Sunlight can help with myopia, but the impact of UV light on myopia is not conclusive. Protect your child's eyes from UV damage and long-term complications.
"I recently came across a study indicating that UV light slows down the progression of myopia. Does this mean that if my child wears his sunglasses outdoors the benefit will be reduced?” This question was raised by a concerned parent.
This is a great question. Research has shown that more outdoor time can help reduce the likelihood of myopia development and progression.1,2 But if the outdoor time is mainly driven by exposure to UV light, is this a catch-22?
In this article, let’s explore the most up-to-date information on the impact of sunlight and UV light on myopia, and what it means for your child.
How does sunlight help with myopia?Â
Increasing your child's time spent outdoors and exposure to sunlight can be a simple yet effective way to prevent myopia or slow down its progression.1,2 (Learn more about how an outdoor activity tracker can help)
Sunlight encompasses a wide range of wavelengths, ranging from ultraviolet (UV) to visible to infrared (IR) light, constituting a continuous spectrum.
Research studies have demonstrated that both the brightness (luminance or light intensity) and the wavelength of light can be beneficial in regulating eye growth and effectively managing myopia in children.3
Is the brightness of light beneficial for myopia?
Research indicates that exposure to sufficient light intensity decreases the likelihood of myopia development or progression. In a study, it was observed individuals exposed to a light level of at least 1,000 to 3,000 lux had a reduced likelihood of myopia development and progression. Interestingly, the more intense the light, the shorter the exposure time required to observe this positive effect.1,2 (For more information on lux levels in different environments and weather conditions.)
Researchers believe that this effect may be attributed to the release of dopamine in the retina, a hormone that aids in regulating eye growth.1 By spending more time in bright outdoor environments, your child's eyes can receive the necessary stimulation to slow down the elongation of the eye's axial length and subsequently reduce myopia.
Moreover, research has also found that by increasing indoor brightness from 100 to 500 lux, the risk of myopia onset and progression in school children was reduced.4 Given that daylight provides more than 1,000 lux, even on overcast days, engaging in outdoor activities can be beneficial for managing myopia.
Which light wavelengths matter in myopia?
Exposure to blue and violet light has been shown to be beneficial in managing myopia, and recent research has verified the benefits of red light to effectively control myopia in clinical studies.3
Research has revealed that exposure to violet light (wavelength of 360–400 nm) may upregulate the expression of a gene called EGR1, which could help suppress myopia progression. In a study involving two groups of children, one group wearing contact lenses that block violet light and the other not, it was observed that contact lenses that allowed the transmission of violet light showed slower myopia progression.5
Similarly, blue light has demonstrated the potential in controlling myopia in numerous animal studies. For instance, in a study in 2002, chickens reared under blue light displayed a tendency toward hyperopia.6 And in a different study, it was found that short-term exposure to blue light suppressed myopia and inhibited axial elongation in human eyes.7
Moreover, red light has been shown to provide benefits in managing myopia. Derived from amblyopia treatment, repeated low-level red-light therapy has been extensively studied in well-designed clinical trials, demonstrating its effectiveness in significantly reducing myopia progression and stabilizing the growth of the eye's axial length in patients with myopia.8
What is the impact of UV light on myopia?
The potential benefits of ultraviolet (UV) light on myopia have been widely discussed, but have less robust support compared to other light wavelengths. Studies investigating the impact of UV light on myopia have produced mixed results.
One widely cited study published in 2016 found that increased exposure to UV-B was associated with reduced myopia in adolescence and young adulthood. The hypothesis was that higher UV-B exposure leads to increased dopamine levels, resulting in less myopia progression.9
However, it's important to note that the study relied on self-reported data regarding outdoor sunlight exposure and meteorological information to estimate the UV-B exposure -- an estimation, not UV-B measured.9 Therefore, it is important to understand that this study establishes an association – other factors may be at play – rather than demonstrating a causal relationship. Further research is warranted to investigate this further.
On the other hand, a research study conducted in Japan presented contrasting results. In this large epidemiological study, which tracked over 57,000 eyes in children and adolescents, refractive changes were observed among individuals who wore either UV-blocking or regular soft contact lenses over a span of five years. The findings of this study suggested that UV exposure could potentially be a risk factor for the progression of myopia, as participants who wore UV-blocking lenses exhibited less myopia progression.10 Nevertheless, since this study is epidemiological in nature, additional research is required to establish a definitive causal relationship.
How does UV affect the eyes?
UV light can cause damage to the eyes and have a long-term negative impact on eye health. To ensure your child's safety and reduce the risk of developing serious eye diseases later in life, it is important for them to wear sunglasses that effectively block UV rays.11
Cataracts: Prolonged exposure to UV light without adequate eye protection increases the likelihood of developing cataracts. Remember, the effects of UV exposure accumulate over time, so every instance your child exposes their eyes to the sun without protection, the risk of developing this condition increases.
Sunburned eyes: Eyes can also experience sunburn. Similar to the skin, prolonged exposure to UV light can cause sunburn on the surface of your child’s eyes, resulting in redness, irritation, and discomfort.Â
Eye surface growths: Pterygium, a flesh-like growth on the white part of the eye. It typically appears during the teenage years or twenties and is linked to prolonged exposure to UV light.Â
Eye cancers: Certain types of eye cancers, such as ocular melanoma, have been associated with UV light exposure. Although these cancers may take years to develop, each exposure to UV radiation raises the risk.Â
Eye protection from the sun
Considering the existing evidence, it is apparent that the benefits of sunlight on myopia are influenced by multiple factors. Therefore, it is important to implement measures aimed at reducing UV exposure and the risks of its harmful effects. Here are some tips to help:Â
Choose appropriate sunglasses: Not all sunglasses provide the same level of protection against harmful UV rays. It is crucial to select sunglasses that offer 100% UV or UV400 protection. These types of sunglasses effectively block both UV-A and UV-B rays, safeguarding your child's eyes.
Wear hats:Â Hats are your child's best friend when it comes to sun protection. Opt for broad-brimmed hats that offer ample shade to the face, eyes, and neck. By pairing sunglasses with a hat, you create a strong defense against harmful UV rays.
Be cautious of the cloudy days:Â Contrary to popular belief, clouds do not block UV light. Even on overcast days, the UV light can penetrate through the haze and clouds, reaching your child's eyes. Therefore, it is essential to consistently maintain UV protection measures even on cloudy days.
Timing matters:Â Sunlight is most intense during midday to early afternoon hours, particularly at higher altitudes or when reflected off water, ice, or snow. During these times, take extra precautions by ensuring your child wears sunglasses and a hat.
Wear anti-UV goggles when swimming outdoors: If your child loves the outdoor pool, make sure they wear anti-UV goggles while splashing around under the sun.
Key takeaways
More outdoor time and exposure to sunlight can effectively help prevent or slow down myopia progression – a minimum of 8 to 15 h of outdoor activity per week.12 Optimal light brightness of over 3000 lux and specific wavelengths such as violet, blue, and red have been found to have positive effects on managing myopia.3
However, it's important to note that while some studies suggest potential benefits of UV light for myopia, prolonged exposure to UV light can lead to long-term damage and eye complications for your child.11Â
Help them choose sunglasses with proper UV protection, encourage them to wear hats, and remain cautious even on cloudy days. Moreover, when swimming outdoors, it's advisable to use anti-UV goggles.
Answering the inquiry from the beginning, protect your child's eyes against harmful UV; other spectrums of light and brightness can still work their magic on myopia.
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- Wu, Pei-Chang et al. “Myopia Prevention and Outdoor Light Intensity in a School-Based Cluster Randomized Trial.” Ophthalmology vol. 125,8 (2018): 1239-1250.Â
- Read, Scott A et al. “Light Exposure and Eye Growth in Childhood.” Investigative ophthalmology & visual science vol. 56,11 (2015): 6779-87.
- Zhang, Pengbo, and Huang Zhu. “Light Signaling and Myopia Development: A Review.” Ophthalmology and therapy vol. 11,3 (2022): 939-957.
- Hua, Wen-Juan et al. “Elevated light levels in schools have a protective effect on myopia.” Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) vol. 35,3 (2015): 252-62.
- Torii, Hidemasa et al. “Violet Light Transmission is Related to Myopia Progression in Adult High Myopia.” Scientific reports vol. 7,1 14523. 6 Nov. 2017.
- Rucker, Frances J, and Josh Wallman. “Chick eyes compensate for chromatic simulations of hyperopic and myopic defocus: evidence that the eye uses longitudinal chromatic aberration to guide eye-growth.” Vision research vol. 49,14 (2009): 1775-83.Â
- Thakur, Swapnil et al. “Short-Term Exposure to Blue Light Shows an Inhibitory Effect on Axial Elongation in Human Eyes Independent of Defocus.” Investigative ophthalmology & visual science vol. 62,15 (2021): 22.
- Jiang, Yu et al. “Effect of Repeated Low-Level Red-Light Therapy for Myopia Control in Children: A Multicenter Randomized Controlled Trial.” Ophthalmology vol. 129,5 (2022): 509-519.Â
- Williams, Katie M et al. “Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study.” JAMA ophthalmology vol. 135,1 (2017): 47-53.
- Yoshida M, Mizuki N, Takeuchi M, et al. A large-scale, epidemiologic study of the influence of ultraviolet exposure on myopia progression—a 5-year follow-up study of approximately 57,000 Japanese patients' eyes. ARVO 2019. Abstract 6347.
- Turbert, David. The Academy of Opthalmology. ”The Sun, UV Light and Your Eyes.” Accessed July 5, 2023. https://www.aao.org/eye-health/tips-prevention/sun
- NĂ©meth, János et al. “Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute.” European journal of ophthalmology vol. 31,3 (2021): 853-883.Â
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