Prevalence of myopia and uncorrected myopia among 721 032 schoolchildren in a city-wide vision screening in southern China: the Shantou Myopia Study

Genome-wide association study identified novel loci and gene-environment interaction for refractive error in children

To identify novel genetic loci for children refractive error, we performed a meta-analysis of two genome-wide association studies (GWASs) of spherical equivalent (SE) in 1,237 children from the population-based Hong Kong Children Eye Study (HKCES) and the Low Concentration Atropine for Myopia Progression (LAMP) study. Replication was conducted in 4,093 Chinese children and 1,814 Chinese adults. Four lead-SNPs (MIR4275 rs292034, TENM3 rs17074027, LOC101928911 rs6925312 and FAM135B rs4609227) showed genome-wide significant association (P ≤ 5.0 × 10-8) with SE. TENM3 had been associated with myopia in adults before, whilst the other three loci, MIR4275, LOC101928911 and FAM135B, were novel. Significant interaction between genetic risk scores (GRS) and near work on SE was also detected (βinteraction = 0.14, Pinteraction = 0.0003). This study identified novel genetic loci for children refractive error and suggested myopia intervention can be individualized based on the genetic risk of children.

Visual environmental risk factors in outdoor activities and near work and potential mechanisms

PURPOSE

Myopia is highly prevalent among children and adolescents and results from abnormal refractive development. Less outdoor time as well as more near work have been recognised as major risk factors for myopia. This study analysed the major environmental factors related to myopia, such as outdoor activities and near work, and reviewed the potential mechanisms of myopia development.

METHODS

A systematic search was conducted across PubMed, Web of Science, Cochrane Library and Ovid databases within the last two decades up to November 2024. This review followed the recommendations of the PRISMA Statement and only full-text review articles in English were included.

RESULTS

Summarising the findings from 13 review articles, the environmental risk factors for myopia included lighting features such as low illumination and monochromatic light as well as aspects of the visual scene, for example, the presence of low spatial frequencies and hyperopic defocus. These particular visual stimuli may contribute to the onset and progression of myopia and increase the risk of retinal disorders by reducing choroidal blood flow, leading to scleral hypoxia and remodelling. When analysing environmental risk factors, it is challenging to isolate the individual contributions of outdoor time and near work. Furthermore, previous studies used different definitions of environmental exposures.

CONCLUSIONS

Future research needs quantitative, objective and standardised measures to improve the comparability and consistency between studies. In addition, work should focus on different ethnic populations and gene-environment studies, so as to determine the influence of environmental risk factors on myopia.

The Peripheral Defocus Designed Spectacle Lenses Might Increase Astigmatism in Myopic Children

Purpose

This study aims to explore the impact of wearing peripheral defocus spectacle lenses (PDSL) on cylindrical refractive error (CYL) in myopic children.

Methods

This study included 1057 myopic children and divided the participants into three groups: the HAL group (spectacle lens with highly aspherical lenslets), the MPV group (spectacle lens based on manipulating peripheral vision), and a control group (without myopia control interventions). The study analyzed the effect of wearing PDSL on changes in spherical equivalent refraction, CYL, and corneal astigmatism (CA). The mediating effect between changes in spherical refractive errors (SPH) and CYL was also investigated.

Results

Compared to the control group (0.05 ± 0.33 D), the annual CYL progression was faster in the HAL group (-0.15 ± 0.33 D, P < 0.001) and the MPV group (-0.09 ± 0.27 D, P = 0.019). More children in the HAL group had an annual CYL progression ≥0.50 D (HAL: 23.6%, Control: 16.2%, P = 0.012). The annual CYL and CA progression were consistent within the PDSL groups (HAL: P = 0.677, MPV: P = 0.683). The total effect of CYL progression in the HAL group was primarily due to direct induction from wearing HAL and indirect induction through the SPH control effect.

Conclusions

The application of PDSL could cause increase in astigmatism in myopic children, which could mainly be contributed to cornea astigmatism change.

Translational Relevance

PDSL may passively affect the anterior ocular biomechanics during myopia control, leading to an increase in astigmatism.

Effect of school entrance age on myopia among primary schoolchildren using mixed-effect model: The Shantou Myopia Study (SMS)

PURPOSE

To investigate the association between children's school entrance age and refractive status and prevalence of myopia in southern China.

METHODS

Population-based Cross-sectional study was conducted from September 2020 to June 2021 in Shantou, southern China, enrolling primary schoolchildren in the city. The school entrance age was calculated as the months from the birth date to the entrance date, divided by 12. Non-cycloplegic refraction and uncorrected visual acuity test were conducted. Myopia was defined as spherical equivalent refraction (SER) < -0.50D with an uncorrected distant visual acuity < Snellen 20/20. We explored the association between the SER and the school entrance age, with the clustering effect within schools adjusted by the linear mixed-model.

RESULTS

We enrolled 410,080 primary schoolchildren, with a mean age of 9.8 ± 1.6 years. The overall prevalence of myopia was 42.04 %. The mean SER of myopic children was - 2.15 ± 1.70 D. The mixed-effects model revealed a significant correlation between the school entrance age and the SER and the prevalence of myopia. One year later for school entrance age would independently result in a less myopic SER of 0.352 D, and significantly decrease the prevalence of myopia. Children born before September 1st had significantly more myopic SER than those born after September 1st.

CONCLUSIONS

Early school entrance, rather than age or prolonged exposure to schooling, was an independent risk factor for myopia. It is important to put forward some scientific and effective measures, preventing children from early exposure to task-heavy school life and near work.

Progression Patterns and Risk Factors of Axial Elongation in Young Adults With Nonpathologic High Myopia: Three-Year Large Longitudinal Cohort Follow-Up

PURPOSE

To investigate the progression patterns and risk factors of axial elongation in young adults with nonpathologic high myopia.

DESIGN

Prospective, clinical observational cohort study with 2- to 4-year follow-up.

METHODS

A total of 1043 eyes of 563 participants (3515 medical records) aged 18 to 50 years with nonpathologic high myopia (axial length [AL] ≥ 26 mm; myopic maculopathy < diffuse chorioretinal atrophy; without posterior staphyloma) were included from 1546 participants (6318 medical records). Annual axial elongation was calculated via linear mixed-effect models. The associated risk factors of axial elongation were determined by ordinal logistic regression analysis, with generalized estimate equations for eliminating an interocular correlation bias.

RESULTS

Based on 5359 times of AL measurements, the annual axial elongation of participants (mean [SD] age 31.39 [9.22] years) was 0.03 mm/year (95% confidence interval [CI], 0.03-0.04; P < .001) during a 30.23 (6.06) months' follow-up. Severe (>0.1 mm/year), moderate (0.05-0.09 mm/year), mild (0-0.049 mm/year), and nil (≤0 mm/year) elongation was observed in 122 (11.7%), 211 (20.2%), 417 (40.0%), and 293 (28.1%) eyes. The following risk factors were significantly associated with axial elongation: baseline AL ≥ 28 mm (odds ratio [OR], 4.23; 95% CI, 2.95-6.06; P < .001); age < 40 years (OR, 1.64; 95% CI, 1.18-2.28; P = .003); axial asymmetry (OR, 2.04; 95% CI, 1.26-3.29; P = .003), and women (OR, 1.52; 95% CI, 1.13-2.2.05; P = .006). Using antiglaucoma medications was a protective factor (OR, 0.46; 95% CI, 0.27-0.79; P = .005), which slowed 75% of axial elongation from 0.04 (0.06) to 0.01 (0.06) mm/y (P < .001).

CONCLUSIONS

Axial elongation continued in young adults with nonpathologic myopia. Risk factors included longer baseline AL and axial asymmetry, younger age, and woman. Topical use of antiglaucoma medications may be useful to reduce ongoing axial elongation.

Prevalence, sociodemographic risk factors, and coverage of myopia correction among adolescent students in the central region of Portugal

BACKGROUND

Knowing the prevalence of myopia at school age is essential to implement preventive measures and appropriate interventions, ensure access to vision care, promote a healthier educational environment and improve academic performance. The purpose of this study was to determine the prevalence of myopia and its associated sociodemographic risk factors, as well as to estimate the coverage of myopia correction among adolescents in center of Portugal.

METHODS

This cross-sectional study evaluated 1115 adolescents from the 5th to the 9th year of school, with an average of 12.9 years (SD = 1.5) ranging from 10.0 to 18.0 years. Optometric evaluations were carried out in a school environment and consisted of the evaluation of distance visual acuity, assessed using a logarithmic visual acuity chart (ETDRS charts 1 and 2) at 4 m, and measured by refractive error with a pediatric autorefractometer (Plusoptix), by non-cycloplegic. Myopia was defined as spherical equivalent (SE ≤ -0.50 diopter (D)) and uncorrected visual acuity (UVA ≤ 95VAR). Adjusted logistic regression analysis was applied to investigate risk factors.

RESULTS

We found a myopia rate of 21.5% and a high myopia rate of 1.4%. Higher school level and attendance at urban schools were associated with myopia, but no association was found with age or sex. Only 34.6% of myopic adolescents use the best optical correction and 26.4% do not use any type of optical correction.

CONCLUSIONS

Data on the prevalence of refractive problems in Portugal are scarce and heterogeneous. This study, although regional, provides a valuable contribution with a clear and reproducible methodology, following international guidelines and filling gaps in the existing literature. The results show that the rate of myopia in this age group is similar to reports from other European studies. The high rate of adolescents with uncorrected or under-corrected myopia in Portugal is a problem that deserves attention.

Continuing benefits of the Montreal Protocol and protection of the stratospheric ozone layer for human health and the environment

The protection of Earth's stratospheric ozone (O3) is an ongoing process under the auspices of the universally ratified Montreal Protocol and its Amendments and adjustments. A critical part of this process is the assessment of the environmental issues related to changes in O3. The United Nations Environment Programme's Environmental Effects Assessment Panel provides annual scientific evaluations of some of the key issues arising in the recent collective knowledge base. This current update includes a comprehensive assessment of the incidence rates of skin cancer, cataract and other skin and eye diseases observed worldwide; the effects of UV radiation on tropospheric oxidants, and air and water quality; trends in breakdown products of fluorinated chemicals and recent information of their toxicity; and recent technological innovations of building materials for greater resistance to UV radiation. These issues span a wide range of topics, including both harmful and beneficial effects of exposure to UV radiation, and complex interactions with climate change. While the Montreal Protocol has succeeded in preventing large reductions in stratospheric O3, future changes may occur due to a number of natural and anthropogenic factors. Thus, frequent assessments of potential environmental impacts are essential to ensure that policies remain based on the best available scientific knowledge.

Prevalence and associated factors of myopia in children and adolescents in Russia: the Ural Children Eye Study

BACKGROUND

To assess the prevalence of myopia and the distribution of ocular axial length as surrogate for myopic refractive error in school children in a population in Russia.

METHODS

The Ural Children Eye Study, a school-based case-control study, was conducted in Ufa/Bashkortostan/Russia from 2019 to 2022 and included 4933 children (age: 9.7±2.6 years; range: 6.2-18.8 years). The parents underwent a detailed interview and the children an ophthalmological and general examination.

RESULTS

Prevalence of any myopia (≤-0.50 dioptres (D)), minor myopia (-0.50 D to -1.0 D), moderate myopia (-1.01 D to -5.99 D) and high myopia (≤-6.0D) was 2187/3737 (46.2%; 95% CI 44.8% to 48.6%), 693/4737 (14.6%; 95% CI 13.6% to 15.6%), 1430/4737 (30.2%; 95% CI 28.9% to 31.5%) and 64/4737 (1.4%; 95% CI 1.0% to 1.7%), respectively. In the children aged 17+ years, prevalence of any, minor, moderate and high myopia was 170/259 (65.6%; 95% CI 59.8% to 71.5%), 130/259 (50.2%; 95% CI 44.1% to 56.3%), 28/259 (10.8%; 95% CI 7.0% to 14.6%) and 12/259 (4.6%; 95% CI 2.1% to 7.2%), respectively. After adjusting for corneal refractive power (beta: 0.09) and lens thickness (beta: -0.08), larger myopic refractive error was associated (r2=0.19) with older age (beta: 0.33), female sex (beta: 0.04), higher prevalence of maternal (beta: 0.15) and paternal (beta: 0.12) myopia, more time spent in school, with reading books or playing with the cell phone (beta: 0.05) and less total time spent outdoors (beta: 0.05). Axial length and myopic refractive error increased by 0.12 mm (95% CI 0.11 to 0.13) and -0.18 D (95% CI 0.17 to 0.20), respectively, per year of age.

CONCLUSIONS

In this ethnically mixed urban school children population from Russia, prevalence of any myopia (65.6%) and high myopia (4.6%) in children aged 17+ years was higher than in adult populations in the same region and it was lower than in East Asian school children, with similar associated factors.

Eye exercises for myopia prevention and control: a comprehensive systematic review and meta-analysis of controlled trials

OBJECTIVES

To evaluate the efficacy of eye exercises in preventing and controlling myopia.

METHODS

We searched studies on eye exercises from nine Chinese and English databases from their inception to December 15, 2022. Using random-effect models and sensitivity/subgroup analyses, we estimated the effects of eye exercises compared to control on changes in three measures: visual acuity, refractive error (both quantified using standardized mean differences, SMDs), and protective/mitigating effects (assessed through risk ratios, RRs).

RESULTS

Eleven studies were included in the meta-analysis, with 921 participants. Nine studies had some concerns of bias in at least two domains, and two studies had a high risk of bias in two domains. Seven studies used visual acuity to measure myopia; visual acuity declined after eye-exercise interventions (SMD = -0.67, 95% CI -1.28 to -0.07, Z = 2.17, P = 0.03) and the effect was not better than control (SMD = -0.50, 95% CI -1.16 to 0.16, Z = 1.49, P = 0.14). Two studies used refractive error to measure myopia; the effect of eye-exercise interventions did not differ from control (SMD = -1.74, 95% CI -6.27 to 2.79, Z = 0.75, P = 0.45). Seven studies reported on protective/mitigating effects; eye exercises exhibited a greater protective/mitigating effect than control (RR = 0.40, 95% CI 0.23-0.71, Z = 3.13, P < 0.01).

CONCLUSIONS

Overall, the results suggest that eye exercises have limited to no efficacy in preventing or controlling myopia progression. Until robust evidence supports their efficacy, available evidence suggests retiring the eye-exercise policy.

Challenges of refractive cataract surgery in the era of myopia epidemic: a mini-review

Myopia is the leading cause of visual impairment in the world. With ever-increasing prevalence in these years, it creates an alarming global epidemic. In addition to the difficulty in seeing distant objects, myopia also increases the risk of cataract and advances its onset, greatly affecting the productivity of myopes of working age. Cataract management in myopic eyes, especially highly myopic eyes is originally more complicated than that in normal eyes, whereas the growing population of cataract with myopia, increasing popularity of corneal and lens based refractive surgery, and rising demand for spectacle independence after cataract surgery all further pose unprecedented challenges to ophthalmologists. Previous history of corneal refractive surgery and existence of implantable collamer lens will both affect the accuracy of biometry including measurement of corneal curvature and axial length before cataract surgery, which may result in larger intraocular lens (IOL) power prediction errors and a compromise in the surgical outcome especially in a refractive cataract surgery. A prudent choice of formula for cataract patients with different characteristics is essential in improving this condition. Besides, the characteristics of myopic eyes might affect the long-term stability of IOL, which is important for the maintenance of visual outcomes especially after the implantation of premium IOLs, thus a proper selection of IOL accordingly is crucial. In this mini-review, we provide an overview of the impact of myopia epidemic on treatment for cataract and to discuss new challenges that surgeons may encounter in the foreseeable future when planning refractive cataract surgery for myopic patients.

Progression and incidence of myopia among schoolchildren in the post-COVID-19 pandemic period: a prospective cohort study in Shantou, China

OBJECTIVES

To determine the progression and incidence of myopia in Chinese schoolchildren in the post-COVID-19 pandemic period in Shantou, China.

DESIGN

Prospective cohort study.

SETTING

Shantou Myopia Study, China.

PARTICIPANTS

1-year follow-up data were available for 621 881 schoolchildren (301 999 females). Data on spherical equivalent refraction (SER) were collected.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcomes were myopia progression and incidence. Myopia progression is defined as a change of SER towards the negative direction in the follow-up visit. Incidence is defined as the proportion of schoolchildren who were not myopic but developed myopia in the follow-up study. Age, sex and SER at baseline were evaluated as associated factors for myopia burden, which were defined as the secondary outcomes.

RESULTS

Mean progression of SER was -0.35±0.97 D for the population (ranging from -0.06 D at 18 years of age to -0.46 D at 11 years of age), with a rapid myopic progression for students at the age of 10-12 years (-0.50 D in girls and -0.44 D in boys). A myopic shift greater than -0.50 D/year occurred in 256 299 eyes (41.21%). Myopic progression in refraction was associated with the 10-12 years age groups (OR 1.42; 95% CI 1.39 to 1.45, p<0.001), female sex (OR 1.09; 95% CI 1.08 to 1.10, p<0.001) and higher refractive errors at baseline (OR>1.00, p<0.001). The annual incidence of myopia among schoolchildren was 24.85%, with an incidence of 26.69% in girls and 23.02% in boys.

CONCLUSIONS

Our study revealed an annual myopia progression of -0.35 D and an incidence of 24.85% among schoolchildren in the post-COVID-19 pandemic period. Myopia progressed rapidly at 10-12 years of age, with -0.50 D in girls and -0.44 D in boys. The incidence was higher for children aged 10-11 years and for girls.