Due to their compact size, low consumption of energy extended, and flexibility light-emitting diodes (LED) lights have found their way into everyday life. From LED bulb room lighting, cars to digital technologies such as TV backlighting, tablets, Smartphone backlighting and LED displays, a vast range of products are adopting LED technology.
However, this has raised fears among the general public and experts that the characteristic radiation of LEDs could have a negative impact on human health. Ophthalmologist and researchers are constantly warning about the dangers of the prolonged use of LED lights to the eyes in particular.
Is there really a danger and if so, why are LED lights dangerous to the eyes? Let’s understand some things about light and LEDs if you are not familiar, or just to brush up on the science without getting too deep into it.
About Light and LEDs
Light is electromagnetic radiation visible by the human eye in the range of 380 – 750 nm, going from violet to red light. Like all radiations, light carries energy, the shorter wavelengths being the most energetic ones. Think of how very high-pitched – high-frequency sounds pierce your ears.
LED’s use semiconductors to produce light from electricity rather than heating a filament as with incandescent lights. The color of an LED is determined by its semiconductor material.
Since there is a wide variety of LED types, making a general statement on LEDs is difficult. When talking about LED lights being harmful to the eye, we will look at the specific color known to harm the eye, which is BLUE in the 450-495 nm range.
Led’s use different materials to produce light of different colors. But even white LEDs emit blue light. This happens because LED’s are made with a blue-emitting semiconductor chip. Coated with phosphor, some of the blue light is absorbed emitting more long-wave radiation (green, yellow, and red).
A giant LED?
Why is the sky blue? That’s because the Sun is the main source of blue light. The high energy of blue light tends to scatter in the atmosphere, making the sky look blue.
Technology such as computer display screens and smartphones emit a lot of blue light, but not near as much as the Sun.
The issue is, we are not staring at the sun all day, but spend a lot of time staring at digital devices. This has many in the optometry field concerned about the long-term effects that blue light has on our eyes.
Blue light endangers the retina
High energy short-wave light is known to cause photochemical retinal damage. High energy photons are absorbed in the tissue and produce reactive oxygen. These free radicals, such as singlet oxygen molecules and hydroxyl radicals, attack cell structures and so may destroy photoreceptors.
The damaging effect for the retina increases with decreasing wavelength, as we have learned the shorter the wavelength the higher the energy level. Violet and Ultraviolet radiation are initially more dangerous than blue light.
However, blue light is the greatest danger for the retina of the adult eye, since the parts of the eye in front of the retina, especially the lens, absorb ultraviolet and violet light to a large extent. The resulting photochemical retinal hazard is described as the transmission of blue light.
The cornea absorbs wavelengths below 300 nm, and the lens absorbs less than 400 nm. The retina is at a higher risk as it absorbs the light over 400 nm that gets past the cornea and lens. Because high-energy blue light is around 380 nm to 460 nm, blue light that is problematic to the retina.
Light around 435 nm (±20 nm) can cause irreversible cell death in the highly pigmented cells that form the outer blood-retina barrier called the retinal pigment epithelium (RPE).
These numbers change throughout life. Children’s eyes absorb much more blue light than adults as the retina continues to develop into the teens.
Light transmittance is higher at a younger age, so protecting children’s eyes is especially important, because higher levels of UV and blue light can reach the lens and retina. With so many kids nowadays and their smartphones looking at blue light at all hours of the night, this is a major concern for them.
Blue light exposure and the risk of macular degeneration
For older adults, there is a concern that blue light exposure may increase their risk of age-related macular degeneration (AMD). The macula is the small central area of the retina responsible for central vision, the fine detail of what we see, and most of our color vision.
AMD causes a person to gradually lose their central vision while still maintaining peripheral or side vision. Macular degeneration is the leading cause of vision loss among older Americans, but blindness is rare.
Blue light effects on sleep
In addition to concerns about damage to the retina, blue light can interfere with the melatonin-driven human day-night rhythm. The formation of melatonin is controlled by the incidence of blue light into the eye. Melatonin is produced in the brain when in the dark when there is no light and decreases when there is light.
The blue light-induced inhibition of melatonin formation bodies makes us more alert, energized, and ready for work and play. As many people look at their digital devices right before bed, this can make it hard to sleep. Lack of good sleep is damaging to the health both physically and mentally
Protecting eyes against blue light
Light-emitting diodes are not the only sources of light that emit light in the blue spectrum. Fluorescent tubes and energy-saving lamps emit light in the spectral range of blue, violet, and ultraviolet light.
And let’s not forget the sun, since day one on earth, has been a light source with a strong blue component. Although you’re not going to stare into the sun all day or stare at a fluorescent bulb continually, all these sources exposing us to blue light can add up.
Sunglasses can help protect your eyes from the ultraviolet radiation of the sun and there are special anti-blue light glasses widely available now to wear while using a computer.
Always remember to head off any damage to your eyes you may have from any cause by scheduling regular comprehensive eye exams. You can also ask your ophthalmologist about prescribing protective lenses with blue light filters.