Myopia is associated with education: Results from NHANES 1999-2008

Association Between Serum Vitamin D Levels and Myopia in the National Health and Nutrition Examination Survey (2001-2006)

PURPOSE

To assess the relationship between serum vitamin D levels and myopia in people aged 12-50 years using the National Health and Nutrition Examination Survey (NHANES) database.

METHODS

Demographics, vision, and serum vitamin D levels from NHANES (2001-2006) were analyzed. Multivariate analyses were performed to examine the relationship between serum vitamin D levels and myopia while controlling for sex, age, ethnicity, education level, serum vitamin A, and poverty status. The main outcome was presence or absence of myopia, defined as a spherical equivalent of -1 diopters or more.

RESULTS

Of the 11669 participants, 5,310 (45.5%) had myopia. The average serum vitamin D concentration was 61.6 ± 0.9 nmol/L for the myopic group and 63.1 ± 0.8 nmol/L for the non-myopic group (p = .01). After adjusting for all covariates, having higher serum vitamin D was associated with lower odds of having myopia (odds ratio 0.82 [0.74-0.92], p = .0007). In linear regression modeling that excluded hyperopes (spherical equivalent > +1 diopters), there was a positive relationship between spherical equivalent and serum vitamin D levels. Specifically, as serum vitamin D doubled, spherical equivalent increased by 0.17 (p = .02) indicating a positive dose-response relationship between vitamin D and myopia.

CONCLUSIONS

Participants with myopia, on average, had lower serum concentrations of vitamin D compared to those without myopia. While further studies are needed to determine the mechanism, this study suggests that higher vitamin D levels are associated with lower incidence of myopia.

Bi-Gaussian analysis reveals distinct education-related alterations in spherical equivalent and axial length-results from the Gutenberg Health Study

PURPOSE

The aim of this study is to investigate the distribution of spherical equivalent and axial length in the general population and to analyze the influence of education on spherical equivalent with a focus on ocular biometric parameters.

METHODS

The Gutenberg Health Study is a population-based cohort study in Mainz, Germany. Participants underwent comprehensive ophthalmologic examinations as part of the 5-year follow-up examination in 2012-2017 including genotyping. The spherical equivalent and axial length distributions were modeled with gaussian mixture models. Regression analysis (on person-individual level) was performed to analyze associations between biometric parameters and educational factors. Mendelian randomization analysis explored the causal effect between spherical equivalent, axial length, and education. Additionally, effect mediation analysis examined the link between spherical equivalent and education.

RESULTS

A total of 8532 study participants were included (median age: 57 years, 49% female). The distribution of spherical equivalent and axial length follows a bi-Gaussian function, partially explained by the length of education (i.e., < 11 years education vs. 11-20 years). Mendelian randomization indicated an effect of education on refractive error using a genetic risk score of education as an instrument variable (- 0.35 diopters per SD increase in the instrument, 95% CI, - 0.64-0.05, p = 0.02) and an effect of education on axial length (0.63 mm per SD increase in the instrument, 95% CI, 0.22-1.04, p = 0.003). Spherical equivalent, axial length and anterior chamber depth were associated with length of education in regression analyses. Mediation analysis revealed that the association between spherical equivalent and education is mainly driven (70%) by alteration in axial length.

CONCLUSIONS

The distribution of axial length and spherical equivalent is represented by subgroups of the population (bi-Gaussian). This distribution can be partially explained by length of education. The impact of education on spherical equivalent is mainly driven by alteration in axial length.

Prevalence of refractive error in Nigerian children

Refractive errors can have profound effects on children. Cost and logistics prohibit national population-based studies and global data do not accurately reflect the burden among Nigerian children. This systematic review and meta-analysis aim to provide pooled prevalence and pattern of refractive error in Nigerian children. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The protocol for this study was pre-specified and registered on the International Prospective Register of Systematic Review (registration number ID: CRD42022303419). A systematic search of PubMed, EMBASE, Scopus, CINAHL Cochrane Library, African Journal Online, and African Index Medicus databases, was done for school-based, or population-based studies on refractive error prevalence in Nigerian children younger than 18 years of age or school children in pre-tertiary institutions. Quality-effect model was used to calculate weighted prevalence, odds ratio, and corresponding 95% confidence interval. Twenty-eight school-based studies including 34,866 children were identified. No population-based studies were found. The pooled prevalence of refractive error in Nigerian children was 5.9% (3.6-8.7%) and varied between regions and with the definition of refractive error used in the studies. The number of children needed to be screened to detect one case of refractive error was 15 (9-21). The odds of refractive error was higher in girls (odds ratio: 1.3 {1.1 to 1.5}), children >10 years (odds ratio: 1.7 {1.3 to 2.2}), and urban residents (odds ratio: 2.0 {1.6 to 2.5}). The high prevalence of refractive error in Nigerian children substantiates the value of screening school children for refractive error, particularly targeting urban and older children. Research is needed to refine case definitions and improve screening protocol. Population-based studies are needed to define the prevalence of refractive error in communities. The epidemiologic and methodological challenges in conducting prevalence reviews is discussed.

Crosstalk between heredity and environment in myopia: An overview

In recent years, the prevalence of myopia has gradually increased, and it has become a significant global public health problem in the 21st century, posing a serious challenge to human eye health. Currently, it is confirmed that the development of myopia is attributed to the combined action of genes and environmental factors. Thus, elucidating the risk factors and pathogenesis of myopia is of great significance for the prevention and control of myopia. To elucidate the impact of gene-environment interaction on myopia, we used the Pubmed database to search for literature related to myopia. Search terms are as follows: myopia, genes, environmental factors, gene-environment interaction, and treatment. This paper reviews the effects of gene and environmental interaction on myopia.

The influence of the environment and lifestyle on myopia

BACKGROUND

Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of myopia during early childhood has heightened the risk of developing high myopia and related sight-threatening eye conditions in adulthood. This surge in myopia rates, occurring within a relatively stable genetic framework, underscores the profound influence of environmental and lifestyle factors on this condition. In this comprehensive narrative review, we shed light on both established and potential environmental and lifestyle contributors that affect the development and progression of myopia.

MAIN BODY

Epidemiological and interventional research has consistently revealed a compelling connection between increased outdoor time and a decreased risk of myopia in children. This protective effect may primarily be attributed to exposure to the characteristics of natural light (i.e., sunlight) and the release of retinal dopamine. Conversely, irrespective of outdoor time, excessive engagement in near work can further worsen the onset of myopia. While the exact mechanisms behind this exacerbation are not fully comprehended, it appears to involve shifts in relative peripheral refraction, the overstimulation of accommodation, or a complex interplay of these factors, leading to issues like retinal image defocus, blur, and chromatic aberration. Other potential factors like the spatial frequency of the visual environment, circadian rhythm, sleep, nutrition, smoking, socio-economic status, and education have debatable independent influences on myopia development.

CONCLUSION

The environment exerts a significant influence on the development and progression of myopia. Improving the modifiable key environmental predictors like time spent outdoors and engagement in near work can prevent or slow the progression of myopia. The intricate connections between lifestyle and environmental factors often obscure research findings, making it challenging to disentangle their individual effects. This complexity underscores the necessity for prospective studies that employ objective assessments, such as quantifying light exposure and near work, among others. These studies are crucial for gaining a more comprehensive understanding of how various environmental factors can be modified to prevent or slow the progression of myopia.

Relationship between visual impairment and school entrance age in rural China

CLINICAL RELEVANCE

Children with uncorrected visual impairment have lower scores on various motor and cognitive tests. Exploring the association between visual impairment and school entrance age among school children in rural China may assist in enhancing the visual health of early-entry school students.

BACKGROUND

Educational pressures may play a role in the visual health of students. School entrance age is associated with educational pressures. This study explored whether school entrance age can contribute to visual impairment among younger generations.

METHODS

A cross-sectional study was conducted with 17,510 students from 252 primary schools in two prefectures in western China. Information on the sampled students was collected through questionnaires and vision examinations. The relationship between visual impairment and school entrance age was further analysed by multiple regression. The school entrance age was classified as early-entry and late-entry, early-entry was defined as students entering school at the age 6 years.

RESULTS

The results showed that the myopia rate of early-entry students (26.92%) was higher than late-entry students (23.86%). Multiple regression showed that visual impairment increased with the earlier age of school entry (P = 0.044). The prevalence of myopia was also significantly higher in higher grades for children of the same age. The prevalence of myopia in 10-year-old and 11-year-old fourth- and fifth-grade students was 20.6% to 30.5%, 21.7% to 27.4% (P < 0.001). The near work with eyes was significantly different among children of the same age in different grades during this study (P < 0.001).

CONCLUSION

Myopia is related to the school entrance age of children. Children who start school earlier are more likely to suffer from myopia. Educational pressures and digital screens may play a role in the association. Changes in the current education mode by reducing the study burden in the early years of learning may be significant.

Axial length and anterior chamber indices in elderly population: Tehran Geriatric Eye Study

AIM

To determine the normative distribution of axial length (AL), anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and some of their associated factors in subjects aged 60 and over.

METHODS

In this cross-sectional study, 160 clusters were sampled using multi-stage cluster sampling in Tehran, Iran. After a preliminary interview, the participants underwent optometric examinations including visual acuity and refraction measurement followed by slit lamp biomicroscopy. Finally, ocular imaging was done using the Pentacam AXL to measure AL, ACD, ACV, and ACA.

RESULTS

A total of 4519 eyes of 2436 participants were evaluated, of whom 58.0% (n=1412) were female. The mean age of the subjects was 67.32±6.05y (range: 60-95y). The mean AL, ACD, ACV, and ACA was 23.22 mm (23.18-23.27 mm), 2.61 mm (2.59-2.62 mm), 126.56 mm3 (125.08-128.04 mm3), and 30.61° (30.3°-30.92°), respectively. In the multivariable model, after adjusting for the effect of both eyes, the longest and shortest AL was seen in myopic and hyperopic subjects, respectively. AL, ACD, ACV and ACA were significantly larger in men compared to women (P<0.001). Except ACA, other evaluated parameters showed an inverse correlation with age (P<0.001), however, this correlation was insignificant for AL (P=0.623).

CONCLUSION

Normative value of AL, and other biometric parameters are specific for each ethnicity, age and sex group. Any alteration in these parameters and their effect on refraction should be considered in this age group, especially in case of cataract surgery.

A Comparison of Optical Biometers Used in Children for Myopia Control

PURPOSE

To assess the reproducibility (i.e., inter-device reliability) of the biometers Topcon MYAH, Oculus Myopia Master, and Haag-Streit Lenstar LS900 with the Carl Zeiss IOLMaster 700 and the intra-subject repeatability in myopic children in order to reliably detect axial growth for myopia management.

METHODS

Twenty-two myopic children (11.1 ± 2.4 yr) with a spherical equivalent of - 3.53 ± 2.35 D were examined with each of the biometers to assess axial length (AL) and corneal parameters (steepK, flatK, meanK, vectors J0, J45), and16 of these children agreed to a second round of measurements. Reproducibility of the first measurements between the IOLMaster and every other biometer was assessed employing a Bland-Altman approach and paired Student's t-test. Repeatability was assessed as intra-subject standard deviation and was used to estimate the minimum time interval required between two AL measurements to reliably detect axial growth of an eye of at least 0.1 mm/year.

RESULTS

Repeatability for AL measurements was as follows: IOLMaster: 0.05 mm, Myopia Master: 0.06 mm, Myah: 0.06 mm, Lenstar: 0.04 mm; the respective minimal time interval for axial growth assessment in myopia management was estimated as 5.6, 6.6, 6.7, and 5.0 months, respectively. Best reproducibility of the AL measurement was found between IOLMaster and Lenstar [95% Limits of Agreement (LoA) for reproducibility - 0.06 to 0.02]. As regards to the measured means, Lenstar gave measures of AL that were longer than with the IOLMaster by 0.02 mm (p < 0.001). Myopia Master measures of meanK were significantly lower (by 0.21 D with p < 0.001) than the values from the IOLMaster. As for J0, all biometers deviated significantly from IOLMaster measurements (p < 0.05).

CONCLUSION

Generally good agreement was observed between all the biometers. When assessing myopia progression in children, a time frame of at least 6 months between the AL measurements is advisable in order to reliably determine any deviation from a normal growth pattern.

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.

Increasing prevalence of myopia and the impact of education in primary-school students in Xi'an, north-western of China

Purpose

The present study was performed to detect the prevalence of myopia among primary-school students in Xi'an, north-western of China.

Methods

The present study was a school-based study with students aged from 6 to 13 years old. All the individuals underwent ophthalmological examination and spherical equivalent (SE) of refractive error were measured with non-cycloplegic refraction. Myopia was defined as a SE of ≤ -0.5 diopters (D), and further divided into three stratified groups based on SE: low myopia (≤ -0.5 to >-3.0 D), moderate myopia (≤ -3.0 to >-6.0 D), and high myopia (≤ -6.0 D). Relative risk factors, including age, sex, grade and ethnicity were investigated using questionnaire.

Results

A total of 4,680 individuals were eligible for this survey and 4,654 (99.4% participation rate) were finally included (51.2% boys). The mean age of participants was 8.756 ± 1.727 years. The whole city-level prevalence of total myopia was 57.1% (95% CI: 55.7-58.6%). Additionally, the prevalence of low, moderate, and high myopia was 45.0% (95% CI: 43.5-46.4%), 11.1% (95% CI: 10.2-12.0%), and 1.0% (95% CI: 0.7-1.3%), respectively. Moreover, grade (education level) instead of age, sex and ethnicity was the most essential risk factor for prevalence of overall myopia (OR = 1.844, 95% CI: 1.605-2.119), and an increase of prevalence by 84.4% per grade was seen. Furthermore, similar associations of grade were significant with low myopia (OR = 1.613, 95% CI: 1.385-1.877) and moderate myopia (OR = 2.186, 95% CI: 1.693-2.823), meanwhile, prevalence of low myopia and moderate myopia demonstrated an increase of prevalence by 61.3 and 118.6% per grade, respectively. None of the factors included in the present study was significant risk factor for high myopia.

Conclusions

The present study investigated a non-negligible high prevalence of myopia among primary-school students in Xi'an, north-western of China, and a gradual increasing in proportion with education level.

Screen time and myopia: A serial multiple mediator SEM analysis

Background

COVID-19 has influenced education systems worldwide, and significantly increased screen time for college students, posing a potential risk of myopia. In China, ninety percent of college students suffer from myopia. Excessive screen time changes college students' lifestyles, imposes potential health risks, and affects opportunities for employment. It is important to identify the potential correlation between screen time use and myopia among college students.

Methods

This paper conducted a nationwide experiment using Chinese college students and set a multiple-mediator SEM model to analyze the potential correlation between screen time and myopia. The two mediators were sedentary behavior and physical activity, respectively.

Results

We obtained three valuable conclusions as follows: First, there was no significant direct relationship between screen time and myopia among Chinese college students during the COVID-19 pandemic. Second, sedentary behavior and physical activity significantly predicted the increase/decrease of myopia among Chinese college students, respectively. Third, a serial multiple mediator that encompassed sedentary behavior and physical activity sequentially fully mediated the relationship between screen time and myopia.

Conclusions

Although there was no directly significant relationship between screen time and myopia, screen time can indirectly influence the risk of suffering myopia by influencing sedentary behavior and physical activity. Our study demonstrates the need to prevent the potential influence of overuse of electronic devices on myopia in college students, especially during the COVID-19 pandemic.

Objective measures of viewing behaviour in children during near tasks

CLINICAL RELEVANCE

Objective assessment of near viewing behaviours performed in a laboratory setting showed that children demonstrate differing viewing distances and angles based on the type of task. Findings will contribute to our understanding of how near work influences myopia.

BACKGROUND

Evidence suggests that near working distance and viewing breaks are associated with myopia. The purpose of this study was to use an objective, continuously measuring range finding device to examine these viewing behaviours in children.

METHODS

Viewing distance, number of breaks, and head and eye angles were assessed in 16 non-myopic and 19 myopic children (ages 13.38 ± 4.14 years) using the Clouclip, an objective rangefinder, during five 15-minute near tasks, including (a) passive reading and (b) active writing on printed material, (c) passive viewing and (d) active engagement on an iPad, and (e) active engagement on a cell phone. Height and Harmon distance were measured. Viewing behaviours were analysed by task, refractive error group, and gender.

RESULTS

Mean viewing distances significantly differed by task (P < 0.001) and were highly correlated with children's Harmon distance and height for all near tasks (P < 0.05), except for the active printed task (P > 0.05). Viewing distances did not differ by gender or refractive error group. During each task, mean number of viewing breaks was 2.6 ± 4.1 and did not vary between task (P = 0.92) or refractive error group (P = 0.65). Head declination and total viewing angle varied by type of near task (P < 0.001 for both).

CONCLUSION

Children demonstrated differing viewing distances and viewing angles based on the type of near task they were performing. Viewing behaviours did not vary between myopic and non-myopic children. Findings will contribute to a better understanding of how near viewing behaviours can be quantified objectively and relationships with myopia.

A systematic review of near work and myopia: measurement, relationships, mechanisms and clinical corollaries

After decades of investigation, the role of near work in myopia remains unresolved, with some studies reporting no relationship and others finding the opposite. This systematic review is intended to summarize classic and recent literature investigating near work and the onset and progression of myopia, potential mechanisms and pertinent clinical recommendations. The impact of electronic device use is considered. PubMed and Medline were used to find peer-reviewed cross-sectional and longitudinal studies related to near work and myopia from 1980 to July 2020 using the PRISMA checklist. Studies were chosen using the Joanna Briggs Institute checklist, with a focus on studies with a sample size greater than 50. Studies were independently evaluated; conclusions were drawn per these evaluations. Numerous cross-sectional studies found increased odds ratio of myopia with increased near work. While early longitudinal studies failed to find this relationship, more recent longitudinal studies have found a relationship between myopia and near work. Rather than daily duration of near work, interest has increased regarding absolute working distance and duration of continuous near viewing. Several reports have found that shorter working distances (<30 cm) and continuous near-work activity (>30 min) are risk factors for myopia onset and progression. Novel objective continuously measuring rangefinding devices have been developed to better address these questions. The literature is conflicting, likely due to the subjective and variable nature in which near work has been quantified and a paucity of longitudinal studies. We conclude that more precise objective measures of near viewing behaviour are necessary to make definitive conclusions regarding the relationship between myopia and near work. Focus should shift to utilizing objective and continuously measuring instruments to quantify near-work behaviours in children, followed longitudinally, to understand the complex factors related to near work. A better understanding of the roles of absolute working distance, temporal properties, viewing breaks and electronic device use on myopia development and progression will aid in the development of evidence-based clinical recommendations for behavioural modifications to prevent and slow myopia.

Dioptric power and refractive behaviour: a review of methods and applications

Myopia is a global healthcare concern and effective analyses of dioptric power are important in evaluating potential treatments involving surgery, orthokeratology, drugs such as low-dose (0.05%) atropine and gene therapy. This paper considers issues of concern when analysing refractive state such as data normality, transformations, outliers and anisometropia. A brief review of methods for analysing and representing dioptric power is included but the emphasis is on the optimal approach to understanding refractive state (and its variation) in addressing pertinent clinical and research questions.

Although there have been significant improvements in the analysis of refractive state, areas for critical consideration remain and the use of power matrices as opposed to power vectors is one such area. Another is effective identification of outliers in refractive data. The type of multivariate distribution present with samples of dioptric power is often not considered. Similarly, transformations of samples (of dioptric power) towards normality and the effects of such transformations are not thoroughly explored. These areas (outliers, normality and transformations) need further investigation for greater efficacy and proper inferences regarding refractive error. Although power vectors are better known, power matrices are accentuated herein due to potential advantages for statistical analyses of dioptric power such as greater simplicity, completeness, and improved facility for quantitative and graphical representation of refractive state.

Lutein and Zeaxanthin Intake during Pregnancy and Visual Function in Offspring at 11–12 Years of Age

(1) Background: Lutein and zeaxanthin (L&Z) are essential dietary nutrients that are a crucial component of the human macula, contributing to visual functioning. They easily cross the placental barrier, so that retinal deposition commences during foetal development. This study aims to assess associations between maternal L&Z intake during pregnancy and offspring visual function at 11–12 years. (2) Methods: Using the Spanish INfancia y Medio Ambiente project (INMA) Sabadell birth cohort, 431 mother–child pairs were analysed. L&Z data were obtained from food frequency questionnaires (FFQ) at week 12 and 32 of pregnancy, alongside other nutritional and sociodemographic covariates. Contrast vision (CS) and visual acuity (VA) were assessed using the automated Freiburg Acuity and Contrast Testing (FRACT) battery. Low CS and VA were defined as being below the 20th cohort centile. Associations were explored using multiple logistic regression. (3) Results: After controlling for potential confounders, L&Z intake during the 1st and 3rd trimester did not reveal any statistically significant association with either CS or VA in offspring at age 11/12 years. (4) Conclusions: No evidence of a long-term association between L&Z intake during pregnancy and visual function in offspring was found. Further larger long-term studies including blood L&Z levels are required to confirm this result.

Bowel Health in U.S. Vegetarians: A 4-Year Data Report from the National Health and Nutrition Examination Survey (NHANES)

Dietary fiber is of paramount importance in the prevention of large-bowel diseases, yet fiber intake in many high income countries is well below daily recommendations. Vegetarian diets high in fiber-rich plant-foods have been associated with a higher frequency of bowel movements and softer stools. Thus, vegetarians appear to suffer less frequently from constipation and other bowel disorders. The number of studies investigating these associations, however, is limited. The present study sought to investigate bowel health and constipation prevalence in a self-identified vegetarian population from the U.S. National Health and Nutrition Examination Survey (2007−2010). Bowel health assessment included Bristol Stool Scale (BSS), Bowel Movement (BM) frequency and Fecal Incontinence Severity Index (FISI). The present study included 9531 non-vegetarians and 212 vegetarians. We found no associations between vegetarian status and all examined bowel health items (BM frequency, BSS and FISI). Vegetarians consumed significantly more fiber than omnivores (21.33 vs. 16.43 g/d, p < 0.001) but had a lower moisture intake (2811.15 vs. 3042.78 g/d, p = 0.045). The lack of an association of vegetarian status and bowel health is surprising, and may be a result of the relatively low fiber intake in this particular vegetarian cohort, which did not meet the daily fiber recommendations.

Diet and Consumer Behavior in U.S. Vegetarians: A National Health and Nutrition Examination Survey (NHANES) Data Report

An increasing number of individuals adopt plant-based diets for their potential health benefits. Understanding vegetarians' dietary behavior in the context of their socioeconomic background is essential for pro-vegetarian messaging and to influence public beliefs about plant food consumption. Thus, this study sought to investigate diet and consumer behaviors in U.S. vegetarians. This is a cross-sectional, population-based study with data from the Nutrition and Health Examination Surveys (2007-2010). Selected items from three modules (diet and nutrition behavior, consumer behavior, and food security) were compared between vegetarians (n = 352) and the general population (n = 14,328). U.S. vegetarians consumed significantly fewer calories and less cholesterol but more fiber than their omnivorous counterparts. Moreover, vegetarians had significantly fewer soft drinks and salty snacks available at home. We also observed significant intergroup differences with regard to the availability of fruit and dark green vegetables. Vegetarians spent less money on eating out and indicated a lower number of not-home-prepared meals and ready-to-eat foods. We found no differences regarding money spent at supermarkets or grocery stores. Our study contributes to a better understanding of dietary and consumer behaviors in vegetarians. We shed a new light on the economic feasibility of vegetarian diets, highlighting that these diets are not necessarily more expensive than an omnivorous diet.

Prevalence of refractive errors and color vision deficiency in a population of industry-workers in Abhar, Iran

Visual impairment due to refractive errors and color vision deficiency (CVD) can affect the visual abilities of workers in workplace. Identifying the prevalence of common visual problems helps us to prevent and treat occupational ocular problems.This study was conducted on 2600 males referring from companies for a routine medical exam to Occupational Medicine Center. In all subjects, visual acuity and refraction were measured. Assessment of color vision was performed by Ishihara color test. In present study, right eyes of subjects were selected to statistical analysis.The mean spherical equivalent was -0.19 ± 1.39 diopter with a range of -11.00 to +10.00 diopter. Whereas 71% of persons were emmetropic, 20% and 9% of them were myopic and hypermetropic, respectively. From a total subjects, 164 of them had CVD with prevalence of color blindness of 6.3%. In comparison with normal subjects, CVD had no significant effect on refractive findings of our subjects (P > .05).Our data present the prevalence of refractive errors and color blindness among Iranian industry-workers. Compared with other studies, our subjects have a lower prevalence of refractive errors, and similar rate of prevalence of color blindness.

Global disease burden of uncorrected refractive error among adolescents from 1990 to 2019

Background

To estimate the global disease burden of uncorrected refractive error (URE) among adolescents and assess the contributions of various risk factors to disability-adjusted life-years (DALYs) due to URE.

Methods

Global, regional and country-level DALY numbers and rates due to URE among adolescents were acquired from the Global Burden of Disease Study 2019 database. Human Development Index (HDI), Socio-Demographic Index (SDI) and other country-level data were obtained from other open databases as potential indicators. Regression analysis was used to evaluate associations between DALY rates among adolescents and potential predictors.

Results

Global DALYs due to URE among adolescents rose by 8% between 1990 and 2019 but moderately decreased by 4.8% during this period after adjusting for population size. Female adolescents showed higher DALY rates. DALY rates sharply increased from 5 to 9 years of age, then rose more slowly, reaching a plateau before 20 years of age. Country-level DALY rates in 2019 were positively associated with HDI, SDI, and urbanization rates but negatively correlated with primary school dropout rates. Higher disease burden of adolescents visually impaired from URE was associated with lower primary school dropout rates (β = − 0.257, 95% CI − 0.376 to − 0.138, P < 0.001) and higher urbanization rates (β = 0.257, 95% CI 0.067 to 0.256, P = 0.001).

Conclusions

Higher socioeconomic status, urbanization rates and education levels are associated with a heavier disease burden of URE among adolescents. The findings of this study can provide a reference for policy making on resource allocation for URE prevention and control in teenagers.

Wearable Sensors for Measurement of Viewing Behavior, Light Exposure, and Sleep

The purpose of this study was to compare two wearable sensors to each other and to a questionnaire in an adult population. For one week, participants aged 29.2 ± 5.5 years (n = 25) simultaneously wore a Clouclip, a spectacle-mounted device that records viewing distance and illuminance, and an Actiwatch, a wrist-worn device that measures illuminance and activity. Participants maintained a daily log of activities and completed an activity questionnaire. Objective measures of time outdoors, near (10–< 60 cm) and intermediate (60–100 cm) viewing, and sleep duration were assessed with respect to the daily log and questionnaire. Findings showed that time outdoors per day from the questionnaire (3.2 ± 0.3 h) was significantly greater than the Clouclip (0.9 ± 0.8 h) and Actiwatch (0.7 ± 0.1 h, p < 0.001 for both). Illuminance from the Actiwatch was systematically lower than the Clouclip. Daily near viewing duration was similar between the questionnaire (5.7 ± 0.6 h) and Clouclip (6.1 ± 0.4 h, p = 0.76), while duration of intermediate viewing was significantly different between methods (p < 0.001). In conclusion, self-reported time outdoors and viewing behaviors were different than objective measures. The Actiwatch and Clouclip are valuable tools for studying temporal patterns of behavioral factors such as near work, light exposure, and sleep.

Characterizing Astigmatism in the United States

PURPOSE

To study astigmatism and astigmatism rule by 1) determining changes in prevalence in the United States between 1971-1975 and 1999-2008 and 2) identifying associations with demographic factors.

SETTING

National survey.

DESIGN

Retrospective cross-sectional study.

METHODS

Participants of the 1971-1975 and 1999-2008 National Health and Nutrition Examination Survey (NHANES) aged 20-74 years representing the United States population. The 1971-1975 NHANES measured astigmatism in individuals using an algorithm based on presenting visual acuity, lensometry and objective refraction. We implemented similar methods using 1999-2008 NHANES data for comparison. We identified prevalence of clinically significant astigmatism (≥1.0 D) and used logistic regression models to assess demographic associations with rule of astigmatism.

RESULTS

Main outcomes were prevalence estimates of astigmatism and odds ratios estimating associations with demographic characteristics. There was an increase in astigmatism from the 1970's to 2000's [14% (95% CI: 13.2-14.5) vs. 24% (22.8-24.6)], which was more pronounced in men [12% (10.8-12.7) vs. 23% (21.9-24.2)] than women [16% (14.9-16.8) vs. 24% (23.0-25.7)]. In adjusted analysis of the 2000's cohort, myopes had 8.34 (CI: 7.30-9.54) times greater odds of astigmatism than non-myopes. In the 2000's, there was increased odds of ATR astigmatism in males (OR, 1.4; 95% CI: 1.1-1.8) compared to females, non-myopes (OR, 2.3; 95% CI: 1.7-3.1) compared to myopes, and 60-74 year olds (OR, 3.7; 95% CI: 2.7-5.1) compared to 20-39 year olds.

CONCLUSIONS

There is greater prevalence of astigmatism and against-the-rule astigmatism in 1999-2008 compared to 30 years prior. Factors associated with against-the-rule astigmatism were being male, white, and nonmyopic.

[Optometric eye screening in schools : First results of a pilot project on logistical feasibility]

BACKGROUND

We present a pilot project to improve eye health in schoolchildren: annual optometric screening with a focus on early detection of school myopia. The logistical proof-of-concept is illustrated by way of a pilot project at a state high school in North Rhine-Westphalia. The collected biometric parameters also contribute to the collection of epidemiological data.

MATERIAL AND METHODS

On organized examination days objective and subjective refractions of schoolchildren in grades 5-7 (ages 9-16 years) were determined, children were tested for abnormalities in binocular vision and the photopic and mesopic pupil diameters were determined. Noncontact biometry was used to measure the corneal radius, central corneal thickness, anterior chamber depth, lens thickness and axial length of the eyes. Optical coherence tomography (OCT) was used to also determine the central choroidal thickness of the eyes. Questionnaires were employed to inquire about the visual habits of the schoolchildren.

RESULTS

In the fall of 2019 a total of 274 schoolchildren (11.2 ± 1.2 years) voluntarily participated in the examinations: 22% (61) showed myopia (spherical equivalent ≤ -0.50 D), of which 11% (7) were previously uncorrected (uncorrected distance visual acuity < 0.8). Of the schoolchildren 8% (5) showed an increase in myopia of more than -0.5 D compared to their actual spectacle values (distance visual acuity with ophthalmic lens < 0.8). A class of about 25 pupils can be examined within 2 regular periods.

CONCLUSION

There is an actual need for optometric screening because a total of 4.4% (12) myopic schoolchildren could be identified who had a distance visual acuity of less than 0.8 even with the correction. By determining the axial length and classifying this value depending on age in the literature can help to predict the individual risk of myopia and to raise awareness among parents and children to address this problem. The planned repetition of these examinations enables a better understanding of eye growth in schoolchildren.

Relationship between Myopia Progression and School Entrance Age: A 2.5-Year Longitudinal Study

Objective

To investigate the association between myopia progression and school entrance age among Chinese schoolchildren and to suggest a more appropriate school age.

Methods

1,463 children aged six to nine years from Wenzhou, China, were examined and followed up for two and a half consecutive years. Their noncycloplegic refraction was measured twice each year by using an automatic refractometer; axial length (AL) and corneal radius of curvature (CRC) were tested annually by using the IOLMaster for 2.5 years. The questionnaires were completed by the children to collect detailed information regarding risk factors. Here, myopia is defined as a spherical equivalent less than −1.0D.

Results

The changes in spherical equivalent (SE) of 7-year-old children in grade 1 and grade 2 were −0.45D and -0.56D, while changes in AL were 0.59 mm and 0.62 mm, respectively. The SE changes of 8-year-old children in grade 2 and grade 3 were −0.54D and −0.75D; meanwhile, the AL changes were 0.57 mm and 0.61 mm, respectively. Significant statistical differences were observed in ocular biological structure parameters, except for corneal radius of curvature (CRC) or anterior chamber depth (ACD), among children with the same age in different grades during this study. The prevalence of myopia was also significantly higher in higher grades for children with same age.

Conclusions

Myopia is related to children's school entrance age. Children who start school in an earlier age are more likely to suffer from myopia, and the progression of myopia can be considerably faster. Therefore, it is recommended to enter school after the age of 7.

Progression of myopia in children and teenagers: a nationwide longitudinal study

Background

Data on myopia prevalence and progression in European children are sparse. The aim of this work was to evaluate the progression of myopia in children and teenagers in a large prospective study.

Methods

A prospective study involving a nationwide cohort. Myopia was defined as a spherical equivalent (SE) of ≤ –0.50 diopters (D). Data on refractive error, gender and age were collected in 696 optical centres in France between 2013 and 2019, including 136 333 children (4–17 years old) in the analysis.

Progression of myopia was assessed between the first visit and the last visit over up to 6.5 years.

Results

Mean age was 11.3±3.8 years (55.0% of female). The proportion of children progressing more than –0.50 D per year was higher in age groups 7–9 years and 10–12 years and in children with SE ≤ –4.00 D at first visit, representing 33.1%, 29.4% and 30.0% of these groups, respectively. In multivariate analysis, progression during the first 11–24 months was higher in the 7–9 and 10–12 age groups (–0.43 D and –0.42 D, respectively), for higher SE at baseline (at least –0.33 D for SE ≤ –1 D) and for girls (–0.35 D).

Conclusion

This is the first French epidemiological study to investigate myopia progression in a large-scale cohort of children. Sex, age groups and myopia severity are associated with differing rates of progression.

Open schools! Weighing the effects of viruses and lockdowns on children

This review weighs the risk of infection with SARS-CoV-2 against the side effects of school closures on physical and mental health, education, and well-being of those affected by the school closures. Whereas short term effects - decreased learning and food security, and increased anxiety, violence against children, child labor and teen pregnancies - are frequently discussed, the long-term effects of school closures will be much more detrimental across the lifespan of the "Generation Corona": Existing pandemics of inactivity and myopia, already affecting billions of people, are worsening due to less physical exercise and less time spent outdoors, poor diet, weight gain, and increased screen time during lockdowns, causing future increases of stroke, heart attack, cancer, and blindness. Socio-emotional complications of isolation, learned helplessness, economic and existential insecurity will include increased depression and suicide, decreased empathy and increased loneliness. Together with decreased educational attainment and economic productivity, the amount of ensuing increased future global morbidity and mortality justifies immediate action of school reopening.

Reducing the Global Burden of Myopia by Delaying the Onset of Myopia and Reducing Myopic Progression in Children: The Academy's Task Force on Myopia

In 2019, the American Academy of Ophthalmology (AAO) created the Task Force on Myopia in recognition of the substantial global increases in myopia prevalence and its associated complications. The Task Force, led by Richard L. Abbott, MD, and Donald Tan, MD, comprised recognized experts in myopia prevention and treatment, public health experts from around the world, and organization representatives from the American Academy of Family Physicians, American Academy of Optometry, and American Academy of Pediatrics. The Academy's Board of Trustees believes that myopia is a high-priority cause of visual impairment, warranting a timely evaluation and synthesis of the scientific literature and formulation of an action plan to address the issue from different perspectives. This includes education of physicians and other health care providers, patients and their families, schools, and local and national public health agencies; defining health policies to ameliorate patients' access to appropriate therapy and to promote effective public health interventions; and fostering promising avenues of research.

Recent Epidemiology Study Data of Myopia

Myopia, a pandemic refractive error, is affecting more and more people. The progression of myopia could cause numerously serious complications, even leading to blindness. This review summarizes the epidemiological studies on myopia after 2018 and analyzes the risk factors associated with myopia. The prevalence of myopia varies in different regions, age, and observation time. East Asia has been gripped by an unprecedented rise in myopia, and other parts of the world have also seen an increase. The prevalence of myopia in children continues to rise and aggravates with age. The prevalence of high myopia has also increased along with myopia. Racial dependence and family aggregation can be seen frequently in myopia patients. Increased outdoor activities are proven to be protective factors for myopia, as near-distance work and higher education levels affect in the opposite. The impact of gender or urbanization on myopia is controversial. The relationship between nutrition, digital screens, Kawasaki disease, pregnant women smoking during pregnancy, and myopia is still not clear for lack of sufficient evidence. Understanding the various factors that affect myopia helps to clarify the mechanism of myopia formation and also to formulate reasonable prevention and control measures of myopia to protect people's health, especially for adolescents.

Validation of the Clouclip and utility in measuring viewing distance in adults

PURPOSE

To validate the Clouclip, a continuously measuring objective rangefinder, and examine viewing behaviours during various near tasks in non-myopic and myopic adults.

METHODS

In experiment 1, five Clouclip devices were utilised. An infrared camera was used to visualise and measure infrared beam size and angle. Repeatability for distance tracking was assessed from 5 to 120 cm in 5 cm increments. Accuracy of distance tracking was investigated for paper and iPad targets, spatial integration was calculated, effects of target tilt were determined and light measurements were compared to a lux meter. In experiment 2, viewing behaviour was assessed in 41 subjects (21 non-myopic, 20 myopic) during four 15-min near tasks; (1) passive reading of printed material, (2) active writing on printed material, (3) passive viewing on an electronic device and (4) active engagement on an electronic device. Working distance was compared between tasks and refractive error groups.

RESULTS

Clouclip distance tracking showed good repeatability, with a mean difference of 0.34 cm and limits of agreement of ±2.0 cm. Clouclip-measured and actual distances were highly correlated for paper and electronic targets from 5 to 120 cm, with mean differences and limits of agreement of 3.96 ± 13.78 cm and 4.48 ± 8.92 cm, respectively; variability increased for distances >100 cm. Tracking ability increased with larger target sizes; tracking was accurate when the target occupied 1.5%-20.3% of tracking beam area, depending on distance and with target tilt up to ±60 degrees. Clouclip- and lux meter-measured ambient illumination were highly correlated for a wide range of intensities (r = 0.96, p < 0.001), but with greater variability for intensities >20 000 lux. The Clouclip infrared beam was measured to have a diameter of 25.6 ± 2.2° and a downward angle of 10.3 ± 0.5°. For subject testing, viewing distance was significantly closer for active and passive printed tasks (29.5 ± 6.7 cm and 33.2 ± 8.8 cm, respectively) than for active and passive electronic tasks (35.4 ± 8.0 cm and 40.8 ± 10.4 cm, respectively), with no differences between refractive error groups (p = 0.88).

CONCLUSIONS

The Clouclip performed well in measuring near and intermediate distances and could distinguish between indoor (<1000 lux) and outdoor (>1000 lux) illumination. A closer working distance was observed for printed tasks compared to those on an iPad, with no difference in viewing distance between non-myopic and myopic adults.

Stability of Ophthalmic Atropine Solutions for Child Myopia Control

Myopia is an ophthalmic condition affecting more than 1/5th of the world population, especially children. Low-dose atropine eyedrops have been shown to limit myopia evolution during treatment. However, there are currently no commercial industrial forms available and there is little data published concerning the stability of medications prepared by compounding pharmacies. The objective of this study was to evaluate the stability of two 0.1 mg/mL atropine formulations (with and without antimicrobiobial preservatives) for 6 months in two different low-density polyethylene (LDPE) multidose eyedroppers. Analyses used were the following: visual inspection, turbidity, chromaticity measurements, osmolality and pH measurements, atropine quantification by a stability-indicating liquid chromatography method, breakdown product research, and sterility assay. In an in-use study, atropine quantification was also performed on the drops emitted from the multidose eyedroppers. All tested parameters remained stable during the 6 months period, with atropine concentrations above 94.7% of initial concentration. A breakdown product (tropic acid) did increase slowly over time but remained well below usually admitted concentrations. Atropine concentrations remained stable during the in-use study. Both formulations of 0.1 mg/mL of atropine (with and without antimicrobial preservative) were proved to be physicochemically stable for 6 months at 25 °C when stored in LDPE bottles, with an identical microbial shelf-life.