Refractive error and visual impairment in Ireland schoolchildren

A review of mechanism of action of outdoor exposure in preventing myopia incidence and progression

Various studies have suggested several environmental, pharmacological, medical, and optical interventions and some are in use but their efficacy in myopia control may be transient, and the cellular, molecular, and biochemical mechanisms involved unclear. Daylight exposure is currently regarded as an effective and enduring strategy in the control of myopia development and progression. However, the mechanism behind the effect of outdoor exposure and its association with genetic predisposition and other relatively more significant environmental factors on myopia is still a conundrum. This review focuses on survey-based and intervention-based studies carried out to propose a mechanism that accounts for myopia development and important for its control.

The CroMyop study: myopia progression in Croatian children and adolescents-a 15-year retrospective analysis

Purpose

Myopia is a major global health issue, especially among children and adolescents. Understanding its traits and progression is vital for proper management and prevention. This study aimed to fill a gap in research by analyzing demographic and refractive data concerning myopia among children and adolescents in Croatia, with the goal of providing insights into myopia prevalence, progression rates, and associated risk factors within the Croatian population.

Design

This retrospective study utilized a comprehensive dataset from pediatric ophthalmology clinics at the University Eye Department, University Hospital "Sveti Duh," Zagreb, Croatia. The dataset included electronic medical records spanning from January 2008 to July 2023, encompassing demographic and refractive data.

Methods

Data analysis focused on individuals aged 4 to 18 years who were diagnosed with primary myopia and/or compound myopic astigmatism. Ophthalmic examinations, including visual acuity tests, cycloplegic refraction, and assessments for eye comorbidities, were conducted by experienced pediatric ophthalmologists. Statistical analysis, including t-tests, survival analysis, and logistic regression, was performed to assess myopia prevalence, progression rates, and associated factors. These analyses were adjusted for covariates such as age, parental myopia, and gender.

Results

The study included 895 individuals, 51 premyopes, 813 low myopes, and 31 high myopes. The average age of diagnosis was 11.37 ± 3.59 years for premyopes, 11.18 ± 3.53 years for low myopes, and 11.44 ± 4.35 years for high myopes. The fastest progression occurred in 2021 and 2022, -0.5 ± 0.12 D/y for premyopes and - 0.45 ± 0.1 D/y for low myopes. Premyopic progression to low myopia was associated with age 7-9 years (HR 2.42, 1.53 to 3.21) and both parents being myopic (HR 920.27. 850.16 to 950.53). Low myopic individuals with both myopic parents displayed the fastest 11-24 months after first visit progression rates, -0.69 (-0.52 to -0.87) D/y, while the 7-9 age group demonstrated -0.36 (-0.24 to -0.45) D/y. Low myopes aged 7-9 years with baseline SE between -6 D and -4 D were more strongly associated with ≤ - 0.5 D progression (OR = 2.0, 95% CI -1.00 to 2.39).

Conclusion

This study highlights the importance of environmental factors, genetics, and age in addressing myopia progression among Croatian youth, urging further research for effective local intervention strategies.

Myopia outcome study of atropine in children: Two-year result of daily 0.01% atropine in a European population

PURPOSE

The Myopia Outcome Study of Atropine in Children (MOSAIC) is an investigator-led, double-masked, randomized controlled trial investigating the efficacy and safety of 0.01% atropine eye drops for managing myopia progression in a predominantly White, European population.

METHODS

Children aged 6-16 years with myopia were randomly allocated 2:1 to nightly 0.01% atropine or placebo eye drops in both eyes for 2 years. The primary outcome was cycloplegic spherical equivalent (SE) progression at 24 months. Secondary outcomes included axial length (AL) change, safety and acceptability. Linear mixed models with random intercepts were used for statistical analyses.

RESULTS

Of 250 participants enrolled, 204 (81.6%) completed the 24-month visit (136 (81.4%) treatment, 68 (81.9%) placebo). Baseline characteristics, drop-out and adverse event rates were similar between treatment and control groups. At 24 months, SE change was not significantly different between 0.01% atropine and placebo groups (effect = 0.10 D, p = 0.07), but AL growth was lower in the 0.01% atropine group, compared to the placebo group (-0.07 mm, p = 0.007). Significant treatment effects on SE (0.14 D, p = 0.049) and AL (-0.11 mm, p = 0.002) were observed in children of White, but not non-White (SE = 0.05 D, p = 0.89; AL = 0.008 mm, p = 0.93), ethnicity at 24 months. A larger treatment effect was observed in subjects least affected by COVID-19 restrictions (SE difference = 0.37 D, p = 0.005; AL difference = -0.17 mm, p = 0.001).

CONCLUSIONS

Atropine 0.01% was safe, well-tolerated and effective in slowing axial elongation in this European population. Treatment efficacy varied by ethnicity and eye colour, and potentially by degree of COVID-19 public health restriction exposure during trial participation.

The long and short of it: a comprehensive assessment of axial length estimation in myopic eyes from ocular and demographic variables

BACKGROUND/OBJECTIVES

Axial length, a key measurement in myopia management, is not accessible in many settings. We aimed to develop and assess machine learning models to estimate the axial length of young myopic eyes.

SUBJECTS/METHODS

Linear regression, symbolic regression, gradient boosting and multilayer perceptron models were developed using age, sex, cycloplegic spherical equivalent refraction (SER) and corneal curvature. Training data were from 8135 (28% myopic) children and adolescents from Ireland, Northern Ireland and China. Model performance was tested on an additional 300 myopic individuals using traditional metrics alongside the estimated axial length vs age relationship. Linear regression and receiver operator characteristics (ROC) curves were used for statistical analysis. The contribution of the effective crystalline lens power to error in axial length estimation was calculated to define the latter's physiological limits.

RESULTS

Axial length estimation models were applicable across all testing regions (p ≥ 0.96 for training by testing region interaction). The linear regression model performed best based on agreement metrics (mean absolute error [MAE] = 0.31 mm, coefficient of repeatability = 0.79 mm) and a smooth, monotonic estimated axial length vs age relationship. This model was better at identifying high-risk eyes (axial length >98th centile) than SER alone (area under the curve 0.89 vs 0.79, respectively). Without knowing lens power, the calculated limits of axial length estimation were 0.30 mm for MAE and 0.75 mm for coefficient of repeatability.

CONCLUSIONS

In myopic eyes, we demonstrated superior axial length estimation with a linear regression model utilising age, sex and refractive metrics and showed its clinical utility as a risk stratification tool.

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.

Myopia progression patterns among paediatric patients in a clinical setting

PURPOSE

This retrospective analysis of electronic medical record (EMR) data investigated the natural history of myopic progression in children from optometric practices in Ireland.

METHODS

The analysis was of myopic patients aged 7-17 with multiple visits and not prescribed myopia control treatment. Sex- and age-specific population centiles for annual myopic progression were derived by fitting a weighted cubic spline to empirical quantiles. These were compared to progression rates derived from control group data obtained from 17 randomised clinical trials (RCTs) for myopia. Linear mixed models (LMMs) were used to allow comparison of myopia progression rates against outputs from a predictive online calculator. Survival analysis was performed to determine the intervals at which a significant level of myopic progression was predicted to occur.

RESULTS

Myopia progression was highest in children aged 7 years (median: -0.67 D/year) and progressively slowed with increasing age (median: -0.18 D/year at age 17). Female sex (p < 0.001), a more myopic SER at baseline (p < 0.001) and younger age (p < 0.001) were all found to be predictive of faster myopic progression. Every RCT exhibited a mean progression higher than the median centile observed in the EMR data, while clinic-based studies more closely matched the median progression rates. The LMM predicted faster myopia progression for patients with higher baseline myopia levels, in keeping with previous studies, which was in contrast to an online calculator that predicted slower myopia progression for patients with higher baseline myopia. Survival analysis indicated that at a recall period of 12 months, myopia will have progressed in between 10% and 70% of children, depending upon age.

CONCLUSIONS

This study produced progression centiles of untreated myopic children, helping to define the natural history of untreated myopia. This will enable clinicians to better predict both refractive outcomes without treatment and monitor treatment efficacy, particularly in the absence of axial length data.

Study of myopia progression and risk factors in Hubei children aged 7-10 years using machine learning: a longitudinal cohort

BACKGROUND

To investigate the trend of refractive error among elementary school students in grades 1 to 3 in Hubei Province, analyze the relevant factors affecting myopia progression, and develop a model to predict myopia progression and the risk of developing high myopia in children.

METHODS

Longitudinal study. Using a cluster-stratified sampling method, elementary school students in grades 1 to 3 (15,512 in total) from 17 cities in Hubei Province were included as study subjects. Visual acuity, cycloplegic autorefraction, and height and weight measurements were performed for three consecutive years from 2019 to 2021. Basic information about the students, parental myopia and education level, and the students' behavioral habits of using the eyes were collected through questionnaires.

RESULTS

The baseline refractive errors of children in grades 1 ~ 3 in Hubei Province in 2019 were 0.20 (0.11, 0.27)D, -0.14 (-0.21, 0.06)D, and - 0.29 (-0.37, -0.22)D, respectively, and the annual myopia progression was - 0.65 (-0.74, -0.63)D, -0.61 (-0.73, -0.59)D and - 0.59 (-0.64, -0.51)D, with the prevalence of myopia increasing from 17.56%, 20.9%, and 34.08% in 2019 to 24.16%, 32.24%, and 40.37% in 2021 (Χ2 = 63.29, P < 0.001). With growth, children's refractive error moved toward myopia, and the quantity of myopic progression gradually diminished. (F = 291.04, P = 0.027). The myopia progression in boys was less than that in girls in the same grade (P < 0.001). The change in spherical equivalent refraction in myopic children was smaller than that in hyperopic and emmetropic children (F = 59.28, P < 0.001), in which the refractive change in mild myopia, moderate myopia, and high myopia children gradually increased (F = 73.12, P < 0.001). Large baseline refractive error, large body mass index, and high frequency of eating sweets were risk factors for myopia progression, while parental intervention and strong eye-care awareness were protective factors for delaying myopia progression. The nomogram graph predicted the probability of developing high myopia in children and found that baseline refraction had the greatest predictive value.

CONCLUSION

Myopia progression varies by age, sex, and myopia severity. Baseline refraction is the most important factor in predicting high myopia in childhood. we should focus on children with large baseline refraction or young age of onset of myopia in clinical myopia prevention and control.

Urban Living Environment and Myopia in Children

Importance

The global prevalence of myopia has shown a steady increase over recent decades, with urban areas seemingly experiencing a more significant impact.

Objective

To assess the association between urbanization and the prevalence, incidence, progression, and severity of myopia.

Design, Setting, and Participants

This cohort study included students in grades 1 to 6 in Tianjin, China, who underwent 3 vision examinations conducted over a 2-year period, from March 1, 2021, to March 31, 2023. Participants from grades 1 to 4 completed the 2-year follow-up.

Exposures

Urban living environment.

Main Outcomes and Measures

The association of urbanization with the incidence, progression, prevalence, and severity of myopia. To quantify urbanization, an urban score was constructed using satellite data and an iterative exploratory factor analysis.

Results

Of 177 894 students (51.7% male; mean [SD] age, 10.27 [1.75] years) included in the study, 137 087 students (52.3% male; mean [SD] age, 8.97 [1.21] years) were followed up for 2 years. A positive association was identified between myopia incidence and urbanization. Specifically, each 1-unit increment in the urban score was associated with an increased risk of myopia over a 1-year period (odds ratio [OR], 1.09; 95% CI, 1.01-1.15; P = .02) and a 2-year period (OR, 1.53; 95% CI, 1.50-1.57; P < .001). Conversely, each 1-unit increase in the urban score was associated with a significant decrease in myopia progression at 1 year (OR, 0.84; 95% CI, 0.82-0.86; P < .001) and 2 years (OR, 0.73; 95% CI, 0.70-0.75, P < .001). In a cross-sectional data analysis, the urban score was positively associated with myopia prevalence (OR, 1.62; 95% CI, 1.08-2.42; P = .02) and negatively associated with myopia severity, as indicated by spherical equivalent refraction (OR, 1.46; 95% CI, 1.07-1.99; P = .02).

Conclusions and Relevance

This study exploring urban living environments and myopia revealed dual associations of urban living with both the incidence and the progression of myopia. The observed patterns emphasize the urgency of promptly implementing myopia control strategies in less urbanized regions, where myopia progression may be accentuated.

Comparison of cycloplegia at 20- and 30-minutes following proxymetacaine and cyclopentolate instillation in white 12-13-year-olds

CLINICAL RELEVANCE

Reducing the time between drop instillation and refraction reduces the time paediatric patients and young adults spend in practice, facilitating more eye examinations daily.

BACKGROUND

The current procedure for paediatric cycloplegic refraction is to wait for at least 30-minutes post-instillation of a cycloplegic before measuring spherical equivalent refraction. This study compared cycloplegia at 20- and 30-minutes following 0.5% proxymetacaine and 1.0% cyclopentolate in 12-13-year-olds.

METHODS

Participants were 99 white 12-13-year-olds. One drop of proxymetacaine hydrochloride (Minims, 0.5% w/v, Bausch & Lomb, UK) followed by one drop of cyclopentolate hydrochloride (Minims, 1.0% w/v, Bausch & Lomb, UK) was instilled into both eyes. Spherical equivalent refraction was measured by autorefraction (Dong Yang Rekto ORK-11 Auto Ref-Keratometer) at 20- and 30-minutes post-instillation. Data were analysed through paired t-testing, correlations, and linear regression analysis.

RESULTS

There was no significant difference in level of cycloplegia achieved at 20- (Mean spherical equivalent refraction (standard deviation) 0.438 (1.404) D) and 30-minutes (0.487 (1.420) D) post-eyedrop instillation (t (98) = 1.667, p = 0.099). The mean spherical equivalent refraction difference between time points was small (0.049 (0.294) D, 95% confidence interval =-0.108 ̶ 0.009D). Agreement indices: Accuracy = 0.999, Precision = 0.973, Concordance = 0.972. Spherical equivalent refraction at 20- and 30-minutes differed by ≤0.50D in 92% of eyes, and by <1.00D in 95%.

CONCLUSIONS

There was no clinically significant difference in spherical equivalent refraction or level of cycloplegia at 20- and 30-minutes post-eyedrop instillation. The latent time between drop instillation and measurement of refractive error may be reduced to 20 minutes in White 12-13-year-olds and young adults. Further studies must determine if these results persist in younger children and non-White populations.

We can't afford to turn a blind eye to myopia

BACKGROUND

Myopia is becoming increasingly prevalent throughout the world. It is an overlooked but leading cause of blindness, particularly among the working aged population. Myopia is often considered benign because it is easily corrected with glasses, contact lenses or refractive surgery. Traditionally myopia has been classified into physiological and pathological subtypes based on the degree of myopia present. Higher levels of myopia are associated with increased risk of pathological complications but it is important to note that there is no safe level of myopia. Even low levels of myopia increase the risk of retinal detachment and other ocular comorbidities which will be discussed in detail later. The most serious complication, myopic maculopathy, is the only leading cause of blindness without an established treatment and therefore leads to inevitable loss of vision in some myopes, even at a young age.

AIM

To highlight the current myopia epidemic and the sight threatening complications associated with it.

DESIGN

This is a commissioned review article. Data were gathered by performing a literature review, searching the PubMed database for recent articles regarding myopia.

CONCLUSIONS

Myopia is a potentially blinding disease. By identifying at risk individuals and intervening before they become myopic, eye care practitioners can prevent or delay spectacle use, reduce the risk of the myriad of myopic complications, thereby improve the patient's quality of life and positively impact its socio-economic effects.

Prevalence and associated factors of myopia among school students in Shenyang, China: a cross-sectional study

Background

In recent years, the prevalence of myopia has increased significantly and caused great concern. Nevertheless, an estimate of myopia in the student population in Shenyang, Liaoning Province, China is still lacking. This study aims to determine the prevalence of myopia among students in Shenyang and investigate the associated factors affecting myopia development.

Methods

Standard logarithmic visual acuity chart and automatic computerized optometry under non-ciliary muscle paralysis were used to test the students' naked visual acuity of their right and left eyes. The included students were organized to fill in questionnaires on WeChat to collect the factors affecting myopia.

Results

A total of 34,644 students with a median age of 11.9 years were examined, including 17,563 males and 17,081 females. The overall prevalence of myopia was 60%, with a prevalence of 45% for mild myopia, 13% for moderate myopia, and 1.9% for high myopia. The sex, high educational stage, family history of myopia, doing homework after school or reading and writing for more than 2 h were associated with a higher risk of myopia, while doing eye exercises twice a day or more, going outdoors during recess, reading and writing with eyes more than one foot from books, and sleeping more than 8 h a day were associated factors for preventing myopia. The associated factors influencing myopia vary among different subgroups.

Conclusion

The prevalence of myopia in Shenyang is at a high level. In addition to sex, high educational stage and genetic factors, environmental factors including length of eye usage, eye exercises, outdoor activities, eye working distance, and sleep duration are associated with myopia prevalence. Therefore, it is recommended that the occurrence and development of myopia can be prevented by controlling the above environmental factors.

Visual factors associated with physical activity in schoolchildren

CLINICAL RELEVANCE

Physical activity is an essential part of childhood physical and mental development. Recent research identified visual problems associated with a sedentary lifestyle in children in Ireland.

BACKGROUND

This study explored the association between visual function in children and their engagement with physical activities outside school.

METHODS

Participants were 1,626 schoolchildren (728 aged 6-7-years, 898 aged 12-13-years) in randomly selected schools in Ireland. Before data collection, parents/legal guardians of participants completed a standardised questionnaire reporting physical activity as no activity (mostly on screens), light activity (occasional walking/cycling), moderate activity (<3 hrs/week engaged in sports), or regular activity (>3hrs/week engaged in sports). Measurements included logMAR monocular visual acuities (with spectacles and pinhole), in the distance (3 m) and near (40 cm), stereoacuity (TNO stereo-test), cover test, and cycloplegic autorefraction (1% cyclopentolate).

RESULTS

Controlling for confounders (socioeconomic disadvantage and non-White ethnicity), linear regression analysis revealed presenting distance visual acuity, near visual acuity, and stereoacuity were significantly better amongst participants who reported regular physical activity rather than moderate, light or no activity in both 6-7-year-old and 12-13-year-old participants. Absence of clinically-significant refractive error (>-0.50D < 2.00D) was associated with regular physical activity. Participants presenting with visual impairment (better-eye vision <6/12) (odds ratio = 5.78 (2.72-12.29)), amblyopia (pinhole acuity ≤6/12 plus an amblyogenic factor) (odds ratio = 5.66 (2.33-13.76)), and participants at school without their spectacles (odds ratio = 2.20 (1.33-3.63)), were more likely to report no activity.

CONCLUSIONS

Children regularly engaged in physical activities, including sports; had better visual and stereoacuity; and were less likely to need spectacles. Visual impairment, amblyopia, and refractive error were associated with no physical activity. Spectacle wear compliance was associated with regular physical activity. Regular physical activity is an essential factor in childhood vision and addressing visual impairment in children is vital to increasing participation in sports and exercise. Socioeconomically disadvantaged and non-White communities would benefit most from these measures.

Factors associated with myopia in 19-year-old adult men in Korea between 2014 and 2020

Numerous environmental factors that influence myopia have been studied, but only few factors have been definitively identified. We examined factors influencing myopia using data from 2014 to 2020 physical examinations received from the Korean Military Manpower Administration. We used the Cochran-Armitage trend test to investigate the annual prevalence of myopia and high myopia. To determine risk factors for myopia, logistic regression was performed. The data of 2,215,126 19-year-old Korean men were examined. The myopia and high myopia prevalences showed significant annual increases; in 2020, these prevalences were 58.9% and 18.0%, respectively. The myopia prevalence was high when the birth season was spring, education level was high, height was small, weight and body mass index (BMI) were low (< 18.5 kg/m²), and color vision was normal (all, p < 0.05). The high myopia prevalence was high when the birth season was spring, education level was high, height was tall, weight and BMI were low (< 18.5 kg/m²), and color vision was normal (all, p < 0.05). The prevalence of myopia and high myopia in this population is increasing annually. The risk of both conditions increased when the birth season was spring, education level was high, BMI was low, color vision was normal, and diabetes was present.

Analysis of Refractive Errors in a Large Italian Cohort of Pediatric Subjects Post the COVID-19 Pandemic

BACKGROUND

The prevalence of refractive errors has sharply risen over recent decades. Despite the established role of genetics in the onset and progression of such conditions, the environment was also shown to play a pivotal role. Indeed, the COVID-19 pandemic has majorly impacted people's lifestyles and healthy habits, especially among the youth, which might have led to a significant increase in this trend. Therefore, the aim of this study was to investigate the actual prevalence of refractive errors in a large cohort of pediatric patients.

METHODS

A large cohort of 496 participants was screened through anamnesis, a non-cycloplegic autorefractometry, a corrected and uncorrected visual acuity assessment, and a questionnaire and was retrospectively evaluated.

RESULTS

Overall, refractive errors were present in 25.1% of eyes, of which 14.6% were diagnosed with myopia/myopic astigmatism and 10.5% with hyperopia/hyperopic astigmatism. Among the patients enrolled, 298 (60%) had their eyes checked one year earlier or before and 122 (25%) had never had ophthalmological consultations; a total of 105 (21%) needed glasses and 34 (7%) required a change in their previous prescription. A substantial increase in daily electronic device screen exposure was declared by 426 patients (87.6%).

CONCLUSIONS

Pediatric patients appear to have a higher prevalence of refractive errors than before.

IMI-Management and Investigation of High Myopia in Infants and Young Children

Purpose

The purpose of this study was to evaluate the epidemiology, etiology, clinical assessment, investigation, management, and visual consequences of high myopia (≤-6 diopters [D]) in infants and young children.

Findings

High myopia is rare in pre-school children with a prevalence less than 1%. The etiology of myopia in such children is different than in older children, with a high rate of secondary myopia associated with prematurity or genetic causes. The priority following the diagnosis of high myopia in childhood is to determine whether there is an associated medical diagnosis that may be of greater overall importance to the health of the child through a clinical evaluation that targets the commonest features associated with syndromic forms of myopia. Biometric evaluation (including axial length and corneal curvature) is important to distinguishing axial myopia from refractive myopia associated with abnormal development of the anterior segment. Additional investigation includes ocular imaging, electrophysiological tests, genetic testing, and involvement of pediatricians and clinical geneticists is often warranted. Following investigation, optical correction is essential, but this may be more challenging and complex than in older children. Application of myopia control interventions in this group of children requires a case-by-case approach due to the lack of evidence of efficacy and clinical heterogeneity of high myopia in young children.

Conclusions

High myopia in infants and young children is a rare condition with a different pattern of etiology to that seen in older children. The clinical management of such children, in terms of investigation, optical correction, and use of myopia control treatments, is a complex and often multidisciplinary process.

Evaluation of the Prevalence of Refractive Defects and Ocular Function in a Group of 1518 Children Aged 8 Years in Northwestern Poland-A Retrospective Study

PURPOSE

To determine the prevalence of refractive errors in a group of 8-year-old school children in northwestern Poland.

MATERIAL AND METHODS

In 2017-2019, refractive errors were examined in a group of 1518 Caucasian children aged 8 years old with cycloplegia. Refraction was obtained with a hand-held autorefractor (Retinomax 3). The refractive error reading was expressed as the spherical equivalent (SE) as myopia (≤-0.5 D), emmetropia (>-0.5 D to ≤+0.5 D), mild hyperopia (>+0.5 D to ≤+2.0 D) and hyperopia (>+2.0 D), and astigmatism (≤-0.75 DC) and anisometropia (≥1.00 D). Data analysis was performed using Statistica 13.5 software and included Pearson's chi-squared and Mann-Whitney U tests. p-values of <0.05 were considered statistically significant.

RESULTS

Mild hyperopia was most common (37.6%), myopia was observed in 16.8% and astigmatism in 10.6% of participants. Pseudomyopia concerned up to 51.91% children. Girls were significantly more likely to have mild hyperopia (p = 0.0144) and were significantly more likely to wear glasses (p = 0.00093).

CONCLUSIONS

Screening children for refractive errors after cycloplegia is key for detecting accommodative spasm and refractive errors. The largest group of children presented with mild hyperopia, which is a physiological feature of refraction in 8-year-old children, but myopia and astigmatism were the most common refractive errors.

Effects of behaviors and surrounding environment on myopia before and during the COVID-19 pandemic: a longitudinal analysis of children and adolescents in China

Aim

To investigate the relationship between related factors and visual acuity of Chinese school students before and during the COVID-19 pandemic.

Subject and methods

Chinese students from primary and secondary schools were included from the Chinese National Surveys on Students' Constitution and Health CNSSCH (2019). A total of 1496 participants completed follow-ups in June and December 2020, respectively. Generalized estimating equations were used to test the differences in visual environment. Logistic regression models were utilized to examine the roles of behaviors and surrounding environment changes associated with myopia before and during the pandemic.

Results

The prevalence of myopia was 47.7%, 55.6%, and 57.2% in baseline and two follow-ups, respectively. Significant differences existed for gender, learning level, and region (all P < 0.05). The proportion of new myopia and myopia torsion was the highest in the primary schools. Multivariate logistic regression analysis found that screen time ≥ 4h/d (OR = 2.717), poor eye habits (OR = 1.477), insufficient lighting for studying at night (OR = 1.779), desk or roof lamps only (OR = 1.388), and poor sleep quality (OR = 4.512) were the risk factors for myopia (all P < 0.05), and eye exercises (OR = 0.417), milk intake (OR = 0.758), and eggs intake (OR = 0.735) were the protective factors for myopia (all P < 0.05).

Conclusion

Prevalence of myopia increased among Chinese students before and during the COVID-19. It is necessary to pay more attention to the pupils' visual acuity, especially in primary school students, in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10389-023-01900-w.

The association between time spent on screens and reading with myopia, premyopia and ocular biometric and anthropometric measures in 6- to 7-year-old schoolchildren in Ireland

PURPOSE

More time spent on near tasks has consistently been associated with the promotion of myopia. The World Health Organization advises limiting daily screentime to less than 2 h for children aged five and over. This study explored the relationship between time spent on screens and reading/writing with refractive status, ocular biometric and anthropometric factors in 6- to 7-year-olds in Ireland.

METHODS

Participants were 723 schoolchildren (377 boys [51.8%]), mean age 7.08 (0.45) years. The examination included cycloplegic autorefraction (1% cyclopentolate hydrochloride), ocular biometry (Zeiss IOLMaster), height (cm) and weight (kg). Screentime and reading/writing time were reported by parents/legal guardians by questionnaire. Myopia (≤-0.50D) and premyopia (>-0.50D ≤ 0.75D) risk assessments were performed using logistic regression, and multivariate linear regression was used to analyse continuous variables.

RESULTS

Reported daily screentimes were 31% <1 h, 49.5% 1-2 h, 15.6% 2-4 h and 3.9% >4 h. Reading/writing times were 42.2% frequently, 48.0% infrequently and 9.8% seldom/never. Linear regression, controlling for age and ethnicity, revealed >2 h/day on screens was associated with a more myopic spherical equivalent [β = -1.15 (95% confidence intervals {CIs}: 1.62-0.69, p < 0.001)], increased refractive astigmatism (β = 0.29, CI: 0.06-0.51, p = 0.01), shorter corneal radius (β = 0.12, CI: 0.02-0.22, p = 0.02), higher axial length/corneal radius (β = 0.06, CI: 0.03-0.09, p < 0.001), heavier weight (β = 1.60, CI: 0.76-2.45, p < 0.001) and higher body mass index (BMI) (β = 1.10, CI: 0.28-1.12, p < 0.001). Logistic regression, controlling for age and ethnicity, revealed daily screentime >2 h was associated with myopia (OR = 10.9, CI: 4.4-27.2, p = 0.01) and premyopia (OR = 2.4, CI: 1.5-3.7, p < 0.001). Frequent reading/writing was associated with screentime ≤2 h/day (OR = 3.2, CI: 1.8-5.8, p < 0.001).

CONCLUSION

Increased screentime was associated with a more myopic refraction, higher axial length/corneal radius ratio, increased odds of myopia, premyopia, higher degrees of astigmatism, increased weight, BMI and decreased reading/writing time. Dedicated education programmes promoting decreased screentime in children are vital to prevent myopia and support eye and general health.

Refractive development I: Biometric changes during emmetropisation

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Prevalence of refractive errors in children of Puerto Rico

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Regional variations and temporal trends of childhood myopia prevalence in Africa: A systematic review and meta-analysis

PURPOSE

To provide contemporary and future estimates of childhood myopia prevalence in Africa.

METHODS

A systematic online literature search was conducted for articles on childhood (≤18 years) myopia (spherical equivalent [SE] ≤ -0.50D; high myopia: SE ≤ -6.00D) in Africa. Population- or school-based cross-sectional studies published from 1 Jan 2000 to 30 May 2021 were included. Meta-analysis using Freeman-Tukey double arcsine transformation was performed to estimate the prevalence of childhood myopia and high myopia. Myopia prevalence from subgroup analyses for age groups and settings were used as baseline for generating a prediction model using linear regression.

RESULTS

Forty-two studies from 19 (of 54) African countries were included in the meta-analysis (N = 737,859). Overall prevalence of childhood myopia and high myopia were 4.7% (95% CI: 3.3%-6.5%) and 0.6% (95% CI: 0.2%-1.1%), respectively. Estimated prevalence across the African regions was highest in the North (6.8% [95% CI: 4.0%-10.2%]), followed by Southern (6.3% [95% CI: 3.9%-9.1%]), East (4.7% [95% CI: 3.1%-6.7%]) and West (3.5% [95% CI: 1.9%-6.3%]) Africa. Prevalence from 2011 to 2021 was approximately double that from 2000 to 2010 for all studies combined, and between 1.5 and 2.5 times higher for ages 5-11 and 12-18 years, for boys and girls and for urban and rural settings, separately. Childhood myopia prevalence is projected to increase in urban settings and older children to 11.1% and 10.8% by 2030, 14.4% and 14.1% by 2040 and 17.7% and 17.4% by 2050, respectively; marginally higher than projected in the overall population (16.4% by 2050).

CONCLUSIONS

Childhood myopia prevalence has approximately doubled since 2010, with a further threefold increase predicted by 2050. Given this trajectory and the specific public health challenges in Africa, it is imperative to implement basic myopia prevention programmes, enhance spectacle coverage and ophthalmic services and generate more data to understand the changing myopia epidemiology to mitigate the expanding risk of the African population.

Using electronic medical record data to establish and monitor the distribution of refractive errors. JOURNAL OF OPTOMETRY 2022;15 Suppl 1:S32-S42. [PMID: 36220741 PMCID: PMC9732486 DOI: 10.1016/j.optom.2022.09.001]

OBJECTIVE

To establish the baseline distribution of refractive errors and associated factors amongst a population that attended primary care optometry clinics.

DESIGN

Retrospective cross sectional cohort study of electronic medical records (EMR).

METHODS

Electronic medical record data was extracted from forty optometry clinics, representing a mix of urban and rural areas in Ireland. The analysis was confined to demographic and clinical data gathered over a sixty-month period between 2015 and 2019. Distribution rates were calculated using the absolute and relative frequencies of refractive error in the dataset, stratified for age and gender using the following definitions: high myopia ≤ -6.00 D, myopia ≤ -0.50 D, hyperopia ≥ +0.50 D, astigmatism ≤ -0.75 DC and anisometropia ≥ 1.00 D. Visual acuity data was used to explore vision impairment rates in the population. Further analysis was carried out on a gender and age-adjusted subset of the EMR data, to match the proportion of patients in each age grouping to the population distribution in the most recent (2016) Irish census.

RESULTS

153,598 clinic records were eligible for analysis. Refractive errors ranged from -26.00 to +18.50 D. Myopia was present in 32.7%, of which high myopia represented 2.4%, hyperopia in 40.1%, astigmatism in 38.3% and anisometropia in 13.4% of participants. The clinic distribution of hyperopia, astigmatism and anisometropia peaked in older age groups, whilst the myopia burden was highest amongst people in their twenties. A higher proportion of females were myopic, whilst a higher proportion of males were hyperopic and astigmatic. Vision impairment (LogMAR > 0.3) was present in 2.4% of participants. In the gender and age- adjusted distribution model, myopia was the most common refractive state, affecting 38.8% of patients.

CONCLUSION

Although EMR data is not representative of the population as a whole, it is likely to provide a reasonable representation of the distribution of clinically significant (symptomatic) refractive errors. In the absence of any ongoing traditional epidemiological studies of refractive error in Ireland, this study establishes, for the first time, the distribution of refractive errors observed in clinical practice settings. This will serve as a baseline for future temporal trend analysis of the changing pattern of the distribution of refractive error in EMR data. This methodology could be deployed as a useful epidemiological resource in similar settings where primary eyecare coverage for the management of refractive error is well established.

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

Background

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

Methods

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

Results

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

Conclusions

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

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-13927-x.

Associations between reading and writing postures and myopia among school students in Ningbo, China

Background

We conducted this study to investigate the prevalence of myopia among school students in Ningbo and to explore the associations between reading and writing postures and myopia.

Methods

A population-based and cross-sectional study was conducted, and 3,256 school students aged 8-19 years were recruited. Each enrolled subject was assessed for uncorrected distance visual acuity (UDVA) using a standard logarithmic visual acuity E-chart and a non-cycloplegic autorefraction examination. Self-administered questionnaires were used to investigate myopia-related reading and writing postures and behavioral habits among school students.

Results

The prevalence of myopia among primary school, middle school, and high school students was 61.49, 81.43, and 89.72%, respectively. Regarding the associations between reading and writing postures and myopia, we identified that a reading distance >33 cm is a protective factor for myopia in female students [odds ratio (OR) = 0.31, 95% confidence interval (CI) = 0.15-0.64], in both primary school (OR = 0.55, 95% CI = 0.30-0.99) and middle school (OR = 0.37, 95% CI = 0.15-0.90).

Conclusions

A reading distance >33 cm can be used as an additional measure to prevent and control myopia. Proper postural measures for reading and writing may have educational and public health benefits.

Will treating progressive myopia overwhelm the eye care workforce? A workforce modelling study

Purpose

Treatments for myopia progression are now available, but implementing these into clinical practice will place a burden on the eye care workforce. This study estimated the full‐time equivalent (FTE) workforce required to implement myopia control treatments in the UK and Ireland.

Methods

To estimate the number of 6‐ to 21‐year‐olds with myopia, two models utilising separate data sources were developed. The examination‐based model used: (1) the number of primary care eye examinations conducted annually and (2) the proportion of these that are for myopic young people. The prevalence‐based model used epidemiological data on the age‐specific prevalence of myopia. The proportion of myopic young people progressing ≥0.25 dioptres (D)/year or ≥0.50 D/year was obtained from Irish electronic health records and the recommended review schedule from clinical management guidelines.

Results

Using the examination and prevalence models, respectively, the estimated number of young people with myopia was 2,469,943 and 2,235,713. The extra workforce required to provide comprehensive myopia management for this target population was estimated at 226–317 FTE at the 0.50 D/year threshold and 433–630 FTE at the 0.25 D/year threshold. Extra visits required for myopia control treatment represented approximately 2.6% of current primary eye care examinations versus 13.6% of hospital examinations.

Conclusions

Implementing new myopia control treatments in primary care settings over the medium‐term is unlikely to overwhelm the eye care workforce completely. Further increases to workforce, upskilling of current workforce and tools to reduce chair time will help to ensure sustainability of the eye care workforce into the future.

Myopia in Bulgarian school children: prevalence, risk factors, and health care coverage

Background

The prevalence of myopia has increased in recent years, with changes being dynamic and uneven in different regions. The purpose of this study is to evaluate the prevalence of visual impairment caused by myopia in Bulgarian school children, associated risk factors, and health care coverage.

Methods

A cross-sectional study among 1401 children (mean age 10.38, standard deviation 2.70) is conducted in three locations in Bulgaria from 2016 to 2020. Refractive error is measured with an auto-refractor in the absence of cycloplegia, the visual acuity is assessed without refractive error correction. A paper-based preliminary questionnaire is used to collect data on previous eye examinations, prescribed optical vision correction, regularity of wearing corrective glasses and risk factors.

Results

Children with myopic objective refraction ≤ -0.75 D and decimal visual acuity ≤ 0.8 on at least one of the eyes are 236 out of 1401 or 16.85%. The prevalence of myopia varies depending on age, geographical location, and school profile. The rate of myopic children in age group 6–10 is 14.2% compared to 19.9% in age group 11–15. The prevalence of myopic children in the urban populations is 31.4% (capital) and 19.9% (medium-sized town) respectively, and only 8.4% in the rural population. Our results show 53% increase of the prevalence of myopia in the age group 11–15 compared to a 2009 report. The analysis of data associated with health care coverage factors of all myopic pupils shows that 71.6% had a previous eye examination, 43.2% have prescription for corrective glasses, 27.5% wear their glasses regularly. Risk factors for higher odds of myopia are gender (female), age (adolescence), and parents with impaired vision. Residence in a small town and daily sport activities correspond to lower odds for myopia. The screen time (time in front of the screen calculated in hours per day) is self-reported and is not associated with increased odds of myopia when accounted for the other risk factors.

Conclusions

The prevalence of myopia in this study is higher compared to previous studies in Bulgaria. Additional studies would be helpful in planning adequate prevention and vision care.

A machine-learning approach to discerning prevalence and causes of myopia among elementary students in Hubei

Objective

Our aim is to establish a machine-learning model that will enable us to investigate the key factors influencing the prevalence of myopia in students.

Methods

We performed a cross-sectional study that included 16,653 students from grades 1–3 across 17 cities in Hubei Province. We used questionnaires to discern levels of participation in potential factors contributing to the development of myopia. The relative importance of potential contributors was ranked using machine-learning methods. The students’ visual acuity (VA) was measured and those with logMAR VA of > 0.0 underwent a autorefraction test to determine students’ refraction status.

Results

The prevalence of myopia in grades 1, 2, and 3 was 14.70%, 20.54% and 28.93%, respectively. Myopia rates among primary school students in provincial capital city (32.35%) were higher than those in other urban (23.03%) and rural (14.82%) areas. Children with non-myopic parents, only one myopic parent, or both parents having myopia exhibited myopic rates of 16.36%, 25.18%, and 41.37%, respectively. Myopia prevalence was higher in the students who continued to use their eyes at close range for a long time and lower in those engaged longer in outdoor activities. The machine-learning model determined that the top three contributing factors were the students’ age (0.36), followed by place of residence (0.34), starting age of education (0.21).

Conclusion

The overall prevalence of myopia was 21.52%. Children’s age and place of residence were the important influencing factors, but genetics and environmental were also played key roles in myopia development.

Estimating need and coverage for five priority assistive products: a systematic review of global population-based research

INTRODUCTION

To improve access to assistive products (APs) globally, data must be available to inform evidence-based decision-making, policy development and evaluation, and market-shaping interventions.

METHODS

This systematic review was undertaken to identify studies presenting population-based estimates of need and coverage for five APs (hearing aids, limb prostheses, wheelchairs, glasses and personal digital assistants) grouped by four functional domains (hearing, mobility, vision and cognition).

RESULTS

Data including 656 AP access indicators were extracted from 207 studies, most of which (n=199, 96%) were cross-sectional, either collecting primary (n=167) or using secondary (n=32) data. There was considerable heterogeneity in assessment approaches used and how AP indicators were reported; over half (n=110) used a combination of clinical and self-reported assessment data. Of 35 studies reporting AP use out of all people with functional difficulty in the corresponding functional domains, the proportions ranged from 4.5% to 47.0% for hearing aids, from 0.9% to 17.6% for mobility devices, and from 0.1% to 86.6% for near and distance glasses. Studies reporting AP need indicators demonstrated >60% unmet need for each of the five APs in most settings.

CONCLUSION

Variation in definitions of indicators of AP access have likely led to overestimates/underestimates of need and coverage, particularly, where the relationship between functioning difficulty and the need for an AP is complex. This review demonstrates high unmet need for APs globally, due in part to disparate data across this sector, and emphasises the need to standardise AP data collection and reporting strategies to provide a comparable evidence base to improve access to APs.

Holistic processing of faces and words predicts reading accuracy and speed in dyslexic readers

We compared the performance of dyslexic and typical readers on two perceptual tasks, the Vanderbilt Holistic Face Processing Task and the Holistic Word Processing Task. Both yield a metric of holistic processing that captures the extent to which participants automatically attend to information that is spatially nearby but irrelevant to the task at hand. Our results show, for the first time, that holistic processing of faces is comparable in dyslexic and typical readers but that dyslexic readers show greater holistic processing of words. Remarkably, we show that these metrics predict the performance of dyslexic readers on a standardized reading task, with more holistic processing in both tasks associated with higher accuracy and speed. In contrast, a more holistic style on the words task predicts less accurate reading of both words and pseudowords for typical readers. We discuss how these findings may guide our conceptualization of the visual deficit in dyslexia.

Prevalence and pattern of refractive error and visual impairment among schoolchildren: the Lhasa childhood eye study

Background

Early and effective ocular screening may help to eliminate treatable eye disorders. The Lhasa Childhood Eye Study (LCES) revealed the particular prevalence of refractive error and visual impairment in grade one schoolchildren (starting age of 6 years old) in Lhasa.

Methods

This is a cross-sectional part of school-based cohort study. One thousand nine hundred forty-three children were enrolled (median age, 6.78 years, range, 5.89 to 10.32). Each child underwent general and ocular examinations, including logarithm of the minimum angle of resolution (logMAR) visual acuity, cycloplegic autorefraction, and slit-lamp biomicroscopy evaluation. Multivariate and correlation analyses were performed to evaluate the association between refractive error with gender and ethnics.

Results

The prevalence of visual impairment (logMAR visual acuity ≥0.3 in the better-seeing eye) of uncorrected, presenting and best-corrected visual acuity (BCVA) was 12.2, 11.7 and 2.7%, respectively. Refractive error presented in 177 (78.0%) out of 227 children with bilateral visual impairment. Myopia (spherical equivalent refractor [SER] ≤ − 0.50 diopter [D] in either eye) was present in 4.7% children when measured after cycloplegic autorefraction. Hyperopia (SER ≥ + 2.00 D) affected 12.1% children. Hyperopia was significantly associated with female gender (P<0.001). Astigmatism (cylinder value ≤ − 0.75 D) was present in 44.8% children. In multivariate regression and correlation analysis, SER had no significant difference between ethnic groups.

Conclusion

The Lhasa Childhood Eye Study is the first school-based cohort study to reveal the prevalence and pattern of refractive error and visual impairment in Lhasa. Effective strategies such as corrective spectacles should be considered to alleviate treatable visual impairment.

The Prevalence of Visual Impairment and Refractive Errors among a Youth Population in Mozambique: Evidence of the Need for Intervention

Visual impairment (VI) can significantly interfere in the child's daily activities and quality of life, having a negative effect on their development and learning. The aim of the study was to determine the prevalence of VI and associated demographic factors in students examined during the program "Moçambique te vejo melhor". This study was cross-sectional and retrospective, based on the 2018/19 edition of the program. Eye examinations were performed in secondary school students, aged between 12 and 20 years, of five districts in Nampula province. The examination included visual acuity, non-cycloplegic refraction and assessment of the anterior and posterior segment and ocular adnexa. The prevalence of uncorrected, presenting and best-corrected VI found was 18.3%, 10.8%, and 5.0%, respectively. Refractive error (RE) had a prevalence of 24.7%, and the age groups between 15-17 years and 18-20 years were significantly associated with myopia (with OR: 4.9 and OR: 8.8, respectively), as well as the 11th and 12th grade (OR: 8.1 and OR: 10.7, respectively), and Malema district had association with myopia (ORa: 0.4) and hyperopia (ORa: 0.4 and OR: 0.3) as a protective factor. The prevalence of RE and VI was relatively high, showing the need for greater intervention at the school level.

Hyperopia Is Not Causally Associated With a Major Deficit in Educational Attainment

Purpose

Hyperopia (farsightedness) has been associated with a deficit in children's educational attainment in some studies. We aimed to investigate the causality of the relationship between refractive error and educational attainment.

Methods

Mendelian randomization (MR) analysis in 74,463 UK Biobank participants was used to estimate the causal effect of refractive error on years spent in full-time education, which was taken as a measure of educational attainment. A polygenic score for refractive error derived from 129 genetic variants was used as the instrumental variable. Both linear and nonlinear (allowing for a nonlinear relationship between refractive error and educational attainment) MR analyses were performed.

Results

Assuming a linear relationship between refractive error and educational attainment, the causal effect of refractive error on years spent in full-time education was estimated as -0.01 yr/D (95% confidence interval, -0.04 to +0.02; P = 0.52), suggesting minimal evidence for a non-zero causal effect. Nonlinear MR supported the hypothesis of the nonlinearity of the relationship (I2 = 80.3%; Cochran's Q = 28.2; P = 8.8e-05) but did not suggest that hyperopia was associated with a major deficit in years spent in education.

Conclusions

This work suggested that the causal relationship between refractive error and educational attainment was nonlinear but found no evidence that moderate hyperopia caused a major deficit in educational attainment. Importantly, however, because statistical power was limited and some participants with moderate hyperopia would have worn spectacles as children, modest adverse effects may have gone undetected.

Translational Relevance

These findings suggest that moderate hyperopia does not cause a major deficit in educational attainment.

Refractive Error of Students (15- to 18-year-olds) in Northwest Mexico

SIGNIFICANCE

We assessed the prevalence of refractive error in a sample of children of Northern Mexico using the Refractive Error Study in Children protocol of the World Health Organization, which allows for the comparison with other global studies.

PURPOSE

Uncorrected refractive error is the main cause of visual impairment in children. The purpose of this study was to assess the refractive error and visual dysfunctions of students (15 to 18 years old) in the upper-middle school system of Sinaloa, Mexico.

METHODS

A total of 3468 students in Sinaloa's high school system participated in the study from 2017 to 2019. Optometrists and student clinicians from the Optometry Program of the Autonomous University of Sinaloa conducted the testing. Tests included visual acuities and static retinoscopy. We did not use a cycloplegic agent.

RESULTS

The results showed a high prevalence of uncorrected refractive errors. Myopia, defined as a refractive error ≤-0.50 D, had a prevalence of 36.11% (95% confidence interval, 33.47 to 38.83%); hyperopia, defined as a refractive error ≥+2.00 D, had a prevalence of 1.49% (95% confidence interval, 0.09 to 2.33%); and astigmatism, defined as a refractive error with a cylinder ≥0.75 D, had a prevalence of 29.17% (95% confidence interval, 26.60 to 31.76%). We found a significant effect of sex on visual acuity.

CONCLUSIONS

Our results are consistent with a high prevalence of myopia reported in adolescents worldwide and in Mexico's northern regions. The results suggest that students attending high school and entering universities should be required to have an optometric eye examination. Additional studies are needed to investigate the prevalence of refractive errors in children in Mexico.

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 cause of myopia development and progression: Theory, evidence, and treatment

I review the key findings and our current knowledge of the cause of myopia, making the connections among the reliable observations on myopia development and theory to arrive at a summary of what we know about myopia, the proposed prevailing theory, and applicable action. Myopia is reaching epidemic proportions. It is estimated that half of the world's population will be myopic by 2050 unless new strategies to fight myopia are developed. Our high-level mathematical description of myopia is translated into clinical applications involving effective treatment and prevention. A regulating mechanism controlling the refraction of the eye is intimately related to myopia. The approach at hand is to review our knowledge about emmetropization, connecting myopia and emmetropization feedback theory to unveil the cause of myopia. Many observations discussed here test the validity of feedback theory positively. The cause of human myopia fits perfectly with the idea that emmetropization, in particular its feedback theory implementation, is the controlling mechanism behind myopia. They include near work, atropine, lenses, defocus, and outdoor versus indoor activities. The key findings in myopia research point the same way: myopia is the result of corrective lenses interfering with emmetropization. We have enough knowledge to answer the question of whether myopia can be reversed or prevented. There is no need to have mathematical skills to apply theory to real cases. It is enough to know the predictions of the feedback theory of emmetropization.

Auricular acupressure for myopia prevention and control in children and its effect on choroid and retina: a randomized controlled trial protocol

BACKGROUND

Nowadays, because of the increasing incidence, the prevention and control of myopia has become an urgent issue. In China, auricular acupressure has been commonly used in the clinical treatment of myopia in children, but the exact effectiveness remains unproven. The purpose of this trial is to observe the efficacy of auricular acupressure in myopia prevention and control, as well as its effect on the choroidal and retinal thickness.

METHOD/DESIGN

A total of 480 subjects at 8-9 years old will be randomized in a 1:1 ratio to an intervention group versus a control group. The intervention group will receive auricular acupressure for 12 months, while the control group will be taken as a blank control. The primary and secondary outcomes will be measured at baseline, and again at 3, 6, 9, and 12 months after recruitment. The myopia incidence (spherical equivalent ≤ - 0.50 D) and the mean change of spherical equivalent will be taken as the primary variables; the secondary outcome measures include axial length, uncorrected visual acuity, and choroidal and retinal thickness.

DISCUSSION

This trial aims to evaluate the effectiveness of auricular acupressure for myopia prevention and control with objective evidence and to preliminarily explore the plausible mechanism and provide reference for adopting this approach to retard the onset and control the progression of myopia.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2000038456 . Registered on September 23, 2020.

IMI Impact of Myopia

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 life-long impact of myopia on an individual and the cost-effectiveness of the various novel approaches in reducing the burden.

Elevated Melatonin Levels Found in Young Myopic Adults Are Not Attributable to a Shift in Circadian Phase

Purpose

To evaluate the relationship between refractive error, circadian phase, and melatonin with consideration of prior light exposure, physical activity, and sleep.

Methods

Healthy young myopic (spherical equivalent refraction [SER] ≤−0.50DS) and emmetropic adults underwent noncycloplegic autorefraction and axial length (AL) measures. Objective measurements of light exposure, physical activity, and sleep were captured across 7 days by wrist-worn Actiwatch-2 devices. Questionnaires assessed sleep quality and chronotype. Hourly evening saliva sampling during a dim-light melatonin onset (DLMO) protocol evaluated circadian phase, and both morning serum and saliva samples were collected. Liquid chromatography/mass spectrometry quantified melatonin.

Results

Subjects (n = 51) were aged 21.4 (interquartile range, 20.1−24.0) years. Melatonin was significantly higher in the myopic group at every evening time point and with both morning serum and saliva sampling (P ≤ 0.001 for all). DLMO-derived circadian phase did not differ between groups (P = 0.98). Multiple linear regression analysis demonstrated significant associations between serum melatonin and SER (B = –.34, β = –.42, P = 0.001), moderate activity (B = .009, β = .32, P = 0.01), and mesopic illumination (B = –.007, β = –.29, P = 0.02), F(3, 46) = 7.23, P < 0.001, R² = 0.32, R²_adjusted = .28. Myopes spent significantly more time exposed to “indoor” photopic illumination (3 to ≤1000 lux; P = 0.05), but “indoor” photopic illumination was not associated with SER, AL, or melatonin, and neither sleep, physical activity, nor any other light exposure metric differed significantly between groups (P > 0.05 for all).

Conclusions

While circadian phase is aligned in adult myopes and emmetropes, myopia is associated with both elevated serum and salivary melatonin levels. Prospective studies are required to ascertain whether elevated melatonin levels occur before, during, or after myopia development.

Children's visual impairment and visual care related to socioeconomic status in Catalonia (Spain)

BACKGROUND

The objective of this study is to assess the prevalence of visual impairment and visual care practices and its association with socioeconomic conditions in the infant population in Catalonia.

METHODS

The Catalan Institute of Statistics provided a random sample of 0 to 14-year-old non-institutionalized children whose parents were interviewed in a continuous health survey from 2011 to 2015 in Catalonia. A multistage stratified and random sampling procedure considering age, sex, county and town was followed. All results have been weighted according to the sample design and are presented as the proportion of the condition with its 95% confidence limits. Chi-square tests were performed to evaluate the association between categorical variables. To study the association of visual care with independent variables, a multiple logistic regression model was used.

RESULTS

In 0 to 14-year-old children, a 12.9% (95% confidence interval [CI] [11.8-13.9]) prevalence of correctable visual impairment was observed. The prevalence of non-correctable visual impairment was 0.9% (95% CI [0.6-1.2]). Non-correctable visual impairment was more prevalent in families with lower education levels, manual professions or unemployed. Of children without visual impairment, 13,5% (95% CI:12.3-14.6) visited a visual care professional in the last 12 months while this proportion was 67.4% (95% CI [63.3-71.5]) among those with correctable visual impairment. When parents have a university degree or non-manual professions, a higher level of visual care was observed. In children with correctable visual impairment, visual reviews were more frequent when parents are employed in a non-manual profession.

CONCLUSIONS

For the first time, indicators related to visual impairment in children in Catalonia have been recorded. There is an association between lower socioeconomic status and having non-correctable visual impairment, and conversely, having correctable visual impairment was significantly associated with employed parents. More visual care is associated with higher socioeconomic status.

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

Purpose

To assess the performance of an open-view binocular handheld aberrometer (QuickSee) for diagnosing refractive errors in children.

Methods

123 school-age children (9.9 ± 3.3 years) with moderate refractive error underwent autorefraction (AR) with a standard desktop device and subjective refraction (SR), with or without cycloplegia to determine their eyeglass prescription. Measurements with QuickSee (QS) were taken in 62 of these patients without cycloplegia (NC), and in 61 under cycloplegia (C). Differences in refraction values (AR vs SR vs QS) as well as the visual acuity (VA) achieved by the patients with each method (QS vs SR) were used to evaluate the performance of the device in measuring refractive error.

Results

The spherical equivalent refraction obtained by QS agreed within 0.5 D of the SR in 71% (NC) and 70% (C) of the cases. Agreement between the desktop autorefractor and SR for the same threshold was of 61% (NC) and 77% (C). VA resulting from QS refractions was equal to or better than that achieved by SR procedure in 77% (NC) and 74% (C) of the patients. Average improvement in VA with the QS refractions was of 8.6 and 13.4 optotypes for the NC and C groups respectively, while the SR procedure provided average improvements of 8.9 (NC) and 14.8 (C) optotypes.

Conclusions

The high level of agreement between QuickSee and subjective refraction together with the VA improvement achieved in both study groups using QuickSee refractions suggest that the device is a useful autorefraction tool for school-age children.

Prevalence of reduced visual acuity among school-aged children and adolescents in 6 districts of Changsha city: a population-based survey

Background

To calculate and evaluate the prevalence of reduced uncorrected distant visual acuity (UCDVA) in primary, middle and high schools in 6 districts of Changsha, Hunan, China.

Methods

A population-based retrospective study was conducted in 239 schools in 6 districts of Changsha. After routine eye examination to rule out diseases that can affect refraction, 250,980 eligible students from primary, middle and high schools were enrolled in the survey. Then the uncorrected distant and near visual acuity of each eye were measured. Categories of schools, districts, grades, eye exercises and sports time were also documented and analyzed.

Results

The overall prevalence of reduced UCDVA was 51.8% (95% confidence interval [CI]: 51.6–52.0%) in 6 districts of Changsha. Results of individual districts were as follows: Furong district 59.9%(95% CI: 57.9–61.8%), Tianxin district 62.3%(95% CI: 60.5–64.0%), Wangcheng district 47.8%(95% CI: 46.8–48.8%), Kaifu district 58.5%(95% CI: 58.0–58.9%), Yuhua district 47.0%(95% CI: 46.7–47.4%) and Yuelu district 52.6%(95% CI: 52.3–52.9%). The proportion of normal VA is seen to decrease from primary grade 3. The proportion of mildly reduced UCDVA is higher in primary grade 1 and 2. The proportion of moderately reduced UCDVA remains similar during 12 grades. The proportion of severely reduced UCDVA increases with grades. Multivariate analysis shows that the prevalence of reduced UCDVA is higher in key schools (risk ratio [RR] = 1.47, 95% CI 1.44–1.50) than non-key schools.

Conclusions

According to the existing data analysis results, the prevalence of reduced UCDVA among primary, middle and high school students in Changsha is very high. Some effective measures need to be taken to prevent it.

Effects of Neonatal Hyperglycemia on Retinopathy of Prematurity and Visual Outcomes at 7 Years of Age: A Matched Cohort Study

OBJECTIVE

To determine whether neonatal hyperglycemia is associated with retinopathy of prematurity (ROP), visual outcomes, and ocular growth at 7 years of age.

STUDY DESIGN

Children born preterm (<30 weeks of gestational age) at a tertiary hospital in Auckland, New Zealand, who developed neonatal hyperglycemia (2 blood glucose concentrations ≥153 mg/dL [8.5 mmol/L] 4 hours apart) were matched with children who were not hyperglycemic (matching criteria: sex, gestational age, birth weight, age, socioeconomic status, and multiple birth) and assessed at 7 years of corrected age. The primary outcome, favorable overall visual outcome (visual acuity ≤0.3 logarithm of the minimum angle of resolution, no strabismus, stereoacuity ≤240 arcsec, not requiring spectacles) was compared between groups using generalized matching criteria-adjusted linear regression models.

RESULTS

Assessments were performed on 57 children with neonatal hyperglycemia (hyperglycemia group) and 54 matched children without hyperglycemia (control group). There were no differences in overall favorable visual outcome (OR 0.95, 95% CI 0.42-2.13, P = .90) or severe ROP incidence (OR 2.20, 95% CI 0.63-7.63, P = .21) between groups. Children with hyperglycemia had poorer binocular distance visual acuity (mean difference 0.08, 95% CI 0.03-0.14 logarithm of the minimum angle of resolution, P < .01), more strabismus (OR 6.22, 95% CI 1.31-29.45, P = .02), and thicker crystalline lens (mean difference 0.14, 95% CI 0.04-0.24 mm, P < .01). Maximum blood glucose concentration was greater in the ROP-treated group compared with the ROP-not treated and no ROP groups after adjusting for sex, gestational age, and birth weight z score (P = .02).

CONCLUSIONS

Neonatal hyperglycemia was not associated with overall visual outcomes at 7 years of age. However, there were between-group differences for specific outcome measures relating to interocular lens growth and binocular vision. Further follow-up is required to determine implications on long-term visual outcome.

Relationship between Geography and Refractive Error from the UCLA Preschool Vision Program

PURPOSE

Using the screening data collected through the University of California, Los Angeles Preschool Vision Program (UPVP) that provides free vision screening to children 2.5 to 6 years of age attending public preschools in five Supervisory Districts in Los Angeles County, this paper explores whether geographic location of where children attended preschool affects the vision screening results.

METHODS

62,936 children were screened using a handheld device (Nikon Retinomax) between academic years 2012 and 2015. The criteria for failing the screening was set to sphere of ≤ -3.25 diopters (D), sphere ≥ +1.75 D, or cylinder of ≥1.50 D in either eye, or inter-ocular difference of >2.00 D in spherical error (>1.50D in case of antimetropia) or ≥1.00 D in cylinder error.

RESULTS

Higher fail rates were found among girls, Latino race, and those who primarily spoke Spanish at home. In addition, there was a geographical variance in screening outcomes among Supervisory Districts with District 1 having the highest fail rate and District 4 having the lowest fail rate.

CONCLUSION

This paper provides preliminary evidence of geographic factors contributing to the development of refractive errors among preschoolers which may be used in future studies to address the unmet needs of children with vision impairments in Los Angeles County.

Prevalence, causes and risk factors of reduced VA and persistent reduced VA among preschool children in Eastern China

AIMS

To determine prevalence, causes, and risk factors of reduced uncorrected visual acuity (UCVA), reduced presenting visual acuity (PVA), and persistent reduced visual acuity (VA) among Chinese preschool children.

METHODS

The longitudinal, population-based Nanjing Eye Study (NES) was carried out. Children underwent baseline comprehensive ocular examinations in 2016 (at 48-60 months old) and the follow-up ocular examinations in 2017. A comprehensive questionnaire about children and their families was completed by their legal guardians. For children having reduced PVA at baseline, a follow-up questionnaire about potential factors concerning VA correction was completed. Reduced VA was defined as VA worse than 0.30 logMAR (Snellen equivalent 6/12, 20/40), and persistent reduced VA was defined as reduced PVA in both 2016 and 2017.

RESULTS

Among 1448 participants with both eye examinations and questionnaires completed, prevalence of reduced UCVA, reduced PVA, and persistent reduced VA at age of 60-72 months were 5.94%, 3.04%, and 1.59% respectively. Causes for reduced PVA were refractive error (79.5%), amblyopia (18.2%), and amblyopia combined nystagmus (2.3%). Among 23 children having persistent reduced VA, causes of reduced PVA remained unchanged in 13 children and 4 children developed amblyopia from refractive error. Younger age (OR = 1.09 for each month decrease, p = 0.01) and non-breastfeeding (OR = 2.08, p = 0.03) were risk factors for reduced UCVA. Younger children with reduced UCVA were at higher risk of having reduced PVA (OR = 1.18 for each month decrease, p = 0.04). Children with siblings (OR = 5.95, p = 0.02) were more likely to have persistent reduced VA.

CONCLUSIONS

Future vision health promotion strategies among preschool children should focus on early vision-screening and timely refractive correction. Apart from children of non-breastfeeding mothers, attention should also be paid to children with siblings.

Prevalence of colour vision deficiency in the Republic of Ireland schoolchildren and associated socio-demographic factors

CLINICAL RELEVANCE

Early screening is essential to counsel schoolchildren with congenital colour vision deficiency (CVD) in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties.

BACKGROUND

Congenital CVD is an X-linked genetic abnormality relatively commonplace in humans. This study aimed to determine the prevalence of congenital CVD in the Republic of Ireland schoolchildren and associated socio-demographic factors.

METHODS

A total of 1,626 schoolchildren (882 boys and 744 girls), in two age groups (728 aged 6-7-years and 898 aged 12-13-years) were examined from randomly selected schools. Colour vision testing was carried out using the Richmond Hardy-Rand-Rittler pseudoisochromatic test for colour vision (fourth edition); diagnostic plates were used to determine CVD type and extent if participants failed to identify symbols on the screening plates.

RESULTS

CVD was detected in 73 boys (8.3 per cent, 95% confidence interval (CI) 6.6-10.3) and in 13 girls (1.8 per cent, 95% CI 1.0-3.1, p < 0.001). As expected, deutan (boys 4.8 per cent, girls 0.8 per cent) was the most common type of CVD, followed by protan (boys 1.7 per cent, girls 0.1 per cent), unclassified red/green CVD (boys 1.2 per cent, girls 0.8 per cent) and then tritan (boys 0.5 per cent). One case of achromatopsia was detected based on failure on all diagnostic plates. Traveller participants (boys 21.0 per cent, girls 8.6 per cent) had a higher CVD prevalence than their White non-Traveller (boys 7.2 per cent, girls 1.0 per cent) and non-White (boys 5.4 per cent, girls 1.1 per cent) counterparts (odds ratio 3.00, 95% CI 1.1-8.1, p = 0.006). In boys, CVD was also associated with twin birth (odds ratio 2.7, 95% CI 1.1-6.7, p = 0.03) and low birthweight (p = 0.04).

CONCLUSION

This investigation of CVD in the Republic of Ireland schoolchildren should alert clinicians to the association between CVD and Traveller ethnicity, twin birth and lower birthweight. The prevalence of CVD found was similar to previous studies involving predominantly White populations and higher among Traveller participants; hence, counselling regarding inherited anomalies in the Traveller community is recommended. Early screening is essential to counsel schoolchildren with CVD in determining their future career path and to advise teachers of the impact of CVD on classroom difficulties.

Prevalence of myopia and associated risk factors among primary students in Chongqing: multilevel modeling

Background

The prevalence of myopia and associated risk factors among children in Chongqing has not yet been determined. This study investigated the prevalence of myopia and possible relationships between myopia and several related factors among school children in Chongqing.

Methods

This cross-sectional study assessed a sample of 997 children (7–13 years of age) attending primary school in Chongqing. Data were obtained from visual acuity and refractive error measurements and a structured questionnaire. Myopia was defined as visual acuity < 5.0 and refractive error (spherical equivalent) of < − 0.50 diopters (D) in either eye. Multilevel modeling was applied to investigate potential risk factors.

Results

The overall prevalence of myopia was 33.9% [95% confidence interval (CI) = 31.0–36.8]; myopia prevalence significantly increased with age. Girls were at a higher risk of myopia than boys [odds ratio (OR) = 1.449, 95% CI = 1.060–1.979]. Children with paternal myopia (OR = 2.130, 95% CI = 1.376–3.297) or maternal myopia (OR = 1.861, 95% CI =1.153–3.002) had a higher risk of myopia than those without myopic parents. Children who spent more than 1 h daily outdoors were less likely to have myopia; meanwhile, children who did homework more than 3 h daily (OR = 2.237, 95% CI = 1.041–4.804), watched television more than 3 h daily (OR = 2.106, 95% CI = 1.200–3.697), or played electronics more than 1 h daily (OR = 2.983, 95% CI = 2.088–4.262) had a higher risk of myopia.

Conclusions

Myopia in school children is a serious public health problem in Chongqing. Myopia was significantly positively associated with higher age, female sex, parental myopia, and spending a long time indoors; notably, playing with electronics had the greatest influence on the risk of myopia.

Prevalence of Visual Impairment and Associated Factors Among Primary Schoolchildren in Addis Ababa, Central Ethiopia

BACKGROUND

Visual impairment (VI) refers to reduction of vision resulting in a lower than normal visual acuity (VA). Although school programs are recommended for early detection and timely interventions of VI, available information with regard to prevalence of VI and associated factors among primary schoolchildren near to the main city, Addis Ababa is inadequate. Thus, we assessed the prevalence of VI and the associated factors among children attending government primary schools of Lideta sub-city, Addis Ababa, Ethiopia.

METHODS

This was a school-based cross-sectional study conducted from April to May 2019, using a two-stage cluster sampling method in Lideta sub-city, Addis Ababa, Ethiopia. From the total 18 government primary schools in Lideta sub-city, six were selected using probability proportionate to size (PPS) method. The study population was primary schoolchildren aged 7 to 17 years in the selected six primary schools. A total of 816 eligible primary schoolchildren were identified to be included in the study. The selected children were examined for the presence of VI. Children's parents/guardians were interviewed using structured pre-tested questionnaires. In this study, myopia and hyperopia were defined as difficulty in viewing distant and near objects, respectively. Similarly, astigmatism was a refractive error which results from an uneven cornea surface, which results in distorted images. Epi-data 3.1 and SPSS version 20 were used for data entry and analysis, respectively. Binary logistic regression was performed to check association between dependent and independent variables. Significance was set at p-value <0.05.

RESULTS

From a total of 816 eligible primary schoolchildren, 773 children were examined for VI, making the response rate 94.7%. Out of the 773 children, 370 (47.9%) were male and 403 (52.1%) were female. The mean age of the participants was 11.69 years (SD 2.64 years). The prevalence of VI among schoolchildren was 4.4%. The causes of VI included myopia (43%), astigmatism with or without amblyopia (31%), hyperopia with or without amblyopia (20%), and others. The parents/guardians not being aware of their children's eye problem (AOR=2.2, 95% CI: 1.2-4.4) was the only significantly associated factor with VI.

CONCLUSION

In this study, the prevalence of VI among schoolchildren was high. The students being unaware about their eye problem was significantly associated with VI. Thus, close monitoring and regular screening for VI in schoolchildren are highly recommended to allow timely intervention.

A Serial Cross-Sectional Analysis of the Prevalence, Risk Factors and Geographic Variations of Reduced Visual Acuity in Primary and Secondary Students from 2000 to 2017 in Hong Kong

Background: We would like to investigate the prevalence trend, potential risk factors and geographic features of reduced visual acuity (VA) in primary and secondary schoolchildren of Hong Kong. Methods: This was a serial cross-sectional study using historical data of schoolchildren aged 6 to 15 years from the annual health checks conducted at Student Health Service Centers across Hong Kong, for the school years of 2000/2001 to 2016/2017. Results: The prevalence of reduced VA increased from 49.23% (95% CI, 48.99-49.47) in 2000/2001 to 54.34% (95% CI, 54.10-54.58) in 2011/2012 but decreased to 51.42% (95% CI, 51.17-51.66) in 2016/2017. Girls were less susceptible than boys at age 6-7 (and in grade primary 1-2), but more susceptible at older ages. The prevalence in junior grades increased while the risk effect of grade reduced over the past 17 years. Geographic variation on the risk for reduced VA existed and spatial autocorrelation was positive. The difference in prevalence of reduced VA between Hong Kong and mainland China has decreased in recent years. Cross-border students living in mainland China were associated with a lower risk for reduced VA. Conclusions: Further study was proposed to investigate the environmental association between students living in and outside Hong Kong with the prevalence of reduced VA. Multi-level research should also be conducted to investigate the influence of compositional and contextual factors on the prevalence of reduced VA.

Prevalence of visual impairment and refractive errors in an urban area of Mexico

AIM

To determine the distribution of refractive errors in a school-age population in Quintana Roo (Mexico) in the framework of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 2647 school-age children (ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity (VA) and refractive errors. The first screening examination included uncorrected distance visual acuity (UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25 (0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25.

RESULTS

A total of 633 (23.9%) children underwent the second complete eye examination. Mean logMAR UDVA was 0.035±0.094 (range 1.00 to 0.00 logMAR) for the right eyes and 0.036±0.160 (range 1.00 to 0.00 logMAR) for the left eyes. Bilateral amblyopia was found in 17 children (2.7% of refracted eyes; 0.64% of the total). The main reason for visual impairment (VI) in the sample analyzed was found to be refractive errors. In 12 children (1.9% of refracted eyes; 0.45% of the total) the VI was bilateral and 9 (1.4% of refracted eyes; 0.34% of the total) achieved a corrected distance visual acuity of 20/25 or better in both eyes. Mean magnitude of sphere and refractive cylinder was +0.20±0.96 D and -0.43±0.85 D in right eyes, and +0.24±1.08 and -0.43±0.83 D in left eyes. The proportion of myopic eyes [standard equivalent (SE) ≤-0.50 D] was 4.6% of the whole sample (5290 eyes). The mean magnitude of myopia was -0.84±3.44 D for the right eyes and -0.82±5.21 D for the left eyes. The proportion of hyperopic patients (SE≥+2.00 D) was 2.4% (15/633), which corresponded to 0.60% of the whole sample (32/5290 eyes). No statistically significant correlation of age to manifest sphere or cylinder was found.

CONCLUSION

VI due to uncorrected refractive errors can be easily corrected with glasses but it is still a burden to be treated. Myopia is prevalent in this sample. More efforts towards correcting uncorrected refractive errors are needed.