- Myopia (nearsightedness) currently affects around 2.8 billion people worldwide. Cases are expected to rise to 4.8 billion by 2050, an increase known as “myopia boom.”
- A recent study found that indigo light could completely suppress lens-induced myopia in tree shrews.
- Researchers suggest that supplementing indoor lighting with indigo light in schools may help prevent myopia, though human studies are needed to prove safety and efficacy.
There are currently around 2.8 billion people worldwide with myopia, also known as nearsightedness or shortsightedness. By 2050, the number of cases will rise to around 4.8 billion. Some people refer to this as the “myopia boom.”
This is according to information from a study published in
The researchers note that evidence suggests environmental factors may play a role in the “myopia boom,” and that there is a relative absence of indigo light in built environments, where people spend around 86% of their time.
In particular, the researchers focused on a model classroom environment, as myopia often first appears in childhood. According to the American Optometric Association (AOA), it typically develops in school-aged children, though it can also begin in adulthood.
According to the study findings, indigo light could help suppress myopia, though more, particularly human-based, research is necessary.
The study researchers used tree shrews as a model for human myopia as they are diurnal mammals — animals that are awake during daylight and asleep during nighttime — and closely related to primates.
They placed spectacles on the tree shrews when they were 24 days old, an age when they are most susceptible to myopia. One lens acted as a control, and the other lens induced myopia in one eye.
The tree shrews were then exposed to different wavelengths of supplemental light.
The researchers ultimately determined that indigo light in the range of 419 to 446 nanometers (nm), which supplemented a warm white LED, completely suppressed minus-lens-induced myopia.
Study author Rafael Grytz, PhD, Dennis Endowed Professor of Glaucoma Research in the University of Alabama at Birmingham Department of Ophthalmology and Visual Sciences, spoke with Medical News Today about these findings.
“A large body of genetic and epidemiological evidence suggests that the epidemic rise of myopia also called the “myopia boom” has an environmental cause. Our findings align with this evidence and suggest that one contributing factor is the relative absence of indigo light in built environments where children spend more and more of their time compared to previous generations.”
As the study was conducted in tree shrews, it is not possible to say from the findings whether supplemental light can help prevent myopia in childhood.
The researchers did create a computer model of a classroom and simulated visual wavelengths and μ-opic illumination — a measurement of light — at the eyes of a seated child.
The results of the test determined that, while warm white LEDs can provide good brightness, combining them with indigo light could better support eye health in indoor locations and potentially prevent or reduce the risk of myopia.
However, as this was a simulation, additional tests in real-world settings would need to be conducted.
Grytz also explained that “[t]he benefit vs. risk of using spectacles with short-wavelength-attenuating (“blue-blocking”) lenses in children should be reevaluated considering our findings. Because these spectacles reduce indigo light transmission to the eyes, daytime use in children could plausibly increase the risk of myopia.”
Speaking to MNT about possible concerns about increasing children’s exposure to short-wavelength light, Grytz said, “It is well known that intense short-wavelength light can harm our eyes, but the benefit vs. risk of exposing the human eye to low-level short-wavelength light needs to be reevaluated.”
He added, “Our findings suggest that indigo light is important for the healthy development of our eyes.”
Brenda Montecalvo, O.D., FOVDR, FAAO, FCSO, AOA Pediatric Eye Health and Vision Access Committee member, and President of the College of Syntonic Optometry, addressed outdoor light exposure in an interview with MNT.
“This study does support outdoor exposure, which has shown to slow down progression. So getting outside without UV protection on the eyes may be a benefit. Currently it is unclear what duration is the safest,” said Montecalvo, who was not involved in the study.
Grytz told MNT that “[s]tudies that directly compare the influence of standard lighting and indigo-supplemented lighting on responses in the human eye are an obvious next step.”
He added, “We anticipate that two new myopia control strategies will emerge from our findings: [n]ew indoor lighting systems that supplement standard light with indigo light in built environments such as schools and daycares for myopia prevention [and new] medical devices that emit low-level indigo light at controlled conditions for the treatment of myopia progression.”
He concluded: “Human studies will need to prove the safety and efficacy of these new strategies.”
Karen S. DeLoss, O.D., Chair, AOA Contact Lens & Cornea Section, who was not involved in the study, also spoke with MNT:
“Much of the research [into myopia] conducted in animal models remains in early stages and has not yet been evaluated in human clinical trials. Translating these findings into evidence-based recommendations will require substantial additional research on dosing, safety, and long-term outcomes in humans,” DeLoss said.
“In the interim, the AOA encourages parents to schedule yearly comprehensive eye exams for their children with a doctor of optometry, both to protect vision today and to ensure early access to proven, evidence-based myopia management options as they become available.”
