MINISTRY OF EDUCATION AND TRAINING THAI NGUYEN UNIVERSITY - VU QUANG DUNG STUDYING THE SCHOOL MYOPIA STATUS AND PREVENTIVE INTERVENTIONS FOR SECONDARY STUDENTS IN MIDLAND REGIONS OF THAI NGUYEN PROVINCE Speciality: Sociological Hygiene and Health Organization Code number: 62.72.01.64 PHD THESIS SUMMARY THAI NGUYEN, 2013 The work was completed in College of Medicine and Pharmacy - ThaiNguyen University Scientific supervisor: Assoc Prof Dr Hoang Thi Phuc Prof Dr Do Van Ham Defender 1: Defender 2: Defender 3: The thesis will be defended at the National level by the Board of examiners in College of Medicine and Pharmacy - Thainguyen University in September 2013 Thesis can be found at: National Library Resource Center ThaiNguyen University Library of ThaiNguyen College of Medicine and Pharmacy LIST OF PUBLISHED PAPERS RELATED TO THESIS Vu Quang Dung, Do Van Ham, Mai Quoc Tung, Vu Thi Kim Lien, Do Thi Yen, Nguyen Manh Hung (2008), "Studying the status of school sanitation in two junior schools in Thai Nguyen", the third International Scientific Conference of Occupational Health and Sanitation, Hanoi, pp 279-286 Vu Quang Dung, Do Van Ham, Mai Quoc Tung, Vu Thi Kim Lien, Dang Thi Tam, Nguyen Manh Hung (2008), "Initial studying on myopia in junior students in Thai Nguyen", the third International Scientific Conference of Occupational Health and Sanitation, Hanoi, pp 287-296 Vu Quang Dung, Do Van Ham, Mai Quoc Tung, Vu Thi Kim Lien, Do Thi Yen, Nguyen Manh Hung (2008), "Studying the status of school sanitation in two junior schools in Thai Nguyen", The seventh National Occupational conferences, Medical Publishing, Hanoi, pp 70 Vu Quang Dung, Do Van Ham, Mai Quoc Tung, Vu Thi Kim Lien, Dang Thi Tam, Nguyen Manh Hung (2008), "Initial studying on myopia in junior students in Thai Nguyen", The report summarizes scientific, scientific conferences nationwide Occupational Health Seventh, Medical Publishing, Hanoi, pp 71 Vu Quang Dung, Do Van Ham, Mai Quoc Tung, Vu Thi Kim Lien, Nguyen Manh Hung, Do Thu Trang (2008), "The studying of refractive errors in school students in Thai Nguyen province", in the National Ophthalmology Conference, Ho Chi Minh City, pp Vu Quang Dung (2008), "The studying on functional tests and the correlation with refractive school students in Thai Nguyen," Vietnam Journal of Medicine, 351 (2), pp 338-344 BACKGROUND School myopia is increasing in many countries around the world as well as in Vietnam According to Kovin Naidoo (ICEE International Center for Eye Care Education), in 2020, the refraction and glasses account for 70% of the global population (5.3 billion people) In which myopia is 33% (3 billion people) Currently, Asia has the highest incidence of school myopia in the world In China (2006), there are more than 300 million people with myopia A study in India (2003) showed that 13% of blindness and 56% of people had visual impairment due to myopia Thus, the program "Vision 2020" the World Health Organization ranked school myopia is one of the five causes of blindness in the prevention programs worldwide According to the investigation of many researchers recently, myopia is increasing rapidly and it is the main cause of vision loss in Vietnam and other regional countries In Ho Chi Minh City (2006), published by Le Thi Thanh Xuyen showed the percentage of myopia students increased alarmingly The rate of myopia was 8.65% in 1994 up to 17.2% in 2002 and 38.88% in 2006 According to a research by the Institute of Educational Sciences of Vietnam (2008), the prevalence of school myopia was high with an average of 26.14% of the total student’s population There have been many studies on school myopia so far in both cities and rural areas in many provinces around the country However, there are no in-depth studies of school myopia in the Midland regions of the Northern Mountains Based on the existent situation and concern for school myopia prevention, this study is undertaken with the aims: To describe the situation and identify a number of risk factors for school myopia in secondary schools in midland regions of Thai Nguyen province in 2006 To assess the effectiveness of preventive interventions for school myopia for years (2006-2008) CONTRIBUTIONS OF THE THESIS Its is the opening study about myopia status and preventive measurements in secondary school in Midlands of Thai Nguyen and the Northern Mountainous region The study has built an intervention model: Combination of community and clinical interventions are effective, practical benefits and feasible It can be widely applied to midland and mountainous region The study has identified a number of risk factors which associated with school myopia that other authors have not mentioned in Vietnam such as an association between myopia and light intensity in each location of the classroom; the relationship between myopia and suitable and unsuitable furniture size; relationship between myopia with outdoor playing time and myopia with family history The study implemented solutions which combined health education and treatment intervention for preventing school myopia These interventions are feasible and are accepted by the community THESIS STRUCTURE The thesis contents 121 pages, including the following parts: Introduction: pages Chapter - Overview: 31 pages Chapter - Subjects and Methods: 18 pages Chapter - Research results: 39 pages Chapter - Discussions: 28 pages Conclusions and Recommendations: pages The list of published articles: page And 148 references, including 66 Vietnamese and 82 English The thesis has 41 tables and charts and diagrams The appendix includes appendixes in 37 pages Chapter OVERVIEW 1.1 Status of school myopia recently 1.1.1 The concept School myopia (nearsightedness) is acquired in school ages Degree of myopia ≤ - 6.00D Myopia is caused by the asymmetric axial length and the eye's optical power that makes light come in front of the retina The eyeball axial length and focusing power increase lightly and often has no pathological lesions (retinal degeneration, cornea, sphere lens…) Evaluation school myopia: there are various methods of determining the school myopia: subjective test (Dondes), retinoscope and autorefractor This study uses autorefractor: Eyes are regarded as myopic when measured by the autorefractor after reducing accommodation is ≥ - 0.50 D 1.1.2 Status of the current school myopia Issue on school myopia has studied only around 70 years of the nineteenth century Earlier, myopia was considered a genetic disease and malignant progression, therefore myopia was considered a disease without prevention and treatment The World Health Organization estimates that there are 2.3 billion people have refractive errors nowadays In which myopia is the first reason for vision loss and blindness (greater times than the blindness caused by cataracts) In Vietnam, school myopia is a public health concern because of a large number of people has myopia which affected their learning, quality of life and social economical development Approximately 15% to 20% of students in urban schools have myopia and even it is higher in some big cities A research in 16 schools in 2008 in Thai Nguyen showed that the rate of myopia accounted for 73.09% of total refractive error The prevalence of school refractive in the city is 16.48% and 6.11% in rural areas 1.2 The risk factors of school myopia There have been many studies on the risk factors leading to school myopia Factors can be classified into risk groups as follows: - The risk factor of family characteristics, congenital and hereditary: family history has people with myopia - The risk factor of school sanitation and hygiene practices: lack of lighting, over or under size of tables and chairs, incorrect practices in learning hygiene - The risk factors of near vision prolongation: high-intensity learning, learning pressure, playing game, less time for far looking, less outdoor activities and limited vision - The risk factor of school myopia prevention is not good enough: the awareness of eye care in schools is not enough attention, the quality of medical activities is insufficient, most students not have routine eye exam, week cooperation between sectors and levels of work-related health care for students - Some other risk factors: lack of sleep, nutrition, ethnic groups and educational level The lack of understanding of myopia, risk factors and preventions is also an important factor contributing to the increased incidence and severity degree of myopia 1.3 Some solutions to prevent myopia school There have been many studies and prevention measures for school myopia in the world and Vietnam There are three stages in intervention to prevent school myopia; however, in most localities in our country only implements Phase Currently, Vietnamese eye institute actively deploys interventional activities in Phase Many provinces have actively implement school myopia preventive activities such as Hanoi, Ho Chi Minh City, Hai Phong, Nam Dinh, Ninh Binh, Thai Nguyen, Hue, Da Nang, Ha Tinh These activities has received support and facilitate of the ministries and society Many local and international organizations have supported for school myopia prevention and intervention by positive activities such as Rang Dong Corporation (RALACO), the Vietnam Urban Lighting , the Vietnam education and health care communities, school equipment companies in Vietnam, Project Management of Public Lighting in Vietnam (VEEPL), the World Health Organization (WHO ), the Organization for International Prevention of Blindness (IAPB), the UN Children's Fund (UNICEF), Christoffel Blindenmission Organization (CBM), the Atlantic Philanthropies (AP), the Fred Hollows Foundation (FHF), The First Sight, ORBIS International (OI) Chapter 2: SUBJECTS AND METHODS 2.1 Subjects Secondary students in Midlands region of Thai Nguyen, parents, secondary school administrators, head teachers, school health personnel, facilities and sanitary conditions of school: tables, chairs, light 2.2 Time and place of study - Study period: from 11/2006 to 12/2008 - Location of research: the study was conducted in four schools in the midland regions of Thai Nguyen province including: Phu Xa, Tan Thanh, Quyet Thang, Hoa Thuong secondary schools 2.3 Research methodology 2.3.1 Study Design: Using types of research design as follows: - Descriptive studies, cross-sectional design to determine the rate of school myopia - Case-control study to identify a number of risk factors for myopia in secondary school students - Intervention study with community and clinical intervention 2.3.2 Sample size and sampling technique * Sample size for the descriptive studies: n = Z (1 − α / ) p (1 − p ) (ε p ) The sample size was calculated at 95% confidence level, the relative accuracy ε = 0.1 and p = 17.42% n = 1,822, in fact, this study was conducted on 1.873 students On average, each secondary school in Thai Nguyen province of has about 450 students, therefore the number of schools should investigate are schools The schools are selected in a random method Results of the random selection are: Tan Thanh, Phu Xa, Quyet Thang, Hoa Thuong * Sample size for case-control studies: - Sample size: n = Z (α / ) {1/[P (1 − P )]+ 1/[P (1 − P )]} ∗ ∗ * 2 ∗ [In(1 − ε )] The sample size is calculated based on the percentage of students with low bowed head when learning It is estimated for the control group 20% and OR = with the expected accuracy of the OR was 0.35 As the sample size for each group are 223 students, rounded to 240 students Select the ratio of case/control is 1/2 Thus the sample size for case groups are 240 students and the control group are 480 students The case group inncludes students identified as myopic from -0.50 D to ≤6.00D as measured by autorefractor after dropping cyclogyl Using single randomized method selects 240 students from the list of myopia students of descriptive study Control group includes students with normal health status; emmetropia, similar to the case group on age, sex, school and class grade following the rate: case and controls * Sample size for the study intervention: - Sample size: n = ( Z 1−α / + Z 1− β ) ( p1 q1 + p q ) ( p1 − p ) The sample size is calculated based on the estimated the ratio of myopia 17.42% and desire to reduce to 7.5% with α = 0.05, β = 0.2 The sample size for each group are 173 students Due to the intervention study is conducted in years, to ensure that studied subjects are continually monitored, this study is conducted on students grade and of the secondary schools, then randomly assigned schools in the intervention group and schools in the control group by lottery method, the results are as follows: - Intervention group (community intervention): students grade and of Tan Thanh secondary school - Interventions group (community combined treatment intervention): students grade and of Phu Xa secondary school - Control group: students grade and of Quyet Thang and Hoa Thuong secondary school As student’s grade and of those schools are more than calculated sample size therefore all students were selected in the sample 2.3.3 Content intervention 2.3.3.1 Intervention 1: Community intervention - Forming the working group of myopia prevention in the interventional schools - Communicating information on school myopia, myopia prevention measures for students, parents and teachers - Fixing Ergonomics: discussing how to fix, set up the standard of furniture, lighting, chalk board Mobilizing the contribution of parents to ensure hygiene in learning - Medical intervention: the head of schools together with leaders of the local to strengthen and promote the school health department and local health services for early detection of school myopia 2.3.3.1 Intervention 2: Community and clinical interventions Conclude the intervention following measures: - Wearing glasses: guiding myopia students used correct glasses and appropriate time to wear (wearing glasses when looking up the chalk board, while traveling; put off glass when using near eyesight) - Medications: + Reduce accommodation: using Cyclogyl 1% or Cyclopentolat eye drops once a day at bedtime + Using drugs to prevent the progression of myopia: using 4-6 bilberry tablets (cranberry extract and vitamin E) per day, 15 days per month for years + Using eye drops to reduce accommodation: solution Correctol 2% x times daily - Guiding the parents and students added vitamin A from foods in their diet daily 2.3.4 The study variables * Status of school myopia: - The rate of myopia by school, grade (grade 6,7,8,9), by gender - Percentage of students with visual impairment in levels: reduced, decreased or blind - Percentage of students with mild, moderate and severe myopia - Percentage of myopia in one or two eye - Percentage of students already had glasses before investigated and the incident of myopia * Risk factors for schools myopia: - Classrooms’ sanitation: lighting system, lighting intensity, chalk board size and the size of tables and chairs - The relationship between light intensity with school myopia - The relationship between the size of chairs and school myopia - The relationship between learning posture and school myopia - The relationship between the home learning place and school myopia - The relationship between the intensity of class learning and home learning and school myopia Chapter FINDINGS 3.1 The situation of school myopia in secondary school in Midlands region of Thai Nguyen province Table 3.3 The rate of school myopia in schools % p School No students No myopia students Phu Xa secondary school 573 95 16.6 Tan Thanh secondary school 441 84 19.1 >0.05 Quyet Thang secondary school 371 51 13.8 Hoa Thuong secondary school 488 85 17.4 Total 1.873 315 16.8 Comment: There was no significant difference in the ratio of myopia among investigated schools (p> 0,05) School myopia rate was 16.8% on average Table 3.4 The rate of school myopia following class grade Class grade Number students Number myopia % investigated students Grade 457 65 14.2 Grade 468 58 12.4 Grade 467 93 19.9 Grade 481 99 20.6 p (test χ ) 7/10 Nearly 30% of myopia students had decreased highly visual acuity (CF3m - 3/10), especially, there were myopia students (1.9%) considered to be blinded as the visual acuity classification of World Health Organization 11 3.2 Risk factors for school myopia in secondary students 3.2.1 Classrooms’ sanitation Table 3.11 Average light illumination in the secondary schools (Lux) Quyet Hoa Thuong Average Phu Xa Tan Thanh Thang Grade 190.78 ± 50.36 65.10 ±30.36 101.53 ±22.09 326.57±125.43 172.52±116.96 Grade 190.78±50.36 45.27 ±14.22 101.53±22.09 71.37 ±51.36 109.05±69.29 Grade 137.88 ±30.38 44.33 ±6.47 148.07±54.91 391.90±108.10 177.26±139.11 Grade 137.88±30.38 80.67±18.87 148.07±54.91 358.35±148.90 190.79±136.26 Average 164.33 ±46.15 58.84 ±22.91 124.80 ±43.18 292.53±164.26 162.94±119.93 Comment: The light illumination in classroom was the lowest in Tan Thanh secondary school and did not reached the standard (> 100lux) Other schools had standard of illumination, especially grades of Hoa Thuong Secondary School Table 3.12 Relationship between light illumination and school myopia Total OR Refractive status Myopia Emmetropia Light illumination (n=240) (n=480) (n=720) (CI95%) Under standard (100 lux) 117 346 463 (1.9-3.8) Total 240 480 720 Comment: There was an association between light illuminations at learning sitting and school myopia students Not enough light illumination in learning area was risk for school myopia 2.7 times myopia (%) Chart 3.2 Correlation between light intensity and school myopia Comment: There was a negative correlation between light intensity and school myopia (r = -0.66) The more light intensity increases, the less school myopia 12 Table 3.13 Effect of average height tables and chairs in the Secondary School (cm) Phu Tan Quyet Hoa Total Standard Xa Thanh Thang Thuong Grade 32.0±0.0 31.0±0.0 32.0±0.0 30.0±0.0 31.3±0.9 23 Grade 32.0±0.0 31.33±0.58 32.0±0.0 29.67±0.58 31.3±1.0 23 Grade 32.0±0.0 31.0±0.0 32.0±0.0 30.0±0.0 31.3±0.9 25 Grade 32.0±0.0 31.0±0.0 32.0±0.0 30.0±0.0 31.3±0.9 28 Total 32.0±0.0 31.0±0.43 32.0±0.0 29.69±0.85 31.2±1.1 Comment: Performance of tables and chairs between schools and classes grades were similar It is beyond the standard: high tables and low chairs Table 3.14 The correlation between the size of tables and chairs and school myopia Refractive Status Myopia OR Emmetropia Total Tables/chair size (n=240) (n=480) (n=720) (CI95%) Suitable 172 304 476 1.5 Unsuitable 68 176 244 (1.1-2.1) Total 240 480 720 Comment: Unsuitable tables and chairs was the risk factor for school myopia 1.5 times higher Table 3.15 The relationship between learning posture and school myopia Myopia Emmetropia Total Refractive Status OR Learning posture (n=240) (n=480) (n=720) (CI95%) Low bowed head (0.05 Table separate chair 158 65.8 366 76.3 0.05 Handmade 10 4.2 0.2 >0.05 Lightings Fluorescent Lamps 77 32.1 191 39.8 0.05 Table lamps 101 42.1 184 38.3 >0.05 Comment: Most of students had learning table and chair separate at home In myopia groups, table separate chair (65.8%) was lower than emmetropia group (76.3%) Especially, there were 6.3% of myopia students regularly learning on the bed Also, artificial lighting fluorescent lamps was lower in myopia group than emmetropia groups with p 100lux) Classrooms with the right 12 100.0 100.0 light regulations Classrooms hanged chalk board in standard 100.0 100.0 regulations Classrooms had tables and chairs to be repaired or 50 100.0 35 100.0 replaced Comment: 100% classrooms in interventional schools reached school sanitary standard after repairing or replacing of furniture, tables, and lights Table 3.29 Intervention results of using medicine and wearing glasses Clinical intervention n % Number of students using medicine 95 100.0 Number of students complying correctly guide 71 74.7 Number of students complying un correctly guide 19 20.0 Number of students withdrawing guide 05 5.3 Comment: Of those 95 students were attended clinical interventions, students withdrawn from the trial (5.3%) Students complying correctly guide was 74.7% 3.3.2 Effectiveness of myopia school interventions In order to follow ongoing school myopia in years, this study used the initial examination results of students in grades 6, and re-examined these students in grade 8, to calculate effectiveness of the interventions 18 Chart 3.3 Comparison of changes in students' knowledge between the intervention groups after years Comment: Knowledge of students in the two intervention groups was significantly changed to compare with before intervention (approximately more than 50%) and there were no difference between community intervention and community and clinical combination Chart 3.4 Comparing the change in students' practice between intervention groups after years Comment: Myopia risk behaviors were declined similarly in the groups, but the behavior of eye protection in intervention group tended to better than intervention group 19 Table 3.36 The ratio of myopia before and after intervention Before Ater Difference p (test χ2) n % n % Tan Thanh >0.05 34 16.1 24 12.1 -4.0 Intervention (Intervention) group 0.05 36 12.1 22 7.5 -4.6 Intervention (Intervention) group