More outdoor time decreases the risk of myopia onset and progression driven by daylight exposure. Outdoor time may also enhance myopia treatment effectiveness.
Do you find it challenging to help your child get two hours of outdoor activities every day? Does it really help prevent myopia from progressing?
Spending time outdoors is an effective way to slow down the worsening of myopia in children.1 However, maintaining persistence and keeping your kids engaged can often be challenging.
In this article, we will delve into the recommendations by the medical community, elucidate the mechanisms through which outdoor time contributes, and explore how it can synergistically enhance the effectiveness of myopia control treatments.
Outdoor time is essential for eye health
The Refractive Errors Preferred Practice Pattern 2022 by the American Academy of Ophthalmology emphasized the significance of increased outdoor time and summarized studies that reviewed, "increasing time spent outdoors significantly decreased risk of myopic progression."1
Moreover, drawing from published interventional studies, the International Myopia Institute advocates for children to have at least 80-120 minutes of outdoor activities per day.2
These recommendations underscore the crucial role that you could play in facilitating outdoor time for your children’s eye health.
How does outdoor time work to protect against myopia?
Exposure to outdoor daylight plays a vital role in diminishing the risk of myopia onset as well as its progression. Various research studies have demonstrated that both the brightness and the type of light (specific light wavelengths) can be beneficial in regulating eye growth and help manage myopia in children.3
The benefits are believed to stem from the release of dopamine – a hormone crucial in the regulation of eye growth. By immersing in bright outdoor environments, your child's eyes can receive the necessary neural signal to slow down the elongation of the eye's axial length and, consequently, the risk of myopia progression.4
It is important to note that the contributing factor is the exposure to daylight, rather than engaging in physical activities. This was shown in a large study in 2012, encompassing approximately 14,000 children, that time spent outdoors was linked to an increased risk of myopia independently of the physical activity level.5
Can outdoor time reduce the worsening of myopia?
Outdoor time has been found to have a significant impact on myopia, particularly in terms of reducing the risk of its onset. Studies have consistently demonstrated that increasing outdoor time can lead to a decrease in the likelihood of developing myopia. For instance, research indicated that each additional hour spent outdoors per week was associated with a 2% reduction in the risk of myopia. Further, the risk of developing myopia was reduced by approximately one-third when outdoor time was increased from less than 5 hours per week to 14 hours or more.6
In studies looking at the effects of outdoor time on myopia progression, the results were mixed. However, advancements in research in recent years have yielded more definitive conclusions about the protective roles of outdoor time – or daylight -- against myopia progression.
A meta-analysis incorporating data from five randomized control trials, with more than 3,000 children, investigated the impact of outdoor time on myopia. The analysis unveiled that outdoor time reduced the risk of myopia and its progression. From the analysis, children within the outdoor-exposed group exhibited a slower change in refractive error of up to 26%, and axial length of up to 24%. The author concluded, "Based on this meta-analysis, the answer is clear that outdoor time has a positive effect on myopia control."7
Additionally, this study reaffirmed that outdoor time helps slow down the speed of change in refractive error and axial length in children with myopia; while for non-myopic children, it helps reduce the likelihood of developing myopia.7
Could outdoor time enhance the effectiveness of myopia control treatments?
When my son commenced his myopia control treatment, our eye doctor emphasized that my son should adhere to healthy lifestyle changes, including an adequate amount of outdoor time, for the most favorable treatment outcomes.
Recently, I came across a specially designed clinical study, and the results echoed his recommendation. The study involved forty-one children undergoing myopia treatment using MiSight contact lenses. The extent of improvement varied among the children; some responded very well, while some didn't. The analysis identified outdoor time as a predictor of treatment success with MiSight; children who responded well to MiSight treatment spent more than 3 to 4 hours outdoors per week.8
Even though my son has been on the overnight contact lens and atropine treatment, his adherence to outdoor time may have contributed to how we were able to completely halt his myopia progression over eight months.
Takeaways
In conclusion, the role of outdoor time in myopia control cannot be overstated. As highlighted by the recommendations of leading medical bodies, increasing outdoor time can reduce the worsening of myopia in children. The likely mechanism through which outdoor time exerts its protective effect lies in the exposure to daylight, triggering the release of dopamine and thereby slowing the elongation of the eye.
Multiple studies have shown the positive impact of outdoor time in preventing myopia onset. Recent studies further provide evidence supporting the efficacy of outdoor time, slowing changes in refractive error and axial length, as well as augmenting myopia control treatments.
Incorporating outdoor time into daily routines is a practical and worthwhile strategy. As my son cleverly puts it, “I’m going out to play to keep myopia at bay.”
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2. International Myopia Institute. 2021. IMI Prevention of Myopia and its Progression. Retrieved, Aug 9, 2023. https://myopiainstitute.org/imi-whitepaper/imi-prevention-of-myopia-and-its-progression/
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