Article

The age- and gender-specific prevalences of refractive errors in Tehran: The Tehran Eye Study

July 2004
Ophthalmic Epidemiology 11(3):213-25

DOI:10.1080/09286580490514513

Source
PubMed

Authors:

Hassan Hashemi

Akbar Fotouhi

Tehran University of Medical Sciences

Kazem Mohammad

Tehran University of Medical Sciences

To determine the age- and gender-specific prevalences of refractive errors in Tehran through a population-based study. A total of 6497 citizens representing a cross-section of the population of Tehran were sampled from 160 clusters using a stratified, random, cluster sampling strategy. Eligible people were enumerated through a door-to-door household survey in the selected clusters and were invited to participate. All participants were transferred to a clinic for an extensive eye examination and interview. Refractive error was determined using manifest and cycloplegic refraction. Myopia was defined as the spherical equivalent of -0.5 diopters (D) or more and hyperopia was defined as the spherical equivalent of more than +0.5 D. Of those sampled, 4565 (70.3%) people participated in the study. Refraction data for 4354 participants aged five years and over are presented. The age- and gender-standardized prevalence of myopia based on manifest refraction was 21.8% (95% confidence interval [CI], 20.1 to 23.5) and that for hyperopia was 26.0% (95% CI, 24.5 to 27.6). The prevalences based on cycloplegic refraction were 17.2% (95% CI, 15.6 to 18.8) and 56.6% (95% CI, 54.7 to 58.6), respectively. Prevalences of myopia and hyperopia differed significantly among the age and gender groups (P < 0.001). Astigmatism of 0.75 cylinder diopter or greater was present in 29.6% (95% CI, 28.0 to 31.3) of right eyes with manifest refraction and in 30.3% (95% CI, 28.5 to 32.1) with cycloplegic refraction. Among the study population, 6.1% (95% CI, 5.3 to 6.8%) had anisometropia of 1 D or more. This report has provided details of the refractive status in the population. We have documented prevalences of myopia, hyperopia, astigmatism and anisometropia by age and gender, identifying more affected age- and gender-groups for prevention programs in the community.

Prevalence of Refractive Errors and Associated Factors in the Population of the Eye Cohort Study in Southeast Iran

Article

Full-text available

Nov 2023

Kourosh Shahraki

Objectives: The study aims to determine the age- and sex-adjusted prevalence of refractive errors and its related factors among the adult population of southeastern Iran. Methods: The current study included 9280 individuals aged 35 to 70 years using a multistage random sample method from October 2015 to January 2019 as a part of a Persian cohort study in Zahedan. Uncorrected and corrected vision, objective noncycloplegic, and subjective refraction were measured, with all participants undergoing ophthalmoscopy, slit-lamp biomicroscopy, fundoscopy, refraction, and retinoscopy. Data were analyzed using SPSS version 23.0 statistic software and described as percentage, odds ratio, and 95% confidence interval. Comparisons between groups and relationships among risk factors and refractive errors were performed with chi-square, nominal, and multiple regression analysis. Results: The prevalence of low and moderate myopia, high myopia, low and moderate hyperopia, high hyperopia, low and moderate astigmatism, and high astigmatism was 24.2 (95% CI: 22.40 - 25.90), 1.5(95% CI: 0.00 - 3.53), 16.1(95% CI: 14.20 - 17.90), 1.3(95% CI: 0.00 - 3.30), 35.6 (95% CI: 33.90 - 37.30), and 3.8 (95% CI: 1.80 - 5.70) percent, respectively. The prevalence of refractive errors significantly varied across different age groups overall and by sex (P = 0.01). The proportion of refractive errors also significantly differed by education (P = < 0.001). The prevalence of against the rule, with the rule, and oblique astigmatism was 32.8 % (95% CI: 31.10 - 34.20), 42.1% (40.50 - 43.60), and 24.9% (23.10 - 26.60), respectively. The risk of astigmatism was significantly lower in men than in women (OR = 0.75; 95 % CI: 0.60 - 0.90). Based on multiple regression, the risk of myopia (OR = 2.07; 95 % CI: 1.60 - 2.60) and hyperopia (OR = 25.38; 95 % CI: 18.70 - 34.3) was higher in the age group 65 to 75 years compared to the younger group. Conclusions: The present study provided valuable information on the prevalence of refractive errors in the adult population in south-eastern Iran. The findings underscore the need for comprehensive eye care services, particularly for older individuals and those with lower education levels. Further prospective research is warranted to explore the factors contributing to refractive errors and to develop effective strategies for its prevention and management.

Prevalence of refractive errors in Villa Maria, Córdoba, Argentina

Article

Full-text available

Jan 2016

Introduction According to World Health Organization (WHO) report in 2004, refractive errors are the second leading cause of Years Lost due to Disability (YLD) in low-and middle-income countries (1). There have been numerous population surveys all over the world in the last 20 years (2-22), showing the prevalence of refractive errors in adults. However, only one population-based study of refractive error is currently available in Argentina (23). As refractive errors are among the most frequent reasons for demand of eye-care services, prevalence data are important for public health care planning, in order to improve vision-specific quality of life. The paper by Barrenechea et al. showed that the prevalence of severe visual impairment and blindness in subjects older than 50 years old in Argentina was 2.5% and uncorrected refractive errors were the main cause of visual impairment. Background: Refractive errors are among the most frequent reasons for demand of eye-care services.

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

Article

Full-text available

Nov 2017

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.

Prevalence of refractive errors in population aged 50 years and over: The Gilan eye study

Article

Full-text available

Jun 2023

Purpose To describe the prevalence of refractive error (RE) and its association with other environmental and health factors among population aged ≥50 years who lived in Gilan, Iran in 2014. Methods In this population-based cross-sectional study, 3281 individuals aged ≥50 years living in Gilan for at least 6 months were enrolled. The prevalence of different types of REs including myopia (spherical equivalent (SE)≤-0.50D), high myopia (SE ≤ -6.00D), hyperopia (SE≥ + 0.50D), high hyperopia (SE≥ + 3.00D), astigmatism (cylinder < -0.50D) and high astigmatism (cylinder < -2.25D) were determined. Anisometropia was defined as the SE difference of ≥1.00D between the two eyes. Associated factors including age, body mass index (BMI) and education were also studied. Results 2587 eligible individuals (58% female subjects) with the mean age of 62.6 ± 8.8 years participated (87.6% response rate). The prevalence of myopia, hyperopia and astigmatism was 19.2%, 48.6% and 57.4%, respectively. 3.6% high hyperopia, 0.5% high myopia and 4.5% high astigmatism were identified. The positive simultaneous effects3 of older age (Odds Ratio (OR) = 3.14), nuclear (OR = 1.71) and posterior subcapsular (OR = 1.61) cataracts as well as the negative effects of higher levels of education (OR = 0.28) were obtained on myopia. Higher BMI was found as a risk factor for hyperopia (OR = 1.67), while older patients were less likely to be hyperopic (OR = 0.31). Conclusion Higher incidence of myopia and astigmatism was found in patients aged over 70 years. It was also found that patients at older ages who suffered with cataracts were at a higher risk of myopia, while elderly people with greater BMI were at a higher risk of hyperopia.

Study of Post Operative Regression after Photorefractive Keratectomy for Treatment of Hyperopia and Hyperopic Astigmatism

Article

Full-text available

Jan 2017

Purpose: To study post operative regression rates after photore-fractive keratectomy among patients with hyperopia and hyperopic astigmatism with follow-up of at least six months. Patients and Methods: In this historical cohort study, 171 eyes from 91 patients with moderate hyperopia and hyperopic astigma-tism were treated using Bausch and Lomb Technolas 217 Z Exci-mer Laser. Pre-operation evaluation included; best spectacle corrected visual acuity, manifest and cycloplegic refraction, diameter of optical zone, central corneal thickness and simulated keratome-try. Postoperative evaluation, performed at least six months after the procedure, included measurement of corneal curvature, manifest and cycloplegic refraction, best corrected visual acuity, uncorrected visual acuity, refraction manifest, haze, and any pathologic finding. Results: The mean regression was 0.35 ± 1.04. Post surgical manifest refraction equivalent in ± 0.5 diopter range of surgeon's desired refraction was observed in 57.1 % of eyes. Manifest refraction equivalent in ± 1.00 diopter range was observed in 85.7 % of eyes, and manifest refraction equivalent in ± 2.00 diopter range in 96.6 % of eyes. Uncorrected visual acuity of 20/20 or better was reported in 37.1 % and 20/40 or better in 92 % of patients. Loss of the best spectacle corrected visual acuity of one line was observed in 13.4 % and 2 lines or more in 5.7 % of patients. Conclusion: In patients with moderate hyperopia and hyperopic astig-matism undergoing PRK the rate of regression was in ± 1 diopter range of surgeon's intended correction in 85.7 % of patients at least six months postoperatively, which is in line with other studies findings. Introduction The prevalence of hyperopia has been reported in various studies 1-4. For example, in an epidemiological survey in the United States, the incidence of hyperopia was reported to be 21 % 1. The lowest reported hyper-opia rate in Asia has been 8.9 % in china 2,3. In a survey conducted by Hashemi et al., the prevalence of hyperopia in Tehran was 26 % 4. At present, the most common surgical technique for correcting hyperopia is corne-al refractive surgery including LASIK and Photorefractive Keratectomy (PRK) 5. Several studies have been conducted regarding the use of LASIK in correcting hyperopia 6-10 , and some researchers have reported that, since in this method the correction is performed at a deeper level of stroma, there is less chance of regression compared to PRK 11. Another advantage of this method compared to PRK is the faster retrieval of stable vision and the rapid reduction of the patients' symptoms such as pain, tearing and photophobia after the procedure 5-14. On the other hand, some complications such as corneal ectasia and epithelial in-growth, which can be the result of LASIK, are less likely to be present in PRK 5,12,15. Up to now, a limited number of studies have been performed in patients with hyperopia, regarding the degree of regression 13,14,16. For example, Juhás et al. reported that among patients with less than 3.5 diopters of hyper-opia between 62 % and 70 % stayed within 1 diopter of desired correction over a 1 year period, and for patients with hyperopia greater than 3.5 diopters this rate was between 32 % and 44 % 17. In another study by Nagy et al., this rate was 84.8 % for patients with hyperopia less than 3.5 diopters and 46.8 % for those patients with hyperopia greater than 3.5 diopters

Prevalence of refractive errors in Colombia: MIOPUR study

Article

Full-text available

Jun 2018

Purpose To determine the prevalence of refractive errors in Colombia and its relations with demographic and socioeconomic variables. Methods A cross-sectional study performed in 10 Colombian administrative districts (MIOPUR study), including children and adolescents from 8 to 17 years old and adults from 35 to 55 years old. Results 3608 individuals (100% of whom agreed to participate) were included. Prevalence estimates of refractive errors were: hyperopia 32.3% (95% CI 30.7 to 33.8), myopia 12.9% (95% CI 11.8 to 14.0), mixed astigmatism 2.8% (95% CI 2.2 to 3.3) and anisometropia 1.9% (95% CI 1.4 to 2.3). Prevalence of myopia in 15-year-old adolescents was 14.7%. In children and adolescents, the hyperopia prevalence decreased while myopia prevalence increased with age. In the adults group, the tendency was the contrary. Myopia prevalence reached 15.7% in urban and 9.2% in rural areas, and for hyperopia, the rates were 29.4% in urban and 36.1% in rural areas. In the multivariate analysis, living in an urban area significantly increased the risk of having myopia (OR: 1.45 (1.12 to 1.89); p<0.01). There were significant regional differences among diverse zones of the country. Conclusions Prevalence estimates of myopia and hyperopia in Colombia were found to be at an intermediate point compared with global data. In adults, myopia frequency was lower than in European and Asian studies. The prevalence of myopia increased during childhood and adolescence and was higher in middle-aged adults (35–39 years) than in older adults. On the other hand, hyperopia rates increased with age, findings that suggest a cohort effect. In the multivariate analysis, residence in urban areas and living in a medium-high socioeconomic status were linked to myopia.

Systematic review and meta-analysis of myopia prevalence in Brazilian school children

Article

Full-text available

Oct 2024

Introduction Myopia is a growing global concern and there is a lack of studies on its prevalence among Brazilian schoolchildren. Methods This study aimed to determine the prevalence of myopia in Brazilian children aged 3–18 years through a review and meta-analysis of published studies. Eleven high-quality studies were analyzed following the 2022 PRISMA guidelines. Prevalence was calculated using a meta-analysis, considering the heterogeneity among the studies. Results The overall crude prevalence of myopia in Brazilian children was 7.65%. There was no significant association with the age of the children examined and no significant temporal trend was observed. Approximately one in 13 Brazilian schoolchildren had myopia. Conclusion Given the increased exposure of Brazilian youth to the risk factors for myopia, it is crucial to monitor myopia in the country. Further studies are required to address and prevent myopia in Brazil. Keywords: Myopia; Prevalence; Child; Brazil

Myopia Prevalence in Latin American Children and Adolescents: A Systematic Review and Meta-Analysis

Article

Full-text available

Jun 2024

Although myopia is a growing global concern, comprehensive studies on its prevalence among Latin American (LATAM) children and adolescents are still lacking. Thus, we conducted a systematic review and meta-analysis to determine the prevalence of myopia in LATAM children and adolescents aged three to 20. The study conducted a thorough literature search from January 1, 1975, to February 28, 2023, identifying 24 studies on the prevalence of myopia in LATAM that met the inclusion criteria. Quality assessment and standardized data collection were performed. The meta-analysis used a random-effects model due to heterogeneity and calculated prevalence rates. Finally, the analysis of data from 24 eligible studies revealed a myopia prevalence of 8.61% (range 0.80-47.36%, 95% confidence interval (CI): 5.22-13.87%, p < 0.05) among 165,721 LATAM children and adolescents. No significant age-based associations or temporal trends were observed in this study. Studies with non-cycloplegic or objective assessment exhibited a numerically higher, although statistically non-significant, myopia prevalence (10.62%, 95% CI: 4.9-21.6%) compared to studies using cycloplegia (7.17%, 95% CI: 3.40-14.50%). In conclusion, myopia affects approximately one in 11 LATAM children and adolescents. Given the increasing exposure of LATAM youth to known myopia risk factors, such as extensive near-work, online learning, and limited outdoor activities, it is crucial to monitor myopia trends in this region. Further research is imperative to address and prevent myopia in LATAM.

Distribution and prevalence of refractive error in Iranian adult population results of the PERSIAN eye cohort study PECS

Article

Full-text available

Jun 2024

The Persian Eye Cohort Study, a population-based cross-sectional study from 2015 to 2020, examined refractive error prevalence among 48,618 Iranian adults aged 31 to 70. The study encompassed six centers in Iran, employing random cluster sampling for demographic, medical, and socioeconomic data collection through interviews. Ophthalmic exams included visual acuity, automated and manual objective refraction, subjective refraction, slit lamp, and fundus examinations. Using the spherical equivalent definition, the sample population was categorized into groups. Results indicated a mean age of 49.52 ± 9.31 and a mean refractive error of 0.26 diopters (D) ± 1.6 SD (95% CI − 0.27 to -0.24), ranging from -26.1 to + 18.5 SD. Prevalence of myopia (< −0.5D) and hyperopia (> + 0.5D) was 22.6% (95% CI 22.2–23%) and 12.5% (95% CI 12.1–12.8%), respectively. Regarding different age groups, the prevalence of hyperopia and astigmatism exhibited a steady and significant rise with increasing age (p-value < 0.001 for both). The prevalence of Myopia, however, showed a distinctive pattern, initially increasing in adults under 45, declining in those aged 55–64, and rising again among individuals aged 60 and older. Female gender, older age, urban residency, higher education, higher income, and Fars ethnicity were significantly related to a higher prevalence of myopia (p-value < 0.001 for all). Female gender (p-value < 0.001), aging (p-value < 0.001), urban residency (p-value = 0.029), and lower-income (p-value = 0.005) were significantly related to higher prevalence of hyperopia. Astigmatism (> 1D) was prevalent in 25.5% of participants (95% CI 25.1–25.9%) and correlated with male gender, aging, urban residency, illiteracy, and higher income (p-value < 0.001, < 0.001, < 0.001, < 0.001, 0.014, respectively). The study’s comparison with regional and international surveys highlighted the increase in myopia among those over 65 due to higher nuclear cataract rates in older adults. Myopia positively related to education, income, and urban residency, while hyperopia did not exhibit such associations.

Myopia intervention and Ultraviolet radiation related eye diseases: A narrative literature review

Article

Full-text available

May 2024

There has been an increased understanding of the protective effect of two or more hours in high lux light on the development and progression of myopia. The aim of myopia management is to reduce the incidence of high myopia and sight-threatening myopic complications. Equally important are the sight-threatening complications of ultraviolet radiation (UVR) on the eye and adnexal structures. This review will analyze the literature for both these epidemics to help guide public health policy. Whilst increasing childhood high lux light exposure is important, consideration of a holistic eye health policy should ensure that UV eye diseases are also prevented. The advent of ultraviolet (UV) fluorescence photography has increased our understanding that significant UV eye damage occurs in childhood, with 81% of children aged 12–15 years having signs of UV eye damage. Hence, the need to reduce myopia and protect from UV-related eye diseases needs simultaneous consideration. Advocating for eye protection is important, particularly as the natural squint reflex is disabled with dark sunglasses lenses. The pathways UV reaches the eye need to be considered and addressed to ensure that sunglasses offer optimum UV eye protection. The design of protective sunglasses that simultaneously allow high lux light exposure and protect from UVR is critical in combating both these epidemics.

Following prevalence of myopia in a large Swiss military cohort over the last decade: where is the European “myopia boom”?

Article

Full-text available

Apr 2024
GRAEF ARCH CLIN EXP

Purpose Myopia prevalence is increasing globally, with the highest rates found in Asia. Data from European countries is scarce. We aimed to investigate whether the prevalence of myopia is rising in our meridians. Methods Data from male military conscripts for the recruitment period of 2008–2017 were retrospectively analyzed. Year of recruitment, conscripts’ birth year, visual acuity, refractive status (spherical equivalent), and spectacle wear (yes/no) were available. Results The dataset contained data of a total of 355,657 male conscripts, who had been recruited in the years 2008 to 2017. The mean number of conscripts per year was 35,566 (MD = 35,440, SD = 1249), reaching a minimum number of 33,998 conscripts in 2017 and a maximum of 37,594 in 2011. Mean age at recruitment was 19.7 years (MD = 19.0 years, SD = 1.1 years). Overall, the number of conscripts wearing spectacles remained stable over the observation time; on average 29.6% (n = 10,540; MD = 10,472; SD = 492) of conscripts wore glasses at recruitment. Of 21.8% (n = 77,698) of conscripts, data on the refractive status was available: The mean spherical equivalent for both right and left eyes was -2.3D (MD = -2 D, SD = 2.4 D). No decrease in mean spherical equivalent per recruitment year was noted over the observation period. Estimated myopia prevalence reached an average of 27.5% (SD = 0.8%) and did not increase during the observation period. Conclusion In summary, no change in spherical equivalent refractive errors of male Swiss army conscripts was found for the years 2008–2017. Equally, the percentage of spectacle wearers (MN = 29.6%) and estimated myopia prevalence (MN = 27.5%) did not significantly increase during the observation time. Trial registration: BASEC 2019-00060 (18/01/2019)

Dissecting the complex sex-based associations of myopia with height and weight

Article

Jan 2024

Objectives: To assess height and weight as possible sex-specific risk factors for bilateral myopia among young adults. Methods: We conducted a cross-sectional study including 101,438 pre-enlisted young adult males and females, aged 17.4 ± 0.6 and 17.3 ± 0.5 years, respectively, and born during 1971-1994. Categories of BMI (body mass index) were defined according to sex-related percentiles for 17-year-olds following U.S. Centers for Disease Control and Prevention growth charts, and subjects were divided into five height and weight categories according to sex-adjusted percentiles. Data included best-corrected visual acuity, diverse socio-demographic variables, anthropometric indices, and refractive errors, namely bilateral myopes and emmetropes. Results: The prevalence of bilateral myopia in males and females was 19.1% and 26.0%, respectively. Bilateral myopia displayed a J-shaped associated with BMI, achieving statistical significance only among males (p < 0.0001). Weight displayed a U-shaped association with bilateral myopia among both young males (p < 0.0001) and females (p < 0.005). A higher prevalence of bilateral myopia was observed only among males of the lower height category (p < 0.0001), even when controlling for BMI (from normal to obesity). In a multivariable regression model, obesity was associated with higher prevalence of bilateral myopia (OR: 1.21; 95% CI: 1.07-1.38, p = 0.002), only among males. There were no interactions of BMI with height or weight. Bilateral myopia was also associated with prehypertension among males (OR: 1.10, 95% CI: 1.04-1.15, p < 0.001). Conclusions: A higher risk for bilateral myopia was associated with either BMI solely or height and weight, as well as pre-hypertension, in males. The possible association with low height requires further research.

Distribution and Prevalence of Refractive Error in Iranian Adult Population, A Cross- sectional Population-based Study (Results of the PERSIAN Eye Cohort Study(PECS))

Preprint

Full-text available

Dec 2023

The PERSIAN Eye Cohort Study, a population-based cross-sectional study from 2015 to 2020, examined refractive error prevalence among 48618 Iranian adults aged 31 to 70. The study encompassed six centers in Iran, employing random cluster sampling for demographic, medical, and socioeconomic data collection through interviews. Ophthalmic exams included visual acuity, automated and manual objective refraction, subjective refraction, slit lamp, and fundus examinations. Using the spherical equivalent definition, the sample population was categorized into groups. Results indicated a mean age of 49.52 ± 9.31 and a mean refractive error of 0.26 diopters (D) ± 1.6 SD (95% CI: -0.27 to -0.24), ranging from − 26.1 to + 18.5 SD. Prevalence of myopia (<-0.5D) and hyperopia ( > + 0.5) was 22.6% (95% CI: 22.2–23%) and 12.5% (95% CI: 12.1–12.8%), respectively. Myopia significantly associated with female gender, older age, urban residency, higher education, higher income, and Fars ethnicity (p-value < 0.001 for all). Hyperopia significantly associated with female gender (p-value < 0.001), aging (p-value < 0.001), urban residency (p-value = 0.029), and lower income (p-value = 0.005). Astigmatism (> 1 D) was prevalent in 25.5% of participants (95% CI: 25.1–25.9%) and correlated with male gender, aging, urban residency, illiteracy, and higher income (p-value < 0.001, < 0.001, < 0.001, < 0.001, 0.014, respectively). The study's comparison with regional and international surveys highlighted the increase in myopia among those over 65 due to higher nuclear cataract rates in older adults. Myopia positively related to education, income, and urban residency, while hyperopia did not exhibit such associations.

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Systematic review and meta-analysis of myopia prevalence in African school children

Article

Full-text available

Feb 2022
PLOS ONE

Purpose Increased prevalence of myopia is a major public health challenge worldwide, including in Africa. While previous studies have shown an increasing prevalence in Africa, there is no collective review of evidence on the magnitude of myopia in African school children. Hence, this study reviews the evidence and provides a meta-analysis of the prevalence of myopia in African school children. Methods This review was conducted using the 2020 Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Five computerized bibliographic databases, PUBMED, Scopus, Web of Science, ProQuest, and Africa Index Medicus were searched for published studies on the prevalence of myopia in Africa from 1 January 2000 to 18 August 2021. Studies were assessed for methodological quality. Data were gathered by gender, age and refraction technique and standardized to the definition of myopia as refractive error ≥ 0.50 diopter. A meta-analysis was conducted to estimate the prevalence. Significant heterogeneity was detected among the various studies (I² >50%), hence a random effect model was used, and sensitivity analysis was performed to examine the effects of outliers. Results We included data from 24 quality assessed studies, covering 36,395 African children. The overall crude prevalence of myopia over the last two decades is 4.7% (95% CI, 3.9–5.7) in African children. Although the prevalence of myopia was slightly higher in females (5.3%, 95%CI: 4.1, 6.5) than in males (3.7%, 95% CI, 2.6–4.7; p = 0.297) and higher in older [12–18 years 5.1% (95% CI, 3.8–6.3) than younger children (aged 5–11 years, 3.4%, 95% CI, 2.5–4.4; p = 0.091), the differences were not significant. There was a significantly lower prevalence of myopia with cycloplegic compared with non-cycloplegic refraction [4.2%, 95%CI: 3.3, 5.1 versus 6.4%, 95%CI: 4.4, 8.4; p = 0.046]. Conclusions Our results showed that myopia affects about one in twenty African schoolchildren, and it is overestimated in non-cycloplegic refraction. Clinical interventions to reduce the prevalence of myopia in the region should target females, and school children who are aged 12–18 years.

Choroidal Thickness Measured by Ocular Coherence Tomography (SD-OCT) and Body Mass Index in Healthy Saudi Women: A Cross-sectional Controlled Study

Article

Full-text available

Jan 2022

Background: Obesity is one of the major public health problems globally, especially among women. Obesity is associated with glaucoma, cataract, age-related macular degeneration and diabetic retinopathy. Although it is clear that the anatomy and physiologic functions of the choroid may be affected by obesity, data investigating the effect of obesity on the choroid is limited, and/or unavailable for the Saudi population. Objective: To assess choroidal thickness (CT) changes in a sample of healthy Saudi Arabian women with different body mass index (BMI) using spectral domain ocular coherence tomography (SD-OCT). Methods: A total of 140 healthy women aged 18-29 years (mean age± standard deviation SD, 24.5 ± 1.7 years) with different BMI, axial length (AL) ≤24 ± 1.0 mm, and spherical equivalent refraction (SER) of ≤±2.0 dioptres were enrolled for the study. The participants were age and refraction-matched, and grouped into underweight (BMI ≤18.0 kg/m2) (n=30), normal (control group) (18.5-24.9 kg/m2) (n=43), overweight (25.0-29.9 kg/m2) (n=37), and obese study groups (≥30.0 kg/m2) (n=30). SD-OCT imaging was performed on one eye of each participant. Comparisons among groups for all locations and the associations between CT and other variables were examined. Results: The mean CT at the subfoveal region (285 ± 31 µm, range: 203 µm to 399 µm) was significantly greater and lowest in the nasal region (248 ± 26 µm, range 154 to 304) compared with other locations, across all the groups (p < 0.05). Compared with the control, the subfoveal choroid was thinner in the obese group (mean difference 22.6µm, 95% confidence interval CI: 8.6 µm to 36.6 µm; p = 0.02) and across all locations (p < 0.05) but thicker at the temporal location in the underweight group (12.4µm, 95%CI: -23.7 µm to -1.04 µm; p = 0.01). No significant association of subfoveal CT with any of the measured parameter including age (p-values ranged from 0.10 to 0.90) was found. Conclusion: BMI may have an influence on the CT of healthy individuals and could be a cofounder in research studies on CT. It is therefore recommended that BMI be evaluated in the clinical diagnosis and management of conditions associated with choroid in healthy individuals.

Refractive and Vision Status in Down Syndrome: A Comparative Study

Article

Full-text available

Aug 2021

Objectives: To determine the prevalence of refractive errors and visual impairment in Down syndrome (DS) patients compared to normal controls. Materials and methods: Cycloplegic refraction was tested in 213 DS patients and 184 normal age- and gender-matched controls using autorefraction followed by retinoscopy. Data from the worse eye of each case were used in the analyses. Results: In the DS and control groups, respectively, mean age was 17.2±4.8 and 17.2±4.4 years (p=0.993) and 53.0% and 49.5% were male (p=0.473). In the DS and control groups, respectively, mean spherical equivalent (SE) was -5.13±4.47 and -4.15±3.04 diopters (D) in myopics (p=0.050) and 2.47±1.64 and 2.36±2.04 D in hyperopics (p=0.482), mean cylinder error was -2.17±1.39 and -2.05±1.57 D (p=0.451), mean J0 was -0.03±0.89 and 0.12±0.76 D (p=0.086), and mean J45 was 0.11±1.02 and -0.13±1.03 D (p=0.024). The prevalence of oblique astigmatism was higher in the DS group (20.4% vs. 6.1%) while against-the-rule astigmatism was more prevalent in the control group (84.0% vs. 71.6%) (p<0.001). The prevalence of anisometropia was not significantly different between the groups (19.4% vs. 13.8%). Visual impairment was detected in 11.7% of the DS and 0.5% of the control group (p<0.001). The prevalence of amblyopia was 36.3% and 3.8% in the DS and control groups, respectively (p<0.001). Based on the multiple model, only absolute SE inversely correlated with age and differed between males and females (all p<0.05). Conclusion: In DS patients, the prevalence rates of refractive errors, amblyopia, and visual impairment are higher than those in non-DS individuals, and emmetropization appears to be either defective or slow. Cylinder error is stable in this age range, but the rotation of astigmatism axis is different from normal samples.

Design, methodology, and baseline of whole city-million scale children and adolescents myopia survey (CAMS) in Wenzhou, China

Article

Full-text available

Dec 2021

Background Myopia is the most common visual impairment in children and adolescents worldwide. This study described an economical and effective population-based screening pipeline and performed the project of a million scale children and adolescents myopia survey (CAMS), which will shed light on the further study of myopia from the level of epidemiology and precision medicine. Methods We developed a novel population-based screening pattern, an intelligent screening process and internet-based information transmission and analysis system to carry out the survey consisting of school children in Wenzhou, China. The examination items include unaided distance visual acuity, presenting distance visual acuity, and non-cycloplegic autorefraction. Myopia and high myopia were defined as spherical equivalent (SE) ≤ − 1.00 diopters (D) and SE ≤ − 6.00 D, respectively. Next, the reports of the vision checking were automatically sent to parents and the related departments. The CAMS project will be done two to four times annually with the support of the government. An online eyesight status information management system (OESIMS) was developed to construct comprehensive and efficient electronic vision health records (EVHRs) for myopia information inquiry, risk pre-warning, and further study. Results The CAMS completed the first-round of screening within 30 days for 99.41% of Wenzhou students from districts and counties, in June 2019. A total of 1,060,925 participants were eligible for CAMS and 1,054,251 (99.37% participation rate) were selected through data quality control, which comprised 1305 schools, and 580,609, 251,050 and 170,967 elementary, middle, and high school students. The mean age of participants was 12.21 ± 3.32 years (6–20 years), the female-to-male ratio was 0.82. The prevalence of myopia in elementary, middle, and high school students was 38.16%, 77.52%, and 84.00%, respectively, and the high myopia incidence was 0.95%, 6.90%, and 12.98%. Conclusions The CAMS standardized myopia screening model involves automating large-scale information collection, data transmission, data analysis and early warning, thereby supporting myopia prevention and control. The entire survey reduced 90% of staff, cost, and time consumption compared with previous surveys. This will provide new insights for decision support for public health intervention.

Risk Factors for Myopia: Putting Causal Pathways into a Social Context

Chapter

Full-text available

Oct 2019

Myopia is often described as resulting from a complex set of interactions between genetic and environmental risk factors. Rare forms of strongly familial myopia account for myopia in around 1% of any population. “School myopia”, the most common form in most modern societies, is also influenced by genetic factors, but changes in environmental risk factors appear to be responsible for the major increases in the prevalence of myopia in some parts of East and Southeast Asia. Two major environmental risk factors have been identified—intensive schooling and limited time outdoors, with educational pressures high and time outdoors particularly limited in the parts of East and Southeast Asia afflicted by an epidemic of school myopia. Several other “independent” risk factors for myopia have been reported. The effects of many of these may be mediated by modulation of the two major risk factors, and in future studies on risk factors, mediation analysis needs to be used systematically. In the case of school myopia, we argue that there are two major environmental risk factors, with a limited role for genetic variation and minimal interactions. We propose a method for comparing the impact of identified genetic risk factors with the cumulative effects of environmental exposures. This suggests that genetic risk factors associated with more myopic refractions generally lead to myopia only when combined with exposures to environmental risk factors. The predominant role played by increased educational pressures and limited time outdoors suggests strategies for controlling the current epidemic of myopia by directly reducing educational pressures, perhaps by limiting homework and rote learning in the early school years, combined with increases in time spent outdoors in schools. Identification of distal environmental factors, such as early onset of competition for selective academic streams and schools, and the use of after-school tutorial classes also suggest strategies for reducing the current epidemic through changes at the school system level. When combined with clinical techniques for controlling the progression of myopia, these measures have the potential to markedly reduce the current high prevalence rates of both myopia and sight-threatening pathological high myopia.

Global Epidemiology of Myopia

Chapter

Full-text available

Oct 2019

East Asia has been faced with an increasing prevalence of myopia and the same trend has been shown in other parts of the world to a lesser extent. In population-based studies on children, the prevalence of myopia varies highly between East Asian populations and other clusters, with generally lower prevalence in rural areas than in urban areas. These geographic and/or ethnic differences can be explained by genetic and/or environmental factors, as evidenced by studies on migrant populations. On the other hand, these differences are not pronounced in adult populations. High myopia may be associated with several ocular complications later in life and can be one of the main causes of visual impairment. In general, the risk of pathologic myopia (PM) increases with the severity of high myopia and age. The prevalence of visual impairment attributed to PM is 7% in Western populations and 12–27% in Asian populations. Studies have reported 25% of high myopia may develop PM; while 50% of those with PM may develop visual impairment as older adults. Based on the current prevalence of high myopia in young adults (6.7–21.6%) in East Asian countries, the prevalence of visual impairment attributed to PM may increase in the future, as these young adults get older. This chapter summarizes current population-based studies and highlights the world pattern and generational trends of the prevalence of high myopia and PM.

Refractive errors in an elderly rural Japanese population: The Kumejima study

Article

Full-text available

Nov 2018
PLOS ONE

The prevalence of refractive errors, which closely relates to visual function difficulties, several ocular disorders, and decreased quality of life, varies among countries and populations. One of the highest prevalence of myopia (spherical equivalent [SE] < -0.5 diopters [D], 41.8%) has been reported in an urban city (Tajimi) in central Japan. Here, we assess refractive conditions in a rural southwestern island (Kumejima) of Japan, where a high prevalence of glaucoma, especially angle-closure glaucoma, has been found. In Kumejima, the prevalence of myopia (SE < -0.5 D), high myopia (SE < -5 D), hyperopia (SE > +0.5 D), refractive astigmatism (cylinder > 0.5 D), and anisometropia (difference in SE between eyes > 1.0 D) were 29.5%, 1.9%, 34.1%, 38.8%, and 15.5%, respectively. Myopia decreased with age up to 70 years old but increased slightly thereafter, whereas hyperopia increased up to 70 years old and was unchanged thereafter. The prevalence of astigmatism and anisometropia was higher in older subjects. The prevalence of myopia and high myopia was higher than most of white, Hispanic, and other Asian populations, while was considerably lower than in the urban city of Japan. The high prevalence of hyperopia should be associated with high prevalence of angle closure glaucoma in this island.

Prevalence of Refractive Errors in Iranian University Students in Kazerun

Article

Full-text available

Sep 2018

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.

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

Article

Full-text available

Dec 2017
BMC Ophthalmol

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. Electronic supplementary material The online version of this article (10.1186/s12886-017-0618-9) contains supplementary material, which is available to authorized users.

Six-year changes in refraction and related ocular biometric factors in an adult Chinese population

Article

Full-text available

Aug 2017
PLOS ONE

Purpose To investigate longitudinal changes in refraction and biometry in Chinese adults. Design Population-based prospective cohort study. Methods 1817 subjects aged ≥ 35 years were randomly recruited from Yuexiu district, Guangzhou, China in 2008. Of which 1595 (87.8%) were reexamined in 2010 and 1427 (78.5%) were reexamined in 2014. Non-cycloplegic automated refraction and visual acuity test were performed at baseline and the 6-year follow-up examination for all participants. In addition, 50% of the participants were randomly selected for axial length (AL), anterior chamber depth (ACD) and lens thickness (LT) measurements using non-contact partial coherence laser interferometry. Lens power (LP) was calculated with the Bennett’s equation. Results A total of 1300 participants were included in current analysis (2008 mean [SD] age, 51.4 [10.6] years; 54.5% women). Mean change in spherical equivalence (SE) was +0.24 (95% confidence interval [CI], +0.19 to +0.30), +0.51 (95% CI, +0.46 to +0.57), +0.26 (95% CI, +0.15 to +0.38) and -0.05 (95% CI, -0.21 to +0.10) diopters (D) for individuals in the age groups of 35 to 44, 45 to 54, 55 to 64 and 65+ years at baseline, respectively. Corneal power, AL and LT increased while ACD and LP decreased during the follow-up. Baseline SE and changes in biometric factors could explain 97.2% of the variance in longitudinal SE change while LP solely could explain 65.2%. Six-year mean change in cylinder power was -0.16 (95% CI, -0.19 to -0.13) D, the axis of astigmatism changed from “with-the-rule” to “against-the-rule” in 16.4% of the participants and to “oblique” in 0.9%. Conclusions This study confirms a hyperopic shift in the elderly before 65 years old and a myopic shift thereafter. Longitudinal refraction change could be well explained by corresponding biometry changes, especially LP. There is also a shift to “against-the-rule” astigmatism for the adult population.

The prevalence of refractive errors among adult rural populations in Iran: Refractive errors in rural Iran Hashemi, Nabovati, Yekta, Shokrollahzadeh and Khabazkhoob

Article

Jul 2017

Prevalence of Refractive Errors among School Children Aged 5 to 15 Years Old at CHU-IOTA

Article

Jan 2024

Prevalence of refractive errors and visual impairment due to refractive errors among school children in Cairo, Egypt

Article

Sep 2023

Aim The aim of this research was to study the distribution and patterns of refractive errors (REs) among school children and the incidence of amblyopia in each type. Patients and methods This is an observational nonrandomized population-based cross-sectional study that included children aged 6-18 years attending the Outpatient Clinic of Al-Zahraa University Hospital, Al-Azhar University, Cairo, Egypt. All children were subjected to comprehensive eye examination including best corrected visual acuity (BCVA), expressed in LogMAR, cycloplegic REs that was documented using a NIDEK auto-refractometer-keratometer, cover-uncover testing, and fundus examination. The prevalence of REs, amblyopia, and anisometropia was estimated. Results The study included 960 children (1920 eyes), with a mean age of 13.08±3.41 years. Emmetropia was found in 834 (43.4%) eyes, while myopia was reported in 587 (30.6%) eyes, hypermetropia in 114 (5.9%) eyes, and myopic astigmatism in 385 (20%) eyes. Anisometropia was reported in 65 (6.77%) children, while amblyopia was found in 49 (5.1%) eyes. The amblyopia prevalence was statistically significantly higher among the hypermetropic group (3.9%) than the myopic astigmatism group (1.2%), ( P = 0.031). Conclusion The overall prevalence of REs among the examined children was 56.6% mainly myopia followed by myopic astigmatism and lastly hypermetropia. This draws the attention to the increased incidence of myopia which needs further social studies.

Peripapillary atrophy area predicts the decrease of macular choroidal thickness in young adults during myopia progression

Article

Full-text available

Apr 2024

Objective This study aimed to investigate the influence of peripapillary atrophy (PPA) area and axial elongation on the longitudinal changes in macular choroidal thickness (ChT) in young individuals with myopia. Methods and analysis In this longitudinal investigation, 431 eyes—342 categorised as non-high myopia (non-HM) and 89 as HM—were examined for 2 years. Participants were examined with swept-source optical coherence tomography. The macular ChT, PPA area and axial length (AL) were measured at baseline and follow-up visits. Multiple regression analysis was performed to identify factors associated with ChT changes. The areas under the receiver operating characteristic curves were analysed to ascertain the predictive capacity of the PPA area and axial elongation for the reduction in macular ChT. Results Initial measurements revealed that the average macular ChT was 240.35±56.15 µm in the non-HM group and 198.43±50.27 µm in the HM group (p<0.001). It was observed that the HM group experienced a significantly greater reduction in average macular ChT (−7.35±11.70 µm) than the non-HM group (−1.85±16.95 µm, p=0.004). Multivariate regression analysis showed that a greater reduction of ChT was associated with baseline PPA area (β=−26.646, p<0.001) and the change in AL (β=−35.230, p<0.001). The combination of the baseline PPA area with the change in AL was found to be effective in predicting the decrease in macular ChT, with an area under the curve of 0.741 (95% CI 0.694 to 0.787). Conclusion Over 2 years, eyes with HM exhibit a more significant decrease in ChT than those without HM. Combining the baseline PPA area with the change in AL could be used to predict the decrease of macular ChT.

Mean cycloplegic refractive error in emmetropic adults - The Tehran Eye Study

Article

Full-text available

Jan 2024

Purpose In children under 20 years, refractive development targets a cycloplegic refractive error of +0.5 to +1.5D, while presbyopes over 40 years generally have non-cycloplegic errors of ≥ +1D. Some papers suggest these periods are separated by a period of myopic refractive error (i.e., ≤ –0.50D), but this remains unclear. Hence, this work investigates the mean cycloplegic refractive error in adults aged between 20 – 40 years. Methods In 2002 a cross-sectional study with stratified cluster sampling was performed on the population of Tehran, providing cycloplegic and non-cycloplegic refractive error data for the right eyes of 3,576 participants, aged 30.6 ± 18.6 years (range: 1–86 years). After grouping these data into age groups of 5 years, the refractive error histogram of each group was fitted to a Bigaussian function. The mean of the central, emmetropized peak was used to estimate the mean refractive error without the influence of myopia. Results The mean cycloplegic refractive error at the emmetropized peak decreased from +1.10 ± 0.11D (95 % confidence interval) to +0.50 ± 0.04D before 20 years and remains stable at that value until the age of 50 years. The non-cycloplegic refractive error also sees a stable phase at 0.00 ± 0.04D between 15 – 45 years. After 45 – 50 years both cycloplegic and non-cycloplegic refractive error become more hypermetropic over time, +1.14 ± 0.12D at 75 years. Conclusions The cycloplegic refractive error in adults is about +0.50D between 20 – 50 years, disproving the existence of the myopic period at those ages.

Profile of Refractive Errors Among Mansoura University Students

Article

Full-text available

Jan 2021

Introduction: To assess the prevalence of refractive errors, identifying the associated factors, and to correlate demographic

Comparative and longitudinal analysis of axial and retinal biometry in prospective models of hyperopia

Preprint

Full-text available

May 2022

Purpose To quantify changes in axial and retinal biometry in aging hyperopic mouse models. Methods Fundus photographs and ocular biometric measurements from Mfrp rd6 , Prss56 glcr4 , Adipor1 tm1Dgen , C1qtnf5 tm1.1(KOMP)Vlcg and Prss56 em2(IMPC)J homozygotes and C57BL/6J control mice were ascertained longitudinally up to one year of age. Parameters including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), outer nuclear layer thickness (ONLT), retinal thickness (RT), vitreous chamber depth (VCD) and posterior length (PL) were measured using Spectral Domain-Optical Coherence Tomography imaging. Mixed-model analysis of variance and factorial analysis of covariance, using body size as a covariate, followed by post-hoc analysis was performed to identify significant strain differences. Results Strain specific changes in axial and retinal biometry along with significant effects of age, sex and body size on AL were noted. Mfrp rd6 , Prss56 glcr4 , Adipor1 tm1Dgen and Prss56 em2(IMPC)J homozygotes had significantly shorter AL than controls. While a comparable decrease in PL was observed in Mfrp rd6 , Prss56 glcr4 , and Adipor1 tm1Dgen homozygotes, the decrease was attributed to changes in different posterior components from each mutant. Mfrp rd6 and Adipor1 tm1Dgen homozygotes developed regularly sized fundus spots across the ocular globe, which differed from the large bright spots seen in aged Prss56 glcr4 and Prss56 em2(IMPC)J homozygotes. While ONLT of C1qtnf5 tm1.1(KOMP)Vlcg mice was less than controls, AL and fundus images appeared normal. Conclusions This study highlights differences in contributions of ocular components to AL among hyperopic mouse models with decreased AL. Understanding the mechanisms through which these proteins function, will help to elucidate their role in controlling ocular growth.

Profile of Refractive Errors Among Mansoura University Students

Article

Full-text available

May 2021

Introduction: To assess the prevalence of refractive errors, identifying the associated factors, and to correlate demographic characteristics (sex, and family history) with different types of refractive errors among Mansoura University students.

Profile of Refractive Errors Among Mansoura University Students

Article

Jun 2021

Tharwat Mokbel

The prevalence of refractive error in schoolchildren

Article

Jan 2022

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.

Orthokeratology Lenses Versus Administration of 0.01% Atropine Eye Drops for Axial Length Elongation in Children With Myopic Anisometropia

Article

Oct 2021
Eye Contact Lens

Objective: To investigate the effect of orthokeratology (OK) lenses and that of 0.01% atropine eye drops on axial length (AL) elongation in children with myopic anisometropia. Methods: Ninety-five children with myopic anisometropia who used OK lenses (N=49) or 0.01% atropine eye drops (N=46) were enrolled in this retrospective 1-year study. For all children, the eyes with higher spherical equivalent refractive error (SER) were assigned to the H-eye subgroup, whereas the fellow eyes with lower SER were assigned to the L-eye subgroup. Results: After 1-year treatment, the mean change in the AL of H eyes and L eyes in the OK lenses group was 0.18±0.16 mm and 0.24±0.15 mm, respectively (P=0.15), and 0.28±0.20 mm and 0.25±0.18 mm, respectively (P=0.48), in the 0.01% atropine group. Multivariate regression analyses showed significant differences in AL change between H and L eyes after treatment with OK lens (P=0.03), whereas no significant difference in the 0.01% atropine (P=0.22). The change in the AL in the H-eye group was less with OK lenses than with 0.01% atropine (P=0.04), whereas there was no significant difference between the change in AL in the L-eye group between treatment with OK lens and 0.01% atropine (P=0.89). Conclusions: In myopic anisometropic children, AL differences between 2 eyes decrease by wearing OK lenses but do not change after administration of 0.01% atropine eye drops. The increased effect of OK lenses, but not 0.01% atropine, in reducing axial elongation at 1 year in the eye with higher SER in anisometropic children warrants further investigation.

Prevalence of High Astigmatism in Salta Province, Argentina

Article

Full-text available

Jan 2021

IMI impact of myopia

Article

Full-text available

Apr 2021

The global burden of myopia is growing. Myopia affected nearly 30% of the world population in 2020 and this number is expected to rise to 50% by 2050. This review aims to analyze the impact of myopia on individuals and society; summarizing the evidence for recent research on the prevalence of myopia and high myopia, lifetime pathological manifestations of myopia, direct health expenditure, and indirect costs such as lost productivity and reduced quality of life (QOL). The principal trends are a rising prevalence of myopia and high myopia, with a disproportionately greater increase in the prevalence of high myopia. This forecasts a future increase in vision loss due to uncorrected myopia as well as high myopia-related complications such as myopic macular degeneration. QOL is affected for those with uncorrected myopia, high myopia, or complications of high myopia. Overall the current global cost estimates related to direct health expenditure and lost productivity are in the billions. Health expenditure is greater in adults, reflecting the added costs due to myopia-related complications. Unless the current trajectory for the rising prevalence of myopia and high myopia change, the costs will continue to grow. The past few decades have seen the emergence of several novel approaches to prevent and slow myopia. Further work is needed to understand the lifelong impact of myopia on an individual and the cost-effectiveness of the various novel approaches in reducing the burden.

Refractive Errors in University Students in Central China: The Anyang University Students Eye Study

Article

Sep 2018

Purpose: To assess the prevalence of refractive errors and associated factors in university students in urban areas of Anyang, Central China. Methods: This is a cross-sectional university-based study of 16- to 26-year-old students in China. Subjects from two universities were invited to undergo a comprehensive eye examination. Cycloplegic refraction was acquired by autorefractor with two drops of 1% cyclopentolate. The prevalence of myopia, high myopia, hyperopia, astigmatism, and anisometropia was calculated. Only data from right eyes were included in analysis. Results: A total of 7732 eligible subjects were included, with an average age of 20.2 ± 1.4 years. Overall, the mean spherical equivalent (SE) was -2.92 ± 2.48 diopters (D). The prevalence of myopia (SE ≤ -0.50 D), emmetropia, and hyperopia (SE ≥ +0.50 D) was 83.2%, 9.5%, and 7.3%, respectively. Female sex (OR = 1.542; P < 0.001) and science and engineering students (OR = 1.219; P = 0.004) were more likely to be myopic. The prevalence of high myopia, defined using SE ≤ -5.0 D, ≤ -6.0 D, and ≤ -10.0 D, respectively, occurred in 20.2%, 11.1 %, and 0.5%. High myopia (SE ≤ -6.0 D) was statistically associated with female sex (OR = 1.202; P = 0.029) and younger age (OR = 0.896; P = 0.001). The prevalence of astigmatism (cylinder of ≤ -0.75 D) was 28.8%. Astigmatism was associated with male sex (OR = 0.824; P = 0.001) and younger age (OR = 0.925; P = 0.001). Conclusions: A prevalence of 83.2% for myopia and 11.1% for high myopia (SE ≤ -6.0 D) was found in central Chinese university students. In the future, this generation of university students may encounter long-term, vision-threatening effects, especially pathologic myopia.

Gender Inequality in Global Burden of Uncorrected Refractive Error

Article

Sep 2018

Purpose: To explore gender inequality in global burden of Uncorrected refractive error (URE) by year, age, and socioeconomic status using disability-adjusted life years (DALYs). Design: International, comparative burden-of-disease study. Methods: Global, regional and national gender-specific DALY numbers, crude DALY rates, and age-standardized DALY rates caused by URE, by year and age, were extracted from the Global Burden of Disease Study 2015. Human development index (HDI) in 2015 as an indicator of national socioeconomic status was extracted from the Human Development Report. Pearson correlation and linear regression analyses were conducted to investigate the association between socioeconomic status and gender inequality. Results: Gender inequality in global URE burden has persisted since 1990 through 2015, with little improvement over the decades. Age-standardized DALY rates were 189.8 among males vs. 223.0 among females in 1990 and 188.4 vs. 225.2 in 2015. Females had higher burden than males of the same age and gender inequality increased with age. Female-minus-male difference in age-standardized DALY rates (r = -0.562, P < 0.001; standardized β = -0.562, P < 0.001) and female to male age-standardized DALY rate ratios (r = -0.258, P < 0.001; standardized β = -0.258, P < 0.001) were negatively related to HDI. Conclusions: Gender inequality in global URE burden has persisted over the past few decades, with females bearing more burden than males. Older age and lower socioeconomic status are related to greater gender inequality. These findings highlight the importance to make gender-sensitive health policy to manage global vision loss caused by URE.

Characteristics of astigmatism in Black South African high school children

Article

Full-text available

Jan 2018
Afr Health Sci

Sam Wajuihian

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.

Evaluation of Efficacy and Results of Photorefractive Keratectomy on Hypermetropia of morethan +3.00 Diopter, 4 Months after Surgery

Article

Full-text available

Mar 2009

Hyperopia is a type of refractive error and photorefractive keratectomy (PRK) is one of the surgical procedures for correction of various types of refractive errors. In this study we decided to evaluate the efficacy and results of PRK on hyperopia of more than 3 diopters 4 months after surgery. Background: Overall, 30 eyes of 19 patients (18-66 years of old) for this clinical trial study were selected from the patients referred to an eye center clinic for PRK. All of these eyes were operated by Technolas 217 Excimer laser system. 4 months postoperative results were compared with preoperative data. Pre and postoperative results were compared using t-paired test via SPSS software. Methods: Postoperative spherical equivalent of patients were - 2.00 to + 5.00 diopter. In 30% of patients there was overcorrection and in 70% of patients there was Undercorrection. None of the patients were in the range of emetropia. Postoperative SE of 46.6% of patients was in the range of ± 1.00 diopter and 80% of patients were in the range of ± 2.00 diopter. The mean preoperative best corrected visual acuity (BSCVA) of patients 0.8 ± 0.18 as well as postoperative BSCVA. The mean of uncorrected visual acuity (UCVA) was 0.13 ± 0.1 and the mean of postoperative UCVA vs 0.51 ± 0.25. The mean of preoperative sphere was +5.45±2.06 and post operative one was + 1.00 ± 1.62 diopter. The mean of preoperative astigmatism was - 1.42 ± 1.13 that change to - 0.95 ± 0.55 postoperatively. Findings: Photorefractive keratectomy has a poor predictability and efficacy for hyperopia of more than + 3.00. Conclusion: Key words: High hyperopia – Hyperopia – Photorefractive Keratectomy.

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

Article

Full-text available

Sep 2017

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.

Need for optical intervention in children attending a school for the blind in Eritrea

Article

Full-text available

Sep 2017
CLIN EXP OPTOM

Purpose: To identify the need for optical intervention including spectacles and low vision devices (LVDs) in children attending the only school for the blind in Eritrea. Methods: A total of 92 children were examined using the World Health Organization Prevention of Blindness program form for the recording of children with blindness and vision impairment. Examination included distance and near visual acuity (VA), refraction, trial of LVDs and evaluation of anterior and posterior segments. All the children who showed at least one line improvement in distance or near VA with refractive correction and/or LVDs were provided with these devices. Results: Six children had distance VA of ≥6/18 (no vision impairment, NVI) at presentation and were excluded from analysis. For the remaining 86 children, male to female ratio was 1.2:1.0 with a mean age of 11.8 ± 2.8 years (range: 6-17 years). At presentation, 47 (54.7 per cent) children were blind (VA <3/60) and 24 (27.9 per cent) were severely visually impaired (VA <6/60-3/60), which reduced to 42 (48.9 per cent) and seven (8.1 per cent) children after refraction, respectively. A further 5.8 per cent (five children) achieved NVI with refractive correction. Using distance LVDs, 26 (30.2 per cent) and 16 (18.6 per cent) children had NVI and moderate vision impairment (VA <6/18-6/60), respectively. In terms of near vision, eight (9.3 per cent) children had near VA better than 1.00 M at presentation, which improved to 11 (12.8 per cent) with refractive correction and 19 (22.1 per cent) with near LVDs. A total of 29 spectacles and 42 LVDs were provided. Conclusion: A significant number of children at the school for the blind benefited from refractive correction and LVDs. With such optical intervention, many of these children could study at mainstream schools with print media. A system including comprehensive vision examinations before admission to the school, refractive services and low vision rehabilitation is required to ensure that children with adequate residual vision do not have to be limited to learning in Braille media.

Excimer laser refractive surgery rate in Iran: 2010–2014

Article

Full-text available

Jun 2017

Purpose To determine the rate of excimer laser refractive surgery in Iran and its trend during 2010–2014, and the number of surgeries per ophthalmologist. Methods Twelve provinces were considered for the study; 4 major referral provinces of Tehran, Fars, Isfahan, and Khorasan, and 8 others which were selected randomly. Then a number of excimer laser centers were chosen from each province. In the timeframe between 2010 and 2014, one week per season was randomly selected for each center, and the number of surgeries conducted in these 20 weeks was determined by trained personnel. Results In the 12 surveyed provinces, 28 of the 57 active surgical centers were selected. The rate of excimer laser refractive surgery in 2010 in Iran was 2764 per million population which reached 3744 per million by 2012 and took a slightly decreasing trend to 3582 until 2014. Based on the number of ophthalmologists and the number of surgeries in 2014, the average number of surgeries per ophthalmologist was 103 surgeries. Conclusion This is the first study to report the rate of excimer laser refractive surgery in Iran.

Intraocular pressure after photorefractive keratectomy in myopic eyes

Article

Full-text available

Oct 2013

Morad Amir Ahmad

Intraocular pressure after photorefractive keratectomy in myopic eyes AhmadMA1, Jafarzadehpur E 2*, Tahir Harki EM 3 1- PhD student of Medical physics, University of Zakho, Kurdistan, Iraq 2- Associate Professor of Optometry Department. Tehran University of Medical Science. Tehran, Iran 3- Assistant Professor of Biophysics. Department of Physics. Salahadin University, Hawler, Iraq. Abstract Background and Aim: Determination of intra ocular pressure is one of the most important ophthalmic dilemmas. This study compares pre and post photorefractive keratectomy (PRK) measures of intraocular pressure (IOP). Materials and Methods: Simple myopic subjects were selected for this study from "Jomhuri" educational hospital in Erbil. All myopic PRK candidates were referred for IOP measurement. IOP was measured by noncontact tonometer (NCT) in all myopic cases pre and 3 months after PRK at the same diurnal time. Pachymetry was done for all participants. Results: Two hundred and twelve participants were evaluated. The IOP was 15.12 ± 1.8 (mean ± SD) before surgery and 12.16 ± 1.9 after surgery (p<0.0001). The residual corneal depth was significantly determining the IOP result (p<0.0001). Conclusion: Apparently, IOP significantly decreases after PRK; however, some ocular diseases that are diagnosed according to the IOP may be missed. Therefore, specific concern should be considered for IOP measurement after refractive surgery. Keywords: PRK, IOP. Refractive error, CCT. *Corresponding author: Dr. Ebrahim Jafarzadehpur, optometry department of Tehran University of Medical Science. Email: jafarzadehpour.e@iums.ac.ir

Myopia is an Adaptive Characteristic of Vision: Not a Disease or Defect

Article

Dec 2016
REV GEN PSYCHOL

Richard M. Wielkiewicz

This article proposes that myopia (nearsightedness) is an adaptive characteristic of human vision. Most theories of the evolution of vision assume myopia is a disease or defect that would have resulted in decreased reproductive fitness in the absence of modern corrective lenses. In contrast, the present article argues that myopic individuals may have played important roles in hunter–gatherer groups such as making tools and weapons, and identifying medicinal plants, contributing to individual and group survival. This idea is called the “adaptive myopia hypothesis.” Evidence favoring this hypothesis is reviewed in the context of the metatheory of evolutionary psychology.

The comparison of head and neck alignment in children with visual and hearing impairments and its relation with anthropometrical dimensions

Article

Full-text available

Jul 2014

Purpose: The aim of this study was to compare head and neck alignment in children with visual and hearing impairments and its relation with anthropometrical parameters. Methods: The study was a descriptive, correlational analysis within which the relations between dependent and independent variables have been studied. Thirty children with poor vision, 30 children with hearing loss and finally 30 healthy ones ranged 6-12 years old were selected randomly. Anteroposterior and mediolateral photographs of the neck were obtained to check forward head and torticollis postures. Anthropometric parameters (head, neck and thorax circumference, neck, shoulder and thorax width, neck length, the distance from tragus to sternal notch and sitting-height) were measured. Statistical analysis of data was performed by 1-way ANOVA and Pearson correlation coefficient. Results: The statistical results indicated that forward head angle was less in the visually impaired group than the group with hearing loss (P = 0.001) and the healthy group (P = 0.017). The lateral flexion angle was more in the group with hearing loss than the healthy group (P = 0.001). There is also a positive significant correlation between head circumference (P = 0.025), neck length (P = 0.001), sternal notch-tragus distance (P = 0.003), and sitting-height (P = 0.014) with forward head posture. No significant relation was observed between other anthropometrical parameters with structural profile variable (Forward head and torticollis). Conclusion: The results of this study indicate that visual and hearing impairments can affect the head and neck alignment of children and this alignment has a significant relation with some of the anthropometrical dimensions. Therefore, it is necessary to pay more attention to treatment exercises in order to correct and improve body posture and changed anthropometrical dimensions in children with visual and hearing impairments.

Prevalence of myopia in a sample of Greek students

Article

Full-text available

Dec 2000
Acta Ophthalmol Scand

Purpose: An epidemiological study, concerning the prevalence of myopia among the student population (15–18 years old) of Northern Greece, was carried out. Methods: Specific questionnaires were used in order to collect data on the refractive condition of students. Results: Myopia prevalence was 36.8% and was found to be more common in females (46.0%) than in males (29.7%). The prevalence increased in students with myopic parents and myopic siblings. It was also found that myopia correlates strongly with nearwork and school performance. Conclusion: The study results suggest that myopia is a rather common refractive error in Greek students. Findings also indicate that myopia is probably hereditary and correlates with educational level, intelligence and excessive nearwork.

Epidemiology of Myopia

Article

Full-text available

Feb 1996

Refractive errors among young adult and university students in Norway

Article

Full-text available

Jan 1999

This study was initiated to compare the refractive state in a population sample to that among university students in Norway and to that among the general population in other Nordic countries. A population sample of 112 individuals and 224 engineering students were randomly selected and examined using automated and clinical refraction in cycloplegia. Statistically significant differences were found in prevalences of myopia (population sample: 33%, students: 47%, p: 0.016) and prevalences of hyperopia (population sample: 47%, students: 30%, p: 0.001) between the two groups. The mean refractive error among the population sample was -0.1+/-2.0 D compared to -0.6+/-2.2 D among the students (p=0.0013). The population sample had a significantly lower prevalence of myopia and a higher prevalence of hyperopia than the student population. The state of refraction in the population sample was found to be in agreement with results reported from other Nordic countries.

Prevalence and risk factors of refractive errors in adult Chinese in Singapore

Article

Full-text available

Sep 2000
INVEST OPHTH VIS SCI

To determine the epidemiology of refractive errors in an adult Chinese population in Singapore. A disproportionate, stratified, clustered, random-sampling procedure was used to select names of 2000 Chinese people aged 40 to 79 years from the 1996 Singapore electoral register in the Tanjong Pagar district in Singapore. These people were invited to a centralized clinic for a comprehensive eye examination, including refraction. Refraction was also performed on nonrespondents in their homes. Myopia, high myopia, and hyperopia were defined as a spherical equivalent (SE) in the right eye of less than -0.5 D, less than -5.0 D, and more than +0.5 D, respectively. Astigmatism was defined as less than -0.5 D of cylinder. Anisometropia was defined as a difference in SE of more than 1.0 D between the two eyes. Only phakic eyes were analyzed. From 1717 eligible people, 1232 (71.8%) were examined. Adjusted to the 1997 Singapore population, the overall prevalence of myopia, hyperopia, astigmatism, and anisometropia was 38.7% (95% confidence interval [CI]: 35.5, 42.1), 28.4% (95% CI: 25.3, 31.3), 37.8% (95% CI: 34.6, 41.1), and 15.9% (95% CI: 13.5, 18.4), respectively. The prevalence of high myopia was 9.1% (95% CI: 7.2, 11.2), with women having significantly higher rates than men. The age pattern of myopia was bimodal, with higher prevalence in the 40 to 49 and 70 to 81 age groups and lower prevalence between those age ranges. Prevalence was reversed in hyperopia, with a higher prevalence in subjects aged 50 to 69. There was a monotonic increase in prevalence with age for both astigmatism and anisometropia. Increasing educational levels, higher individual income, professional or office-related occupations, better housing, and greater severity of nuclear opacity were all significantly associated with higher rates of myopia, after adjustment for age and sex. The results indicate that whereas myopia is 1.5 to 2.5 times more prevalent in adult Chinese residing in Singapore than in similarly aged European-derived populations in the United States and Australia, the sociodemographic associations are similar.

Refractive error in children in an urban population in New Delhi

Article

Full-text available

Apr 2002
INVEST OPHTH VIS SCI

To assess the prevalence of refractive error and related visual impairment in school-aged children in an urban population in New Delhi, India. Random selection of geographically defined clusters was used to identify a sample of children 5 to 15 years of age. From December 2000 through March 2001, children in 22 selected clusters were enumerated through a door-to-door survey and examined at a local facility. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. Myopia was defined as spherical equivalent refractive error of at least -0.50 D and hyperopia as +2.00 D or more. Children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance in four of the clusters. A total of 7008 children from 3426 households were enumerated, and 6447 (92.0%) examined. The prevalence of uncorrected, baseline (presenting), and best corrected visual acuity of 20/40 or worse in the better eye was 6.4%, 4.9%, and 0.81%, respectively. Refractive error was the cause in 81.7% of eyes with vision impairment, amblyopia in 4.4%, retinal disorders in 4.7%, other causes in 3.3%, and unexplained causes in the remaining 5.9%. There was an age-related shift in refractive error from hyperopia in young children (15.6% in 5-year-olds) toward myopia in older children (10.8% in 15-year-olds). Overall, hyperopia was present in 7.7% of children and myopia in 7.4%. Hyperopia was associated with female gender. Myopia was more common in children of fathers with higher levels of education. Reduced vision because of uncorrected refractive error is a major public health problem in urban school-aged children in India. Cost-effective strategies are needed to eliminate this easily treated cause of vision impairment.

Prevalence of Astigmatism among Students in Northern Greece

Article

Full-text available

Jan 2002

Purpose To assess the prevalence of astigmatism in a sample of 1738 students (15–18 years old) from Northern Greece. Methods Collection of the sample was based on a questionnaire method. Statistical analysis included estimation of the prevalence of astigmatism and the distribution of students according to their cylindrical values. We also checked whether heredity or sex affected the occurrence of astigmatism. Results The prevalence of astigmatism was 10.2%. It was mostly at low levels, up to 2 D cyl. Females ran a significantly higher risk of astigmatism than males, and heredity seemed to be an important predisposing factor for this refractive error. Conclusions There is considerable variability in the prevalence of astigmatism worldwide, as indicated by different studies. However, this refractive error prevails at low levels in the Greek student population, compared with other countries.

Prevalence rates of refractive errors in Sumatra, Indonesia

Article

Full-text available

Nov 2002
INVEST OPHTH VIS SCI

To determine the prevalence rates of myopia, hyperopia, astigmatism, and anisometropia in a prevalence survey of adults in Sumatra, Indonesia. A population-based prevalence survey of 1043 adults 21 or more years of age was conducted in five rural villages and one provincial town of the Riau Province, Sumatra, Indonesia. A one-stage household cluster sampling procedure was used wherein 100 households were selected from each village or town. Refractive error measurements were obtained with one of two handheld autorefractors. Household interviews were conducted to obtain information on relevant lifestyle risk factors. The age-adjusted overall prevalence rates of myopia (SE [spherical equivalent] at least -1.0 D), hyperopia (SE of at least +1.0 D), astigmatism (cylinder of at least -1.0 D), and anisometropia (SE difference of +1.0 D) were 26.1% (95% confidence interval [CI]: 23.4-28.8), 9.2% (95% CI: 7.4-11.0), 18.5% (95% CI: 16.2-20.8), and 15.1% (95% CI: 12.9-17.4), respectively. The age-adjusted overall prevalence rate of high myopia (SE at least -6.0 D) was 0.8% (95% CI: 0.2-1.5). In a multiple logistic regression model, myopia rates varied with age and increased with income. Hyperopia, astigmatism, and anisometropia rates were independently higher in older adults. The prevalence rates of myopia in provincial Sumatra are higher than the rates in white populations, but lower than the rates in other urbanized Asian countries such as Singapore. The prevalence rate of high myopia is lower than in most other populations, and other refractive errors are common.

Prevalence of refractive errors in young middle-aged adults in Norway

Article

Full-text available

Oct 2002

To determine the prevalence of refractive errors in the young and middle-aged adult population in Norway. Refractive errors were measured in a population-based sample of young (20-25 years) and middle-aged (40-45 years) adults participating in the Helseundersøkelse i Nord Trøndelag (HUNT) Health Study, conducted in the County of Nord-Trøndelag in Norway. A total of 3137 persons (1248 young and 1889 middle-aged adults) with corrected visual acuity > or = 0.5 (in either eye) were included in the study. The prevalence of myopia was 35.0% in the young adult group and 30.3% in the middle-aged group. Myopia was significantly higher in women aged 20-25 years (36.4%) than in men aged 40-45 years (28.1%). Prevalence of hyperopia increased with age from 13.2% (20-25 years) to 17.4% (40-45 years). The highest rate of hyperopia (20.1%) was encountered in middle-aged women. The results show a slightly higher prevalence of myopia in the general population of Norway than previously estimated.

The Tehran Eye Study: Research design and eye examination protocol

Article

Full-text available

Aug 2003
BMC Ophthalmol

Background Visual impairment has a profound impact on society. The majority of visually impaired people live in developing countries, and since most disorders leading to visual impairment are preventable or curable, their control is a priority in these countries. Considering the complicated epidemiology of visual impairment and the wide variety of factors involved, region specific intervention strategies are required for every community. Therefore, providing appropriate data is one of the first steps in these communities, as it is in Iran. The objectives of this study are to describe the prevalence and causes of visual impairment in the population of Tehran city; the prevalence of refractive errors, lens opacity, ocular hypertension, and color blindness in this population, and also the familial aggregation of refractive errors, lens opacity, ocular hypertension, and color blindness within the study sample. Methods Design Through a population-based, cross-sectional study, a total of 5300 Tehran citizens will be selected from 160 clusters using a stratified cluster random sampling strategy. The eligible people will be enumerated through a door-to-door household survey in the selected clusters and will be invited. All participants will be transferred to a clinic for measurements of uncorrected, best corrected and presenting visual acuity; manifest, subjective and cycloplegic refraction; color vision test; Goldmann applanation tonometry; examination of the external eye, anterior segment, media, and fundus; and an interview about demographic characteristics and history of eye diseases, eye trauma, diabetes mellitus, high blood pressure, and ophthalmologic cares. The study design and eye examination protocol are described. Conclusion We expect that findings from the TES will show the status of visual problems and their causes in the community. This study can highlight the people who should be targeted by visual impairment prevention programs.

Development of Refractive Errors into Old Age

Article

Full-text available

Nov 2002

To evaluate refractive errors in older adults. The distribution of refractive error components was evaluated in a sample of 569 older adults including 171 participants over the age of 80 years. The mean age was 75.2 years with a range from 59 to 106 years. Emphasis was placed on modern methods of analyzing astigmatic refractive errors, which convert cylindrical refractive errors into primary and oblique components. The known increase in hyperopia after maturity continues into old age. The primary negative astigmatic component increases dramatically in prevalence and amount after age 70 years, whereas the oblique component remains unchanged. Significant anisometropia is common in the oldest old, suggesting failure of emmetropization mechanisms with age. Substantial gender differences exist in refractive changes with age. The continuing changes in all components of refractive error into old age and the surprisingly high prevalence of large amounts of astigmatism and anisometropia emphasize the importance of regular refractive evaluations among the oldest old.

Familial Aggregation and Prevalence of Myopia in the Framingham Offspring Eye Study

Article

Mar 1996
ARCH OPHTHALMOL-CHIC

Sperduto

Objectives: To examine familial relationships for myopia among siblings and the distribution of myopia in an adult population aged 23 to 78 years. Methods and participants: Eye examinations were conducted in a cross-sectional study on the offspring of the Framingham Eye Study cohort. Between 1989 and 1991, 1585 persons, the offspring of 1319 parents, underwent refraction and were tested for best corrected visual acuity. A person was considered myopic if at least one eye had a spherical equivalent refractive error of at least -1.00 diopter. Results: For both sexes, prevalence of myopia decreased with increasing age, from about 60% for ages 23 to 34 years to about 20% for ages 65 years and older. Among men, both age and years of education were related to myopia. Among women, age was related to myopia, but years of education were not. Age-, sex-, and education-adjusted analyses, using the second-order generalized estimating equations approach, showed a strong association of myopia between siblings. The association between siblings decreased with increasing between-siblings age difference: the estimated odds ratio was about 5 for an age difference of 2 years and half that for an age difference of 10 years. Conclusions: The relative importance of genetic and environmental factors in explaining familial relationships for myopia remains unclear. Nevertheless, the large increase in myopia prevalence for more recent birth cohorts and the decrease in the strength of the between-siblings association for myopia with increasing between-siblings age difference suggest an important role for environmental factors in the cause of myopia.

“With the rule” astigmatism is not the rule in the elderly: Reykjavik Eye Study: A population based study of refraction and visual acuity in citizens of Reykjavik 50 years and older

Article

Dec 2000

Purpose: To study refractive state and visual acuity in citizens of Reykjavik 50 years and older. Methods: 1700 persons were randomly selected from the national population census. 1379 could be located and qualified whereof 1045 participated. Evaluation of refraction was performed using Nidek ARK 900 autorefracto-keratometer. Visual acuity was tested on a Snellen chart. Results: The prevalence of hypermetropia increases with age by 0.3 D in five years. The prevalence of “against the rule” astigmatism increased on average 5.3% and oblique 3.9% in five years. Analysis of corneal astigmatism measured by keratometer shows an “against the rule” change with age. Conclusions: Hypermetropia increases by age. The prevalence of astigmatism increases and the axis turns to “against the rule”. The changes in total astigmatism and corneal astigmatism is almost parallel which might indicate that the “against the rule” change is related to changes in the cornea.

Population-based assessment of refractive error in India: The Andhra Pradesh eye disease study

Article

Feb 2002
CLIN EXP OPHTHALMOL

Purpose: To assess the prevalence, distribution, and demographic associations of refractive error in the population of the southern Indian state of Andhra Pradesh. Methods: From 94 clusters in one urban and three rural areas of Andhra Pradesh, 11 786 persons of all ages were sampled using a stratified, random, cluster, systematic sampling strategy in the Andhra Pradesh Eye Disease Study, a population-based cross-sectional study. A total of 10 293 people underwent an interview and detailed dilated eye examination. Refraction was performed by ophthalmic personnel trained in the study procedures. Objective refraction under cycloplegia was assessed for participants ≤ 15 years of age and subjective refraction for those > 15 years of age. Myopia was defined as spherical equivalent worse than -0.50 D and hyperopia as spherical equivalent worse than +0.50 D. Results: In the participants ≤ 15 years of age, the prevalence of myopia was 3.19% (95% confidence interval [CI] 2.24−4.13%) and of hyperopia was 62.62% (95% CI 57.10−68.13%). In this age group, myopia increased with increasing age and was more prevalent in the urban study area, and hyperopia prevalence was greater in the participants < 10 years of age. In participants > 15 years of age, the prevalence of myopia was 19.45% (95% CI 17.88−21.02%) and of hyperopia was 8.38% (95% CI 6.91−9.85%). Myopia and hyperopia increased with increasing age. Myopia was more common in males, those with education higher than class 12, those with nuclear cataract, and those living in rural study areas. Hyperopia was more common in females, those with any level of formal education, and those living in the urban area and in the well-off rural study area. Conclusions: There is significant refractive error in this population. These data on the distribution and associations of refractive error can be useful for the planning of refractive eye-care services.

A simplified general method for cluster-sample surveys of health in Developing Countries

Article

Feb 1991

General guidelines are presented for the use of cluster-sample surveys for health surveys in developing countries. The emphasis is on methods which can be used by practitioners with little statistical expertise and no background in sampling. A simple self-weighting design is used, based on that used by the World Health Organization's Expanded Programme on Immunization (EPI). Topics covered include sample design, methods of random selection of areas and households, sample-size calculation and the estimation of proportions, ratios and means with standard errors appropriate to the design. Extensions are discussed, including stratification and multiple stages of selection. Particular attention is paid to allowing for the structure of the survey in estimating sample size, using the design effect and the rate of homogeneity. Guidance is given on possible values for these parameters. A spreadsheet is included for the calculation of standard errors.

Refractive Status in the Beaver Dam Eye Study

Article

Jan 1995
INVEST OPHTH VIS SCI

To describe the prevalence of refractive errors in a population of adult Americans. From 1988 to 1990, 4926 adults who were 43 to 84 years of age and living in Beaver Dam, Wisconsin at the time of the 1987-1988 census were examined. Refractions were performed according to a modification of the Early Treatment Diabetic Retinopathy Study protocol. Included in this study were 4533 people who had not undergone cataract surgery and who had a best corrected visual acuity better than 20/40 in at least one eye. Myopia was defined as a refractive error less than -0.50 diopters; hyperopia was defined as a refractive error greater than +0.50 diopters. Hyperopia was more frequent than myopia in the study group (age-adjusted of 49.0% and 26.2% in right eyes, respectively, P = 0.0001). The prevalence of hyperopia in the right eye increased with increasing age from 22.1% in those 43 to 54 years of age to 68.5% in those 75 years of age or older. The prevalence of myopia in the right eye decreased from 43.0% in those 43 to 54 years of age to 14.4% in those 75 years of age or older. There was significant relationship between education level and refractive error (age adjusted r = -0.32, P = 0.0001). Neither household income nor occupation was associated with refractive error in our data. These cross-sectional data indicate age-related differences in refractive status in an adult population and suggest that education is associated with myopia independent of age.

Prevalence of refractive errors on a VOSH mission to Nicaragua

Article

Mar 1994
J Am Optom Assoc

Timothy A Wingert

Optometric services in many parts of the world are unavailable with a resultant lack of information on the epidemiology of visual problems in those countries as well. A retrospective analysis was conducted on the records of 3,281 patients seen on a VOSH mission to Nicaragua. The mean spherical correction for each eye was a low hyperopic correction. For eyes having an astigmatism the mean cylinder correction was -1.00 and was usually oriented against the rule. There was a lower incidence of myopia in this population than for many others that have been studied. There was also a need for a presbyopic correction at an earlier age than for Mid-European populations. A very large number of spectacles must be donated in order to get a sufficient supply for a successful VOSH mission.

A population-based survey of refractive error in Malawi

Article

Dec 1995

Refractive errors, particularly myopia, are a common problem in industrialized countries, but the impression exists that myopia may be relatively uncommon in non-industrialized societies. We conducted a population-based survey of refractive error in two groups of Malawians: a group of rural agricultural workers (n = 510) and a group of students at an urban teachers' college (n = 534). The overall prevalence of myopia was low; 2.5% (95% confidence interval 1.3%, 3.7%) of participants had an error of -0.5 D or greater. The mean refractive error (right eye) in the urban student group was +0.52 D compared to +0.62 D among the rural agricultural workers and the excess myopia was accounted for by significant myopia (> or = -0.75 D) in a few individuals, rather than an overall shift towards myopia within the urban student group. Among the rural agricultural workers, literacy predicted refractive error (right eye), with a mean of +0.59 D in the rural literate compared to +0.67 D in the rural illiterate. These findings support the notion that myopia is uncommon in non-industrialized societies and that it is associated with increased literacy but we have not identified specific risk factors within this group to predict the occurrence of significant myopia. In settings such as Malawi, refractive services should be targeted to urban centers, where more educated populations are likely to be found.

Prevalence and Risk Factors for Refractive Errors in an Adult Inner City Population

Article

Feb 1997
INVEST OPHTH VIS SCI

To estimate the prevalence of refractive errors among adult black and white Americans and to identify risk factors associated with these refractive errors. Refractive error was measured in a population-based sample of black and white adults age 40 or older residing in east Baltimore from 1985 through 1988. Aphakic eyes were excluded from analysis. The prevalence of myopia varied from 10.5% among black men 80 years and older to 42.1% among white women 40 to 49 years of age. Hyperopia ranged from 11.8% among black men 40 to 49 years to 68.1% among white men 80 years of age and older. Astigmatism ranged from 15.8% to 45.2%, and anisometropia ranged from 2.8% to 8.1%, depending on age, race, and gender. Black persons had less myopia, hyperopia, astigmatism, and anisometropia than did white persons. Myopia (< -0.5 diopter [D] spherical equivalent) declined with age, whereas hyperopia (> +0.5 D), astigmatism (> 0.5 D of cylinder), and anisometropia (> 1.0 D between eyes) increased with age. Myopia increased with increasing years of education, although this association was stronger for white persons than for black persons and among younger subjects. Hyperopia declined with increasing years of education, and this association was stronger among younger than older subjects. Education was not associated with astigmatism or anisometropia. Black persons had lower rates of refractive error than did white persons, except for hyperopia prevalence, which was comparable in black and white women. Refractive errors are common among adult inner city Americans, but rates vary substantially by age, race, gender, and education levels.

Prevalence and Risk Factors of Myopia in Victoria, Australia

Article

May 1999
ARCH OPHTHALMOL-CHIC

To determine the prevalence and risk factors of myopia in urban and rural Victoria, Australia. The Visual Impairment Project is a population-based prevalence study of eye disease in which both urban and rural adult populations were examined. Refractive data on the participants were collected using logMAR visual acuity, corrective lens measurement, and subjective refraction. All refractive error data were converted into spherical equivalent and myopia was defined at 2 levels: worse than -0.5 diopters (D) and worse than -1.00 D. A total of 3271 (83%) urban and 1473 (91%) rural residents were examined. The overall prevalence of myopia worse than -0.50 D in the population was 17% (95% confidence limit = 15.8%, 18.0%). Prevalence of myopia decreased from 24% in those aged 40 to 49 years to 12% in those aged 70 to 79 years, and then increased to 17% in people older than 80 years. The younger age groups also had higher usage of myopic corrective lenses throughout their lives than the older age groups, indicating an increased use of myopic corrective lenses in recent times. Myopia was found to be significantly higher in people with higher education levels (chi2 = 119.20, P < .001), in clerks and professionals (chi2 = 132.53, P < .001), in people born in southeast Asia (chi2 = 77.62, P < .001), and in people with higher degrees of nuclear opacity (chi2 = 55.26, P < .001). Myopia rates in the Visual Impairment Project generally decrease with age and use of myopic correction has increased in recent times. Myopia was significantly related to education level, occupation, country of birth, and nuclear opacity.

Prevalence and predictors of uncorrected refractive error in the Victorian population

Article

Jun 1999
AM J OPHTHALMOL

To investigate the prevalence and predictors of undercorrected refractive errors in the Victorian population. In this prospective study, a population-based sample of residents was recruited. The improvement in visual acuity with subjective refraction was assessed. Several individual characteristics were investigated as predictors of undercorrected refractive error. There were 5,615 eligible residents, of which 4,735 (84%) participated in the study (53% were women). In all, 466 participants (10%) had significant undercorrected refractive error leading to an improvement of 1 or more lines of visual acuity with refraction. Age was the most important predisposing factor. The risk of undercorrected refractive error increased by 1.8 times for every decade of life starting at 40 years of age. The next most important factor was the absence of distance refractive correction. These individuals were 6.8 times more at risk compared with those who wore distance spectacles. Other significant predictors of undercorrected refractive error were the presence of cataract and European or Middle Eastern languages spoken at home. People with tertiary education or hypermetropia were less likely to need refractive error improvement. Gender, country of birth, and employment status did not have any statistically significant effect after controlling for confounders. The results of this study disclose people in the community who are more at risk of compromising their vision because of undercorrected refractive errors. A campaign is warranted to alert people that it may be possible to improve their vision.

Refractive errors in an older population: The Blue Mountains Eye Study

Article

Jun 1999
OPHTHALMOLOGY

To determine prevalence and associations with refractive errors in a defined older population. Cross-sectional study. A total of 3654 residents, aged 49-97, of the Blue Mountains, west of Sydney, Australia. Comprehensive questionnaire and detailed eye examination, including refraction. Refractive error of phakic eyes, age, gender, and education. Prevalence rates were determined for myopia (15%), hyperopia (57%), and emmetropia (28%). Hyperopia prevalence was age-related, increasing from 36% in persons aged <60 years to 71 % of persons aged > or = 80 (P < 0.0001), whereas myopia prevalence decreased with age, from 21 % in persons aged <60 years to 10% of persons aged > or = 80 years (P < 0.0001). Younger myopic subjects in this population reported first wearing distance correction at a significantly younger age than older subjects, P < 0.0001. After adjustment for age, women were slightly more hyperopic (mean +0.75 diopters [D]) than men (mean +0.59 D, P = 0.0012. The gender-adjusted mean spherical error increased with age from +0.03 D in persons aged <60 years to +1.2 D in persons aged > or = 80 years (P < 0.0001). The gender-adjusted mean cylinder power also increased with age, from -0.6 D in persons aged <60 years to -1.2 D in persons aged > or = 80 years (P < 0.0001). The mean axis of astigmatism was "against the rule" in all age groups. Anisometropia increased with age, from a mean of 0.4 D in persons aged <60 to 0.9 D in persons aged > or = 80 years (P < 0.0001). Higher education was associated with myopia in men (P = 0.009) but not in women (P = 0.21) after adjustment for age. This report has documented the detailed refractive status of an older population, confirming previously described trends but also finding an apparent higher prevalence of myopia among younger members of this community.

Prevalence of myopia in school children in the Sultanate of Oman: A nation-wide study of 6292 randomly selected children

Article

Jun 1999

Joan Lithander

Between 1992 to 1994 in the Sultanate of Oman, 6292 randomly selected school children from Grade 1 (6-year-olds) and Grade 6 (12-year-olds) were examined for visual acuity. The purpose of this paper is to present results that relate to the prevalence of myopia in this population. All children with uncorrected visual acuity below 0.5 in one or both eyes received a thorough eye examination including cycloplegic retinoscopy. In the 6-year-olds there was an overall myopia (> or =-1.0 D) of 0.56% and in the 12-year-olds there was 5.16%. In rural, remote areas there was statistically significantly less myopia in the older group when compared with the rest of the country. In the town of Nizwa in the region of Dakhlia, the value for high myopia (> or =-7.0 diopters) in 12-year-old girls was 2.82% compared to an average prevalence 0.13%. In the Sultanate of Oman the prevalence of myopia showed consistency with findings in Europe and North America. There was significantly less myopia in remote areas. An increased prevalence of high myopia was seen in one of Oman's major cities.

Refractive Errors in a Black Adult Population: The Barbados Eye Study

Article

Sep 1999
INVEST OPHTH VIS SCI

To describe the prevalence of refractive errors in a black adult population. The Barbados Eye Study, a population-based study, included 4709 Barbados-born citizens, or 84% of a random sample, 40 to 84 years of age. Myopia and hyperopia were defined as a spherical equivalent <-0.5 diopters and >+0.5 diopters, respectively, based on automated refraction. Analyses included 4036 black participants without history of cataract surgery. Associations with myopia and hyperopia were evaluated in logistic regression analyses. The prevalence of myopia was 21.9% and was higher in men (25.0%) than in women (19.5%). The prevalence of hyperopia was 46.9% and was higher in women (51.8%) than in men (40.5%). The prevalence of myopia decreased from 17% in persons 40 to 49 years of age to 11% in those 50 to 59 years of age, but increased after 60 years of age. The prevalence of hyperopia increased from 29% at 40 to 49 years of age to 65% at 50 to 59 years of age, and tended to decline thereafter. A higher prevalence of myopia was positively associated (P < 0.05) with lifetime occupations requiring nearwork, nuclear opacities, posterior subcapsular opacities, glaucoma, and ocular hypertension. Factors associated with hyperopia were the same as for myopia, except for occupation, and in the opposite direction. High prevalences of myopia and hyperopia were found in this large black adult population. The prevalence of myopia (hyperopia) increased (decreased) after 60 years of age, which is inconsistent with data from other studies. The high prevalence of age-related cataract, glaucoma, and other eye conditions in the Barbados Eye Study population may contribute to the findings.

Refractive errors in an urban population in Southern India: The Andhra Pradesh Eye Disease Study

Article

Nov 1999
INVEST OPHTH VIS SCI

To assess the prevalence, distribution, and demographic associations of refractive error in an urban population in southern India. Two thousand five hundred twenty-two subjects of all ages, representative of the Hyderabad population, were examined in the population-based Andhra Pradesh Eye Disease Study. Objective and subjective refraction was attempted on subjects >15 years of age with presenting distance and/or near visual acuity worse than 20/20 in either eye. Refraction under cycloplegia was attempted on all subjects < or =15 years of age. Spherical equivalent >0.50 D in the worse eye was considered as refractive error. Data on objective refraction under cycloplegia were analyzed for subjects < or =15 years and on subjective refraction were analyzed for subjects >15 years of age. Data on refractive error were available for 2,321 (92.0%) subjects. In subjects < or =15 years of age, age-gender-adjusted prevalence of myopia was 4.44% (95% confidence interval [CI], 2.14%-6.75%), which was higher in those 10 to 15 years of age (odds ratio, 2.75; 95% CI, 1.25-6.02), of hyperopia 59.37% (95% CI, 44.65%-74.09%), and of astigmatism 6.93% (95% CI, 4.90%-8.97%). In subjects >15 years of age, age-gender-adjusted prevalence of myopia was 19.39% (95% CI, 16.54%-22.24%), of hyperopia 9.83% (95% CI, 6.21%-13.45%), and of astigmatism 12.94% (95% CI, 10.80%-15.07%). With multivariate analysis, myopia was significantly higher in subjects with Lens Opacity Classification System HI nuclear cataract grade > or =3.5 (odds ratio, 9.10; 95% CI, 5.15-16.09), and in subjects with education of class 11 or higher (odds ratio, 1.80; 95% CI, 1.18-2.74); hyperopia was significantly higher in subjects > or =30 years of age compared with those 16 to 29 years of age (odds ratio, 37.26; 95% CI, 11.84-117.19), in females (odds ratio, 1.86; 95% CI, 1.33-2.61), and in subjects belonging to middle and upper socioeconomic strata (odds ratio, 2.10; 95% CI, 1.09-4.03); and astigmatism was significantly higher in subjects > or =40 years of age (odds ratio, 3.00; 95% CI, 2.23- 4.03) and in those with education of college level or higher (odds ratio, 1.73; 95% CI, 1.07-2.81). These population-based data on distribution and demographic associations of refractive error could enable planning of eye-care services to reduce visual impairment caused by refractive error. If these data are extrapolated to the 255 million urban population of India, among those >15 years of age an estimated 30 million people would have myopia, 15.2 million hyperopia, and 4.1 million astigmatism not concurrent with myopia or hyperopia; in addition, based on refraction under cycloplegia, 4.4 million children would have myopia and 2.5 million astigmatism not concurrent with myopia or hyperopia.

Refractive Error Study in Children: Results from La Florida, Chile

Article

May 2000
AM J OPHTHALMOL

To assess the prevalence of refractive errors and vision impairment in school-age children in a suburban area (La Florida) of Santiago, Chile. Random selection of geographically defined clusters was used to identify a representative sample of children 5 to 15 years of age. Children in the 26 selected clusters were enumerated through a door-to-door survey and invited to report to a community health clinic for examination. Visual acuity measurements, cycloplegic retinoscopy, cycloplegic autorefraction, ocular motility evaluation, and examination of the external eye, anterior segment, media, and fundus were done from April through August 1998. Independent replicate examinations of all children with reduced vision and a sample of those with normal vision were done for quality assurance monitoring in six clusters. A total of 6,998 children from 3,830 households were enumerated, and 5,303 children (75.8%) were examined. The prevalence of uncorrected, presenting, and best visual acuity 0.50 (20/40) or worse in at least one eye was 15.8%, 14.7%, and 7.4%, respectively; 3.3% had best visual acuity 0.50 or worse in both eyes. Refractive error was the cause in 56.3% of the 1,285 eyes with reduced vision, amblyopia in 6.5%, other causes in 4.3%, with unexplained causes in the remaining 32.9%. Myopia -0.50 diopter or less in either eye was present in 3.4% of 5-year-old children, increasing to 19.4% in males and 14.7% in females by age 15. Over this same age range, hyperopia 2.00 diopters or greater decreased from 22.7% to 7.1% in males and from 26.3% to 8.9% in females. Females had a significantly higher risk of hyperopia than males. Refractive error, associated primarily with myopia, is a major cause of reduced vision in school-age children in La Florida. More than 7% of children could benefit from the provision of proper spectacles. Efforts are needed to make existing programs that provide free spectacles for school children more effective. Further studies are needed to determine whether the upward trend in myopia continues far beyond 15 years of age.

Refractive error study in children: RESULTs from Mechi Zone, Nepal

Article

May 2000
AM J OPHTHALMOL

To assess the prevalence of refractive error and vision impairment in school age children in the terai area of the Mechi zone in Eastern Nepal. Random selection of village-based clusters was used to identify a sample of children 5 to 15 years of age. Children in the 25 selected clusters were enumerated through a door-to-door household survey and invited to village sites for examination. Visual acuity measurements, cycloplegic retinoscopy, cycloplegic autorefraction, ocular motility evaluation, and anterior segment, media, and fundus examinations were done from May 1998 through July 1998. Independent replicate examinations for quality assurance monitoring took place in all children with reduced vision and in a sample of those with normal vision in seven villages. A total of 5,526 children from 3,724 households were enumerated, and 5,067 children (91.7%) were examined. The prevalence of uncorrected, presenting, and best visual acuity 0.5 (20/40) or worse in at least one eye was 2.9%, 2.8%, and 1.4%, respectively; 0.4% had best visual acuity 0.5 or worse in both eyes. Refractive error was the cause in 56% of the 200 eyes with reduced uncorrected vision, amblyopia in 9%, other causes in 19%, with unexplained causes in the remaining 16%. Myopia -0.5 diopter or less in either eye or hyperopia 2 diopters or greater was observed in less than 3% of children. Hyperopia risk was associated with female gender and myopia risk with older age. The prevalence of reduced vision is very low in school-age children in Nepal, most of it because of correctable refractive error. Further studies are needed to determine whether the prevalence of myopia will be higher for more recent birth cohorts.

Refractive Error Study in Children: Results from Shunyi District, China

Article

May 2000
AM J OPHTHALMOL

To assess the prevalence of refractive errors and vision impairment in school-age children in Shunyi District, northeast of Beijing, the Peoples Republic of China. Random selection of village-based clusters was used to identify a sample of children 5 to 15 years of age. Resident registration books were used to enumerate eligible children in the selected villages and identify their current school. Ophthalmic examinations were conducted in 132 schools on children from 29 clusters during May 1988 to July 1998, including visual acuity measurements, cycloplegic retinoscopy, cycloplegic autorefraction, ocular motility evaluation, and examination of the external eye, anterior segment, media, and fundus. Independent replicate measurements of all children with reduced vision and a sample of those with normal vision were done for quality assurance monitoring in three schools. A total of 6,134 children from 4,338 households were enumerated, and 5,884 children (95.9%) were examined. The prevalence of uncorrected, presenting, and best visual acuity 0.5 (20/40) or worse in at least one eye was 12.8%, 10.9%, and 1.8%, respectively; 0.4% had best visual acuity 0.5 or worse in both eyes. Refractive error was the cause in 89.5% of the 1,236 eyes with reduced vision, amblyopia in 5%, other causes in 1.5%, with unexplained causes in the remaining 4%. Myopia -0.5 diopter or less in either eye was essentially absent in 5-year-old children, but increased to 36.7% in males and 55.0% in females by age 15. Over this same age range, hyperopia 2 diopters or greater decreased from 8.8% in males and 19.6% in females to less than 2% in both. Females had a significantly higher risk of both myopia and hyperopia. Reduced vision because of myopia is an important public health problem in school-age children in Shunyi District. More than 9% of children could benefit from prescription glasses. Further studies are needed to determine whether the upward trend in the prevalence of myopia continues far beyond age 15 and whether the development of myopia is changing for more recent birth cohorts.

Myopisation: The refractive tendency in teenagers. Prevalence of myopia among young teenagers in Sweden

Article

Apr 2000

1045 children between 12 and 13 years old were examined in a field study in the Göteborg area (Sweden). The aim of this study was to report the prevalence of refractive errors, with special attention to myopia, since there are no previous reports in Sweden about this age group. The examination included visual acuity testing and refraction under cycloplegia. We found a prevalence of myopia (> or = -0.5D) of 49.7% and a prevalence of bilateral myopia of 39%. In the whole population, 23.3% were considered to need glasses (> or = -0.75D). We also found a prevalence of high myopia (> or = -5D) in 2.5% of the children. No statistically significant difference in myopia with respect to gender was found. The proportion of children needing glasses is considered the best indicator of the prevalence of myopia in this sample. The results confirm that this tendency towards myopisation in a teenage population in Göteborg is similar to the prevalence found in other parts of the world.

Refractive Error in Children in a Rural Population in India

Article

Apr 2002
INVEST OPHTH VIS SCI

To assess the prevalence of refractive error and related visual impairment in school-aged children in the rural population of the Mahabubnagar district in the southern Indian state of Andhra Pradesh. Random selection of village-based clusters was used to identify a sample of children 7 to 15 years of age. From April 2000 through February 2001, children in the 25 selected clusters were enumerated in a door-to-door survey and examined at a rural eye center in the district. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. Myopia was defined as spherical equivalent refractive error of at least -0.50 D and hyperopia as +2.00 D or more. Children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance in seven clusters. A total of 4414 children from 4876 households was enumerated, and 4074 (92.3%) were examined. The prevalence of uncorrected, baseline (presenting), and best corrected visual acuity of 20/40 or worse in the better eye was 2.7%, 2.6%, and 0.78%, respectively. Refractive error was the cause in 61% of eyes with vision impairment, amblyopia in 12%, other causes in 15%, and unexplained causes in the remaining 13%. A gradual shift toward less-positive values of refractive error occurred with increasing age in both boys and girls. Myopia in one or both eyes was present in 4.1% of the children. Myopia risk was associated with female gender and having a father with a higher level of schooling. Higher risk of myopia in children of older age was of borderline statistical significance (P = 0.069). Hyperopia in at least one eye was present in 0.8% of children, with no significant predictors. Refractive error was the main cause of visual impairment in children aged between 7 and 15 years in rural India. There was a benefit of spectacles in 70% of those who had visual acuity of 20/40 or worse in the better eye at baseline examination. Because visual impairment can have a significant impact on a child's life in terms of education and development, it is important that effective strategies be developed to eliminate this easily treated cause of visual impairment.

Refractive Errors and Factors Associated with Myopia in an Adult Japanese Population

Article

Feb 2003

To investigate the refractive status and factors associated with myopia by a population-based survey of Japanese adults. A total of 2168 subjects aged 40 to 79 years, randomly selected from a local community, were assessed in a cross-sectional study. The spherical equivalent of the refractive error was calculated and used in a multiple logistic regression analysis to evaluate the relationships between myopia and possible related factors. The mean (+/- SD) of the spherical equivalent was -0.70 +/- 1.40 diopters (D) in men, and -0.50 +/- 1.44 D in women. Based on +/- 0.5 D cutoff points, the prevalence of myopia, emmetropia, and hypermetropia were 45.7%, 40.8%, and 13.5% in men, and 38.3%, 43.1%, and 18.6% in women, respectively. A 10-year increase in age was associated with reduced risk of myopia [men: odds ratio (OR) = 0.53, 95% confidence interval (CI): 0.44-0.62; women: OR = 0.65, 95% CI: 0.54-0.78]. In men, myopia was significantly associated with higher education (high school: OR = 1.6, 95% CI: 1.1-2.3; college: OR = 2.0, 95% CI: 1.3-3.1) and management occupations (OR = 1.6, 95% CI: 1.0-2.4). For women, high income (OR = 1.5, 95% CI: 1.1-2.2), and clerical (OR = 1.5, 95% CI: 1.0-2.4) and sales/service occupations (OR = 1.7, 95% CI: 1.1-2.6) were also associated with myopia. The prevalence of myopia in a Japanese population was similar to that in other Asian surveys but higher than in black or white populations. Our study confirmed a higher prevalence of myopia among younger vs. older populations, and a significant association with education levels and socioeconomic factors.

Refractive errors and cataract as causes of visual impairment in Brazil

Article

Mar 2003

To identify the main causes of visual impairment (VA <or= 0.2) within the population over 50 years of age examined in "Cataract Free Zone" projects sponsored by the University of Campinas from 1986 to 1995. A retrospective review of the ophthalmic forms used for 60,404 patients examined in 74 Cataract Projects was performed. Through mass media information, adults of the target region or city were asked to self-test their vision. Patients with VA <or= 0.2 in the better eye were to come to a visual acuity test. Using Snellen charts, visual acuity testing was done by trained auxiliaries and medical students. The positive cases were then examined by ophthalmologists Criteria were established for the classification of the diagnoses and statistical analysis was performed. After the self-test of visual acuity, 60,404 patients came to have their visual acuity tested; 11,462 (18.97%) cases were considered positive and were submitted to complete eye examination; 5447 (42.7%) received spectacles for vision improvement, and 2704 (23.59%) had cataract surgery done. Other important causes of visual impairment were senile macular degeneration (5.4%) and glaucoma (4.02%). The main causes of visual impairment were non-corrected refractive errors and senile cataract. Ophthalmic community-based campaigns to serve the older population are recommended in order to detect and treat the identified cases and to indicate possible changes in the health care system.

The report of the 1996 population census

Apr 2003

Statistics 29 Iranian
Center

29 Iranian Statistics Center. The report of the 1996 population census. http://amar.sci.or.ir (10 March 2003).

The age- and gender-specific prevalences of refractive errors in Tehran: The Tehran Eye Study

Abstract

No full-text available

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