prevalence of myopia, hyperopia, and astigmatism was 3.5%, 12.4%, and 9.0% in male and 4.2%, 13.1%, and 9.9% in female subjects aged ≤ 15 years, respectively. In subjects aged > 15 years, the prevalence was 31.7%, 14.5%, and 31.5% in males and 31.9%, 11.2%, and 31% in females, respectively.

CONCLUSION

The prevalence of hyperopia is relatively high in Middle Eastern children, while the prevalence of myopia is higher in adults in this region. It seems that astigmatism is not a serious refractive problem in this region compared to the rest of the world.

Are the results of handheld auto-refractometer as valid as the result of table-mounted refractometer?

Purpose

To determine the agreement of table-mounted and handheld auto-refractometers and to evaluate the effect of age and different types of refractive errors on this comparison.

Methods

In this cross-sectional study conducted in 2015 using multi-stage cluster sampling, two underserved villages were selected randomly in the north and southwest of Iran. All the selected participants underwent optometric and ophthalmic examinations. Refraction was measured using handheld and table-mounted auto-refractometers in 652 subjects.

Results

The mean age of the subjects was 32.7 ± 18.72 years, and 58.3% of them were female. A significant difference was observed in the results of sphere, spherical equivalent (SE), and J45 vector between the two devices (P < 0.012), but there was no significant difference in J0 vector. There was a significant difference in the results of sphere between the two devices in all age groups under 50 years (P = 0.005), but there was no difference in age groups above 50 years. Correlation coefficients of the two devices were 0.989, 0.986, 0.908, and 0.951 for the results of sphere, SE, J0 vector, and J45 vector, respectively (P < 0.0001). The 95% limit of agreement (LOA) of the two devices was -0.31 to +0.53 for sphere, -0.27 to +0.63 for SE, -0.27 to +0.27 for J0 vector, and -0.16 to -0.17 for J45 vector.

Conclusions

According to our findings, the spherical error and cylindrical power measurements of the two devices have a significant correlation. Although there is a significant difference in the mean values between the two devices, this difference may be considered clinically insignificant, and considering the narrow 95% LOA between the two devices, the results may be used interchangeably.

The Effect of Dietary Supplementation of Crocetin for Myopia Control in Children: A Randomized Clinical Trial

The prevalence of myopia has been increasing in recent years. The natural carotenoid crocetin has been reported to suppress experimental myopia in mice. We evaluated the effects of crocetin on myopia suppression in children. A multicenter randomized double-blind placebo-controlled clinical trial was performed with 69 participants aged 6 to 12 years, whose cycloplegic spherical equivalent refractions (SER) were between -1.5 and -4.5 diopter (D). The participants were randomized to receive either a placebo or crocetin and followed up for 24 weeks. Axial length (AL) elongation and changes in SER were evaluated for 24 weeks. Both written informed assent from the participants and written informed consent from legal guardians were obtained in this study because the selection criteria of this trial included children aged between 6 and 12 years old. This trial was approved by the institutional review boards. A mixed-effects model was used for analysis, using both eyes. Two participants dropped out and 67 children completed this trial. The change in SER in the placebo group, -0.41 ± 0.05 D (mean ± standard deviation), was significantly more myopic compared to that in the crocetin group, -0.33 ± 0.05 D (p = 0.049). The AL elongation in the placebo group, 0.21 ± 0.02 mm, was significantly bigger than that in the crocetin group, 0.18 ± 0.02 mm (p = 0.046). In conclusion, dietary crocetin may have a suppressive effect on myopia progression in children, but large-scale studies are required in order to confirm this effect.

Prevalence and Possible Factors of Myopia in Norwegian Adolescents

East Asia has experienced an excessive increase in myopia in the past decades with more than 80% of the younger generation now affected. Environmental and genetic factors are both assumed to contribute in the development of refractive errors, but the etiology is unknown. The environmental factor argued to be of greatest importance in preventing myopia is high levels of daylight exposure. If true, myopia prevalence would be higher in adolescents living in high latitude countries with fewer daylight hours in the autumn-winter. We examined the prevalence of refractive errors in a representative sample of 16–19-year-old Norwegian Caucasians (n = 393, 41.2% males) in a representative region of Norway (60° latitude North). At this latitude, autumn-winter is 50 days longer than summer. Using gold-standard methods of cycloplegic autorefraction and ocular biometry, the overall prevalence of myopia [spherical equivalent refraction (SER) ≤−0.50 D] was 13%, considerably lower than in East Asians. Hyperopia (SER ≥ + 0.50 D), astigmatism (≥1.00 DC) and anisometropia (≥1.00 D) were found in 57%, 9% and 4%. Norwegian adolescents seem to defy the world-wide trend of increasing myopia. This suggests that there is a need to explore why daylight exposure during a relatively short summer outweighs that of the longer autumn-winter.

The prevalence of amblyopia in Iran: A systematic review

PURPOSE

The aim of this study was to determine the prevalence of amblyopia in the population of Iran.

METHODS

This article is a systematic review. A comprehensive search was conducted in PubMed, Scopus, Science Direct, Ovid, Web of Science, SID, Magiran, with appropriate terms. Information related to the sample size and the prevalence of amblyopia was extracted and summarized in tables. Analysis was performed using STATA software.

RESULTS

From 551 articles that were originally extracted from the databases, 31 articles met the criteria for entering the review. These studies were conducted in different regions of Iran. The prevalence of amblyopia in different regions varied between 0.19 and 3.69%. Study results were heterogeneous (I2 = 99.7%), and therefore, a meta-analysis was not done.

CONCLUSIONS

The prevalence of amblyopia in Iran is very different. In addition to conducting national screenings, it is necessary to report the incidence of amblyopia and its related factors in different parts of the country.

Prevalence of uncorrected refractive errors among children aged 3-10 years in western Saudi Arabia

Objectives:

To determine the prevalence of uncorrected refractive errors (URE) among children 3-10 years and to affirm the necessity of a national school-based visual screening program for school-aged children.

Methods:

This retrospective cross-sectional study was conducted in Medina, Saudi Arabia in 2015. Children were selected through a multistage stratified random sampling from 8 kindergarten and 8 primary schools. Those included were screened to diagnose UREs using a visual acuity chart and an auto refractometer according to American guidelines. The prevalence and types of UREs were estimated.

Results:

Of the 2121 children enumerated, 1893 were examined, yielding a response rate of 89.3%. The prevalence of UREs was 34.9% (95% CI = 32.8%-37.1%), with significant differences in different age groups. The prevalence of astigmatism (25.3%) was higher compared to that of anisometropia (7.4%), hypermetropia (1.5%), and myopia (0.7%). Risk of uncorrected refractive error was positively associated with age, and this was noted in astigmatism, myopia, and anisometropia. In addition, the risk of hypermetropia was associated with boys and that of myopia was associated with girls.

Conclusions:

The prevalence of UREs, particularly astigmatism, was high among children aged 3-10 years in Medina, with significant age differences. Vision screening programs targeting kindergarten and primary schoolchildren are crucial to lessen the risk of preventable visual impairment due to UREs.

Knowledge, attitude and associated factors among primary school teachers regarding refractive error in school children in Gondar city, Northwest Ethiopia

Introduction

Refractive error is an important cause of correctable visual impairment in the worldwide with a global distribution of 1.75% to 20.7% among schoolchildren. Teacher’s knowledge about refractive error play an important role in encouraging students to seek treatment that helps in reducing the burden of visual impairment.

Objective

To determine knowledge, attitude and associated factors among primary school teachers regarding refractive error in school children in Gondar city.

Methods

Institution based cross-sectional study was conducted on 565 primary school teachers in Gondar city using pretested and structured self-administered questionnaire. For processing and analysis, SPSS version 20 was used and variables which had a P value of <0.05 in the multivariable analysis were considered as statistically significant.

Result

A total of 565 study subjects were participated in this study with a mean age of 42.05 ± 12.01 years. Of these study participants 55.9% (95% CI: 51.9, 59.8) had good knowledge and 57.2% (95% CI: 52.9, 61.4) had favorable attitude towards refractive error. History of spectacle use [AOR = 2.13 (95% CI: 1.32, 3.43)], history of eye examination [AOR = 1.67 (95% CI: 1.19, 2.34)], training on eye health [AOR = 1.94 (95% CI; 1.09, 3.43)] and 11–20 years of experience [AOR = 2.53 (95% CI: 1.18, 5.43)] were positively associated with knowledge. Whereas being male [AOR = 2.03 (95% CI: 1.37, 3.01)], older age [AOR = 3.05 (95% CI: 1.07, 8.72)], 31–40 years of experience [AOR = 0.23 (95% CI: 0.07, 0.72)], private school type [AOR = 1.76 (95% CI: 1.06, 2.93)] and 5^th -8^th teaching category [AOR = 1.54 (95% CI: 1.05, 2.24)] were associated with attitude.

Conclusion

Knowledge and attitude of study subjects were low which needs training of teachers about the refractive error.

The prevalence of visual disorders in Iranian students: A meta-analysis study and systematic review

Background

Visual defects have dramatic effects on health, self-esteem, and educational function of students, and delayed diagnosis will cause complications, like academic failure and psychologic disorders.

Objective

The present study aimed to investigate the prevalence of ocular disorders in Iranian students in a systematic review.

Methods

We searched databases, including PubMed, SID, Magiran, Google Scholar, and Iranmedex using the following keywords in Persian and English: disorders, vision, amblyopia, refractive errors, astigmatism, student, and Iran with all the possible combinations, important, chief, and sensitive words. Search resulted in 28 articles, conducted during a period from 1996 to 2014 in Iran and their data was analyzed using meta-analysis and random effects model. Heterogeneity of studies was assessed using I2 index, and data was finally analyzed with R Software and STATA (Version 11.2).

Results

Total number of subjects in the study was 1,117,274, aged 2 to 18 years. The prevalence of disorders related to amblyopia, refractive error, and strabismus was 8%, 7% and 1%, respectively. The greatest amount of refractive error was related to astigmatism (19%) followed by myopia (17%).

Conclusion

According to the study results, the prevalence of visual disorders among Iranian students indicated the critical necessity of screening programs for prevention of visual disorders in this age group.

Refractive Error in a Sample of Black High School Children in South Africa

SIGNIFICANCE

This study focused on a cohort that has not been studied and who currently have limited access to eye care services. The findings, while improving the understanding of the distribution of refractive errors, also enabled identification of children requiring intervention and provided a guide for future resource allocation.

PURPOSE

The aim of conducting the study was to determine the prevalence and distribution of refractive error and its association with gender, age, and school grade level.

METHODS

Using a multistage random cluster sampling, 1586 children, 632 males (40%) and 954 females (60%), were selected. Their ages ranged between 13 and 18 years with a mean of 15.81 ± 1.56 years. The visual functions evaluated included visual acuity using the logarithm of minimum angle of resolution chart and refractive error measured using the autorefractor and then refined subjectively. Axis astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule astigmatism, negative values indicated against-the-rule astigmatism, whereas J45 represented oblique astigmatism.

RESULTS

Overall, patients were myopic with a mean spherical power for right eye of -0.02 ± 0.47; mean astigmatic cylinder power was -0.09 ± 0.27 with mainly with-the-rule astigmatism (J0 = 0.01 ± 0.11). The prevalence estimates were as follows: myopia (at least -0.50) 7% (95% confidence interval [CI], 6 to 9%), hyperopia (at least 0.5) 5% (95% CI, 4 to 6%), astigmatism (at least -0.75 cylinder) 3% (95% CI, 2 to 4%), and anisometropia 3% (95% CI, 2 to 4%). There was no significant association between refractive error and any of the categories (gender, age, and grade levels).

CONCLUSIONS

The prevalence of refractive error in the sample of high school children was relatively low. Myopia was the most prevalent, and findings on its association with age suggest that the prevalence of myopia may be stabilizing at late teenage years.

Evidence for the need for vision screening of school children in Turkey

BACKGROUND

In many countries, access to general health and eye care is related to an individual's socioeconomic status (SES). We aimed to examine the prevalence of oculo-visual disorders in children in Istanbul Turkey, drawn from schools at SES extremes but geographically nearby.

METHODS

Three school-based vision screenings (presenting distance visual acuity, cover test, eye assessment history, colour vision, gross stereopsis and non-cycloplegic autorefraction) were conducted on 81% of a potential 1014 primary-school children aged 4-10 years from two private (high SES) schools and a nearby government (low SES) school in central Istanbul. Prevalence of refractive errors and school-based differences were analysed using parametric statistics (ANOVA). The remaining oculo-visual aspects were compared using non-parametric tests.

RESULTS

Of the 823 children with mean age 6.7 ± 2.2 years, approximately 10% were referred for a full eye examination (8.2% and 16.3% of private/government schools respectively). Vision had not been previously examined in nearly 22% of private school children and 65% of government school children. Of all children, 94.5% were able to accurately identify the 6/9.5 [LogMAR 0.2] line of letters/shapes with each eye and 86.6% the 6/6 line [LogMAR 0], while 7.9% presented wearing spectacles, 3.8% had impaired colour vision, 1.5% had grossly impaired stereo-vision, 1.5% exhibited strabismus, 1.8% were suspected to have amblyopia and 0.5% had reduced acuity of likely organic origin. Of the 804 without strabismus, amblyopia or organic conditions, 6.0% were myopic ≤ - 0.50DS, 0.6% hyperopic ≥ + 2.00DS, 7.7% astigmatic ≥1.00 DC and 6.2% anisometropic ≥1.00DS.

CONCLUSIONS

The results highlight the need for general vision screenings for all children prior to school entry given the varied and different pattern of visual problems associated with lifestyle differences in two populations raised in the same urban locale but drawn from different socioeconomic backgrounds.

Characteristics of astigmatism in Black South African high school children

Background

Astigmatism impairs vision at various distances and causes symptoms of asthenopia which negatively impacts reading efficiency.

Objective

The aim of conducting this study was to determine the prevalence and distribution of astigmatism and its relationship to gender, age, school grade levels and spherical ametropia.

Methods

Using a multi-stage random cluster sampling, 1589 children who included 635 (40%), males, and 954 (60%), females were selected from 13 out of a sample frame of 60 schools. Their ages ranged between 13 and 18 years with a mean of 15.81±1.56 years. The parameters evaluated included visual acuity using the LogMAR chart and refractive errors measured using an autorefractor and then refined subjectively. Axis of astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule, negative values described against-the-rule and J45 represented oblique astigmatism.

Results

The mean cylinder power was −0.09 ± 0.27 and mainly with-the-rule, J0 = 0.01 ± 0.11. The overall prevalence of clinically significant astigmatism (≤ − 0.75 cylinder) in the sample was 3.1% [(95% Confidence interval = 2.1–4.1%)]. Cylinder of at least − 0.25 power was considered to classify astigmatism types. Thus, the estimated distributions of types of astigmatism were: axis- 11.5%, sphero-astigmatism 10.1% and magnitude-astigmatism 11.2% while 67.2% had no cylinder of any magnitude.

Conclusion

The prevalence of astigmatism is relatively low in this population studied. Older children and those in high school grade levels were more likely to have with-the-rule or against-the-rule astigmatism. The prevalence of astigmatism were comparable within but not across regions.

Global and regional estimates of prevalence of refractive errors: Systematic review and meta-analysis

Purpose

The aim of the study was a systematic review of refractive errors across the world according to the WHO regions.

Methods

To extract articles on the prevalence of refractive errors for this meta-analysis, international databases were searched from 1990 to 2016. The results of the retrieved studies were merged using a random effect model and reported as estimated pool prevalence (EPP) with 95% confidence interval (CI).

Results

In children, the EPP of myopia, hyperopia, and astigmatism was 11.7% (95% CI: 10.5–13.0), 4.6% (95% CI: 3.9–5.2), and 14.9% (95% CI: 12.7–17.1), respectively. The EPP of myopia ranged from 4.9% (95% CI: 1.6–8.1) in South–East Asia to 18.2% (95% CI: 10.9–25.5) in the Western Pacific region, the EPP of hyperopia ranged from 2.2% (95% CI: 1.2–3.3) in South-East Asia to 14.3% (95% CI: 13.4–15.2) in the Americas, and the EPP of astigmatism ranged from 9.8% in South-East Asia to 27.2% in the Americas. In adults, the EPP of myopia, hyperopia, and astigmatism was 26.5% (95% CI: 23.4–29.6), 30.9% (95% CI: 26.2–35.6), and 40.4% (95% CI: 34.3–46.6), respectively. The EPP of myopia ranged from 16.2% (95% CI: 15.6–16.8) in the Americas to 32.9% (95% CI: 25.1–40.7) in South-East Asia, the EPP of hyperopia ranged from 23.1% (95% CI: 6.1%–40.2%) in Europe to 38.6% (95% CI: 22.4–54.8) in Africa and 37.2% (95% CI: 25.3–49) in the Americas, and the EPP of astigmatism ranged from 11.4% (95% CI: 2.1–20.7) in Africa to 45.6% (95% CI: 44.1–47.1) in the Americas and 44.8% (95% CI: 36.6–53.1) in South-East Asia. The results of meta-regression showed that the prevalence of myopia increased from 1993 (10.4%) to 2016 (34.2%) (P = 0.097).

Conclusion

This report showed that astigmatism was the most common refractive errors in children and adults followed by hyperopia and myopia. The highest prevalence of myopia and astigmatism was seen in South-East Asian adults. The highest prevalence of hyperopia in children and adults was seen in the Americas.

The prevalence of refractive errors in 5-15 year-old population of two underserved rural areas of Iran

Purpose

To determine the prevalence of hyperopia and myopia and their associations with age and gender in 5- to 15-year-old children in underserved rural areas in Iran.

Methods

In this cross-sectional study, sampling was done using a multistage cluster sampling method from two underprivileged rural regions in Iran, and 3851 persons over 1 year old of age were invited to the study. After inviting the selected participants, examinations were conducted at a designated site in the selected villages. All participants underwent measurements of uncorrected and corrected visual acuity, manifest refraction, and a slit-lamp examination. Cycloplegic refraction was done by instilling cyclopentolate 1% eye drops in under 15-year-old participants.

Results

Of the 3851 selected persons, 3314 subjects participated (86.5%), and of these, 602 were in the 5–15 year age group. The prevalence of myopia and hyperopia in the studied children was 2.60% [95% confidence interval (CI): 1.10–4.10] and 4.00% (95% CI: 1.84–6.15), respectively. The prevalence of myopia in male and female children was 2.65% and 2.55%, respectively (P = 0.951). The prevalence of hyperopia in male and female children was 2.83% and 5.25%, respectively (P = 0.130). The prevalence of myopia in the villages of southwest and north was 2.42% and 3.09%, respectively (P = 0.618), and the prevalence of hyperopia was 4.71% and 2.10%, respectively (P = 0.0056).

Conclusion

The present report is a brief description of the status of refractive errors in children residing in underprivileged villages of two rural districts in Iran. As presented, the prevalence of myopia is not high, although the prevalence of hyperopia is in the mid-range compared to previous studies.

The prevalence of uncorrected refractive errors in underserved rural areas

Purpose

To determine the prevalence of uncorrected refractive errors, need for spectacles, and the determinants of unmet need in underserved rural areas of Iran.

Methods

In a cross-sectional study, multistage cluster sampling was done in 2 underserved rural areas of Iran. Then, all subjects underwent vision testing and ophthalmic examinations including the measurement of uncorrected visual acuity (UCVA), best corrected visual acuity, visual acuity with current spectacles, auto-refraction, retinoscopy, and subjective refraction. Need for spectacles was defined as UCVA worse than 20/40 in the better eye that could be corrected to better than 20/40 with suitable spectacles.

Results

Of the 3851 selected individuals, 3314 participated in the study. Among participants, 18.94% [95% confidence intervals (CI): 13.48–24.39] needed spectacles and 11.23% (95% CI: 7.57–14.89) had an unmet need. The prevalence of need for spectacles was 46.8% and 23.8% in myopic and hyperopic participants, respectively. The prevalence of unmet need was 27% in myopic, 15.8% in hyperopic, and 25.46% in astigmatic participants. Multiple logistic regression showed that education and type of refractive errors were associated with uncorrected refractive errors; the odds of uncorrected refractive errors were highest in illiterate participants, and the odds of unmet need were 12.13, 5.1, and 4.92 times higher in myopic, hyperopic and astigmatic participants as compared with emmetropic individuals.

Conclusion

The prevalence of uncorrected refractive errors was rather high in our study. Since rural areas have less access to health care facilities, special attention to the correction of refractive errors in these areas, especially with inexpensive methods like spectacles, can prevent a major proportion of visual impairment.

Is there an association between convergence insufficiency and refractive errors?

Background: Refractive errors and convergence insufficiency play major roles in reading efficiency. Uncorrected refractive errors are a primary cause of binocular anomalies, including convergence insufficiency. Symptoms of asthenopia in both refractive and binocular vision anomalies are similar. Despite the relationships that exist between them, the extent of association between refractive errors and convergence insufficiency has not been studied extensively.Aim: The aim of this study was to determine the prevalence of convergence insufficiency and refractive errors and investigate their associations with gender and age in a sample of high school children.Methods: The study design was cross-sectional and comprised data from 1056 African high school students aged 13–18 years, who were randomly selected from 13 high schools in uMhlathuze municipality in the province of KwaZulu-Natal, South Africa. In the final sample, 403 (38%) were males and 653 (62%) were females. The participants’ mean age and standard deviation were 15.89 ± 1.58 years and median age was 16 years. Refractive errors, heterophoria, near point of convergence, fusional vergences and accommodative functions were evaluated.Results: Prevalences for convergence insufficiency were as follows: low suspect 12.4% (confidence interval, [CI] 10.2–14.4), high suspect 6.3% (CI, 5.0–7.9), definite 4.6% (CI, 3.4–5.9), and pseudo-convergence insufficiency 2.1% (CI, 1.2–3.0). Refractive errors were: hyperopia 6.8% (CI, 5.3–8.4), myopia 6.0% (CI, 4.6–7.5), astigmatism 2.3% (CI, 1.8–3.2), anisometropia 1.3% (CI, 0.7–2.0) and emmetropia 86.2% (CI, 85.1–89.1). There were no significant associations between convergence insufficiency and gender (p = 0.32), age (p = 0.38), grade levels (p = 0.99) or refractive errors (p = 0.08).Conclusion: The prevalence of clinically significant convergence insufficiency and refractive errors was low in this sample of black high school students in South Africa, and there was no significant correlation between them.

Neonatal Hypoglycaemia and Visual Development: A Review

BACKGROUND

Many newborn babies experience low blood glucose concentrations, a condition referred to as neonatal hypoglycaemia (NH). The effect of NH on visual development in infancy and childhood is of interest because the occipital lobes, which include the primary visual cortex and a number of extrastriate visual areas, may be particularly susceptible to NH-induced injury. In addition, a number of case series have suggested that NH can affect eye and optic nerve development.

OBJECTIVE

To review the existing literature concerning the effect of NH on the visual system.

METHODS

A PubMed, Embase, Medline, and Google Scholar literature search was conducted using prespecified MeSH terms.

RESULTS

The literature reviewed revealed no clear evidence for an effect of NH on the development of the eye and optic nerve. Furthermore, occipital and occipital-parietal lobe injuries following NH often occurred in conjunction with comorbid conditions and were not clearly linked to subsequent visual dysfunction, possibly due to difficulties in measuring vision in young children and a lack of studies at older ages. A recent, large-scale, prospective study of NH outcomes at 2 years of age found no effect of mild-to-moderate NH on visual development.

CONCLUSION

The effect of NH on visual development is unclear. It is currently unknown whether NH affects visual function in mid-to-late childhood when many visual functions reach adult levels.

The Prevalence of Amblyopia, Strabismus, and Ptosis in Schoolchildren of Dezful

Purpose To determine the prevalence of amblyopia, strabismus, and ptosis among schoolchildren in Dezful in the west of Iran. Methods In this cross-sectional study, 1,375 schoolchildren of Dezful were selected through multistage cluster sampling. After obtaining written consents, participants had uncorrected and corrected visual acuity tests, cycloplegic refraction, and the cover test, and were examined for ptosis at the school site. Results Of the 1,151 study participants (83.7%), examinations were completed for 1,130 schoolchildren. Prevalence rates of amblyopia, strabismus, and ptosis were 2.7% (95% confidence interval [CI] 0.8-4.7), 1.9% (95% CI: 0.2-3.8), and 0.8%, respectively. Anisometropia was the most common cause of amblyopia; 45.2% of cases had anisometropic amblyopia. Among cases with strabismus, 63.6% were exotropic and 36.4% were esotropic. Conclusion The present study indicated that the prevalence of amblyopia and strabismus in Dezful schoolchildren falls in the average range. Since the Amblyopia Screening Program has been running for years, we expected lower rates compared to previous years, but this was not observed. Correcting refractive errors can significantly reduce amblyopic cases.

Prevalence of Amblyopia and Refractive Errors Among Primary School Children

Purpose:

To determine the prevalence of amblyopia and refractive errors among 7 to 12-year-old primary school children in Tehran, Iran.

Methods:

This population-based cross-sectional study included 2,410 randomly selected students. Visual acuity was tested using an E-chart on Yang vision tester. Refractive errors were measured by photorefractometry and cycloautorefraction. Strabismus was checked using cover test. Direct ophthalmoscopy was used to assess the anterior segment, lens opacities, red reflex and fundus. Functional amblyopia was defined as best corrected visual acuity ≤20/40 in one or both eyes with no anatomical problems.

Results:

Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9%) of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004). Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D) was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001), that of hyperopia decreased (P=0.007), but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9) and refractive errors, especially anisometropia (OR=12.87) and hyperopia (OR=11.87), were important amblyogenic risk factors.

Conclusion:

The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations.

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.

High Prevalence of Refractive Errors in 7 Year Old Children in Iran

BACKGROUND

The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran.

METHODS

In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All children were tested by an optometrist for uncorrected and corrected vision, and non-cycloplegic and cycloplegic refraction. Refractive errors in this study were determined based on spherical equivalent (SE) cyloplegic refraction.

RESULTS

From 4614 selected children, 89.0% participated in the study, and 4072 were eligible. The prevalence rates of myopia, hyperopia and astigmatism were 3.04% (95% CI: 2.30-3.78), 6.20% (95% CI: 5.27-7.14), and 17.43% (95% CI: 15.39-19.46), respectively. Prevalence of myopia (P=0.925) and astigmatism (P=0.056) were not statistically significantly different between the two genders, but the odds of hyperopia were 1.11 (95% CI: 1.01-2.05) times higher in girls (P=0.011). The prevalence of with-the-rule astigmatism was 12.59%, against-the-rule was 2.07%, and oblique 2.65%. Overall, 22.8% (95% CI: 19.7-24.9) of the schoolchildren in this study had at least one type of refractive error.

CONCLUSION

One out of every 5 schoolchildren had some refractive error. Conducting multicenter studies throughout the Middle East can be very helpful in understanding the current distribution patterns and etiology of refractive errors compared to the previous decade.

Global variations and time trends in the prevalence of childhood myopia, a systematic review and quantitative meta-analysis: implications for aetiology and early prevention

The aim of this review was to quantify the global variation in childhood myopia prevalence over time taking account of demographic and study design factors. A systematic review identified population-based surveys with estimates of childhood myopia prevalence published by February 2015. Multilevel binomial logistic regression of log odds of myopia was used to examine the association with age, gender, urban versus rural setting and survey year, among populations of different ethnic origins, adjusting for study design factors. 143 published articles (42 countries, 374 349 subjects aged 1–18 years, 74 847 myopia cases) were included. Increase in myopia prevalence with age varied by ethnicity. East Asians showed the highest prevalence, reaching 69% (95% credible intervals (CrI) 61% to 77%) at 15 years of age (86% among Singaporean-Chinese). Blacks in Africa had the lowest prevalence; 5.5% at 15 years (95% CrI 3% to 9%). Time trends in myopia prevalence over the last decade were small in whites, increased by 23% in East Asians, with a weaker increase among South Asians. Children from urban environments have 2.6 times the odds of myopia compared with those from rural environments. In whites and East Asians sex differences emerge at about 9 years of age; by late adolescence girls are twice as likely as boys to be myopic. Marked ethnic differences in age-specific prevalence of myopia exist. Rapid increases in myopia prevalence over time, particularly in East Asians, combined with a universally higher risk of myopia in urban settings, suggest that environmental factors play an important role in myopia development, which may offer scope for prevention.