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Blue light facts: Is blue light bad for your eyes?

What is blue light?

Visible light contains a range of wavelengths and energy. Blue light is the part of the visible light spectrum that contains the highest energy. Because of its high energy, blue light has more potential to cause harm to the eye than other visible light.

Blue light and visible light

White light is the light produced when all wavelengths of visible light are combined. Sunlight on a clear, smog-free day is natural, full-spectrum white light.

White light can be separated into different color bands, based on wavelength. The main color bands within white light are:

  • Blue

  • Green

  • Yellow

  • Orange

  • Red

Individual wavelengths of white light form a continuous spectrum of color. Each of the five color bands listed above has its own range of wavelengths and shades of that color.

Digital electronic devices emit blue light that can cause eye strain and may lead to eye problems over time.

The wavelength of each light ray determines both its color and energy. Light rays with short wavelengths have more energy, and those with longer wavelengths have less energy.

Within the entire visible light spectrum:

  • Blue light has the shortest wavelengths and highest energy.

  • Red light has the longest wavelengths and lowest energy.

Wavelengths of light are measured in nanometers (nm). A nanometer is one billionth of a meter — that's 0.000000001 meter!

The visible light spectrum includes light rays with wavelengths that range from 380 nm on the high-energy blue end of the spectrum to about 700 nm on the low-energy red end of the spectrum.

Visible light is just one type of electromagnetic radiation (EMR), which is radiation that has both electric and magnetic fields and travels in waves. EMR comes from natural and man-made sources and varies in strength from very low energy to very high energy. Types of electromagnetic radiation (from low to high energy) include:

  • Radio waves

  • Microwaves

  • Infrared light

  • Visible light

  • Ultraviolet (UV) light

  • X-rays

  • Gamma rays

Only visible light can be seen. All other types of EMR are invisible.

The blue light spectrum

Blue light ranges in wavelength and energy from 380 nm (highest energy to 500 nm (lowest energy). So, about one-third of all visible light is blue light

Blue light is further categorized into these (high-energy to low-energy) subgroups:

  • Violet light (roughly 380-410 nm)

  • Blue-violet light (roughly 410-455 nm)

  • Blue-turquoise light (roughly 455-500 nm)

Because of their higher energy, violet and blue-violet rays are more likely to damaging to the eye. For this reason, these rays (380-455 nm) also are called "harmful blue light."

Blue-turquoise light rays, on the other hand, have less energy and appear to help maintain a healthy sleep cycle. For this reason, these rays (455-500 nm) are sometimes called "beneficial blue light."

Invisible ultraviolet (UV) rays lie just beyond the highest-energy (violet) end of the blue light spectrum. UV rays have shorter wavelengths and more energy than high-energy visible blue light. UV radiation has been proven to be damaging to eyes and skin.

Blue light facts

To better understand the risks and benefits of blue light, here are a few things you should know:

1. Blue light is everywhere.

Sunlight is the main source of blue light. Most of your exposure to blue light occurs when you're outside during the day. But there are artificial sources of blue light as well — including computer and phone screens, and fluorescent and LED lights.

2. Blue light makes the sky look...blue.

Blue light rays scatter more easily than other visible rays when they strike air and water molecules in the atmosphere. This greater degree of scattering of blue light is what makes a cloudless sky look blue.

3. The retina is susceptible to blue light.

The cornea and lens are effective at blocking UV rays from reaching the light-sensitive retina at the back of the eyeball. But virtually 100% of high-energy visible blue light passes through these structures and reaches the retina.

4. Blue light might increase the risk of macular degeneration.

The fact that blue light reaches the retina is important. In laboratory studies, blue light has been shown to be harmful to light-sensitive cells like those in the retina. The damage resembles that caused by macular degeneration, which can lead to permanent vision loss.

More research is needed to determine how much blue light from sunlight and digital devices is “too much" blue light for the retina. But many eye doctors are concerned.

It's possible that blue light exposure from extensive use of digital devices might increase a person's risk the of macular degeneration later in life. Until long-term population studies can be done, though, it's too soon to tell.

5. Blue light contributes to digital eye strain.

Blue light scatters easily and is the first to go out of focus. Poorly focused blue light reduces contrast and can contribute to digital eye strain.

6. Blue light protection is important after cataract surgery.

A cataract is a clouding of the natural lens inside the eye. During cataract surgery, your surgeon will replaced the cloudy lens with a clear intraocular lens (IOL) to restore your vision.

Some IOLs protect the retina from blue light better than others. Ask your cataract surgeon for advice about which IOL is best for you.

Also, be sure to wear sunglasses that block blue light (as well as 100% UV light) when outdoors after cataract surgery. When using digital devices, wear computer glasses that provide better blue light protection than standard reading glasses.

7. Not all blue light is bad.

Long-term exposure to high-energy blue light may have risks, but some blue light exposure is essential for good health. So, 100% protection from all blue light is not a good idea.

Beneficial blue light (455-500 nm) boosts alertness, helps memory and cognitive function, and elevates mood. Also, beneficial blue helps regulate circadian rhythm — our natural wakefulness and sleep cycle.

But too much blue light at night can cause sleep problems, daytime fatigue, and even serious health problems.

Blue light filters and protective eyewear

A convenient way to reduce your blue light exposure is to apply a blue light filter to the screens of your digital devices. These filters are available for smartphones, tablets and computers of all sizes.

Computer glasses also can reduce blue light exposure from digital devices. These special-purpose glasses are available without an eyeglass prescription if you don't need corrective lenses or if you wear contact lenses to correct your eyesight.

If you have nearsightedness, farsightedness or astigmatism, prescription computer glasses can optimize your vision specifically for computer and phone use. This is especially important if you also have age-related presbyopia.

If you're over age 40 and need progressive lenses or bifocals, consider prescription computer glasses with single vision (one-power) lenses. These customized lenses will give you a much larger field of view for seeing your entire screen clearly.

Keep in mind, though, that computer glasses are for seeing objects within arm’s length only. Do not wear them for driving or other distance-vision needs.

Some anti-reflective coatings for eyeglasses and computer glasses (such as Essilor's Crizal Prevencia AR Coating) provide an added degree of blue light protection.

You may also want to consider all-purpose prescription glasses with photochromic lenses. They protect your eyes from UV and blue light and automatically darken in sunlight to increase comfort and reduce glare outdoors.

See your eye doctor or optician for more advice on the best computer glasses for viewing your screens and protecting your eyes from blue light.


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