Near work is the Most Important Factor in the Myopia Progression among Children in Elementary School: A Two-year Follow-up Study

• Main Authors: Pin-Chen Huang, 黃品蓁
• Other Authors: Yiing Mei Liou
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3453fk

碩士 === 國立陽明大學 === 社區健康照護研究所 === 106 === Background: Myopia is a critical health problem that should be managed seriously, particularly in young age groups. Children’s time in outdoor have decreased due to the popularity of electronic devices and the urbanized environment. The age of onset of myopia is decreasing, and its prevalence is extremely high. This problem is especially serious in the East Asian nation such as Taiwan. According to the statistics, the prevalence of myopia may exceed 60% in sixth grade students. Once myopia has occurred, the person’s vision will deteriorate rapidly, especially in children of school age. In order to address the major health problem of childhood myopia in developed countries around the world, aside from preventing myopia in students, developing a wide-range program in order to control the progression of myopia effectively and efficiently is an extremely important issue. From past research, we know that near work and less sun exposure in outdoor are important risk factors for myopia. We need to know more about the impact of these two risk factors on myopia. Aim: The aim of this study is to understand the length of time taken for students to maintain their vision distance while performing near work, shorten the time spent on continuous near work, and increase the levels of outdoor in the metropolitan area after 2 years of myopia interventions in elementary school children intended to influence the incidence of myopia and myopia progression. Additionally, the study aims to determine which of these factors is the most important for myopia progression. Method: In this study, we conducted a citywide vision care intervention for all elementary school children in Taipei, Taiwan. In order to establish a vision-friendly environment, several evidence‐based and feasible vision‐protecting teaching materials and teaching aids were designed for all elementary schools in Taipei and for use by ophthalmology departments or clinics. Furthermore, we also made use of vision-protection activities, internet and poster campaigns, and other media targeting multiple sectors to increase public exposure to this issue. On a medical level, all second-grade students were recruited by their school nurses to visit ophthalmology departments or clinics for free ocular cycloplegic refraction every 6 months, covered by the department of Health, Taipei. However, the myopia treatment covered by national health insurance. The results of ocular refraction were recorded on the children’s health passports to allow parents to follow the change in their children’s refractive error. A questionnaire on myopia was answered by parents every year to follow up the students’ eye-protective behavior. This study reports the progression of myopia in second-grade students with a 2-year follow up from 2015 to 2017. Investigators assessed the effect of eye-protective behavior (near work distance and continuous time spent on near work, as well as outdoor time) on myopia progression at 0.5, 1, 1.5, and 2 years. Statistical analysis of the data consisted of linear regression, logistic regression, and generalized estimation from the linear regression equation. Results:Ocular cycloplegic refraction provided every 6 months and a comprehensive and extensive eye-protective intervention can help parents to detect myopia early and pay attention to their children’s eye-protective behavior. Regarding near work distance, students who keep their near work at a longer distance (≥ 30 cm) decreased their risk of developing myopia in 6 months OR = 0.70 (0.62–0.80) after controlling for background variables (gender, parental high myopia, and myopia treatment or not), continuous time spent on near work, and participation in outdoor activities at recess. This effect could be continued for at least 2 years. Similar ORs were seen at 1 year [OR = 0.75 (0.66‒0.85)], 1.5 years [OR = 0.74 (0.65–0.84)], and 2 years [OR = 0.71 (0.63–0.82)]. The diopter shift was significantly lower in those who kept a near work distance ≥ 30 cm on 6-month follow-up compared with those who kept a near work distance < 30 cm (‒0.16 ± 0.07 D vs. ‒0.38 ± 0.08 D; P = 0.001) after controlling for background variables (gender, parental high myopia, and treatment or not), continuous time spent on near work, and participation in outdoor activity at recess. Moreover, the effect on the diopter shift was continued for at least 2 years (‒0.70 ± 0.08 D vs. ‒1.04 ± 0.08 D; P = 0.001). Regarding continuous time spent on near work, students who spent less time on continuous near work (≤ 30 minutes) decreased their risk of developing myopia in 6 months OR = 0.77 (0.68–0.88) after controlling for background variables, near work distance, and outdoor time at recess. The diopter shift was significantly lower on 6-month follow-up compared with those who spend a longer time on continuous near work (≥ 30 minutes) (‒0.22 ± 0.08 D vs. ‒0.36 ± 0.08 D; P = 0.023) after controlling for background variables, near work distance, and outdoor time at recess, and the effect on the diopter shift was continuous for at least 2 years (‒0.77 ± 0.09 D vs. ‒0.96 ± 0.09 D; P = 0.005). Regarding outdoor time, students with greater participation in outdoor activity at recess decreased their risk of myopia in 6 months OR = 0.77 (0.68‒0.88) after controlling for background variables, near work distance, and continuous time spent on near work, and this effect was continuous for at least 2 years. Similar ORs were seen at 1 year [OR = 0.77 (0.65–0.90)], 1.5 years [OR = 0.77 (0.65–0.90)], and 2 years [OR = 0.77 (0.66–0.91)]. The diopter shift was also significantly lower on 6-month follow-up compared with students who participated in less outdoor activity (‒0.19 ± 0.07 D vs. ‒0.35 ± 0.08 D；P = 0.005) when controlling for background variables, near work distance, and continuous time spent on near work. This effect on the diopter shift was continuous for at least 2 years (‒0.75 ± 0.07 D vs. ‒0.98 ± 0.08 D; P = 0.012). Compare the effects of three behaviors on diopter, we find near work distance (β = 0.27, P < 0.001) was most effective and followed by outdoor time (β = 0.17, P< 0.001) and continuous time spent on near work (β = 0.13, P < 0.001). Conclusion: The study demonstrates how long it takes for a behavior change following intervention to delay the increase in refractive error. After controlling for background variables and other two behaviors such as longer near work distance (≥ 30 cm), less continuous near work (< 30 minutes), and more time of outdoor activity can all prevent nearsightedness and delay the progression of ocular refraction in 6 months. Increasing near work distance was more effective in myopia prevention and decreasing diopter shift than decreasing continuous near work time and increasing time in outdoor.