Xác định tỷ lệ cận thị, một số yếu liên quan và hiệu quả truyền thông giáo dục sức khỏe ở học sinh trung học cơ sở thị xã hoàng mai, tỉnh nghệ an (2019 2020) TT TIENG ANH

1 STRUCTURE OF THESIS The thesis has 127 pages, including: pages of Introduction; 33 pages of Overview; 25 pages of Research object and method; 31 pages of Research findings; 21 pages of Discussion; page of Petition The thesis has 14 figures, 39 tables, appendixes There are 152 references, in which there are 36 Vietnamese references and 116 English references and more than 50% reference are prepared for recent years NEW CONTRIBUTIONS AND SCIENTIFIC MEANINGS, ACTUAL MEANINGS OF THESIS It is the first study and researches the myopia situation in Hoang Mai Town in the large scope The research place is the rural area where the urbanization process is happening The study provides evidences on myopia prevalence, myopia tendency according to classes and factors associated with myopia among secondary school students in Hoang Mai Town This is a study with data that estimate the time for indoor and outdoor activities, and also near seeing behavior and the first continuous near seeing time without eye resting time collected sufficiently in questionnaire for high school students Although, it is difficult to avoid errors in data collected thorough questionnaire, this is evidence with scientific value as the basis of analyzing and learning about factors associated with myopic students Based on related factors founded in the study, we can propose the intervention methods and strategies for school myopia prevention The study finds out the roles of outdoor activities which are able to prevent from myopia among secondary school students INTRODUCTION The prevalence of myopia is increasing more and more and it is considered as a big matter for public health over the world Untreated myopia is the leading reason which leads to vision impairment for children and it has extremely big impacts on education, life quality and social economy Because of early starting time and progressing properties of myopia during the studying process, children have many risks of developing complications leading to permanent vision impairment [1] [2], [3] The rate of short-sighted people changes depending on regions in the world, the rate of short-sighted people is high in Asia and low in Africa [2] The reasons of myopia is currently unclear [8], [9] The studies show that the children with short-sighted parents are easier to be short-sighted [8], [10] On the other hand, the prevalence of myopia increases fast in countries with intensive education system and high competition, which shows the impacts of environmental factors, such as: increase of nearsighting works time, lack of activities contacting with outdoor light, socio-economic factors and urbanization process [11], [12], [13] In Vietnam, for recent years, there are many studies on current situation of myopia among secondary school students [7], [14], [15] in order to discover nearsighted children to correct glasses and to propose several community prevention solutions as health education, ensuring school sanitation conditions, in order to change the eye caring behavior and than help to lower the prevalence of myopia [14], [16], [17] Hoang Mai Town belongs to Nghe An Province, lies in the coastal delta Its economic conditions are mainly agriculture and fishery For recent years, the urbanization process in this area also happens dramatically Although the school myopia is also the attention in the locality, there is no study on this matter in Hoang Mai Town to answer the questions, such as: What is the rate of nearsighted students in secondary schools? What factors are associated with myopia? What prevention methods can prevent from myopia for secondary school students? Because of urgency of school myopia in Hoang Mai Town, we conduct the study: Identification of prevalence of myopia and factors associated with it and health education among secondary school students in Hoang Mai Town, Nghe An Province (2019 – 2020) With following objectives: Identification of prevalence of myopia and several factors associated with it among secondary school students in Hoang Mai Town, Nghe An Province in 2019 Evaluation of health education communication intervention effects in behavior change for prevalence of newly detected cases of myopia and myopia progression (2019 – 2020) Chapter 1: OVERVIEW 1.1.Several concepts and myopia classification Myopia is the current situation of myopia in people who can see near things, but they cannot see clearly far things Based on optical characteristics of eye, myopia is defined as refractive error when the light rays from infinity go into eyes parallel to optical axis of eyeball and the image of thing falls before retina in the condition of unregulated eyes (illustrated in Figure 1.1) This phenomenon can caused by excessive refraction of cornea, crystalline lens or by eyeball axis longer than normal eyeball axis from front to back, or by combination of two factors [23], [24] In the epidemiological study, the myopia is defined as condition when the spherical degree is equivalent to ≤ - 0.50 D after the either eye is paralyzed to regulate [25] Spherical equivalent (SE) is calculated by total spherical capacity + ½ pillar capacity Retina Light beam Figure1.1 Optical diagram of myopic eye [23] Classification of myopia: Myopia is divided into two degrees: low myopia is the condition when SE is ≤ -0.50D or >-3.00 D and moderate myopia is the condition when SE is from -3D to -6D and high myopia is when SE < -6D after the either eye is paralyzed to regulate [23] 1.1.1 Prevalence of myopia in the world and in Vietnam - Prevalence of myopia in the world Many studies based on population show that the prevalence of myopia and high myopia is growing rapidly, especially in urban area of East Asian countries [3] The systematic study of Rudnicka (2016) shows that the prevalence of myopia among East Asian people is the highest, occupying about 69% (95% CI; 61%-77%) for 15 aged children The prevalence of myopia among South Asian people, colored people in Africa has the tendency of prevalence lower than South East Asian people and white people, but it is still significantly lower than East Asian people Meanwhile, for similar age, the colored people in Africa has the lowest prevalence of myopia 5,5% (95% CI; 3%-9%) [27] The data from study on prevalence of myopia and high myopia over the world shows that in 2010, there are about 28.3% myopic people and 4.0% people suffering high myopia It is estimated that in 2050, the prevalence of myopia will increase up to 50% and high myopia will increase to 10% over global population (Chart 1.1) [4] - Prevalence of myopia in Vietnam Vietnam is one of rapidly urbanized countries, which have impacts on health index Myopia is also known as consequence of impacts caused by environmental factors The prevalence of myopia is rapidly growing in rural and urban areas [42] The research results of myopia among students in big cities show that: in Ho Chi Minh City, the author Le Thi Thanh Xuyen (2009) and et al studied the students in Secondary Schools and High Schools, it showed that the prevalence of myopia is 38.9% [43] In Hanoi, the study conducted by Vu Thi Thanh and et al in 2009 showed that the general prevalence of myopia among Primary School students and Secondary School students are 33.7%, in which the prevalence of myopia in urban areas is up to 40.0% [15] The prevalence of myopia shows the increasing tendency chronologically In 2014, the study of Paudel showed that the prevalence of myopia among secondary school students in Ba Ria – Vung Tau Province was 20.4%, in which the prevalence of myopia among students in urban area was 27.5% and in rural area it was 16.3% [7] In addition, the increase of prevalence of myopia among students is also known as related to age, or on the other hand, the prevalence of myopia among students in higher classes is higher The study in Hanoi (2006) conducted by the author Hoang Van Tien recorded the prevalence of myopia among students of class 3, class and class 10 are 32.2%, 40.6% and 58.5%, respectively [48] In Thai Nguyen, the author Vu Quang Dung, in 2007, also discovered that the prevalence of myopia among Secondary School students had the gradually increasing tendency according to class; for class it is 14.2%, for class 7, it is 12.4%, for class it is 19.9% and for class it is 20.6% [14] The study of Paudel in Ba Ria – Vung Tau had the similar results, the prevalence of myopia among Secondary School students increases 16.7% in class 6, 19.1% in class 7, 20.7% in class and 24.8% in class 9, respectively Recently, the study of author Tran Duc Nghia (2019) for Primary School students in Dien Bien Phu City also showed that the prevalence of myopia had the tendency of increasing gradually from 10.3% in class to 26.7% in class [17] 1.2 Myopia control methods Because the prevalence of myopia is growing over the world, especially in East Asia, there are big challenges in adjusting myopia and controlling pathological myopia Onset delay and progress limitation of myopia will reduce the prevalence of myopia and also high myopia among school-aged children 1.2.1 Education interventions and behavior and lifestyle changes The model of education intervention and behavior and lifestyle chance for myopia control among children has been presented in different epidemiological studies [87] The intervention models concentrate into education for changing behaviors associated with outdoor activities and near sighting activities Several studies on myopia among children with big sample size as: Study of myopia in Sudney, study of Orinda and cohort study on risk factors of myopia in Singapore [10], [88], [89] shows that increase of outdoor time is one of factor which held to prevent from myopia progression There are several clinical experimental studies which show that the increase of outdoor activities in break time in school can limit the onset and progression of myopia among students In 2015, Jin and et al have conducted an intervention study based on school for Primary School students and Secondary School students from to 14 ages who live in urban and rural areas of Northern China by adding 20 minutes into break time of school in mornings and afternoons, simultaneously in the break time, children are encouraged to play in yard Consequently, after year, the rate of children who suffer newly from myopia in intervention group decreases 4.8% in comparison with control group (3.7% compared with 8.5%, p = 0.048), SE change of intervention group is -0,10 ± 0,65 D/ year in comparison with control group -0,27 ± 0,52 D/ year, p=0,005 [90] Similarly, in the intervention test in Taiwan among Primary School students by increase of time of contacting with outdoor light at school in each day, the students are requested to participate into outdoor activities for 40 minutes per day in break time, teachers are supervisors Apart from school time, students are encouraged to increase the time of other outdoor activities The results evaluated after one supervision year show that the rate of people who suffer newly from myopia is 14.5% lower than in intervention group in comparison with control group 17.4%, p = 0.054 SE change in intervention group is 0.35D in comparison with -0.47D in control group, p=0,002 [70] 1.2.2 Rimmed spectacles Initially, the single rimmed spectacles are used to limit the progression of myopia in animal studies, the usage of spectacles lower than myopic degree causes the myopic-type retinal eccentricity and consequently it reduces the stimulus causing myopia progression However, in clinical tests on human, the spectacles with lower myopia degree have the opposite results, and make the myopia progression faster [92] 1.2.3 Contact spectacles Orthokeratology (Ortho-K): is a kind of air permanent contact lenses designed specially, worn overnight to re-shape the cornea and consequently it corrects temporarily the myopia from low to moderate degree Beside vision strengthening without spectacles in daytime, Ortho-K also controls the progression of myopia Ortho-K spectacles are known as effective in controlling myopia because of eyeball axis lengthening limit This result fluctuates from 32% to 63% in comparison with untreated group The overall treatment efficiency is about 50% [95] A recent study shows that the combination of contract spectacles Ortho-K and eyewash atropine with low concentration (0.01%) is more effective than delay of axis lengthening for more than 12 months in comparison with only treating by Ortho-K among myopic children It is necessary to have more studies to present whether this efficiency can be maintained in long time or not? [96] 1.2.4 Intervention by drug The pharmacological intervention to control myopia by atropine eyewash with high dose (concentration from 0.5% to 1.0%) is known as delay of myopic progression more than 70% among children – 13 ages within – years [98] But this intervention relates to side effects of drug, including mydriasis, dazzled eyes and burred eyes) [99], [100] The studies show if atropine with high dose (0,5% and 0,1%) is canceled to use for children during the treatment process, which will lead to fast recovery of myopia [101] However, it is remarkable that now Food and Drug Administration (FDA) still does not approve to use any pharmacologic agents in controlling myopia 1.4 Health communication – education on school myopia Health education in schools has significant impacts on establishing the healthy behaviors and lifestyles for students, because the period of school for each student is very long For everybody, the time of school is an important time with significant impacts on the whole process of progression, in terms of physical, spirit and personality, because it is a sensitive period, the students can acquire easily new knowledge and the sustainable attitudes and behaviors are formed in each human The health education’s contents in school create the best conditions for students to prevent from popular diseases in school, to discover and prevent from abnormal physical and physiological progressions, simultaneously to provide knowledge and to develop proper altitude in order to help each person able to select the most intelligent decision for protecting and improving their health and having healthy habits and lifestyles To educate and improve health for students, it is necessary to combine school, family and society [102], [103] Chapter 2: RESEARCH OBJECT AND METHOD 2.1 Identification of prevalence of myopia and several factors associated with it among Secondary School students in Hoang Mai Town, Nghe An Province in 2019 2.1.1 Research object - The object selected for study is: Secondary School students in the area of Hoang Mai Town These students have the age fluctuating from 12 to 15 ages, equivalent to class to class - Parents of students in the research group have the factors associated with myopia - Selection standard: Secondary School students participate voluntarily into study - Elimination standard: Students have any congenital defects or injuries associated with eyes previously 2.1.2 Research time and place 2.1.2.1 Research time The study identifies the prevalence of myopia and factors associated with it among Secondary School students and it was conducted in January 2019 2.1.2.2 Research place The study was conducted in Hoang Mai Town, Nghe An Province 2.1.3 Research method 2.1.3.1 Research design The cross-sectional descriptive study has an analysis to identify the rate and learn about several factors associated with myopia among Secondary School students 2.1.3.2 Sample size and research sample selection methods Sample size: The sample size for myopia situation identification study is calculated according to one percentage estimation formula based on population in refractive error study in children [115] as follows: 1−p n = Z1−α/2 𝐷𝐸 (1) εp2 In which: n is the minimal sample size which should be selected; p is the estimated myopia percentage 𝑍1−α/2 is the reliability factor ; 𝜀 is the relative accuracy; DE (design effect) is the design factor In this study, we select the estimated myopia percentage p = 16.8% according to previous research results in Thai Nguyen [14] If the reliability factor is 95%, 𝑍1−α/2=1,96, the selected relative accuracy is 𝜀 = 0,15, DE = Applying the formula (1), we will calculate the minimal sample size 1,691 students In reality, to prevent from sample losing, we examined 1,987 students The research sampling method: the sampling method in cross-sectional descriptive study is conducted in many periods and in combination with purposive sampling method and percentage cluster sampling method - School selection: The sample frame is Secondary School students in the area of Hoang Mai Commune provided by Department of Education and Training of Town In the list of sample frame, there are 10 Secondary Schools, total number of students in school year 2019 is 7,146 students From list of 10 Secondary Schools and High Schools in Hoang Mai Town, we select purposively 04 schools which have been recognized as National standard schools for Secondary School to put into study The selected schools include Quynh Xuan Secondary School, Quynh Phuong Secondary School, Quynh Thien Secondary School and Quynh Lap Secondary School All schools selected are the schools which ensure the conditions on class room, table and chair, blackboard, lights according to regulations on school medicine of Ministry of Health – Ministry of Education and Training [76] - Grade selection: The living conditions in the area of Hoang Mai Town are rather similar, thus in the study, we not stratify according to socio-economic condition (urban and rural areas) The study conducts the stratified sampling method according to grade on the principle of percentage sample Secondary School students include grades (from grade to grade 9) equivalent to selected layers The distributions of students according to each grade in each school is rather similar, thus the number of classes in each selected grade of each school is similar - Class selection: From each grade in research sample, we sample in random the classes of schools equivalent to proportion Classes in each grade are selected in the cluster sampling method, each class is considered as a cluster and the number of clusters is selected to have enough sample size According to minimal sample dimension calculated, we select in random 12 clusters of each grade (equivalent to 12 classes per grade) In each grade, there are to classes In each class, there are 40 students on average All students in each class are invited to participate If in a class, there are not enough 40 students, we select students from other classes in same floor, to ensure the medical ethics in research, for classes added students, we select all students in class to satisfy the requirements of sample size Based on results of cross-sectional descriptive study, we select purposively a small group of students in research object group to analyze and learn about the factors associated with myopia, the group selecting steps are as follows: - Selection of myopia group: Among myopic students who are examined and discovered in the cross-sectional descriptive study (282 myopic students), we select all students with enough information in the survey form as myopia group to analyze The number of students in myopia group is 265 students - Selection of non-myopia group: the students who are identified as non-myopic at the time of cross-sectional survey are selected to compare with students of myopia group at the proportion of myopia group and non-myopia group 1:2 Selecting students in myopia group and non-myopia group according to similar standards in terms of age (same class), sex (same sex), living place (close living places) 2.1.4 Research contents The cross-sectional descriptive study is conducted to identify the prevalence of myopia among Secondary School students belonging to grade – grade (ages from 12 – 15) in the area of Hoang Mai Commune, Nghe An Province To learn about several factors associated with myopia, we conduct a cross-sectional descriptive study with analysis The factors associated with myopia among students are assumed in the study 2.2 Research object, method of target Evaluating the communication effects of health education, limiting the prevalence of newly detected cases of myopia and myopia progression 2.2.1 Research object and place - The objects were selected to put into intervention study: students are studying in grades and 8, parents of students, management boards of Secondary Schools, teachers in charge, medical officers in the intervention schools - Selection standard: the students agreed to participate into study These students had not been educated about myopia prevention - Elimination standard: the myopic students were using atropine drug or wear Orthokeratology spectacles to limit the myopia progression Reasons of selecting students of class and class 8: the intervention study was conducted after cross-sectional descriptive study with combination of analysis (January 2019), the intervention study was deployed within year To deploy and monitor the research process continuously, the period of intervention period was conducted at the beginning of school year from September 2019 Therefore, the students of grade who began studying in school and the students of grade who were transferred to High School will be eliminated from out study to prevent from loss of monitored information 2.2.2 Research time The intervention was conducted from September 2019 to October 2020 2.2.3 Research method 2.2.3.1 Research design The research design of community intervention with longitudinal supervision was applied with control group The intervention applied for research was the preventive intervention of newly detected students of myopia and limit of myopia progression in myopia group Both myopic non-myopic students were put into intervention group with comparison with control group The intervention contents for myopic and non-myopic students were similar By designing this intervention study, the following questions and research suppositions were mentioned: - Was the proportion of newly myopic students accumulated in the intervention group different from control group after intervention? - Was myopia progression degree (SE difference) among myopic objects of control group different from myopic objects of control group after intervention? 2.2.3.2 Sample size and research sample selecting method Sample size: For intervention study, the sample size will be estimated according to formula of sample size calculation to have two percentages: 𝑛 = 𝑍 ( ,  ) [p (1 − p ) + p (1 − p )] (p − p )2 (2) In which: n is the minimal sample size for a intervention or control group p1 myopia prevalence of intervention group after intervention is estimated as 15% p2 myopia prevalence of control group after intervention is estimated as 25% p1-p2 is the difference on myopia prevalence between intervention group and control group that the researcher wants to extrapolate to population In this case, the researcher can calculate based on difference between p1 and p2 Z2(α, β) is the value Z referred to table with value α selected = 0,05 and β selected =0,20 Applying the formula (2), we calculated the minimal sample size for each intervention group or control group as 247 students We estimated more 15% students refusing to answer and lost supervision, the minimal sample size for each group was 286 students In reality, before intervention, there were totally 340 students selected into control group and 300 students selected into intervention group Sampling method for research period of intervention: The intervention group and control group were selected purposively, Selecting in random classes of schools The classes in each grade were selected according to cluster selecting method, each class was considered as a cluster and the number of clusters was selected to have enough samples According to minimal sample size calculated, cluster were selected in random in each class (equivalent to classes per grade), it means that in each school, we only selected classes in each grade All students in each class were registered into study At the end of intervention period in September 2020, the students researched were students in grade and grade 9, respectively 2.2.4 Research content The intervention study was conducted in Quynh Thien Secondary School and Quynh Lap Secondary School in the area of Hoang Mai Town The principle of intervention was making impacts on community on the basis of school with participation of community The intervention study was deployed after there were the results from analyzing and learning about factors associated with myopia The communication intervention solutions were health education, behavior changes of students with target of delaying newly detected cases of myopia and myopia progression The contents of intervention methods were deployed through periods: - Improving capabilities of teachers - Surveying before intervention in intervention schools and control schools (including myopia group and non-myopia group) - Communicating health education, providing basic knowledge on myopia prevention for students of intervention schools - Surveying after intervention to identify the prevalence of new cases of myopia and myopia progression degree, to change knowledge and to practice for students During the summer holiday, the students born the supervision and management of families, the intervention only had indirect impacts through communication activities for students’ parents previously, while the students of non-intervention schools still studied the former programs 2.4 Errors and error limitation For random error: selecting enough sample size and force of sample For systematic error: designing the questionnaire that was clear, easy to understand and easy to answer The officials who examined and interviewed were trained carefully and unified the data collection method Do not change any officials who collect main information Data were prepared well before analyzing 2.5 Data collection, analysis and processing methods Data are collected by software EpiData software 3.1 Using software STATA 14.0 to analyze and process data - The cross-sectional descriptive study: using the statistical description as: frequency, percentage % for describing the qualitative variables, average value, standard deviation done to describe the quantitative variables For qualitative variables, the difference between two or more percentages verified by test χ2 The difference between quantitative variables was verified by method t-tests for variables with normal distribution 2.6 Ethics in researching The thesis has been approved by Council of Ethics in biomedical study of National Institute of Malariology, Parasitology and Entomology and agreed by Department of Education and Training of Nghe An Province, Education Office of Hoang Mai Commune and Management Boards of Secondary Schools in the research group Chapter 3: RESEARCH FINDINGS 3.1 Situation of myopia among Secondary School students Table 3.3 Distribution of myopia prevalence among students in schools and general myopia School Research objects Myopic students Number Percentage (%) Quỳnh Thiện 472 101 21,4 Quỳnh Phương 667 107 16,0 Quỳnh Xuân 491 42 8,6 Quỳnh Lập 357 32 9,0 1.987 282 14,2 Total The findings from data show that in total 1987 students participating into study, 282 myopic students were discovered The prevalence of myopia was 14.2% Table 3.4 Distribution of myopia prevalence in class among research objects Class Research objects Myopic students Value p Number Percentage (%) 514 54 10,5 < 0,01 507 60 11,8 485 83 17,1 481 85 17,7 The prevalence of myopia is 10.5% in class student group, 11.8% in class student group, 17.1% in class student group and 17.7% in class student group, respectively The prevalence of myopia among Secondary School students of classes in the study are different; this difference had the statistical meaning, p < 0.01 10 Class (age) Class (12) Class (13) Class (14) Class (15) Figure 3.1 Prevalence of myopia according to sex, class For students of class and class 9, the prevalence of myopia was 1.7 times as high as students of class (CI 95% = 1,2–2,5) and 1.8 times (CI 95% = 1,2–2,6) Table 3.5 Distribution of myopia prevalence according to sex in research object Sex Research objects Myopia Value p Number Percentage % Male 1000 117 11,7 p