¿Cómo ayudar a los niños a protegerse de la luz azul? Un apoyo de Vision Kids!

Between LED lights and digital screens, our children are increasingly exposed to blue light. Concerns about its possible effects on their health are growing: both the retina and circadian rhythms could be affected. But how can we protect them? Screens and filtering lenses seem to offer limited help, while enhancing the intake of nutrients that make up the eye’s natural defenses has proven to be a more promising strategy.

The use of LED lights has gradually increased from the 1990s to today, driven by the necessary attention to the economic and environmental costs of lighting indoor spaces. As a result, our exposure to blue light — of which LEDs are particularly rich — has increased. 

The proliferation of digital devices such as computers, tablets, and smartphones has also contributed; the backlighting system of their screens, in fact, uses LEDs.

Considering that today we spend more than 90% of our time indoors, often in front of screens or exposed to artificial lighting, an important question has arisen: does increased exposure to blue light affect our eyes and overall health?

Indeed, the use of digital screens has been associated with undesirable effects on vision. Blue light triggers reactions in most eye tissues, particularly in the cornea, the lens, and the retina. 

Depending on the type of blue light we are exposed to, temporary or permanent damage may occur. Even if the immediate consequences seem insignificant, experts are concerned about potential long-term effects, especially for children, who will likely spend a greater portion of their lives exposed to high levels of blue light.

Furthermore, while concerns mainly focus on increased exposure to blue light from artificial sources, it is important to remember that this light exists everywhere in our environment and also comes from the Sun, the Moon, and flames. 

The intensity of this natural blue light varies throughout the day — highest at noon and lower at dawn and dusk — and is influenced by latitude, altitude, weather conditions, and the season.

The human body has evolved to use these changes in light intensity to regulate circadian rhythms, meaning the functions that must synchronize with the passage of day and night, such as the sleep-wake cycle. It is therefore reasonable to ask whether increased exposure to blue light may also influence these rhythms.

Let us therefore explore the potential risks associated with increased exposure to blue light and how to reduce them, focusing especially on the part of the eye that seems most at risk: the retina.

What the retina is and how it works

The retina is a structure composed of ten layers containing cells capable of capturing and interpreting visible light (400–700 nm). 

Its innermost layer contains the nerve fibers of the optic nerve, which transport the signals captured by the retina to the brain and distribute them to its various areas. 

The outermost layer (the pigment epithelium) is essential for supplying the retina with nutrients necessary for the proper functioning of the two structures classically associated with vision: cones and rods. It is also essential for retinal development, for counteracting oxidative stress caused by light exposure, and for other key processes needed for healthy eye function.

Cones and rods capture light, but they are not the only retinal cells capable of doing so. Deeper within the retina are the intrinsically photosensitive retinal ganglion cells (ipRGCs), which contain melanopsin — a pigment that absorbs blue light in particular.

Stimulation of ipRGCs by blue light plays an important role in light responses that are not related to image perception. Thus, blue light is involved both in vision and in other light-related physiological processes. 

What blue light is and its effects on the eyes

Blue light is the highest-energy electromagnetic radiation within the visible spectrum. It can be divided into two categories: blue-violet light (380–450 nm, also known as “high-energy violet”) and blue-turquoise light (450–500 nm). 

Most research has focused on blue-violet light, but blue-turquoise light can also reach the retina, reducing melatonin levels (a key hormone in regulating sleep) and consequently affecting circadian rhythms. Light exposure also stimulates the release of dopamine and serotonin, neurotransmitters that influence mood.

As for the effects on ocular structures, shorter wavelengths can alter the surface of the eye by generating oxidative stress and inflammation and inducing cell death. 

In the retina, prolonged exposure to blue light increases reactive oxygen species, promotes deposits and microvascular changes — all associated with age-related visual problems. Photoreceptors decrease, lipids oxidize, and cells die.

Blue light can also damage the lens, particularly during aging, causing gradual yellowing and increasing cataract risk.

Studies conducted to date suggest that even short exposures at doses considered safe may influence the functioning of rods and cones, and that blue light can trigger toxic effects even at intensities commonly found in our homes.

Some research has focused on digital screens, revealing chronic damage associated, for example, with exposure to smartphone screens for more than 8 hours per day over more than 5 years. The damage appears to involve all retinal layers and seems cumulative and time-dependent.

More recent studies suggest additional effects unrelated to vision, such as a possible role of blue light in triggering migraines.