| Objective:Visual impairment(VI)is one of the most serious public health and socioeconomic problems worldly.Good vision is critical to school age students.Therefore,the problem of VI of adolescents is a problem that needs to be concerned all over the world.According to WHO,There are about 19 million children with VI,of which 12 million are caused by ametropia which is easier to diagnose and treat.Vision is a certain reversible,active and effective in adolescents,and intervention can prevent the occurrence and development of VI.Therefore,it is necessary to take measures to effectively interfere with the sight of young people to alleviate their harm,and to understand the risk factors of adolescent VI,to explore the mechanism of its impact mechanism is to carry out targeted intervention necessary conditions and basic protection.This study will address the following questions:(1)To explore the risk factors for VI in adolescents using the latent variable analysis.(2)To analyze the mechanism of BMI on VI by mediator effect analysis.(3)To evaluate the effect of adolescent vision prevention and treatment interventions,to explore the differences,trends and characteristics of intervening effects of potential different types of people,and to provide the basis for the later development of individualized intervention programs.Methods:(1)Using the stratified random cluster sampling,24 primary and middle school students in Huangpi District of Wuhan were randomly selected,and the structured quantitative questionnaires were compiled to understand the relevant factors of students' vision,including general situation(such as age,sex,height,weight,eye history,eye health habits,eye time and life,eye care,other learning hobbies),family factors(such as poor family history,family reading lighting environment,parental care(such as the level of knowledge of parents' learning pressure on their children)and school factors(such as daily student class time,get out of class or inter-class breaks for quizzes or examinations,daily physical activity and extracurricular activities,daily school eye exercises,etc.);through the visual inspection of each student's uncorrected visual acuity and daily life vision,the basic information and the data related to VI were collected;We used Epidata3.1 software to establish the original database.Statistical analysis was performed using EmpowerStates and R software(http://www.R-project.org),with P<0.05 as statistically significant.The distribution of variables is described by mean ± SD and median.Orthogonal distribution variables were analyzed by one-way ANOVA and multi-group chi-square test.Nonparametric analysis was used to analyze non-normal distribution variables.The logistic regression model was used to screen the relevant risk factors of VI.(2)In order to understand the specific mechanism of BMI on VI,we used the method of latent variable analysis to explore the mechanism of action by using mediation effect analysis.The adolescents were classified by the potential category analysis of the mixed model.Potential population BMI acted on the direct effect of VI and the size of the indirect effect,with a view to the late targeted for different groups of people to develop targeted plans and measures.Analysis of the results for the prevention and treatment of adolescents to provide scientific evidence can be used to guide the implementation of interventions,and ultimately achieve effective improvement of the status of our young people vision.Statistical analysis was performed using Mplus 7.4.Statistical analysis of the data included mixed model analysis,latent class analysis and mediator effect analysis.(3)This study explored and validated the factors influencing the effect of adolescent vision intervention by structural equation model.A total of 24 schools in the Huangpi district of Wuhan were investigated by questionnaire,and the questionnaire was conducted before and after the intervention to understand the general situation of the students which included the use of eye-related habits,the use of eye behavior,and the effect of intervention.To analysis potential changes of adolescents' eye habits and behavor before and after the intervention and analysis the specific characteristics of the better ones.Results:(1)This study focused on the three main factors affecting the VI:BMI,outdoor activities every day and daily operating time.The incidence of VI increased with the increase of students' grade(the incidence of high school students was higher than that of junior high school students and junior high school students was higher than that of primary school students(P<0.001)).There was still a dose-response curve relationship between BMI and VI after adjusting the respective confounding factors:the risk of VI increased with BMI when BMI reached the inflection point(BMI = 19.8 kg/m2).However,when BMI was higher than 19.81 kg/m2,the VI increased with the increase of BMI(? = 1.20,95%).The relationship between the risk of the VI and the time of the outdoor activity was basically a straight line after the outdoor activity time reaches the inflection point(outdoor activity time = 2.40h/d).When the outdoor activity time<2.40h/d,the incidence of VI decreased with the increase of outdoor activity time(correlation coefficient ? = 0.06,95%CI:0.05,0.08);that is,when the outdoor activity time per day<2.40h/d,the risk of VI was reduced by 94%for every 1 hour of outdoor activity.According to the multiple regression analysis,the results showed that the longer the homework time every day,the higher the risk of VI,when the time of operation every day more than 2 hours,the risk of VI increased 60%(OR = 1.60,95%CI = 1.22,2.12;P = 0.0008).(2)BMI affected VI through outdoor activities.In primary school students,BMI and outdoor activity were negatively correlated with VI;The effect of BMI on VI was 89.54%in the loss weight population,and the effect of BMI on VI was only 9.91%in the obese ones through the role of outdoor activities.In the junior and high school students,BMI and VI were positively correlated and outdoor activity time was negatively correlated with VI of normal weight students;BMI effect on VI was 41.77%due to the role of outdoor activity time.The outdoor activities time have a protective effect for eyes'protection.(3)Intervention groups were divided into four subcategories by eye habit:the first group of people had 1656 people(29.93%),which showed no change before and after the intervention,and the performance was poor;the second category was 1602(28.95%).This class of students was poor before the intervention,with the eye habits becoming better after the intervention;the third category was only 10 people.They performed well before the intervention,but badly after the intervention;the fourth category of 2265 people(40.94%),thses ones were very good and very stable before and after the intervention.The trend of change with eye behavior before and after the intervention can also be divided into four groups:the first class of people had 1874(33.87%)students,they are good before and after the intervention;the second category was 1784(32.24%),poor performance before intervention,significantly improved after intervention;the third category was 303(5.48%),poor performance before intervention,significantly improved after intervention;the fourth class of 1572 students(28.41%),the intervention did not affect the behavior of these people,before and after the performance of poor.Grade and age were inversely proportional to the effect of intervention,the younger the age,the higher the chance of changing,the less the effect of intervention,the basic intervention before and after no change;primary school students intervention effect was better than middle school students;ordinary school students intervention effect was better than the students in key schools;the city was better than the rural students;the students did not participate in the remedial classes on weekend were better;overweight and obese student' intervention effect was worse than normal weight students;annual interventions were at least 2-3 times,and the comprehensive intervention effect was better.Conclusion:(1)BMI was closely related to the occurrence of VI.When BMI was greater than 19.81 kg/m2,there was a non-linear dose-response relationship.Outdoor activity time was a vision protection factor.After the influence of the mixed factors,there was a curve relationship between the length of the outdoor activities per day and the existence of between the VI.When the outdoor activity time is<2.40h/d,the risk of VI was reduced by 94%for every 1 hour of outdoor activity.Primary and secondary school students did homework every day and the occurrence of visual impairment was negatively related,if the time of operation every day more than 2h,the risk of visual impairment would increase by 60%.(2)In this study,we first explored the mechanism of BMI acting on VI by LVMM.The results showed that the mechanism of BMI affecting the role of VI was through the outdoor activities of the intermediary effect,and the BMI level was different from the school level of different students.The size of the intermediary effect was inconsistent,and the higher the BMI the role of its intermediary effect was smaller.The LVMM mediator effect analysis can deeply analyze the internal mechanism between the independent variables and the dependent variables,and consider the differences among different potential populations,which have strong theoretical and practical significance for analyzing the internal causality between certain variables.(3)For the first time,the LTA model was used to evaluate the characteristics of the dynamic evolution of adolescent vision prevention and intervention,and the factors influencing the effect of intervention were analyzed.The LTA is well suited to analyze the changes in individuals,which can help to analyze which potential categories of people will have a greater probability of change as the intervention progresses;and what can be predicted by the characteristics of the population with significant changes in intervention.These may help us to provide targeted interventions for potential populations with these characteristics,thereby increasing the effectiveness of the intervention. |
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