Abstract Myopia is becoming a global public health problem, the prevalence of myopia among Chinese children and adolescents is high. The nature and nurture etiologies of myopia have been debated for a long time, and current evidence suggests that behavioral and environmental factors are the main causes of myopia in children and adolescents. Challenges in research on behavioral risk factors include cross sectional design, as well as limited longitudinal and intervention. Therefore, future studies need to highlight cohorts study and intervention study, and bring in implementation research to evaluate the significance of application, so as to bridge gaps between research evidence and practice for prevention and control of myopia.

Abstract In order to improve the prevention and control of myopia, this paper examines the significance of hyperopia reserves and its correct application, identifies problems requiring further attention and sums up past experiences. It puts forward a prevention and control system of myopia after introduction of the physiotherapy instruments, especially those based on the principle of red light. This paper discusses some mechanisms of low concentration atropine eye drops in preventing and controlling myopia. Finally, future research directions are proposed.

Objective: To investigate the current status of myopia in children and adolescents in Qamdo, Tibet, and analyze related influencing factors, so as to provide a basis for the prevention and control of adolescents in plateau areas. Methods: A cross sectional study was conducted among 959 children and adolescents randomly selected from one district and two counties in Qamdo (from the fourth grade of elementary school to the second grade of high school) for visual acuity and refraction tests and filled out a vision related behavior questionnaire to analyze the incidence of myopia among adolescents in the region and its associated factors. Results: The myopia rate of adolescents in grades 4-11 was 54.43%, the rate of undercorrection of refractive errors was 85.25%, and the percentage of students wearing eyeglasses was 34.67%,fully vision correction rate was 42.54%. The myopia rate of students in grades 4-6 was 35.14%, 64.71% in grades 7-9, and 73.48% in grades 10-11. The myopia rate increased with grades( χ 2= 101.18 , P <0.01). The myopia rate (70.40%) of urban students (grades 4-9) was higher than that of county level(41.45%), and the myopia rate of students with myopia from either parent (68.24%) was higher than that of students without myopia (51.91%) , the myopia rate of girls (59.96%) was higher than that of boys (48.36%)( χ 2=53.19，13.46，12.98， P <0.01). Use electronic products for more than 2.5 hours per day, electronic devices usage after bedtime, the light low indoor brightness when studying on a sunny day, and only use one of the table lamps or roof lights when studying at night, preference for fried food, poor sleep quality, in the morning the students who still feel tired are at higher risk of myopia( χ 2=10.35, 10.91, 6.87, 4.25, 4.97, 5.71, 12.11, P < 0.05). Multivariate regression analysis showed that the occurrence of myopia was related to region, grade, gender, parental myopia, time spent on electronic products every day in the past 5 months, and sleep quality( P <0.05). Conclusion The high rate of myopia in children and adolescents in Qamdo may be related to the quality of sleep, the length of time electronic products are used, the eye environment, and the frequency of eating fried foods. Outdoor activities do not show significant differences.

Objective: To explore relationship between screen time and myopia in children aged 11-14 years in China. Methods: The data were extracted from "National Nutrition and Health Systematic Survey and Application for 0-18 Years Old Children". A total of 12 397 children aged 11-14 years old from 14 provinces and 28 districts/counties in seven regions of China were surveyed by using multi stage stratified random sampling method. Daily screen time and visual acuity information were collected through a questionnaire. Results: The myopia rate of 11-14 years old children in China was 45.0%, among which the rate of girls was higher than that of boys, and the rate of urban was higher than that of rural, and it increased with age ( χ 2=178.82,79.25, 495.96 , P <0.01). The daily screen time median of 12 397 children was 40.0 minutes, with boys(40.0 min) longer than girls( 35.0 min ) and urban children(40 min) longer than rural children(33.0 min) ( χ 2=20.86，102.68， P <0.01). The myopia rate of boys ( 42.5 %) with daily screen time greater than or equal to 60 minutes was higher than that of boys (36.4%) with daily screen time less than 60 minutes, and the myopia rate of girls (55.6%) with daily screen time greater than or equal to 60 minutes was higher than that of girls (48.0%)( χ 2=23.62，34.15， P <0.01). After adjusting for age, gender, region, time of medium and high intensity physical activity, intake of sugary food and sugary beverages, daily sleep time, multivariable Logistic regression model showed that girls with daily screen time greater than or equal to 60 minutes ( OR=1.14, 95%CI =1.03-1.27) had a higher risk of myopia than those with less than 60 minutes. After adjusting for confounding factors, there was no correlation between daily screen time and the degree of myopia in boys or girls( P >0.05). Conclusion Daily screen time greater than or equal to 60 minutes may be a risk factor for myopia in girls aged 11 to 14 years old. Given the complexity of the factors that affect vision, researches are needed to examine the relationship between screen time and myopia.

Objective: To analyze the effect of sunlike spectrum LED illumination on retinal blood flow perfusion, and to explore the the correlation between sunlike spectrum LED illumination and eye health indicators in children and adolescents. Methods: A randomized control double blind trial was conducted. The ordinary LED table lamp in the control group(11) and the sunlike spectrum LED table lamp in the experimental group(12) had a fitting degree of 87% and 95% with the daylighting spectrum, respectively. Two sample independent t test and multivariable linear regression model were applied to compare the changes of retinal blood perfusion before and after the trial. Results: After near reading for 1 hour, the retinal capillary density in the superficial and deep layers of the subjects in the ordinary LED illumination group decreased (superficial layer: -3.05±2.04 , P <0.01; deep layer: -4.03± 4.94, P =0.02), no significant decrease was found in the sunlike spectrum LED illumination group (superficial layer: -0.59± 1.44, P =0.18; deep layer: -0.49±4.27, P =0.70). Multivariable regression analysis found that compared with ordinary LED illumination, sunlike spectrum LED illumination could significantly alleviate the decrease in capillary density in the superficial and deep retinal layers, respectively ( β =2.83, 95% CI =1.54-4.12, P <0.01; β =4.21,95% CI =0.58-7.84, P =0.02). Conclusion Sunlike spectrum LED illumination can alleviate the decrease in retinal blood perfusion caused by near work among children and adolescents, suggesting that it may delay the onset and development of myopia. Prevention and control of myopia needs to pay attention to the spectral power distribution of artificial illumination.

Objective: To understand the online learning related screen use duration and screen types in school aged children in Shanghai during the COVID-19 epidemic. Methods: Random clustering sampling was used to select 5 591 parents of students from 8 primary and junior schools that are in the sampling pool of the national myopia survey in districts of Jiading, Pudong and Baoshan in Shanghai in April 2020. Electronic questionnaire was administered to parents regarding their child s online learning related screen use. Results: On average, the median weekly duration of online learning related screen use was 13.33 hours, the curricular and extracurricular parts of which were 10(8.75，16.67) and 0(0，3.33) hours, respectively. About 29.44% of investigated school aged children only used small size screen for online learning. Children in higher grades, being myopic and parents neither being myopic were associated with reporting higher weekly duration( P <0.05); children in higher grades of primary school and parents neither being myopic were associated with a higher likelihood of using small size screen for online learning( P <0.05). Conclusion At the early stage of the COVID-19 epidemic, the burden associated with online learning related screen use was high in school aged children in Shanghai. Health education regarding online learning related screen use should be addressed in parents to guide their children to use screen appropriately.

Objective: To determine the influencing factors of electronic screen time of urban preschoolers before and after the COVID-19 outbreak, so as to provide a scientific basis for the control of digital screen use and early prevention of myopia among preschoolers. Methods: Using multi stage cluster random sampling method, a cross sectional survey of 8 244 kindergarten students in a district of Shanghai was implemented, through parent questionnaire collecting the time child spent on various electronic screens before and after the COVID-19 outbreak, estimated the weighting screen time, and emphatically analyzed the relationship between family electronic screen supervision behavior and preschoolers weighting screen time. Results: The proportion of daily over use time on average of mobile phones, computers and TV/projection screens among the surveyed preschool children during COVID-19 was 30.52%, 51.40% and 56.82%, respectively. On school days before the epidemic, the proportion was 21.94%, 41.80% and 47.51% respectively. After controlling for primary covariates, parents frequent control of children s electronic screen use, parents guidance for electronic screen use were significantly associated with lower weighted screen refractive time ( OR =0.60-0.77, P < 0.05 ). The use of electronic screen when parents accompanied their children, the use of electronic screen time by parents but not strictly implemented were significantly associated with higher weighted screen refractive time and increased screen refractive time ( OR =1.18-1.80, P <0.05). Conclusion Urban preschoolers electronic screen time was high during and before COVID-19. In the control measures of preschool children s electronic screen time, attention should be paid to the management of electronic screen use within the family and parents role model.

Objective: To investigate the effects and patterns of cumulative ecological risk on currrent and 6 month follow up healthy lifestyle among college students. Methods: A total of 1 156 freshmen and sophomores students randomly selected from 3 universities in Hebei Province were administered with College Students Health Lifestyle Scale and the Cumulative Ecological Risk Scale in November 2020 and May 2021 respectively. SPSS 24.0 statistical software was used for hierarchical regression analysis. Results: Cumulative ecological risk was both negatively associated with current healthy lifestyle ( β =-0.29, P <0.01), and healthy lifestyle 6 month after ( β =-0.11, P <0.01). The effects of cumulative ecological risks on current healthy lifestyle showed non linear pattern, with healthy lifestyle rapidly decline after accumulated more than 4 factors. The effects of umulative ecological risks on 6 month follow up healthy lifestyle showed a linear pattern. No moderating effect of gender was observed in the linear relationship between the cumulative ecological risk and 6 month follow up healthy lifestyle( β =-0.02， P >0.05), however, significant moderating effects of gender was found in the nonlinear relationship between cumulative ecological risk and current healthy lifestyle( β =0.12， P < 0.01). Conclusion Cumulative ecological risk is negatively associated with healthy lifestyle of college students cross sectionally and longitudinally, in a non linear and linear association pattern, respectively. Gender plays a moderating effect on the cross sectional asscociation between cumulative ecological risk and healthy lifestyle.

Objective: To understand parental feeding behavior and cognitive development among Kazak preschool children in agricultural and pastoral areas in Xinjiang, and to provide reference for anemia prevention in preschool children in this area. Methods: In May 2019, a total of 1 846 Kazak preschool children were selected from the agricultural and pastoral areas of Xinjiang by stratified cluster sampling method, and parental feeding behavior and child anemia status were assessed. Results: The detection rate of anemia in Kazak preschool children in agricultural and pastoral areas in Xinjiang was 49.19%, and the detection rates of mild and moderate anemia were 29.52% and 19.66%, respectively. There were statistically significant differences in the detection rate of anemia in preschool children in terms of age, father s education, mother s education, and family per capita income ( χ 2= 162.06 , 8.17, 16.86, 11.14, P <0.05); There were statistically significant differences in the types of complementary food, nutritional anemia, breastfeeding time, and whether or not to force feeding ( χ 2=6.33, 8.91, 4.06, 21.55, P ＜0.05). Logistic regression analysis showed that parents unclear about the type of complementary food ( OR=1.36, 95%CI =1.09-1.68), nutritional anemia ( OR=1.38, 95%CI =1.08-1.77), feeding time less than 24 months or unawareness ( OR=1.46, 95%CI =1.01-2.11) and forced feeding ( OR=1.42, 95%CI =1.13-1.78) were positively correlated with the detection rate of anemia in preschool children ( P < 0.05 ). Conclusion Kazak preschool children in agricultural and pastoral areas in Xinjiang have severe anemia. There is a relationship between parental feeding behavior and children s anemia, which warrants further efforts to improve preschool children s anemia.

Objective: To understand levels of various foods and nutrients in school lunch based on digital platform and to provide reference for food preparation and serving. Methods: A total of 13 018 school lunch recipes in Binhai New Area of 96 schools in Tianjin from November 2020 to April 2021 were collected by using digital management platform for food safety and nutritional health.Food types including cereals and tubers, vegetables, fruits, livestock and poultry meat, fish and shrimp, eggs, milk and dairy products, legumes and their products/nuts and others energy, and nutrients including protein, fat, carbohydrate, calcium, iron, zinc, selenium, vitamin A, vitamin B 1, vitamin B 2, vitamin C and dietary fiber were evaluated. Results: The qualified rate of all kinds of food for students lunch from high to low were 96.8% (116.4 g) of livestock and poultry meat, 92.3% (179.5 g) of cereal and potato, 65.0% (170.6 g) of vegetables, 47.7% (21.4 g) of soybeans and their products/nuts, 33.4% (18.0 g) of eggs, 14.4% (8.5 g) of fish and shrimp, 14.1% (19.6 g) of fruits, 0.3% (35.4 g) of milk and dairy products. There were significant differences in the qualified rate of various food intake among different grades( P <0.05). The qualified rate of students lunch energy was 76.9%(932.6 kcal). The qualified rates of various nutrients from high to low were iron 96.9%(9.7 mg), zinc 96.8%(5.9 mg), protein 96.4%(43.8 g), carbohydrate 87.6%(130.8 g) and selenium 82.9%(23.5 μg), vitamin C 78.5%(48.8 mg), vitamin B 1 75.9%(0.5 mg), fat 74.3%(28.5 g), vitamin A 74.1%(327.1 μ g) vitamin B 2 49.9%(0.5 mg), dietary fiber 19.5%(5.9 g) and calcium 13.4%(246.1 mg). There were significant differences in the qualified rates of energy and nutrients among different grades( P <0.05). Conclusion The digital platform basically meets school lunch requirments on food types and nutrients, but still with problems regarding insufficient fish and shrimp, fruits, milk and dairy products, vitamin B 2, dietary fiber and calcium. It is suggested to optimize school lunch recipes or increase corresponding nutrients content in other meals.