Outdoor walks: the best myopia prevention

When it comes to preventing myopia in children, most parents first think about limiting screen time. And that is, without a doubt, important. However, researchers have discovered an even more powerful protective factor -- the time a child spends outdoors. Bright daylight has a direct biological effect on the developing eye of a child, slowing down the processes that lead to myopia development.

Over the past 15 years, this finding has been confirmed by dozens of large-scale studies conducted in different countries around the world. And today, the recommendation to spend at least two hours a day outdoors is part of the official clinical guidelines for myopia prevention in children.

Science has proven: daylight protects the eyes

The mechanism of the protective effect of daylight was deciphered in a series of fundamental research studies. When bright light reaches the retina, the production of the neurotransmitter dopamine increases in its cells. In turn, dopamine inhibits the elongation of the eyeball -- the very process that underlies the development of axial myopia.

Research on animal models demonstrated this with high reliability: chicks and monkeys kept under conditions of bright illumination developed myopia significantly less often than animals under dim lighting conditions. Moreover, it was the intensity of light, not its spectral composition, that played the determining role.

In 2015, a research team led by Mingguang He conducted one of the largest randomized controlled trials in this field. Over 1,900 children aged 6-7 from 12 schools in Guangzhou (China) participated in the experiment. Schools were randomly divided into two groups: in the experimental group, 40 mandatory minutes of outdoor time were added during the school day. After three years of observation, the incidence of new myopia cases in the experimental group was 23% lower.

Source: He M, Xiang F, Zeng Y, et al. Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China. JAMA, 2015; 314(11): 1142-1148

Even earlier, in 2008, Australian researchers Kathryn Rose and Ian Morgan published the results of the Sydney Myopia Study, which included over 4,000 students. They established that children who spent more time outdoors had a significantly lower risk of developing myopia -- even if they read a lot and worked on computers. This finding was a turning point: it was not just about reducing close-up visual effort, but about an independent protective effect of spending time outdoors.

Source: Rose KA, Morgan IG, Ip J, et al. Outdoor Activity Reduces the Prevalence of Myopia in Children. Ophthalmology, 2008; 115(8): 1279-1285

How much time should be spent outdoors?

International recommendations, based on the totality of scientific evidence, indicate a minimum of 2 hours per day outdoors for effective myopia prevention. This figure is confirmed by meta-analyses that include data from Australia, China, Taiwan, Singapore, and European countries.

An important detail: the two hours do not need to be spent outdoors continuously. Research shows that cumulative time throughout the day works just as effectively. This means that 30 minutes of walking in the morning to school, 40 minutes during recess breaks, 20 minutes on the way home, and 30 minutes of playing in the yard in the evening -- all together provide the same protective effect as a continuous two-hour walk.

Also, the type of outdoor activity is not fundamentally important. The child can run, play football, ride a bicycle, or simply sit on a bench and read a book -- what matters is being under open sky and the eyes receiving enough natural light.

Research from different countries

One of the most convincing examples was the program implemented in Taiwan. In 2010, the island's government introduced the national program "Tian Tian 120" ("120 minutes every day"), requiring schools to ensure at least 120 minutes of outdoor time for children daily.

The results were impressive. In schools that seriously followed the program and increased outdoor time by at least 40 minutes per day, the prevalence of myopia among children decreased by nearly 50% over 4 years of observation. This was one of the first major state-level studies to demonstrate the effectiveness of population-level intervention.

Source: Wu PC, Tsai CL, Wu HL, Yang YH, Kuo HK. Outdoor Activity during Class Recess Reduces Myopia Onset and Progression in School Children. Ophthalmology, 2013; 120(5): 1080-1085

Australian researchers, as part of the large ALSPAC study (Avon Longitudinal Study of Parents and Children), discovered a dose-response relationship: each additional hour spent outdoors per week reduced the risk of developing myopia by approximately 2%. Children who spent more than 14 hours per week outdoors (an average of 2 hours per day) had half the risk of myopia compared to those who spent less than 7 hours per week.

In Singapore, the SCORM study (Singapore Cohort Study of the Risk Factors for Myopia) confirmed these conclusions for the Southeast Asian population, where genetic predisposition to myopia is traditionally considered high. Even in this population, children who spent more time outdoors developed myopia less frequently and later.

Each additional hour a child spends outdoors per week reduces the risk of developing myopia by approximately 2%. The protective effect works independently of the volume of close-up visual effort and genetic predisposition.

Source: Sherwin JC, Reacher MH, Keogh RH, et al. The Association between Time Spent Outdoors and Myopia in Children and Adolescents: A Systematic Review and Meta-analysis. Ophthalmology, 2012; 119(10): 2141-2151

Season and weather are not obstacles

One of the most common questions from parents: "But how do we walk in winter? It gets dark early and it is cold." In fact, research shows that even a cloudy winter day provides illumination an order of magnitude greater than the strongest artificial lighting indoors.

On a sunny day, outdoor illumination is 80,000-120,000 lux. On a cloudy day -- 10,000-25,000 lux. By comparison, a well-lit classroom or office provides only 300-500 lux. Even on a gloomy winter day, a child outdoors receives 20-50 times more light than indoors.

It is important to note that ultraviolet radiation, according to available data, is not the key protective factor. The protective effect is provided by the overall brightness of visible light. This is confirmed by the fact that wearing sunglasses, which filter UV, does not reduce the preventive effect of outdoor walks. Therefore, the use of sunglasses and hats in strong sunlight is perfectly acceptable and does not diminish the benefit of outdoor time for vision.

In northern countries, where the winter daylight period is short, researchers recommend making maximum use of the hours of daylight. Morning walks and walks during breaks become especially valuable in winter, when evening darkness comes early.

How to ensure 2 hours outdoors during the school year

It sounds simple -- two hours a day. But many parents rightly observe that during the school year, when the child is at school from morning until afternoon, then at extracurricular activities, and then doing homework -- accumulating those two hours is not easy. Here are practical strategies that can help:

The morning commute

If the school is less than 2 kilometers away -- let the child walk (if the age and route safety allow). 20-30 minutes of walking in the morning under daylight is an excellent start to the day. If the school is far away, you can get off 1-2 stops earlier and walk part of the way.

Outdoor recess breaks

Many schools allow or even encourage outdoor breaks. Discuss with the teacher the possibility of spending long recess breaks outside. The Taiwan experience showed that even 40 additional minutes outdoors during the school day have a significant effect.

Outdoor extracurricular activities

Instead of another indoor club, consider options that involve outdoor time: football, track and field, tennis, cycling, Nordic walking. Outdoor sports sections solve two problems simultaneously -- physical activity and vision protection.

Weekends and holidays

Use weekends for long walks, hikes, picnics. A family outing to the park, a trip to the countryside, games in the yard -- all of these are a "reserve" of bright light for your child's eyes. During holidays, try to have the child spend as much time as possible outdoors -- this compensates for the deficit during school days.

Homework outdoors

In the warm season, some homework can be done on the balcony, patio, or in the yard. Reading on a park bench means learning and myopia prevention at the same time.

The combined effect: walks + healthy visual habits

The strongest preventive effect is achieved by combining two strategies: sufficient outdoor time and reasonable limitation of prolonged close-up visual work.

A 2019 meta-analysis that combined data from 25 studies with over 30,000 children showed that children with high levels of outdoor time and low volumes of close-up work had the lowest risk of myopia. Moreover, even with a high volume of visual effort (lots of reading and studying), sufficient outdoor time significantly reduced the risk.

Particularly beneficial were outdoor team sports. Football, badminton, basketball require constant switching of focus between near and far objects -- ball, partners, field. This additionally trains the eye's accommodation system and reduces fatigue from prolonged close-up focusing.

Practical recommendations for optimal protection:

• At least 2 hours outdoors daily -- cumulative, can be split into several outings
• The 20-20-20 rule -- every 20 minutes of reading or screen time, look at an object 6 meters away for 20 seconds
• Distance from book/notebook -- at least 30 cm; from monitor -- at least 50 cm
• Reading breaks -- at least 10 minutes of rest after every 40-45 minutes of close-up visual work
• Outdoor sports -- preferable over gym or indoor pool activities from a vision protection perspective
• Evening screen time -- limited to 1-2 hours for students, excluding school homework

It is important to understand that walks are a preventive measure. If the child already has myopia, walks alone are not sufficient to slow its progression. In this case, it is necessary to consult an ophthalmologist and discuss modern myopia control methods -- special spectacle lenses, orthokeratology or soft contact lenses, low-dose atropine therapy.

But for prevention -- for children who do not yet have myopia or who are in the risk group (myopic parents, lots of close-up visual effort) -- regular outdoor walks remain the simplest, most accessible, and most scientifically supported way to protect children's vision.