Study design, rationale and methods for a population-based study of myopia in schoolchildren: the Myopia Investigation study in Taipei

Risk factors for anisometropia in schoolchildren: A population-based, longitudinal cohort study

PURPOSE

To investigate the incidence rate and risk factors for anisometropia among young schoolchildren.

METHODS

A population-based cohort study, the Myopia Investigation Study in Taipei, was conducted in primary schools in Taipei City. Children were recruited for biannual comprehensive eye examinations over 2 years. Cycloplegic autorefraction and slit lamp examinations were performed biannually. Data on demographic information, parental history, lifestyle and near-work activities were collected using parent-administered questionnaires at the first and final visits. Anisometropia was defined as ≥1 D difference in the spherical equivalent (SE) refractive error.

RESULTS

A total of 7035 8-year-old children completed the 2-year follow-up evaluations. The average annual incidence of anisometropia was 3.8%. Multivariable logistic regression analysis revealed that baseline SE (odds ratio [OR]: 0.87 95% CI: 0.80-0.95) and female sex (OR: 1.24, 95% confidence interval [CI]: 1.02-1.50) were significantly associated with incident anisometropia. Among lifestyle risk factors, spending <1 h per day in after-school outdoor activities on weekdays (OR: 1.38, 95% CI: 1.08-1.76) and performing near work at a distance <30 cm (OR: 1.33, 95% CI: 1.08-1.64) were significantly associated with an increased risk of incident anisometropia. In the multiple linear regression analysis, the inter-eye difference in SE increased significantly in children performing near work at distances <30 cm (adjusted β = 0.03; p = 0.02).

CONCLUSIONS

This study indicated the annual incidence of anisometropia in Taiwanese schoolchildren. Less time spent outdoors and shorter eye-to-object distances during near work increased the risk of incident anisometropia.

Myopia and Near Work: A Systematic Review and Meta-Analysis

BACKGROUND

Myopia is a global public health problem affecting quality of life and work productivity. Data is scarce regarding the effects of near work on myopia. Providing a larger meta-analysis with life-long perspective, including adults and occupational exposure seemed needed.

METHODS

We searched PubMed, Cochrane Library, Embase and Science Direct for studies reporting myopia prevalence in near work. Myopia was defined as a mean spherical equivalent ≤ -0.50 diopter. We performed a meta-analysis using random-effects model on myopia prevalence, myopia progression per year, and odds ratio (OR) of myopia in near work, completed by subgroup analyses and meta-regressions on patients' characteristics, type of work in adults, geographic zones, time and characteristics of near work.

RESULTS

We included 78 studies, representing a total of 254,037 participants, aged from 6 to 39 years. The global prevalence of myopia in near work was 35% (95% CI: 30 to 41%), with a prevalence of 31% (95% CI: 26 to 37%) in children and 46% (95% CI: 30 to 62%) in adults. Myopia progression was -0.39 diopters per year (-0.53 to -0.24 D/year), ranging from -0.44 (-0.57 to -0.31) in children to -0.25 D/year (-0.56 to 0.06) in adults. The odds of myopia in workers exposed vs. non-exposed to near work were increased by 26% (18 to 34%), by 31% (21 to 42%) in children and 21% (6 to 35%) in adults. Prevalence of myopia was higher in adults compared to children (Coefficient 0.15, 95% CI: 0.03 to 0.27).

CONCLUSIONS

Near work conditions, including occupational exposure in adults, could be associated with myopia. Targeted prevention should be implemented in the workplace.

Trajectories of myopia control and orthokeratology compliance among parents with myopic children

SIGNIFICANCE

This study set out to illustrate the trajectories of myopia control in time sequence and explore orthokeratology compliance for parents with myopic children in the first fitting within one year. Profiling these results is crucial to improving myopia control and orthokeratology care.

PURPOSE

To obtain a better understanding of myopia control and orthokeratology care that could promote compliance with orthokeratology (ortho-K) lenses for parents with myopic children.

METHODS

We conducted semi-structured qualitative interviews and pre-interview questionnaire surveys of the parent who is mainly responsible for complying to ortho-K lens care for their myopic children aged 7-12 years, including 16 mothers and 4 fathers. A framework analytical approach that involved gaining familiarity with the data to identify a thematic framework was used for data analysis. It was written in line with the COREQ (Consolidated Criteria for Reporting Qualitative Research) checklist.

RESULTS

Five themes and twelve subthemes depicted the parents' trajectory during myopia diagnosis, treatment, and compliance with ortho- K for their children in the first fitting within one year. Myopia control and the convenience of outdoor activities were important reasons for parents to actively ask for ortho-K lenses for their children. Parents have non-compliance behaviors after the children wore the lenses for three months, including not scheduling follow-up visits, simplifying cleaning procedures, not replacing accessories. The degree of parents' non-compliance differed based on the uncomfortable feelings of their child's eyes. In general, clear, unaided vision (visual acuity > 0.9) during the day was an indicator of ortho-K's effectiveness, according to parents.

CONCLUSIONS

Although parents play a passive role when a child is diagnosed with myopia, they take on a proactive role when deciding on ortho-K treatment. Myopia treatment for children is a long-term process. Understanding the course of treatment and non-compliance helps eye care professionals provide parents with the necessary assistance and resources, and enables myopia treatment to yield maximum effects.

Protective behaviours of near work and time outdoors in myopia prevalence and progression in myopic children: a 2-year prospective population study

AIM

To investigate the protective behaviours of longer near work distance, discontinuing near work and more time outdoors in recess from parent self-report in the myopia prevalence and progression among myopic children aged 9-11 years.

METHODS

Myopia Investigation study in Taipei is a longitudinal population-based study that enrolled elementary school students in Taipei. We provided vision and refraction examination every 6 months. Spherical equivalent (SE) of cycloplegic refraction ≤-0.50 Diopter (D) is defined as myopia. Total 10 743 (70.4%) students completed 2-year refraction data and questionnaire. The myopia prevalence and progression (difference of SE) in baseline, 6, 12, 18 and 24 months were compared by generalised estimating equations.

RESULTS

Children with persistent protective behaviour had significant lower prevalence of myopia. The protective impact was statistically significant from 6 to 24 months. In 2 years follow-up, risk ratio after adjusting the background variables and the other two behaviours in near work distance, near work time and outdoor time were 0.71, 0.89 and 0.77. In SE analysis, after adjusting the other two behaviours, near work distance >30 cm (-0.7 vs -1.04 D; p<0.001), discontinuing near work every 30 min (-0.77 vs -0.96 D, p=0.005) and more time outdoors in recess from parent self-report (-0.75 vs -0.98 D; p=0.012) revealed protective impacts on diminishing myopia progression from 6 to 24 months.

CONCLUSION

In myopic children aged around 10 years in Taipei, longer distance in near work, discontinuing near work every 30 min and more outdoor time from parent self-report are protective behaviours in myopia prevalence and progression in 6-24 months.

Seasonal variation of refractive error change among young schoolchildren in a population-based cohort study in Taipei

PURPOSE

To investigate the relationship between seasonal variation of daylight length and spherical equivalent (SE) progression among the schoolchildren participating in the Myopia Investigation Study in Taipei.

METHODS

We used the first-year data from grade 2 schoolchildren who completed all the baseline and two follow-up examinations (n=6790). There were two 6-month intervals between visits over winter and summer, respectively. For each interval, we calculated average daily daylight length using data from Taiwan's Central Weather Bureau and measured 6-month SE progression rate based on right eye cycloplegic autorefraction data. The midpoint month was defined as the month midway between two consecutive visits.

RESULTS

By the midpoint month, average daily daylight length was the shortest in December (671±7 min/day) and the longest (785±7 min/day) in June, and SE progression rate was the fastest (-0.23±0.48 D) in December and the slowest (-0.17±0.51 D) in June. Significant variation of SE progression rate with season can be observed only among the schoolchildren (n=1905) whose midpoint months for the winter and summer intervals were December and June (winter rate, -0.25±0.47 D; summer rate, -0.17±0.49 D; p<0.001). Of those, the summer progression rate was approximately 80%, 65% and 61.5% of that measured in winter for myopic (p=0.252), emmetropic (p=0.012) and hyperopic (p=0.012) schoolchildren, respectively.

CONCLUSION

Our data demonstrate a seasonal variation of minus shift in refractive error among Taipei schoolchildren who had significant daytime fluctuation during the 1-year follow-up. Of those, non-myopic children had significant and more pronounced variation of SE progression than myopic children.

Strengthening teachers' abilities to implement a vision health program in Taiwanese schools

We designed a school-based, nationwide program called the 'New Era in Eye Health' to strengthen teacher training and to examine whether the existence of a government vision care policy influenced teachers' vision care knowledge and students' behavior. Baseline data and 3-month follow-up data were compared. A random sample of teachers (n = 660) from school vision health clusters in 22 cities/counties in Taiwan were invited to participate in our study and 436 agreed to participate (response rate = 66.1%). The mean age of participant teachers was 41.2 years, while the length of service mean was 14.6 years. For monitoring teacher outcomes, five cities/counties were selected as the intensely monitored group based on certain criteria. Sunlight diaries (n = 5434) were distributed and 3342 (61.5%) were returned. Teachers showed significant improvements in knowledge and behavior on the school vision health questionnaire. At the 3-month follow-up, the number of recesses as recorded by students' 'sunlight diary' increased. When teachers had better knowledge and behavior, recesses also increased. This study provided valuable insights to guide dissemination efforts for school vision health interventions and to help teachers implement research into their school vision health activities.

Risk factors for myopia progression in second-grade primary school children in Taipei: a population-based cohort study

PURPOSE

To evaluate the 1-year progression of myopia and associated risk factors in second-grade primary school children.

METHODS

The myopia investigation study in Taipei provided semiannual visual acuity testing and cycloplegic refraction for all second-grade primary school children (mean age: 7.49 years) in Taipei who provided parental consent. A questionnaire was distributed to the participants' parents before the first and third examinations. We evaluated 1-year follow-up data for children noted to have myopia on the first examination. Multinomial logistic regression models were applied to assess risk factors associated with myopia progression. Myopia progression was categorised, based on the change in spherical equivalent (ΔSE) over 1 year, as slow (ΔSE>-0.5 dioptres (D)), moderate (-1.0 D<ΔSE≤-0.5 D) or fast (ΔSE≤-1.0 D). Of the 4214 myopic children, data were analysed for 3256 (77.3%) who completed the 1-year follow-up evaluation.

RESULTS

The baseline SE was -1.43±1.1 D. The average ΔSE was -0.42±0.85 D, with 46.96%, 28.50% and 24.54% of the study subjects showing slow, moderate and fast myopia progression, respectively. When compared with slow myopia progression, fast myopia progression was associated with a greater myopic SE at baseline (OR: 0.67, 95% CI: 0.61 to 0.72) and a shorter eye-object distance when doing near work (OR: 1.45, 95% CI: 1.18 to 1.78). More outdoor activity time and self-reported cycloplegic treatment were not associated with slow myopia progression.

CONCLUSIONS

Children with fast annual myopia progression were more myopic at baseline and had a shorter reading distance. Our study results highlight the importance of having children keep a proper reading distance.

Prevalence and association of refractive anisometropia with near work habits among young schoolchildren: The evidence from a population-based study

Background

Lifestyle behaviour may play a role in refractive error among children, but the association between near work habits and refractive anisometropia remains unclear.

Methods

We estimated the prevalence of refractive anisometropia and examined its association with near work activities among 23,114 children in the Myopia Investigation Study in Taipei who were grade 2 elementary school students at baseline in 2013 and 2014. Baseline data on demographics, medical history, parental history and near work habits were collected by parent-administered questionnaire survey. Refractive status was determined by cycloplegic autorefraction. Refractive anisometropia was defined as the spherical equivalent difference ≥ 1.0 diopter between eyes.

Results

The prevalence of refractive anisometropia was 5.3% (95% confidence interval [CI], 5.0% to 5.6%). The prevalence and severity of refractive anisometropia increased with both myopic and hyperopic refractive error. Multivariate logistic regression analysis revealed that refractive anisometropia was significantly associated with myopia (odds ratio [OR], 2.98; 95% CI, 2.53–3.51), hyperopia (OR, 2.37; 95% CI, 1.98–2.83), degree of astigmatism (OR, 1.005; 95% CI, 1.005–1.006), amblyopia (OR, 2.54; 95% CI, 2.06–3.12), male gender (OR, 0.88; 95% CI, 0.78–0.99) and senior high school level of maternal education (OR, 0.69; 95% CI, 0.52–0.92). Though anisometropic children were more likely to spend more time on near work (crude OR, 1.15; 95% CI, 1.02–1.29) and to have less eye-to-object distance in doing near work (crude OR, 1.15; 95% CI, 1.01–1.30), these associations became insignificant after additional adjustment for ocular, demographic and parental factors.

Conclusions

The present study provides large-scale, population-based evidence showing no independent association between refractive anisometropia and near work habits, though myopia is associated with refractive anisometropia.