Chennai, Aug. 20 -- Highlights:
* Indigo light between 419-446 nm prevented induced myopia in tree shrews
* Around 435 nm showed the strongest potential effect in the study
* Human studies are //still needed before special indoor lighting can be recommended
A new study has identified a specific part of sunlight that may help prevent myopia. In experiments with tree shrews, adding indigo light in the 419-446 nanometer range to indoor lighting completely prevented experimentally induced myopia.
The findings, published, in Cell Reports Medicine, raise an important question: Could changing the light children are exposed to indoors eventually become another tool for preventing short-sightedness? ( ref1 )
The answer is not known yet, because the findings have so far been demonstrated in an animal model, not children.
How Did The Researchers Test Indigo Light Against Myopia?
Researchers investigated whether specific wavelengths of light could influence myopia development. Instead of testing children, the researchers used northern tree shrews, whose eyes share several important similarities with human eyes.
The animals were fitted with specially designed spectacles containing a strong prescription lens over one eye to trigger myopia.
The researchers then exposed them to different wavelengths of light and measured changes in eye length and vision.
The main findings were:
* Indigo Light Showed the Strongest Effect: Light between 419 and 446 nm completely prevented the experimentally induced myopia.
* Violet and Blue Light Were Less Effective: These wavelengths provided some protection, but the effect was weaker than with indigo light.
* Indigo Light Prevented Abnormal Eye Growth: The treated eyes did not develop the excessive elongation associated with the induced myopia.
* The Light Was Added to Warm-White LEDs: This suggests that the potential benefit may depend not only on how bright indoor lighting is but also on which wavelengths it contains.
The researchers caution that these results come from a tree shrew model , not children. Further studies are needed to determine whether indigo-enriched lighting can produce the same protective effect in humans and what level and duration of exposure would be appropriate.
Why Are Researchers Interested In Indigo Light?
According to the study, the focus on indigo light came from earlier research showing that the eye contains a light-sensitive protein called OPN5, which may help regulate eye growth.
However, researchers found that violet light works poorly because much of it is blocked by the eye's natural lens. This prompted them to test slightly longer wavelengths that can still reach the retina.
* Indigo Light Reached The Eye Better: Unlike violet light, indigo wavelengths can pass through the eye's lens more effectively.
* 435 nm Appeared Most Promising: Researchers identified around 435 nanometers as the wavelength most likely to activate OPN5 in young tree shrews.
* Sunlight Naturally Contains Indigo Light: These wavelengths are abundant outdoors but are present at much lower levels in many standard indoor LED lights.
* Indoor Lighting May Be Missing an Important Component: The findings suggest that the issue may not only be how much light children receive indoors, but also the type of light they are exposed to. Researchers believe that modern indoor lighting may not fully mimic natural sunlight. The missing indigo portion of the light spectrum is now being investigated as one possible factor behind the growing rates of childhood myopia.
Why Is Myopia Becoming A Bigger Concern?
Myopia, or short-sightedness, occurs when the eye grows too long, causing distant objects to appear blurred. It usually begins during childhood and can continue to worsen through the teenage years.
The global burden is already substantial. About 2.8 billion people currently have myopia, and that number could reach 4.8 billion by 2050.
The problem is also important for India. A systematic review, which examined 59 studies covering nearly 2.86 lakh Indian children, found an overall myopia prevalence of 7.5% among children aged 5-15 years. It was 8.5% in urban children and 6.1% in rural children ( ref2 ).
More importantly, the Indian review found that myopia was increasing in rural areas too, suggesting that changing lifestyles and increasing indoor exposure may be altering the country's eye-health landscape.
Can Better Indoor Lighting Offer Some Of The Benefits Of Outdoor Light?
The new study does not replace the evidence that spending time outdoors helps protect children against myopia. Instead, it adds a possible explanation: the type of light reaching the eyes may be part of that protection.
A recent review in the International Journal of Ophthalmology found that light intensity, wavelength, and exposure time may all influence myopia development. It also highlighted concerns about children spending less time outdoors and more time with electronic devices ( ref3 ).
Research so far suggests:
* Outdoor Time Matters: Around 13 hours outdoors per week, or nearly two hours a day, has been associated with a lower risk of developing myopia ().
* Outdoor Light Is Much Brighter: Even outdoor shade can provide far more light than a typical indoor environment.
* It May Be the Light, Not Just The Activity: Evidence suggests the protective effect of outdoor time is more closely linked to light exposure than simply being physically active.
* Indoor Lighting Is Also Being Studied: Some research suggests brighter classroom lighting may help reduce myopia, although findings are not yet consistent.
This is where the new research becomes interesting: instead of asking children to spend all their time outdoors, researchers are exploring whether indoor lighting can be designed to provide some of the light signals that developing eyes receive outdoors.
What Did Researchers Say About The Next Step?
The Cincinnati Children's team is now interested in moving beyond animal experiments. The proposed next stage is to test indigo-enriched lighting in daycare settings and compare children's eye development with children exposed to standard indoor lighting.
This is important because the current study has a clear limitation: tree shrews are not children.
he researchers themselves state that the animal model does not fully reproduce how myopia naturally develops and progresses in humans. Human studies are therefore needed to determine whether the same protective effect occurs in children.
The team also says the goal would not simply be to make indoor spaces brighter. Instead, future lighting could potentially be designed to provide a broader, more sunlight-like range of wavelengths.
What Should Parents Do Right Now? Parents should not rush to buy special indigo lamps based on this study. There is currently no human evidence showing that installing such lighting prevents childhood myopia.
For now, the better-supported approach remains:
* Give Children Regular Outdoor Time: Aim for around two hours a day where practical, while using normal sun-protection measures.
* Balance Screen and Close-Up Work: Encourage regular breaks from prolonged near work.
* Use Comfortable Indoor Lighting: Avoid glare and poorly lit study areas.
* Get Children's Vision Checked: Especially if they frequently squint, sit very close to screens or books, or have difficulty seeing distant objects.
* Do Not Treat Blue-Light Glasses As Myopia Prevention: Current evidence does not support claims that blue-light-blocking spectacle coatings protect children's eye health. The new finding is promising, but it is best understood as an early step toward a possible new prevention strategy. If human studies confirm that adding the right wavelengths to indoor lighting can protect developing eyes, classrooms and other children's spaces could eventually be designed to provide a more eye-friendly light environment. medfaq References:
* Prevention of myopia in a near-primate by supplemental indigo light suggests a hypothesis for the myopia boom - (https://www.cell.com/cell-reports-medicine/fulltext/S2666-3791(26)00416-7)
* Prevalence of myopia in Indian school children: Meta-analysis of last four decades - (https://pmc.ncbi.nlm.nih.gov/articles/PMC7571694/)
* Influence of light on myopia-a review - (https://pmc.ncbi.nlm.nih.gov/articles/PMC13103200/)
* Indoor and outdoor lighting and visual development - (https://www.mykidsvision.org/knowledge-centre/indoor-and-outdoor-lighting-and-visual-development)
Source-Medindia