Increased Time Outdoors Is Followed by Reversal of the Long-Term Trend to Reduced Visual Acuity in Taiwan Primary School Students

Abstract

Purpose: To investigate the change in the prevalence of reduced visual acuity (VA) in Taiwanese school children after a policy intervention promoting increased time outdoors.Design: Prospective cohort study based on the Taiwan School Student Visual Acuity Screen (TSVAS) by the Ministry of Education in Taiwan.Participants: All school children from grades 1 through 6 were enrolled in the TSVAS from 2001 through 2015.Methods: The TSVAS requires each school in Taiwan to perform measurements of uncorrected VA (UCVA) on all students in grades 1 through 6 every half year using a Tumbling E chart. Reduced VA was defined as UCVA of 20/25 or less. Data from 1.2 to 1.9 million primary school children each year were collected from 2001 through 2015. A policy program named Tian-Tian 120 encouraged schools to take students outdoors for 120 minutes every day for myopia prevention. It was instituted in September 2010. To investigate the impact of the intervention, a segmented regression analysis of interrupted time series was performed.Main Outcome Measures: Prevalence of reduced VA. Results: From 2001 to 2011, the prevalence of reduced VA of school children from grades 1 through 6 increased from 34.8% (95% confidence interval [CI], 34.7%e34.9%) to 50.0% (95% CI, 49.9%e50.1%). After the implementation of the Tian-Tian 120 outdoor program, the prevalence decreased continuously from 49.4% (95% CI, 49.3%e49.5%) in 2012 to 46.1% (95% CI, 46.0%e46.2%) in 2015, reversing the previous long-term trend. For the segmented regression analysis controlling for gender and grade, a significant constant upward trend before the intervention in the mean annual change of prevalence was found (þ1.58%; standard error [SE], 0.08; P < 0.001). After the intervention, the trend changed significantly, with a constant decrease by e2.34% annually (SE, 0.23; P < 0.001).Conclusions: Policy intervention to promote increased time outdoors in schools was followed by a reversal of the long-term trend toward increased low VA in school children in Taiwan. Because randomized trials have demonstrated outdoor exposure slowing myopia onset, interventions to promote increased time outdoors may be useful in other areas affected by an epidemic of myopia. Ophthalmology 2020;-:1e8 ª 2020 by the American Academy of Ophthalmology. This is an open access article under the CC BY-NC-ND license (http://creativecommons. org/licenses/by-nc-nd/4.0/).

Comparison of myopic progression in Finnish and Singaporean children

“…Studies both in Finland (Pärssinen 1986) and Singapore (Dirani et al 2009) along with several other studies (Rose et al 2008; He et al 2015; Guo et al 2017; Huang et al 2019; Wu et al 2020) have found that individuals who spent more time outdoors were less likely to be myopic. In the present study, the considerable differences between the Singaporean and Finnish children in time spent outdoors did not explain the differences between the two populations in myopic progression.…”

“…About 70% of the children in both the SCORM groups spent ≤0.5 h/d outdoors and only about 10% ≥1 h/d, whereas more than 70% of the Finnish children, but only about 1% of the Singaporean children, spent ≥2 h/d outdoors. In a prospective cohort study started in 2010 among schoolchildren in Taiwan, recommendations were 2 h/d outdoor time and a break of 10 min after every 30 min of near‐work (Wu et al 2020). During the follow‐up, the trend towards an increase in poor uncorrected distant vision significantly reversed (Wu et al 2020).…”

Myopia

“…The protective effect of more outdoor time was further confirmed in an RCT in Taiwan 13 . The same investigators in Taiwan reported that the prevalence of myopia was reduced from 49.4% in 2012 to 46.1% in 2015, when an outdoor time intervention programme was implemented 73 . The association between outdoor light exposure and myopia has been further supported by some observational studies on seasonal variation and myopia development, which found that myopia progression and eye growth were slower in the summer 74 .…”

“…Nevertheless, a campaign conducted in Taiwan to educate parents about the benefits of spending time outdoors outside of school time and an incentive-based outdoor programme with family did not have a significant effect on increasing outdoor time 12,188 . Of note, a 15-year study in Taiwan (the Tian-Tian 120 programme) encouraged schools to allow students to spend 2 hours outdoors daily and demonstrated a reversal in the long-term trend of increased prevalence of reduced visual acuity (which has a high correlation with myopia) in schoolchildren 73 . This finding shows that a school policy for increasing outdoor time might be a direct and effective way of maintaining visual acuity.…”

The Outcome and Implications of Public Precautionary Measures in Taiwan–Declining Respiratory Disease Cases in the COVID-19 Pandemic

“… A unique situation may not have been considered yet. Taiwan is one of the countries which has a very high rate of myopia, e.g., around 84% of high school students [ 22 ], and the group with presbyopia means roughly 40 to 50% of all citizens wear glasses. The combination of eyewear, medical masks, and frequent hygiene might play a synergistic role in preventing the spread of COVID-19.…”