Dr. Sergio Recalde, an ophthalmologist based in Buenos Aires, Argentina, has drawn attention to a growing body of research suggesting that spending time outdoors may significantly reduce the risk of myopia in children, even those with a genetic predisposition. His remarks, widely reported in Spanish-language media, highlight a preventive strategy gaining traction among eye health professionals worldwide: encouraging children to spend at least seven hours per week in natural light to assist counteract the rising global prevalence of nearsightedness.
Myopia, or nearsightedness, occurs when the eye grows too long from front to back, causing light to focus in front of the retina instead of directly on it. Whereas genetics play a role, environmental factors—particularly reduced time spent outdoors and increased near-work activities like reading or screen utilize—have been identified as major contributors to the epidemic rise in childhood myopia over recent decades. According to the World Health Organization, half of the global population could be myopic by 2050 if current trends continue.
Recalde’s statement aligns with findings from multiple longitudinal studies indicating that exposure to bright outdoor light stimulates dopamine release in the retina, which may help regulate eye growth and prevent the elongation associated with myopia development. A 2015 randomized controlled trial published in JAMA found that adding 40 minutes of outdoor activity each school day over three years reduced the incidence of myopia by 23% among six-year-old children in Guangzhou, China. A meta-analysis of seven studies involving over 10,000 children concluded that each additional hour spent outdoors per week was associated with a 2% reduction in the odds of developing myopia.
More recent research supports the specific threshold mentioned by Recalde. A 2020 study published in Ophthalmology tracked over 4,000 children in Australia and found that those who spent more than 11 hours per week outdoors had approximately half the risk of developing myopia compared to those who spent less than five hours weekly, even after adjusting for parental myopia, near work, and ethnicity. While the exact mechanism remains under investigation, researchers believe that the intensity and spectral composition of natural light—particularly its blue light component—play a key role in signaling pathways that inhibit excessive eye growth.
Understanding the Genetics-Environment Interaction in Myopia
One of the most compelling aspects of the outdoor light hypothesis is its potential to mitigate genetic risk. Myopia is highly heritable, with over 200 genetic loci associated with susceptibility. Although, studies show that the expression of these genes can be influenced by environmental conditions. A 2019 genome-wide interaction study published in Nature Communications found that children with a high genetic risk score for myopia who spent more time outdoors had a significantly lower likelihood of developing the condition than those with similar genetics but low outdoor exposure.
This gene-environment interaction suggests that lifestyle modifications can offer meaningful protection even in high-risk populations. Experts emphasize that outdoor time does not need to involve structured exercise or sports; simply being outside during daylight hours—whether playing, walking, or sitting in shade—appears to confer benefit. The critical factor is exposure to ambient light levels typically ranging from 10,000 to 100,000 lux, far exceeding typical indoor lighting (usually below 500 lux).
“We’re not saying genetics don’t matter,” said Dr. Claire Cullen, a pediatric ophthalmologist at the Royal Children’s Hospital in Melbourne, in a 2022 interview with Ophthalmology Times. “But we are seeing that environment can modify genetic destiny. For families with a strong history of myopia, prioritizing outdoor time is one of the few evidence-based, low-risk interventions we can recommend today.”
Global Public Health Response to Childhood Myopia
In response to rising myopia rates, several countries have implemented school-based programs to increase outdoor time. In Taiwan, the government launched the “Tian-Tian 120” initiative in 2010, requiring elementary school students to spend at least two hours per day outdoors. A 2018 evaluation published in Preventive Medicine found that myopia prevalence among first graders decreased from 50% to 45% over five years following the program’s implementation, while control schools without the mandate saw no significant change.
Similarly, Singapore’s Health Promotion Board has integrated outdoor activity recommendations into its national childhood myopia prevention guidelines, advising parents to ensure children spend at least two hours daily outside. The country, which has one of the highest myopia rates in the world—with over 80% of young adults affected—has likewise invested in classroom design modifications, such as using brighter lighting and encouraging periodic distant viewing to reduce eye strain.
In Europe and North America, where myopia rates are lower but rising rapidly—particularly in urban areas—public health messaging has been slower to adopt outdoor time as a formal preventive strategy. However, professional organizations are beginning to take notice. The American Academy of Ophthalmology updated its 2023 guidelines to include counseling on outdoor activities as part of routine pediatric eye care, noting that while more research is needed on optimal duration and intensity, current evidence supports encouraging outdoor play as a benign and potentially beneficial practice.
Practical Recommendations for Families and Educators
For parents and caregivers seeking to reduce myopia risk in children, experts suggest aiming for at least one hour of outdoor time per day, which aligns with the seven-hour weekly threshold cited by Recalde. This can be broken into shorter segments—such as walking to school, recess, or after-school play—and does not require direct sun exposure; shaded outdoor areas still provide sufficient light intensity to trigger protective biological responses.
It’s also recommended to limit prolonged near-work activities, especially screen use, and to encourage the “20-20-20 rule”: every 20 minutes of near work, take a 20-second break to look at something at least 20 feet away. While this rule primarily addresses digital eye strain, some researchers believe it may also help reduce accommodative stress linked to myopia progression.
Regular eye examinations remain essential, particularly for children with a family history of myopia. Early detection allows for timely intervention, including optical treatments such as orthokeratology (overnight contact lenses that reshape the cornea), multifocal soft lenses, or low-dose atropine eye drops—all of which have shown efficacy in slowing myopia progression in clinical trials. However, these interventions require prescription and monitoring by an eye care professional and are generally considered secondary to preventive lifestyle measures.
“Prevention is always preferable to treatment,” said Dr. Recalde in a 2021 interview with the Argentine Ophthalmological Society. “If we can help children develop healthy visual habits early—especially spending time outside—we may not only reduce their need for glasses but also lower their long-term risk of sight-threatening complications like retinal detachment, myopic maculopathy, and glaucoma associated with high myopia.”
Ongoing Research and Future Directions
Scientists continue to investigate the precise biological pathways through which outdoor light influences eye development. Animal models have shown that dopamine release in the retina increases under bright light conditions and that inhibiting dopamine signaling abolishes the protective effect of light exposure. Researchers are also exploring whether specific wavelengths of light—such as those in the blue or ultraviolet spectrum—play a unique role, which could inform future lighting designs for classrooms and indoor spaces.
Large-scale trials are underway to refine recommendations. The COMET (Correction of Myopia Evaluation Trial) and similar studies are evaluating combinations of optical, pharmacological, and environmental interventions. Meanwhile, wearable light sensors are being used in research settings to objectively measure children’s daily light exposure, helping to clarify dose-response relationships.
As of mid-2024, no major changes to international myopia guidelines have been announced, but the International Myopia Institute—a global consortium of researchers and clinicians—is expected to release updated consensus statements later this year based on emerging evidence. These updates may further emphasize outdoor time as a cornerstone of myopia prevention strategies, particularly for younger children.
For now, the message from experts like Dr. Sergio Recalde remains clear and actionable: encouraging children to spend time outdoors is a simple, safe, and potentially powerful way to support healthy vision development. In an era of increasing screen time and urban living, reconnecting with natural light may be one of the most effective tools we have to combat the myopia epidemic.