The prevalence of myopia and the factors associated with it among university students in Nanjing: A cross-sectional study

Association between sleep and myopia in children and adolescents: a systematic review and meta-analysis

PURPOSE

There is a scarcity of literature focusing on sleep's impact on myopia in children despite an epidemic rise of myopia among the age group and the importance of early prevention. As such, this systematic review-meta-analysis aims to evaluate the association between various aspects of sleep and myopia in children and adolescents aged 0-19 years.

METHODS

We searched PubMed, EMBASE, and Cochrane Library on 08/12/2022 for studies reporting sleep in relation to myopia among children and adolescents. Myopia was defined as spherical equivalent refraction < -0.5 diopter. The primary outcome was the relationship between sleep duration and myopia prevalence. Secondary outcomes include the effect of sleep quality, bedtime, and waketime on myopia prevalence, incidence, and progression. Odds ratio (OR) was estimated with a 95% confidence interval (95% CI).

RESULTS

Eighteen studies (49,277 participants) were included in the review, and six studies (14,116 participants) were included in the meta-analysis for the primary outcome. There was no significant correlation between sleep and myopia prevalence (OR = 0.905, 95% CI = 0.782 to 1.047). Some studies suggested that better sleep quality (2 of 6 studies), earlier bedtime (3 of 5 studies), and later waketimes (2 of 3 studies) had protective effects on myopia.

CONCLUSION

Sleep duration did not affect myopia prevalence in children, while other aspects of sleep had plausible but inconclusive impacts on myopia development and progression. More research with diverse populations and standardized methods of reporting is needed.

Development and validation of a smartwatch algorithm for differentiating physical activity intensity in health monitoring

To develop and validate a machine learning based algorithm to estimate physical activity (PA) intensity using the smartwatch with the capacity to record PA and determine outdoor state. Two groups of participants, including 24 adults (13 males) and 18 children (9 boys), completed a sequential activity trial. During each trial, participants wore a smartwatch, and energy expenditure was measured using indirect calorimetry as gold standard. The support vector machine algorithm and the least squares regression model were applied for the metabolic equivalent (MET) estimation using raw data derived from the smartwatch. Exercise intensity was categorized based on MET values into sedentary activity (SED), light activity (LPA), moderate activity (MPA), and vigorous activity (VPA). The classification accuracy was evaluated using area under the ROC curve (AUC). The METs estimation accuracy were assessed via the mean absolute error (MAE), the correlation coefficient, Bland-Altman plots, and intraclass correlation (ICC). A total of 24 adults aged 21-34 years and 18 children aged 9-13 years participated in the study, yielding 1790 and 1246 data points for adults and children respectively for model building and validation. For adults, the AUC for classifying SED, MVPA, and VPA were 0.96, 0.88, and 0.86, respectively. The MAE between true METs and estimated METs was 0.75 METs. The correlation coefficient and ICC were 0.87 (p < 0.001) and 0.89, respectively. For children, comparable levels of accuracy were demonstrated, with the AUC for SED, MVPA, and VPA being 0.98, 0.89, and 0.85, respectively. The MAE between true METs and estimated METs was 0.80 METs. The correlation coefficient and ICC were 0.79 (p < 0.001) and 0.84, respectively. The developed model successfully estimated PA intensity with high accuracy in both adults and children. The application of this model enables independent investigation of PA intensity, facilitating research in health monitoring and potentially in areas such as myopia prevention and control.

Myopia: Its Status and Environmental Correlations Among School Students in Fushun, China

Our objective was to investigate the status and influence of myopia among primary school students in Fushun, Liaoning Province, China. We aimed to provide a theoretical and epistemological basis for implementing myopia prevention initiatives. We employed cluster sampling and surveyed 5216 primary school students from grades 1-6 across eight primary schools in Fushun City. Our participants included 2606 males and 2610 females whose average age was 9.25 (SD = 1.76) years. The rate of myopia among these primary school students was 29.54%, with statistically significant differences among students of different genders and grades. Logistic regression analysis further identified several possible protective factors, including appropriate reading distance, adequate home lighting, regular breaks between classes, conscientious eye exercises, and daily outdoor physical activity. Conversely, the associated risk factors were being female, being in a higher grade level, spending more than 4 hours on homework, occasionally reading while lying down, and having one or both parents with myopia. Overall, our results indicated a high incidence of myopia, highlighting the need for scientifically controlled interventions to manage and mitigate the occurrence and progression of myopia in this population.

Association of sleep traits with myopia in children and adolescents: A meta-analysis and Mendelian randomization study

PURPOSE

The association between sleep and myopia in children and adolescents has been reported, yet it remains controversial and inconclusive. This study aimed to investigate the influence of different sleep traits on the risk of myopia using meta-analytical and Mendelian randomization (MR) techniques.

METHODS

The literature search was performed in August 31, 2023 based on PubMed, Embase, Web of Science, and Cochrane library. The meta-analysis of observational studies reporting the relationship between sleep and myopia was conducted. MR analyses were carried out to assess the causal impact of genetic pre-disposition for sleep traits on myopia.

RESULTS

The results of the meta-analysis indicated a significant association between the risk of myopia and both short sleep duration [odds ratio (OR) = 1.23, 95% confidence interval (CI) = 1.08-1.42, P = 0.003] and long sleep duration (OR = 0.75, 95% CI = 0.66-0.86, P < 0.001). MR analyses revealed no significant causal associations of genetically determined sleep traits with myopia, including chronotype, sleep duration, short sleep duration and long sleep duration (all P > 0.05).

CONCLUSIONS

No evidence was found to support a causal relationship between sleep traits and myopia. While sleep may not independently predict the risk of myopia, the potential impact of sleep on the occurrence and development of myopia cannot be disregarded.

Systematic Review of Sleep Duration and Development of Myopia

There is a knowledge gap in the relationship between sleep duration and myopia. Since sleep duration is a modifiable risk factor, its association with the development and progression of myopia has implications for public health. This review was conducted in accordance with the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The bibliographic databases of PubMed and Scopus were searched for published studies on the association between sleep duration and myopia. These databases were searched in December 2023 with no date or study design limits. The relevant literature was extracted and met the priori determined population (children, adolescents, and adults suffering from myopia with or without corrective glasses), intervention/exposure (sleep), and the outcome (various indicators of sleep especially sleep duration/bedtime/wake time and sleep quality). Data were gathered by gender, age, and refraction technique and standardized to the definition of myopia as refractive error ≥0.50 diopter. The relevant literature was extracted from these electronic databases using the keywords "sleep," "sleep duration," "bedtime," and "myopia." English language articles related to the topic were included. Articles that have discussed the role of risk factors for myopia but did not mention any relation to sleep were excluded. Sixteen studies were included after reviewing the relevant literature, and only six studies have shown a significant relationship between shorter duration of sleep and the development of myopia. This review suggests that apart from other environmental factors, sleep duration may have a role in developing myopia. Thus, increasing awareness about optimum sleep duration has a potential utility to reduce the development and progression of myopia.

Could Children's Myopization Have Been Avoided during the Pandemic Confinement? The Conjunctival Ultraviolet Autofluorescence (CUVAF) Biomarker as an Answer

BACKGROUND

The objective of this study was to evaluate the association of the presence of conjunctival ultraviolet autofluorescence (CUVAF) with the level and progression of myopia and the impact of reduced sunlight exposure during the COVID-19 pandemic confinement (PC).

METHODS

A retrospective observational study was carried out using three cohorts, children (9-17 years old), young adults (18-25 years old), and adults (>40 years old) with myopia (≤0.75D) and at least three annual eye examinations (before and after PC). All participants underwent an automatic objective refraction and CUVAF area analysis. All the participants filled out a questionnaire regarding lifestyle and myopia history.

RESULTS

The 298 recruited participants showed that during the PC, children's and young adults' myopia progression rate increased on average by -0.50 and -0.30 D/year, respectively, compared with the pre-pandemic level (p < 0.0001 and p < 0.01). A significantly greater progression was observed in those with low baseline myopia compared to those with moderate or high myopia (p < 0.01). CUVAF shows its protective effect associated with outdoor activity (OA) with regard to the age of onset of myopia and mean diopters (p < 0.01). In fact, although there were no differences in the increase in diopters between children with and without CUVAF during the PC, those who had CUVAF started with lower gains (-0.3 D/year) compared to those who did not (-0.5 D/year; p < 0.05). The myopia treatments (atropine drops, Ortho-K, and MiSight® contact lenses) showed a reduction effect in myopic progression rate post-PC in comparison with non-treated children (p < 0.0001, p < 0.0001 and p < 0.01, respectively).

CONCLUSIONS

The strict restriction of OA during PC led to the rate of myopia progression doubling among children and young adults. This progression occurred mainly in children with previously low myopia, and CUVAF, as a biomarker of OA, reflects its potential to provide benefits in the form of recommended behavioral changes to protect against the development of myopia.

Associations of Near Work, Time Outdoors, and Sleep Duration With Myopic Regression 5 Years After SMILE and FS-LASIK: A Cross-sectional Study

PURPOSE

To investigate the association of near work, time outdoors, and sleep duration with myopic regression 5 years after small incision lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK) .

METHODS

This cross-sectional study included patients who received SMILE or FS-LASIK at Beijing Tongren Hospital 5 years ago. The patients underwent ophthalmic examinations including visual acuity, intraocular pressure, subjective refraction, slit-lamp examination, keratometry, corneal topography, optical coherence tomography, and fundus examination from January 2020 to March 2023. Fluorescein break-up time was measured and the Ocular Surface Disease Index questionnaire was completed to exclude dry eye. A self-administered questionnaire was used to collect data on near work exposure, physical activities, and sleep duration.

RESULTS

A total of 323 eyes were included in the analysis, with a 5-year incidence rate of myopic regression after SMILE or FSLASIK of 16.1%. After adjusted for all confounders, total near work more than 8 hours/day revealed a significant association with myopic regression (odds ratio: 2.461; 95% CI: 1.143 to 5.298, P = .021), particularly in younger adults, women, and patients with high myopia and FS-LASIK treatment. The significant association between sleep duration 8 hours/day or more and myopic regression was restricted to women and patients with FS-LASIK (near significant). However, no significant associations were observed between continuous near work or time outdoors and myopic regression.

CONCLUSIONS

Excessive near work exposure was associated with greater myopic regression 5 years after SMILE or FS-LASIK. It is crucial to maintain good visual behavior and care for preventing regression after SMILE or FS-LASIK, especially for younger patients and eyes with high myopia. [J Refract Surg. 2024;40(1):e10-e19.].

Prevalence of Myopia and Its Related Factors Among University Students in Madinah, Saudi Arabia

BACKGROUND

Myopia, a common refractive error, is a growing global health burden influenced by both genetic and environmental factors. Despite its high prevalence, studies on its prevalence and risk factors among university students are lacking.

OBJECTIVES

The objective of this study is to investigate the prevalence of myopia and its associated factors among college students in Saudi Arabia's Madinah region.

METHODS

A cross-sectional study was conducted in Al-Madinah, Saudi Arabia, from February to June 2023, utilizing a survey that was distributed to college students through a social media application.

RESULTS

A total of 433 university students from Al-Madinah province were enrolled in this study; 66.3% were females and 33.7% were males. Participants' ages ranged from 18 to 33 years with a mean of 21.3 ± 2.0 years. The prevalence of myopia among college students in Al-Madinah and its provinces was 57.3%, and 87.9% of them had myopia in both eyes. Respondents with an electronic screen time of more than three hours and a reading distance of less than 15cm were at significant risk of myopia with p-values of 0.037 and 0.019, respectively.

CONCLUSIONS

A significant prevalence of myopia has been observed among university students in Madinah. Studying in scientific and medical fields, having eye diseases, prolonged use of digital devices, limiting daily outdoor activities to one hour, and having a reading distance of less than 15 cm significantly increased the risk of myopia. Encouraging education and screening programs for myopia prevention and control is crucial.

Sleep duration and the risk of major eye disorders: a systematic review and meta-analysis

BACKGROUND

To assess the relationship between sleep duration and the risk of major eye disorders including myopia, glaucoma, cataract, age-related macular degeneration (AMD), and diabetic retinopathy (DR).

METHODS

Databases including PubMed, Embase, Web of Science, and Cochrane library were searched for eligible publications before July 2021. Studies assessing the relationship between sleep duration and any one of the major eye disorders were identified. Pooled odds ratios (ORs) and their corresponding 95% confidence intervals (95% CIs) were estimated using random-effects models.

RESULTS

We identified 21 relevant articles including 777348 participants, and 17 were cross-sectional, 3 were longitudinal, and 1 was case-control. Pooled results indicated that long sleep duration was significantly associated with the risk of DR (OR = 1.84, 95% CI 1.24, 2.73), and short sleep duration was significantly associated with the risk of cataract (OR = 1.20, 95% CI 1.05, 1.36). Besides, a significant relationship was observed between the risk of DR and long sleep duration per day (i.e., nighttime sleep plus daytime napping, OR = 1.74, 95% CI 1.23, 2.44) rather than per night (OR = 2.17, 95% CI 0.95, 4.99). The extreme of long sleep duration (i.e., >10 h per night) increased the risk of myopia (OR = 1.02, 95% CI 1.01, 1.04).

CONCLUSIONS

Inappropriate sleep duration might increase the risk of major eye disorders. The findings could contribute to the growing knowledge on the possible relationship between circadian rhythms and eye disorders.

Association between sleep duration, sleep quality, bedtime and myopia: A systematic review and meta-analysis

BACKGROUND

We performed a systematic review and meta-analysis to investigate the links between different sleep characteristics and risk of myopia.

METHODS

PubMed, EMBASE, Web of Science, the Cochrane Library, PsycINFO, Wanfang, and CNKI were searched from inception to August 26, 2022, without any language restriction. Cross-sectional, case-control, or cohort studies that explored the association between sleep duration, sleep quality, bedtime, and myopia were included. NIH quality assessment tools were used to assess the methodological quality of included studies. Random-effect or fixed-effect models were used to pool the associations according to whether there is heterogeneity.

RESULTS

A total of 31 studies with 205 907 participants were included in the final analysis (25 studies reporting sleep duration; four studies examining sleep quality and six studies evaluating bedtime). Compared to reference sleep duration, sufficient sleep duration (OR = 0.63, 95% CI = 0.51-0.78) was associated with a lower risk of myopia, and short sleep duration (OR = 1.66, 95% CI = 1.14-2.42) was associated with a higher risk of myopia. In addition, poor sleep quality (OR = 1.24, 95% CI = 1.05-1.47) was associated with a higher risk of myopia while late bedtime (OR = 1.30, 95% CI = 0.96-1.75) was not significantly associated with an increased risk of myopia.

CONCLUSIONS

Alteration in sleep duration and sleep quality may influence the risk of myopia. Well-designed cohort studies are needed in future investigations to identify a causal relationship between different sleep characteristics and myopia.

Prevalence of myopia among senior students in Fenghua, Eastern China, before and during the COVID-19 pandemic

Background

Myopia is a common cause of vision impairment worldwide. In China, the prevalence, the affected population, and the onset age of myopia are prominent issues. Prevention and intervention of myopia are great public health concerns.

Methods

This school-based retrospective study retrieved visual acuity and refractive data of senior students (grade 12th) from six high schools in Fenghua City, Zhejiang Province, eastern China, from 2016 and 2022. Noncycloplegic autorefraction was performed for refractive status. Students were divided into three subgroups by their school types. The overall myopia prevalence, as well as the prevalence of low myopia, moderate myopia, and high myopia, were calculated separately for each year. Statistical analyzes were performed using SPSS 25.0 and Graphpad Prism software.

Results

The mean myopia prevalence in Fenghua was 84.5% (95% CI: 84.0-85.0%), and a slightly downward trend was found in myopia prevalence after 2019, but the change was not statistically significant (p = 0.078). The overall prevalence of myopia was 79.6, 85.2, and 86.1% in vocational high schools, general high schools, and key high schools, respectively, with statistically significant differences (p < 0.001). The prevalence of myopia among senior students in the vocational high school was significantly lower than that in the other two high schools. There's no significant change in the overall prevalence of myopia (84.7% vs. 84.3%, p = 0.265) before and during the COVID-19 pandemic, and it remained statistically insignificant after stratifying by gender (male p = 0.207, female p = 0.918) or school types (vocational high school p = 0.112; general high school p = 0.299; key high school p = 0.393).

Conclusion

The prevalence of myopia among senior students in Fenghua is relatively high, and the COVID-19 pandemic has no significant impact on it. The prevalence of myopia among vocational high school students is lower than that of general high school and key high school. Attention should be paid to the effects of educational pressure on the prevalence of myopia among students.

Machine learning to analyze the factors influencing myopia in students of different school periods

Purpose

We aim to develop myopia classification models based on machine learning algorithms for each schooling period, and further analyze the similarities and differences in the factors influencing myopia in each school period based on each model.

Design

Retrospective cross-sectional study.

Participants

We collected visual acuity, behavioral, environmental, and genetic data from 7,472 students in 21 primary and secondary schools (grades 1-12) in Jiamusi, Heilongjiang Province, using visual acuity screening and questionnaires.

Methods

Machine learning algorithms were used to construct myopia classification models for students at the whole schooling period, primary school, junior high school, and senior high school period, and to rank the importance of features in each model.

Results

The main influencing factors for students differ by school section, The optimal machine learning model for the whole schooling period was Random Forest (AUC = 0.752), with the top three influencing factors being age, myopic grade of the mother, and Whether myopia requires glasses. The optimal model for the primary school period was a Random Forest (AUC = 0.710), with the top three influences being the myopic grade of the mother, age, and extracurricular tutorials weekly. The Junior high school period was an Support Vector Machine (SVM; AUC = 0.672), and the top three influencing factors were gender, extracurricular tutorial subjects weekly, and whether can you do the "three ones" when reading and writing. The senior high school period was an XGboost (AUC = 0.722), and the top three influencing factors were the need for spectacles for myopia, average daily time spent outdoors, and the myopic grade of the mother.

Conclusion

Factors such as genetics and eye use behavior all play an essential role in students' myopia, but there are differences between school periods, with those in the lower levels focusing on genetics and those in the higher levels focusing on behavior, but both play an essential role in myopia.

Myopia progression risk assessment score (MPRAS): a promising new tool for risk stratification

Timely identification of individuals "at-risk" for myopia progression is the leading requisite for myopia practice as it aids in the decision of appropriate management. This study aimed to develop 'myopia progression risk assessment score' (MPRAS) based on multiple risk factors (10) to determine whether a myope is "at-risk" or "low-risk" for myopia progression. Two risk-score models (model-1: non-weightage, model-2: weightage) were developed. Ability of MPRAS to diagnose individual "at-risk" for myopia progression was compared against decision of five clinicians in 149 myopes, aged 6-29 years. Using model-1 (no-weightage), further 7 sub-models were created with varying number of risk factors in decreasing step-wise manner (1a: 10 factors to 1g: 4 factors). In random eye analysis for model-1, the highest Youden's J-index (0.63-0.65) led to the MPRAS cut-off score of 41.50-43.50 for 5 clinicians with a sensitivity ranging from 78 to 85% and specificity ranging from 79 to 87%. For this cut-off score, the mean area under the curve (AUC) between clinicians and the MPRAS model ranged from 0.89 to 0.90. Model-2 (weighted for few risk-factors) provided similar sensitivity, specificity, and AUC. Sub-model analysis revealed greater AUC with high sensitivity (89%) and specificity (94%) in model-1g that has 4 risk factors compared to other sub-models (1a-1f). All the MPRAS models showed good agreement with the clinician's decision in identifying individuals "at-risk" for myopia progression.

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 Chinese eye exercises and myopia in children and adolescents: A systematic review and meta-analysis

Objective

This study aims to summarize the relevant evidence on the association between eye exercises and myopia in children and adolescents in China.

Methods

The meta-analysis pooled the results of 12 studies, with a total of 134,201 participants. Another five studies (no OR for myopia as an outcome and meeting inclusion criteria) were reported in the systematic review. We searched PubMed, Web of Science, CNKI, Wan Fang, and reference lists of retrieved studies. Association estimates were pooled using random-effects meta-analyses. Odds ratios (ORs) and 95% confidence intervals (CIs) for eye exercises and myopia were pooled from a meta-analysis.

Results

After standardizing the reference values, a pooled OR of the univariate analysis showed a 24% reduction in myopia in children and adolescents who performed eye exercises (OR = 0.76; 95% CI: 0.62–0.89). After adjusting the covariate, a pooled OR of multiple logistic analysis for myopia (OR = 0.87; 95% CI: 0.72–1.02) showed that there is no significance between eye exercises and myopia. However, in subgroup studies of the multivariate analysis, the large sample (OR = 0.84; 95% CI: 0.74–0.94) and Chinese database (OR = 0.80; 95% CI: 0.67–0.93) subgroup showed modest protective effects. In addition, five studies in the systematic review also evaluated the risk of myopia events, and Chinese eye exercises had a modest protective effect on myopic control, but the incorrect performance of and attitude toward eye exercises posed negative effects on their eyesight health.

Conclusion

Chinese eye exercises have a modest protective effect on myopic control, but considering that the incorrect performance of and attitude toward eye exercises have a significant influence on the effect of eye exercises, the effect of eye exercises may not be enough to prevent the progress of myopia in the long term, and more standardized eye exercises need to be conducted.

Using the C-Read as a Portable Device to Evaluate Reading Ability in Young Chinese Adults: An Observational Study

We evaluated the reading characteristics of normal-sighted young adults using C-Read to provide baseline healthy population values. We also investigated the relationship between the National Eye Institute’s Visual Functioning Questionnaire (VFQ-25) score and reading ability, myopia, and hours of screen use, focusing on the extent to which these factors affect participants’ visual function and, ultimately, their vision-related quality of life (QoL). Overall, 207 young, healthy participants (414 eyes) aged 18–35 years were tested for reading speed using C-Read connected to a smartphone-based application between December 2022 and January 2023. Each participant received a VFQ-25 questionnaire to evaluate vision-related QoL. Data on daily e-screen usage hours were collected. Among the participants, 91 (44.0%) were women; their mean (SD) age was 22.45 (4.01) years. The mean (SD) reading acuity (RA) was 0.242 (0.124), 0.249 (0.120), and 0.193 (0.104) logarithmic minimum angle of resolution (logMAR) for the right, left, and both eyes, respectively. The mean (SD) maximum reading speed (MRS) was 171.65 (46.27), 168.59 (45.68), and 185.16 (44.93) words per minute (wpm) with the right, left, and both eyes, respectively. The mean (SD) critical print size (CPS) was 0.412 (0.647), 0.371 (0.229), and 0.419 (1.05) logMAR per the right, left, and both eyes, respectively. The RA and CPS were significantly different between sexes (p = 0.002 and p = 0.001). MRS was significantly different between the education level (p = 0.005) and myopia level groups (p = 0.010); however, it was not clear whether this difference was confounded by age. The myopic power in diopters significantly affected RA (coefficient, −0.012; 95% CI, −0.018 to −0.006; p = 0.001); screen time significantly affected MRS (coefficient, 0.019; 95% CI, 0.57 to 6.33; p = 0.019). RA (coefficient, −21.41; 95% CI, −33.74 to −9.08; p = 0.001) and duration of screen use (coefficient, -0.86; 95% CI, −1.29 to −0.43; p < 0.001) independently had a significantly negative correlation with VFQ-25 scores. Our findings provide a baseline value for C-Read in normal-sighted young adults. Refractive status significantly affected RA, while screen time significantly affected MRS. Interventions aimed at enhancing RA may have the potential to maximize vision-related QoL and enable older adults with impaired vision to achieve greater outcomes. Future, larger-scale, C-Read experiments will help provide newer, more optimal methods for the early diagnosis of visual impairment.

Progression of myopia among undergraduate students in central China

AIM

To investigate the progression of myopia and risk factors among university students in central China.

METHODS

A total of 7359 first-year undergraduate students at Huazhong University of Science and Technology in central China were recruited to the study and invited to a centralized clinic for medical examination, including optometry, and re-examined after one year. Correlation analyses were performed to assess the associations between one-year myopia progression and various parameters.

RESULTS

The spherical equivalent refraction for the overall population was -3.14±2.28 D at baseline. The rate of myopia progression over 0.50 D after one year was 41.9%, and the 1-year progression of myopia was -0.47±0.58 D. There was no difference of mean 1-year myopia progression between male and female or difference among age group. The myopia progression of original myopia was severer than progression of new-onset myopia. There was also difference of mean myopia progression among different degrees of myopia at baseline. The under corrected eyes had a higher percentage of myopia progression than well corrected eyes (χ ²=7.90, P<0.01). There was no correlation between myopia progression and height, weight, body mass index, hemoglobin (Spearman correlation, ρ=-0.078, -0.152, -0.170, -0.096, respectively, all P>0.05).

CONCLUSION

Myopes still progress in undergraduate students, especially in high myopes.

Prevalence and Patterns of Refractive Errors in Children and Young Adults in an Urban Region in South India: the Hyderabad Eye Study

PURPOSE

To determine the prevalence of refractive error (RE) and associated risk factors for myopic refractive errors in children and young adults from the urban region of Hyderabad, South India.

METHODS

Four thousand sixty-five (4,065) participants aged 6-22 years were enrolled and examined in this cross-sectional study conducted from October 2013 to January 2015. Participants were enrolled from a random sample of schools and universities in regions representative of urban Hyderabad. RE was determined using cycloplegic autorefraction. The association of demographic factors such as age, gender, and socio-economic category (SEC) (low/mid/high) with myopia was explored with logistic regression with robust standard error.

RESULTS

Of the total participants, 2,259 were children aged 6-15 years and 1,806 were adolescents and young adults aged 16-22 years. Overall prevalence of myopia, high myopia (≤ -5.00D and ≤ -6.00 D), hyperopia, emmetropia, and astigmatism was 29.8% (95% CI: 26.0% to 33.6%, n = 1,216), 2.9% (95% CI: 1.9% to 3.9%, n = 120), 1.1% (95%CI: 0.7% to 1.5%, n = 46), 14.7% (95% CI: 12.4% to 17.0%, n = 599), 46.9% (95% CI: 43.7% to 50.1%, n = 1913) and 8.6% (95% CI: 7.4% to 9.9%, n = 352) respectively. A strong correlation existed between age and prevalence of myopia (R² = 0.88, p < .001) and high myopia (R² = 0.71, p < .001). Children from schools of low SEC (34.7%) had higher prevalence of myopia compared to the mid SEC (16.8%) (p = .043).

CONCLUSION

Myopia was the most prevalent refractive error and increased with age in this urban population. More myopia was observed in schools of low SEC.

Association between sleep duration and myopia among Chinese children during the COVID-19 pandemic: A cross-sectional study

Background

The studies on the association between sleep duration and myopia are limited, and the evidence is inconsistent. This study aimed to evaluate the association between sleep duration and myopia, cycloplegic spherical equivalent (SE) and axial length (AL) among Chinese children during the Corona Virus Disease 2019 (COVID-19) pandemic.

Methods

The study was a cross-sectional study on Chinese children aged 6-18 years. The comprehensive ophthalmic examinations for children included cycloplegic SE, AL, and standardized questionnaires. The questionnaire included sleep duration, parental myopia, outdoor time, and continuous near work duration without breaks. Myopia was defined as SE ≤-0.50 diopters (D).

Results

A total of 1,140 children were included in the analyses, with 84.7% of myopic children and 74.4% of children's daily sleep duration being more than 8 h/d. In univariate regression analysis, compared with sleep duration < 8 h/d, children with sleep duration of 8-9 and >9 h/d were less myopia (p < 0.01 for all), and had less myopic SE (p < 0.01 for all), and shorter AL (p < 0.01 for all). After adjusting for age, gender, parental myopia, outdoor time, and continuous near work duration without breaks, sleep duration was not associated with myopia, cycloplegic SE, and AL (p > 0.05 for all).

Conclusions

This study showed sleep duration was related to myopia, cycloplegic SE, and AL among Chinese children during the COVID-19 pandemic-related lifestyles, but no independent association.

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.

Prevalence of myopia and associated risk factors among key schools in Xi'an, China

BACKGROUND

The aim of this study is to investigate the prevalence of myopia and high myopia and the associated risk factors in key schools in Xi'an, China.

METHODS

This cross-sectional study started in September 2021 and was conducted for one month. A total of 11,011 students from 10 key primary schools, five key junior high schools and five key high schools in Xi'an were randomly selected to undergo visual acuity measurement and non-cycloplegic autorefraction. The questionnaire was completed by the students and their parents together.

RESULTS

The prevalence of myopia and high myopia in key schools were 75.7% and 9.7%, respectively. The prevalence of myopia and high myopia rose significantly as grade or age increased (all P < 0.001), and the prevalence of myopia and high myopia in females was higher than that in males (P < 0.001, P < 0.5). According to the multivariable logistic regression analysis, older age (OR=1.42), female compared with male (OR=1.43), having one myopic parent (OR=1.64), having two myopic parent (OR=2.30) and often taking extracurricular tuition (OR=1.35) were more likely to be associated with develop myopia (P < 0.001). Older age (OR=1.39), having one myopic parent (OR=2.29), having two myopic parent (OR= 3.69), and often taking extracurricular tuition (OR=1.48) were more likely to be associated with high myopia (P < 0.001).

CONCLUSIONS

The overall rate of myopia and high myopia in key schools in Xi'an, China, is extremely high. Myopia and high myopia are associated with increasing age, parents' myopia, few outdoor exercises, and extracurricular tuition. Myopia is also associated with female and not having the habit of "one punch, one foot, one inch (when reading and writing, 10 cm from the chest to the table, 33 cm from the eye to the book and 3.3 cm from the tip of the pen to the finger)".

A Cross-Sectional Observational Study of the Relationship between Outdoor Exposure and Myopia in University Students, Measured by Conjunctival Ultraviolet Autofluorescence (CUVAF)

Myopia is the most common refractive error worldwide. This cannot be explained by genetic factors alone, therefore, environmental factors may play an important role. Hence, the main objective of this study was to analyse whether outdoor exposure could exert a protective effect against the development of myopia in a cohort of young adults and to investigate ultraviolet autofluorescence (CUVAF), as a biomarker of time spent outdoors. A cross-sectional observational study was carried out using two cohorts. A total of 208 participants were recruited, 156 medical students and 52 environmental science students. The data showed that 66.66% of the medical students were myopic, while 50% of the environmental science students were myopic (p = 0.021). Environmental science students spent significantly more hours per week doing outdoor activities than medical students (p < 0.0001), but there was no significant difference with respect to near work activities between them. In both cohorts, the degree of myopia was inversely associated with CUVAF, and a statistically significant positive correlation was observed between spherical equivalent and CUVAF (Pearson’s r = 0.248). In conclusion, outdoor activities could reduce the onset and progression of myopia not only in children, but also in young adults. In addition, CUVAF represents an objective, non-invasive biomarker of outdoor exposure that is inversely associated with myopia.

The Association Between Environmental and Social Factors and Myopia: A Review of Evidence From COVID-19 Pandemic

Purpose

To review the association between children's behavioral changes during the restriction due to the pandemic of Coronavirus disease (COVID-19) and the development and progression of myopia.

Design

A literature review.

Method

We looked for relevant studies related to 1) children's behavioral changes from COVID-19 restriction and 2) children's myopia progression during COVID-19 restriction by using the following keywords. They were “Behavior,” “Activity,” “COVID-19,” “Lockdown,” “Restriction,” and “Children” for the former; “Myopia,” “COVID-19,” “Lockdown,” “Restriction” for the latter. Titles, abstracts and full texts from the retrieved studies were screened and all relevant data were summarized, analyzed, and discussed.

Results

Children were less active and more sedentary during COVID-19 restriction. According to five studies from China and six studies, each from Hong Kong, Spain, Israel, South Korea, Turkey and Taiwan included in our review, all countries without myopia preventive intervention supported the association between the lockdown and myopia progression by means of negative SER change ranging from 0.05–0.6 D, more negative SER change (compared post- to pre-lockdown) ranging from 0.71–0.98 D and more negative rate of SER changes (compared post- to pre-lockdown) ranging from 0.05–0.1 D/month. The reported factor that accelerated myopia is an increase in total near work, while increased outdoor activity is a protective factor against myopia progression.

Conclusion

The pandemic of COVID-19 provided an unwanted opportunity to assess the effect of the behavioral changes and myopia in the real world. There is sufficient evidence to support the association between an increase in near work from home confinement or a reduction of outdoor activities and worsening of myopia during the COVID-19 lockdown. The findings from this review of data from the real world may help better understanding of myopia development and progression, which may lead to adjustment of behaviors to prevent myopia and its progression in the future.

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

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

Association of Axial Length and Refraction with Near Horizontal Heterophoria in Chinese Children: An Observational Cross-Sectional Study

Purpose

To evaluate the association of near heterophoria with refraction and axial length (AL) in Chinese school children.

Methods

This school-based cross-sectional study included 15,081 Chinese primary school children (grades 1-6) examined during 2017. Near heterophoria was measured at 33 cm using the Maddox rod and prism test. Noncycloplegic refraction and AL were also measured. A generalized additive model with a Gaussian link was used to determine the association of near heterophoria with refraction and AL. Analyses were adjusted for age to account for differences in the age distribution of the sample.

Results

Overall, data were analyzed for 11,013 students ranging in age from 6 to 13 years. The most common type of near heterophoria was exophoria (64.96%), the proportion and value of which increased according to grade. Exophoria accounted for 62.53% (2,328/3,723), 65.03% (2,501/3,846), and 67.51% (2,325/3,444) of near heterophoria cases for grades 1-2, grades 3-4, and grades 5-6, respectively. Prism diopter (PD) values for near heterophoria in these grades were -6.30 ± 3.69, -6.81 ± 4.01, and -8.32 ± 5.12 PD, respectively. The average spherical equivalent (SE) in children with orthophoria was 0.23 D and 0.25 D lower than those in children with exophoria and esophoria, respectively (P < 0.001). The mean AL in children with orthophoria was 0.11 mm shorter than that in children with either exophoria or esophoria (P < 0.001). Near heterophoria exhibited a significant correlation with refraction and AL, irrespective of age.

Conclusions

Exophoria represents the most common type of near heterophoria in children. Children with more severe near heterophoria, whether exophoria or esophoria, exhibited a higher degree of myopia and longer AL than those with relatively less severe near heterophoria. These results highlight the need for further, long-term investigation regarding the role of near heterophoria in visual development.

High prevalence of myopia and low hyperopia reserve in 4411 Chinese primary school students and associated risk factors

Purpose

To investigate the prevalence of myopia in Chinese primary school students and their ocular biometrics including axial length (AL), corneal radius of curvature (CRC) and spherical equivalent refraction (SER). To analyze their association with potential myopia risk factors, such as body mass index (BMI), cram school, time of outdoor activity and electronic screen use.

Methods

In this cross-sectional study of 4500 primary school students from 5 schools, participants underwent refraction using non-cycloplegic autorefractor and visual acuity testing. A follow-up study in the same schools was conducted in 2022. Myopia was defined as SER ≤ -0.50 diopter (D) and uncorrected visual acuity (UCVA) < 0.00 logMAR (6/6). Logistic regression models were used to determine factors associated with myopia.

Results

After excluding 389 participants, the overall prevalence of myopia was 33.6%. The prevalence of high myopia was 0.6%. The prevalence of myopia in girls was significantly higher than that in boys (37.6% vs. 30.0%, p < 0.001). The height, weight and BMI were significantly associated with AL (r = 0.471, r = 0.440, r = 0.276, p < 0.001, respectively). AL/CRC ratio was more highly correlated with SER than AL alone. Regression analysis showed that AL/CRC and hyperopia reserve were associated with myopia onset in the subsequent year (F = 201.557, p < 0.001; F = 68.934, p < 0.001). The cut point of hyperopia reserve for myopia in the subsequent year for grade 1 students was + 0.31D. Age (p < 0.001), parental myopia (p = 0.001) and lack of outdoor activity between classes (p = 0.049) were independently associated with higher prevalence rates of myopia.

Conclusion

The prevalence of myopia among Chinese schoolchildren is alarming high. Consistent with previous cross-sectional data, AL/CRC and hyperopia reserve could function as myopia detection indicators. The hyperopia reserve among children aged between 6 ~ 7 years was low. Healthcare providers need to raise parents’ awareness of the importance of regular eye examination and proper optical correction.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02436-5.

Prevalence of Myopia and Influencing Factors among High School Students in Nantong, China: A Cross-Sectional Study

INTRODUCTION

Myopia is an increasingly serious health problem in China. The aim of this study was to investigate the prevalence of myopia and the factors associated with it among students in Nantong, China, to show the current status of myopia prevention.

METHODS

This school-based, cross-sectional study examined students from all high schools in an urban area of Nantong, China. At least two classes were randomly selected from each grade of each school. A self-reported questionnaire was used to collect the required information. Univariate analyses were performed to identify associations between myopia and various parameters. Noncycloplegic autorefraction and visual acuity were assessed for each student. Factors that were statistically significant in univariate analyses were selected for multivariate analyses. Myopia was defined as a spherical equivalent refraction of ≤-0.5 diopters.

RESULTS

The completion percentage of students out of the whole high school was 6.5%. The overall prevalence of myopia was 94%. The response percentage of the number of validated questionnaires was 90.2%, of which 50.2% (n = 1,466) were from male participants, and 49.8% (n = 1,452) were from female participants. The mean (SD) of age was 15.22 ± 1.75 years, ranging from 12 to 18 years. Factors such as female sex, older age, parental myopia, sitting in the back of the classroom, increased homework time, and minimal outdoor activity were significantly associated with a higher risk of myopia (p < 0.05). In the myopic population, most students (67.9%) did not take measures to prevent further progression of myopia.

CONCLUSION

The prevalence of myopia among high school students was 94%. Female sex, older age, parental myopia, sitting in the back of the classroom, increased homework time, and minimal outdoor activity were significantly associated with a higher risk of myopia. Most students with myopia (67.9%) did not take measures to prevent further progression of myopia.

Refractive errors and risk factors for myopia in infants aged 1-18 months in Tianjin, China

BACKGROUND

Infancy is the of a child's visual development. Refractive errors, especially myopia, are a common vision disorder. Thus, the purpose of this study was to explore refractive errors and risk factors for myopia among infants aged 1-18 months in Tianjin, China.

METHODS

A total of 583 infants aged 1-18 months participated in this cross-sectional study at Tianjin Women's and Children's Health Center in China from February 2019 to November 2020. Each infant received a complete ophthalmologic examination, and myopia-related risk factors were investigated using a questionnaire.

RESULTS

A total of 583 eligible infants participated in this study, including 312 (53.5%) boys and 271 (46.5%) girls. There were 164 (28.1%) premature born infants. The mean age was 6.59 ± 4.84 months (range, 1-18 months). The mean spherical equivalent (MSE) for the right eye was 1.81 D ± 1.56 D, with no difference related to sex (P = 0.104). Refractive state showed an average hyperopia of +2.74 ± 1.74 D at early ages, followed by a trend toward less hyperopia, finally reaching +1.35 ± 1.44 D at the age of 18 months (P ≤0.001). The overall prevalence rates of myopia (MSE ≤ -0.50 D), emmetropia (-0.50 D<MSE<+0.50 D), hyperopia (MSE ≥ +2.00 D), and astigmatism (≥ 1.50 D) were 5.1%, 10.8%, 42.7%, and 49.9%, respectively. The chi-square tests showed that gender, gestational age ≥37 weeks, winter birth, prenatal exposure to environmental tobacco smoke, and parental history of high myopia were associated with children's myopia (P = 0.022, P = 0.023, P = 0.038, P = 0.015, P<0.001, respectively).

CONCLUSIONS

Among Chinese infants in Tianjin, hyperopia and astigmatism were the most frequent refractive errors, and the diopter was lower in individuals with higher age. In a small number of infants with myopia, genetic factors and the prenatal environment were associated with the early onset of myopia.

Effect of Sunshine Duration on Myopia in Primary School Students from Northern and Southern China

Background

To assess the current myopia prevalence rate and evaluate the effect of sunshine duration on myopia among primary school students in the north and south of China.

Methods

This prospective cross-sectional study pooled data from 9171 primary school students (grades from 1 to 6) from four cities in the north and south of China. National Geomatics Center of China (NGCC) and China Meteorological Administration provided data about altitude, latitude, longitude, average annual temperature, and average annual sunshine duration. Non-cycloplegic refraction was recorded, and prevalence rates in primary school students and factors associated with myopia were analyzed. Univariate and multivariate logistic regression models were used to determine the independent association of risk factors of myopia.

Results

The overall myopia prevalence was 28.0%, from 7.5% to 50.6% for first and sixth grades, respectively. Low, moderate and high myopia significantly increased with school grades from 7.30% to 35.0%, 0.3% to 13.60% and 0.00% to 1.9%, respectively. Multiple regression analysis revealed that longer average cumulative daylight hours were connected to lower myopia prevalence in primary school students (OR, 0.721; 95% CI, [0.593–0.877]; P=0.001), whereas girls and higher grade was independently associated with higher myopia prevalence (girls: β=0.189; OR, 1.208; 95% CI, [1.052–1.387]; P=0.007; higher grade: β=0.502; OR, 1.652; 95% CI, [1.580–1.726]; P<0.001).

Conclusion

This study demonstrated that myopia was highly prevalent in southern Chinese cities over northern ones, linked to shorter light exposure, higher education level, and female gender. Such findings reinforced the beneficial impact of daylight exposure with a protective role against myopia development.

IMI Risk Factors for Myopia

Risk factor analysis provides an important basis for developing interventions for any condition. In the case of myopia, evidence for a large number of risk factors has been presented, but they have not been systematically tested for confounding. To be useful for designing preventive interventions, risk factor analysis ideally needs to be carried through to demonstration of a causal connection, with a defined mechanism. Statistical analysis is often complicated by covariation of variables, and demonstration of a causal relationship between a factor and myopia using Mendelian randomization or in a randomized clinical trial should be aimed for. When strict analysis of this kind is applied, associations between various measures of educational pressure and myopia are consistently observed. However, associations between more nearwork and more myopia are generally weak and inconsistent, but have been supported by meta-analysis. Associations between time outdoors and less myopia are stronger and more consistently observed, including by meta-analysis. Measurement of nearwork and time outdoors has traditionally been performed with questionnaires, but is increasingly being pursued with wearable objective devices. A causal link between increased years of education and more myopia has been confirmed by Mendelian randomization, whereas the protective effect of increased time outdoors from the development of myopia has been confirmed in randomized clinical trials. Other proposed risk factors need to be tested to see if they modulate these variables. The evidence linking increased screen time to myopia is weak and inconsistent, although limitations on screen time are increasingly under consideration as interventions to control the epidemic of myopia.

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

Objective

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

Methods

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

Results

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

Conclusions

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

Dysfunction of VIPR2 leads to myopia in humans and mice

Background

Myopia is the leading cause of refractive errors. As its pathogenesis is poorly understood, we determined if the retinal VIP-VIPR2 signalling pathway axis has a role in controlling signalling output that affects myopia development in mice.

Methods

Association analysis meta-study, single-cell transcriptome, bulk RNA sequencing, pharmacological manipulation and VIPR2 gene knockout studies were used to clarify if changes in the VIP-VIPR2 signalling pathway affect refractive development in mice.

Results

The SNP rs6979985 of the VIPR2 gene was associated with high myopia in a Chinese Han cohort (randomceffect model: p=0.013). After either 1 or 2 days’ form deprivation (FD) retinal VIP mRNA expression was downregulated. Retinal single-cell transcriptome sequencing showed that VIPR2 was expressed mainly by bipolar cells. Furthermore, the cAMP signalling pathway axis was inhibited in some VIPR2+ clusters after 2 days of FD. The selective VIPR2 antagonist PG99-465 induced relative myopia, whereas the selective VIPR2 agonist Ro25-1553 inhibited this response. In Vipr2 knockout (Vipr2-KO) mice, refraction was significantly shifted towards myopia (p<0.05). The amplitudes of the bipolar cell derived b-waves in 7-week-old Vipr2-KO mice were significantly larger than those in their WT littermates (p<0.05).

Conclusions

Loss of VIPR2 function likely compromises bipolar cell function based on presumed changes in signal transduction due to altered signature electrical wave activity output in these mice. As these effects correspond with increases in form deprivation myopia (FDM), the VIP-VIPR2 signalling pathway axis is a viable novel target to control the development of this condition.

Association between time spent outdoors and myopia among junior high school students: A 3-wave panel study in China

This study sought to investigate the recent incidence rate of myopia in Chinese junior high school students and analyze the effect of time spent outdoors on myopia, in addition to facilitating the prevention and control of myopia among students.This study was derived from a national panel study, the China Education Panel Survey. We conducted three rounds of follow-up visits among 10,279 seventh grade students from 112 middle schools in 20 provinces in 2013. In total, 3571 students were selected for the analysis in 2020 by excluding those lost to follow-up and students who were myopic in the first round. The primary outcomes were the prevalence of myopia and the effect of time outdoors on myopia. The baseline characteristics of the included students were described, and the correlation between time spent outdoors and myopia in the three rounds of data was analyzed by a correlation chi-square test. Then, the generalized estimation equation (GEE) was used to estimate the influence of time spent outdoors on myopia after follow-up.There were 3571 students with normal baseline vision, and 1508 (42.23%) students progressed from having a normal vision to myopia in the third round, of whom 706 (46.82%) were male and 802 (53.18%) were female. The results of the chi-square test showed that the time spent outdoors of all students and girls, specifically, was related to myopia (P < .05). Next, the GEE was used to analyze the influence of time spent outdoors on myopia after follow-up. After two model adjustments (individual and family-related characteristics of students), students with < 7 hours/week time spent outdoors retained a high myopia rate than ≥14 hours/week (OR = 1.250; 95% CI: 1.070-1.460). Among boys, there was no statistical correlation between time spent outdoors and myopia (P > .05). For girls, compared with students who spent ≥14 hours/week outdoors, students with <7 hours/week spent outdoors retained a higher myopia rate (OR = 1.355; 95%CI: 1.067-1.720).Increased time spent outdoors can delay the development of myopia. In terms of gender, girls should be targeted to more effectively prevent and control the development and progression of myopia.

Smartphone Overuse and Visual Impairment in Children and Young Adults: Systematic Review and Meta-Analysis

BACKGROUND

Smartphone overuse has been cited as a potentially modifiable risk factor that can result in visual impairment. However, reported associations between smartphone overuse and visual impairment have been inconsistent.

OBJECTIVE

The aim of this systematic review was to determine the association between smartphone overuse and visual impairment, including myopia, blurred vision, and poor vision, in children and young adults.

METHODS

We conducted a systematic search in the Cochrane Library, PubMed, EMBASE, Web of Science Core Collection, and ScienceDirect databases since the beginning of the databases up to June 2020. Fourteen eligible studies (10 cross-sectional studies and 4 controlled trials) were identified, which included a total of 27,110 subjects with a mean age ranging from 9.5 to 26.0 years. We used a random-effects model for meta-analysis of the 10 cross-sectional studies (26,962 subjects) and a fixed-effects model for meta-analysis of the 4 controlled trials (148 subjects) to combine odds ratios (ORs) and effect sizes (ES). The I² statistic was used to assess heterogeneity.

RESULTS

A pooled OR of 1.05 (95% CI 0.98-1.13, P=.16) was obtained from the cross-sectional studies, suggesting that smartphone overuse is not significantly associated with myopia, poor vision, or blurred vision; however, these visual impairments together were more apparent in children (OR 1.06, 95% CI 0.99-1.14, P=.09) than in young adults (OR 0.91, 95% CI 0.57-1.46,P=.71). For the 4 controlled trials, the smartphone overuse groups showed worse visual function scores compared with the reduced-use groups. The pooled ES was 0.76 (95% CI 0.53-0.99), which was statistically significant (P<.001).

CONCLUSIONS

Longer smartphone use may increase the likelihood of ocular symptoms, including myopia, asthenopia, and ocular surface disease, especially in children. Thus, regulating use time and restricting the prolonged use of smartphones may prevent ocular and visual symptoms. Further research on the patterns of use, with longer follow up on the longitudinal associations, will help to inform detailed guidelines and recommendations for smartphone use in children and young adults.

Association between Time Spent on Smart Devices and Change in Refractive Error: A 1-Year Prospective Observational Study among Hong Kong Children and Adolescents

This study examined the association between smart device usage and the 1-year change in refractive error among a representative sample of Hong Kong children and adolescents aged 8–14 years. A total of 1597 participants (49.9% male, mean age 10.9, SD 2.0) who completed both baseline (2017–2018) and 1-year follow-up (2018–2019) eye examinations were included in the present study. The non-cycloplegic auto-refractive error was measured and the average spherical equivalent refraction (SER) was analyzed. The participants also self-reported their smart device usage at baseline. Multivariate regression adjusted for age, sex, baseline SER, parents’ short-sightedness, BMI, time spent on moderate-to-vigorous physical activity (MVPA), and caregiver-reported socio-economic status showed that, compared with the reference group (<2 h per day on both smartphone and tablet usages), those who spent ≥2 h per day using a smartphone and <2 h per day using a tablet had a significantly negative shift in refractive error (1-year change in SER −0.25 vs. −0.09 D, p = 0.01) for the right eye, while the level of significance was marginal (1-year change −0.28 vs. −0.15 D, p = 0.055) for the left eye. To conclude, our data suggested spending at most 2 h per day on both smartphones and tablets.

Prevalence of Refractive Errors and its Associated Risk Factors among Medical Students of Jazan University, Saudi Arabia: A Cross-sectional Study

PURPOSE

Refractive errors (REs) are common and continue to increase globally, particularly myopia. Uncorrected REs are the second leading cause of preventable blindness and the most common cause of visual impairment. The main objective of this study is to assess the prevalence of REs and to investigate its associated risk factors among medical students of the Jazan region, Saudi Arabia.

METHODS

An observational analytical cross-sectional study was conducted among a random sample of 447 medical students at Jazan University. Eye examination was conducted using an autorefractor test (Huvitz HRK-8000A Autorefractor Keratometer) to measure spherical refraction (emmetropia, myopia, and hyperopia) and cylindrical refraction (astigmatism). Factors associated with myopia and hyperopia were evaluated using logistic regression models.

RESULTS

The overall prevalence of REs was 48.8% (95% confidence interval [CI] [44.2, 53.4]). The prevalence of REs among female medical students was 55.1% (95% CI [48.6, 61.5]), which was significantly higher than that among males (42.3%, 95% CI [36.0, 48.9]), with a P = 0.007. Of the 447 medical students examined, approximately one-third (33.8%) had myopia, 10.5% had astigmatism, and only 10.5% had hyperopia. The results of logistic regression indicated that females were 52% more myopic than males (odds ratios [OR] = 1.52, 95% CI [1.04, 2.22]), while participants with both parents having a history of REs were twofold more myopic than students with no family history of REs (OR = 2.01, 95% CI [1.2, 3.4]). A history of blurred vision also increases the risk of myopia by seven times (OR = 7.2, 95% CI [6.4, 11.3]).

CONCLUSION

RE among medical students is a problem. Thus, it needs to be assessed carefully before students choose a specialty that may need very good near and far vision for postgraduate study.

Correlation of Myopia with Physical Exercise and Sleep Habits among Suburban Adolescents

Purpose

To analyse the correlation of myopia with physical exercise and sleep habits to explore the possible risk or protective factors of juvenile myopia.

Methods

This study was a retrospective cross-sectional study. A total of 1831 students aged 11-18 years from five schools in Qingpu completed questionnaires from 2018 to 2019; the students were divided into the nonmyopia group and the myopia group, with students in the myopia group having myopia in at least one eye. Based on the chi-square test, the variables with statistical significance were selected for the logistic regression analysis. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were determined.

Results

Myopia was positively associated with older age (OR = 2.216, 95% CI: 1.720-2.855), having a parent with myopia (father: OR = 2.463, 95% CI: 1.900-3.193; mother: OR = 2.853, 95% CI: 2.232-3.646), and a late bedtime during holidays (before 10 pm: p = 0.002; 10 pm-11 pm: OR = 1.516, 95% CI: 1.095-2.100; 11 pm-12 am: OR = 1.966, 95% CI: 1.383-2.795), but negatively correlated with male gender (OR = 0.693, 95% CI: 0.549-0.876), a late daily wake time (OR = 0.782, 95% CI: 0.621-0.985), and having more days per week of outdoor activities during the semester (OR = 0.764, 95% CI: 0.597-0.978). After adjustment for demographic characteristics, myopia was positively associated with a late bedtime during holidays (before 10 pm: p = 0.003; 10 pm-11 pm: OR = 1.570, 95% CI: 1.076-2.289; 11 pm-12 am: OR = 2.173, 95% CI: 1.451-3.253; after 12 am: OR = 1.786, 95% CI: 1.093-2.919), but negatively correlated with a late daily wake time during the semester (OR = 0.761, 95% CI: 0.581-0.997).

Conclusion

The association of outdoor exercise with myopia among Chinese suburban adolescents does not seem to be as strong as that of sleep habits. Future research could seek to provide consistent evidence for a potential association between myopia and sleep habits.