The prevalence of refractive errors in 6- to 15-year-old schoolchildren in Dezful, Iran

Myopia Is an Ischemic Eye Condition: A Review from the Perspective of Choroidal Blood Flow

Myopia is a common refractive error that affects a large proportion of the population. Recent studies have revealed that alterations in choroidal thickness (ChT) and choroidal blood flow (ChBF) play important roles in the progression of myopia. Reduced ChBF could affect scleral cellular matrix remodeling, which leads to axial elongation and further myopia progression. As ChT and ChBF could be used as potential biomarkers for the progression of myopia, several recent myopia treatments have targeted alterations in ChT and ChBF. Our review provides a comprehensive overview of the recent literature review on the relationship between ChBF and myopia. We also highlight the importance of ChT and ChBF in the progression of myopia and the potential of ChT as an important biomarker for myopia progression. This summary has significant implications for the development of novel strategies for preventing and treating myopia.

Prevalence and risk factors for astigmatism in 7 to 19-year-old students in Xinjiang, China: a cross-sectional study

BACKGROUND

To investigate the prevalence and risk factors for astigmatism in 7-19-year-old students in Xinjiang, China.

METHODS

A school-based, cross-sectional study was conducted on students who underwent refraction examination in Xinjiang, China, between May and December 2019. The prevalence of astigmatism was determined. Astigmatism was defined as cylinder power (C) ≤-0.75 D, undefined astigmatism as ≤-1.50 D, and high astigmatism as C ≤-3.00 D. Astigmatism types were: against-the-rule astigmatism (maximum refraction of the main meridian in 180° ± 30°), with-the-rule astigmatism (maximum refraction of the main meridian at 90°±30°), and oblique astigmatism (all other cases).

RESULTS

Of the 71,838 students examined (51.0% boys, 7 - 19 years old), 25,945 (36.1%, 95%CI: 35.52-36.68%) had astigmatism and 1267 (1.8%, 95%CI: 1.07-2.53%) had high astigmatism. The prevalence of astigmatism was greater in Han individuals (39.6%) compared with the Hui (34.0%), Kazakh (34.0%), Kyrgyz (32.1%), and Uyghur (26.4%) populations. Among the 25,945 students with astigmatism, 19,947 had with-the-rule astigmatism (76.9%), 3405 had against-the-rule astigmatism (13.1%), and 2593 had oblique astigmatism (10.0%). Multivariable logistic regression analysis showed that ethnicity (Han individuals more susceptible), male gender, age, and refractive errors (myopia and hyperopia) were independently associated with astigmatism, high astigmatism, and with-the-rule astigmatism (all P < 0.05).

CONCLUSIONS

The prevalence of astigmatism among children and adolescents in Xinjiang was 36.1%, including 1.8% of high astigmatism. In this population, astigmatism was mainly of the with-the-rule astigmatism type (76.9%). Han ethnicity, male gender, and myopia or hyperopia were independently associated with a high risk of astigmatism.

Pediatric Eye Care Treatment Rates and Community Compliance to a Spectacle Provision Program in an Underserved School District in San Diego, CA

Significance

The need for early identification and treatment of young children's refractive error needs has become a public health concern. The UCSD Eyemobile for Children (EyeMobile) provides vision screenings and comprehensive eye exams on the Eyemobile among a population of underserved, predominantly Hispanic preschool and elementary school children. The program also provides spectacles for children who fail eye exams due to refractive error.

Methods

We performed a retrospective cross-sectional analysis of all children screened from 2011 to 2017 by the Eyemobile across 10 San Diego elementary schools. We examined demographics, distance and near visual acuity, autorefraction, stereopsis, and color vision. To measure compliance to our spectacle program, we checked if children who were prescribed spectacles were wearing them, as instructed, at the following year's screening. Differences between compliance measures with respect to school, age, ethnicity, and gender were determined using chi-square analysis, while all other measures were fit to a binary logistic regression to determine statistically significant factors.

Results

A total of 12,176 elementary school children were screened between 2011 and 2017. Of these children, 5269 (43.3%) were referred for a comprehensive eye examination. Across six years, 3163 (60.0%) of the children referred completed their eye examinations. There was a significant increase (p < 0.001) in exam completion in the successive years. Exam completion was significantly higher in ten-year-olds (p = 0.0278) and in 3 of the 10 schools (p < 0.0001, p = 0.0027, and p = 0.0309). A total of 1089 (8.9% of screened) children were prescribed spectacles. Of the 409 children that were recorded with the compliance method, 342 (83.6%) were found to be fully compliant and wearing their spectacles as prescribed.

Conclusion

The Eyemobile program demonstrated high levels of compliance for both eye examination completion and prescribed spectacle wear in underserved populations in the San Diego region, compared to similar national programs.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Uncorrected Refractive Errors Among Children Attending Pediatric Ophthalmology Clinic at Security Forces Hospital, Makkah, Saudi Arabia

BACKGROUND

Refractive errors are globally one of the most prevalent ocular disorders among pediatrics. This study aimed to determine the pattern of uncorrected refractive errors among children attending pediatric ophthalmology clinics at Security Forces Hospital, Makkah, Saudi Arabia.

METHODS

This was a retrospective cohort clinic-based study including the records of children attending the pediatric ophthalmology clinic at Security Forces Hospital, Makkah, Saudi Arabia, between July 2021 and July 2022 who were diagnosed with refractive errors, ages between 4 and 14 years.

RESULTS

A total of 114 patients were included in the study while 26 patients with other ocular disorders were excluded from the study. The mean age of children included in the study was 9.1 ± 2.9. The most prevalent refractive errors were hyperopic astigmatism (64%), followed by myopic astigmatism (28.1%), then myopia (5.3%), and hyperopia (2.6%). The overall uncorrected refractive error of this study was estimated to be 36%. No significant association was found between the factors of age and gender on the type of refractive errors (P-value > 0.05).

CONCLUSION

The most prevalent pattern of uncorrected refractive errors among children attending pediatric ophthalmology clinics at Security Forces Hospital, Makkah, Saudi Arabia was hyperopic astigmatism followed by myopic astigmatism. No differences were found between different age groups and between genders on the type of refractive errors. Implementation of adequate vision screening programs for school-aged children is essential to detect uncorrected refractive errors at an early age.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prevalence of refractive errors in school-going children of Taif region of Saudi Arabia

PURPOSE

To determine the prevalence of refractive errors in the pediatric population in Taif, Saudi Arabia.

METHODS

This cross-sectional study included 7356 eyes of 3678 primary and secondary school children (males = 1837; females = 1841) with a mean age of 11.8 ± 2.2 years (range: 7-18) (males = 11.4 ± 2.0 [range: 8-16]; females = 12.2 ± 2.3 [range: 7-18]). All participants were selected from the school registers. The participants underwent noncycloplegic refraction to determine refractive errors. Students who refused visual acuity assessment or eye examination and were inconsistent in visual acuity assessment were excluded.

RESULTS

The manifest refraction spherical equivalent of the study population was 0.37 ± 1.52 D (range from - 18.4 to 8.8 D) (males = -0.32 ± 1.4 D [range - 15.88-8.8 D]; females = -0.42 ± 1.6 D [range - 18.38-8.0 D]). The overall prevalence of uncorrected refractive errors among school children in this study was 50.91%. The overall distribution of astigmatism (cylinder error of ≥0.50 D) in the current study population was found to be 50.14% (3688/7356 eyes).

CONCLUSION

Nearly half of the study population in this area was affected with at least one type of refractive error. The findings reveal the necessity for implementing timely and sensitive screening programs/methods to identify and correct refractive errors in this age group.

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

Background

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

Methods

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

Results

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

Conclusions

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

Prevalence of Refractive Error in School Children in Suining City of Sichuan Province, China: A School-Based Cross-Sectional Study

Objective

To investigate the prevalence of refractive errors among school children in Suining City, Sichuan Province, and to provide a scientific basis for prevention and control of myopia.

Methods

This was a school-based cross-sectional study. Children aged 6-15 years were selected from kindergartens, primary schools, and middle schools in the urban setting of Suining City. The children underwent ocular examination including measurement of uncorrected visual acuity (UCVA), visual acuity when wearing glasses, and noncycloplegic autorefractometry.

Results

Of the 1200 eligible students, 1138 children (94.8%), 553 of them girls (47.4%), participated. The mean age was 10.64 ± 2.89 years. The prevalence of myopia, hyperopia, astigmatism, and emmetropia was 59.1% (95% confidence interval (CI): 57.6, 60.5), 5.0% (95% CI: 4.7, 6.1), 38.4% (95% CI: 55.5, 58.5), and 25% (95% CI: 23.7, 26.2), respectively. In univariate analysis, the prevalence of myopia was correlated with age, female gender, and learning stage. The prevalence of hyperopia and astigmatism was correlated with age and learning stage. The prevalence of mild myopia, moderate myopia, and high myopia in the 1138 students was 17.7%, 41.4%, and 3.3%, respectively. The prevalence of mild, moderate, and high myopia all increased with age and learning stage. The prevalence of myopia differed by gender. The mean spherical equivalents of the right and left eyes were -1.40 ± 1.99 diopters (D) and -1.29 ± 1.93 D, respectively, and the median values were -0.75 D and -0.6 D, respectively. The mean spherical equivalent increased with age, learning stage, and female gender.

Conclusions

The most common type of refractive error was myopia which was associated with higher age, female gender, and higher learning stage. This study provides new data and recommendations for myopia-control in school-aged children in Sichuan province.

The prevalence of refractive error in schoolchildren

CLINICAL RELEVANCE

Information on the refractive error prevalence in school-aged children will result in delivering the optimal eye health service to this group.

BACKGROUND

Understanding the prevalence of refractive error in school-aged children is crucial to reduce the consequences of uncorrected refractive error. This study aims to investigate the prevalence of refractive error among school-aged children in Shiraz, Iran.

METHODS

In this cross-sectional population-based study, 2001 schoolchildren aged 6-12 years participated. All participants underwent cycloplegic refraction. Spherical equivalent (SE) of -0.50 dioptre or more was considered as myopia, SE of +2.00 dioptre or more as hyperopia, and astigmatism as cylinder power of 0.75 dioptre or more. The difference of 1.00 dioptre or more between two eyes defined as anisometropia.

RESULTS

The prevalence of myopia was 11.6% (95% confidence interval [CI]: 10.2-13.1%), hyperopia 6.7% (95%CI: 5.6-7.9%), and astigmatism 28.9% (95%CI: 26.9-31.0%), out of which 82.1% had with the rule astigmatism. Anisometropia was detected in 4.0% (95%CI: 3.2-5.0%) of children. Astigmatism and anisometropia were significantly higher in boys (p < 0.001, p = 0.03 respectively). The SE decreased significantly with increasing age (p < 0.001) indicating an increase in myopia with age. In addition, the rate of myopic astigmatism increased with age (p < 0.001). Among studied schoolchildren 97.0% could achieve the best-corrected visual acuity of 6/6 and 3.0% could not in the better eye.

CONCLUSION

Astigmatism was the most common refractive error among primary school children. The prevalence of myopia was relatively higher than other studies conducted in Iran, and it increased with age. These results may highlight the role of lifestyle changes and increased near work activities on the myopic shift in school-aged children. The findings provide information for screening programmes in school-aged children.

Prevalence of Health Problems Targeted by the National School-Based Screening Program among Primary School Students in Saudi Arabia, 2019

The Saudi Ministry of Health (MOH) established a National School-Based Screening Program (NSBSP) for health screening of schoolchildren. Students from specific grades were systematically screened for several health problems, including obesity, visual and auditory problems, dental cavities, scoliosis, and attention-deficit/hyperactivity disorder (ADHD). This cross-sectional study aimed to determine the prevalence of these health problems among primary school students based on secondary data obtained from the NSBSP. We included 444,259 screened school children from the first and fourth grades of 50% of the selected schools (both private and public) across the Kingdom of Saudi Arabia (KSA) during the academic year 2018-2019. Among them, the most prevalent health problems identified were dental cavities (38.7%), eye refractory errors (10.9%), and overweight and obesity (10.5%); the less prevalent problems included ADHD (2.81%), auditory problems (0.6%), and scoliosis (0.48%). A greater prevalence of most health problems was observed in girls more than boys. The NSBSP successfully aided the detection of health conditions with high and low prevalence among primary school students in the KSA, and thus, the identification of health problems of specific concern. Implementation of effective school health services for the prevention, early detection, diagnosis, and treatment of these health problems are imperative.

The prevalence and predictors of refractive error among school children in Riyadh, Saudi Arabia

PURPOSE:

Refractive error (RE) is one of the most common ocular disorders among children worldwide. This study aimed to investigate the prevalence of RE and possible risk factors among school children in Riyadh.

METHODS:

This is a cross-sectional study using data collected at various schools. To achieve the aim of the study, we selected a random sample of 850 school children aged 6–15 years. The examination was based on the RESC protocol and included full visual assessment. Furthermore, a questionnaire was sent to the parents of the participants to ascertain information about lifestyle factors. We constructed a logistic regression model to evaluate the predictors of RE.

RESULTS:

Close to a third of the children had a RE. Of those identified as having the condition, 60% did not wear glasses (newly diagnosed). Nearly all the children (95.4%) in our sample reported using electronic devices, according to parents. No association was found between using electronic devices and having a RE (P = 0.26). Doing outdoor activities was associated with 52% lower odds of a RE (odds ratio = 1.52).

CONCLUSION:

We found a higher prevalence of uncorrected RE than previously reported in other Saudi studies. About 60% of children who had RE were not wearing glasses, highlighting the need for a standardized school screening program for early detection and management. Outdoor activities were associated with a lower likelihood of having a RE. These findings might support initiatives to encourage outdoor activities among school children.

The profile of astigmatism in 6-12-year-old children in Iran

PURPOSE

To determine the prevalence of astigmatism and its determinants in schoolchildren aged 6-12 years.

METHODS

The students selected by stratified cluster random sampling in Shahroud, north of Iran. Optometric examination included uncorrected visual acuity, refraction with autorefractometer, manifest refraction with retinoscopy followed by subjective and cycloplegic refraction (after two drops of cyclopentolate 1% with 5min interval were instilled in each eye). A cylinder power ≥0.75diopter (D) in at least one eye was considered as astigmatism. The prevalence of astigmatism was reported based on a cylinder power higher than 0.50, 1.00, and 2.00D in cycloplegic refraction, followed by power vector analysis.

RESULTS

After applying the inclusion criteria, the data of 5528 children were analyzed. The prevalence of astigmatism was 16.7% (95% CI: 15.6-17.7) in total, 16.6% (95% CI: 15.2-18.0) in boys and 16.8% (95% CI: 15.2-18.3) in girls (p=0.920) and decreased from 21.5% in 6-year-old children to 13.7% in 10-year-olds, and then again increased to 18.3% in children aged 12 years. Moreover, 17.2% (95% CI: 16.0-18.3) of urban and 12.1% (95% CI: 10.0-14.1) of rural children had astigmatism (p<0.001). The prevalence of with-the-rule, against-the-rule, and oblique astigmatism was 14.2%, 2.1%, and 0.33%, respectively. The mean cylinder power was -1.31, -0.46, and -0.44D in children with spherical myopia, emmetropia, and hyperopia, respectively (p<0.001). Urban students had a higher J₀ and boys had a higher J₄₅.

CONCLUSION

The prevalence of astigmatism in this study was lower than previous studies. Astigmatism prevalence was markedly higher in urban children.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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

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

Enantiomorphism and rule similarity in the astigmatism axes of fellow eyes: A population-based study

PURPOSE

To evaluate the relationship patterns between astigmatism axes of fellow eyes (rule similarity and symmetry) and to determine the prevalence of each pattern in the studied population.

METHODS

This population-based study was conducted in 2015 in Iran. All participants had tests for visual acuity, objective refraction, subjective refraction (if cooperative), and assessment of eye health at the slit-lamp. Axis symmetry was based on two different patterns: direct (equal axes) and mirror (mirror image symmetry) or enantiomorphism. Bilateral astigmatism was classified as isorule if fellow eyes had the same orientation (e.g. both eyes were with-the-rule) and as anisorule if otherwise.

RESULTS

Of the total cases of bilateral astigmatism, 80% were isorule, and in the studied population, the prevalence of isorule and anisorule astigmatism was 14.89% and 3.53%, respectively. The prevalence of isorule increased with age (p<0.001). The prevalence of both isorule and anisorule increased at higher degrees of spherical ametropia (p<0.001). Median inter-ocular axis difference was 10° in mirror symmetry and 20° in direct symmetry with no significant difference between two genders (p>0.288). Both symmetry patterns reduced with age (p<0.001). Among cases of bilateral astigmatism, 15.5% and 19.8% had exact direct and mirror symmetry, respectively.

CONCLUSION

Bilateral astigmatism is mainly isorule in the population and anisorule astigmatism is rare. The enantiomorphism is the most common pattern in the population of bilateral astigmatism.

The Shiraz Pediatric Eye Study; a Population Based Survey of School Age Children: Rationale, Design and Baseline Characteristics

Purpose:

To describe the rationale, study design, methodology, and baseline characteristics of the Shiraz Pediatric Eye Study, a population-based survey of schoolchildren in Shiraz, Iran.

Methods:

This population-based study included schoolchildren aged 6–12 years from all four educational districts of Shiraz who were recruited in years 2015–2016. Stratified random sampling was used to select 2400 participants from all districts. Data were recorded from a detailed interview and ocular evaluation of each eligible student. The eye examination comprised uncorrected and best corrected visual acuity measurement, refraction, external eye examination (including specific strabismus and lid evaluation tests), slit lamp biomicroscopy, intraocular pressure measurement, the Ishihara color vision test, and stereoacuity. Exophthalmometry, optical biometry, and optical coherence tomography were performed for a randomly selected subset of children. General characteristics and socioeconomic variables were also recorded to assess risk factors.

Results:

From a total of 2400 selected students, 2001 (83.3%) participated in the study. The mean age of the students was 9.1 ± 1.6 years, and 59.7% were girls. Most children had at least one parent with a diploma or less than diploma (63.5%), and 2.2% had illiterate parents.

Conclusion:

This study is expected to provide accurate estimates of the prevalence of visual impairments and their related determinants in Shiraz. In addition, it will identify children who should be targeted by blindness prevention programs.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

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

Background

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

Objective

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

Methods

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

Results

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

Conclusion

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

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

Purpose

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

Methods

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

Results

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

Conclusion

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