Visible light is much more complex than you might think.

What Is Blue Light?
Sunlight contains red, orange, yellow, green and blue light rays and many shades of each of these colors, depending on the energy and wavelength of the individual rays (also called electromagnetic radiation). Combined, this spectrum of colored light rays creates what we call “white light” or sunlight. The electromagnetic rays just beyond the red end of the visible light spectrum are called infrared — they are warming, but invisible. (The “warming lamps” you see keeping food warm at your local eatery emit infrared radiation. These lamps also emit visible red light when they are on. On the other end of the visible light spectrum, blue light rays with the shortest wavelengths (and highest energy) are sometimes called blue-violet or violet light. This is why the invisible electromagnetic rays just beyond the visible light spectrum are called ultraviolet (UV) radiation. So approximately one-third of all visible light is considered high-energy visible (HEV) or “blue” light.

The Perils And Benefits Of UV
UV rays have higher energy than visible light rays, which makes them capable of producing changes in the skin that create a suntan. In fact, the bulbs in tanning booths emit a controlled amount of UV radiation specifically for this reason.
But too much exposure to UV causes a painful sunburn — and even worse, can lead to skin cancer. These rays also can cause sunburned eyes — a condition called photokeratitis or snow blindness. But ultraviolet radiation, in moderation, also has beneficial effects, such as helping the body manufacture adequate amounts of vitamin D.

Key Points About Blue Light
Like ultraviolet radiation, visible blue light — the portion of the visible light spectrum with the shortest wavelengths and highest energy — has both benefits and dangers. Here are important things you should know about blue light:

Blue light is everywhere.
Sunlight is the main source of blue light, and being outdoors during daylight is where most of us get most of our exposure to it. But there are also many man-made, indoor sources of blue light, including fluorescent and LED lighting and flat-screen televisions.
Most notably, the display screens of computers, electronic notebooks, smartphones and other digital devices emit significant amounts of blue light. The amount of HEV light these devices emit is only a fraction of that emitted by the sun. But the amount of time people spend using these devices and the proximity of these screens to the user’s face have many eye doctors and other health care professionals concerned about possible long-term effects of blue light on eye health.
Apple Released Blue Light Filter In iOS Update For iPhones And iPad

HEV light rays make the sky look blue.
The short-wavelength, high-energy light rays on the blue end of the visible light spectrum scatter more easily than other visible light rays when they strike air and water molecules in the atmosphere. The higher degree of scattering of these rays is what makes a cloudless sky look blue.

Blue light exposure may increase the risk of macular degeneration.
The fact that blue light penetrates all the way to the retina (the inner lining of the back of the eye) is important, because laboratory studies have shown that too much exposure to blue light can damage light-sensitive cells in the retina. This causes changes that resemble those of macular degeneration, which can lead to permanent vision loss.
Although more research is needed to determine how much natural and man-made blue light is “too much blue light” for the retina, many eye care providers are concerned that the added blue light exposure from computer screens, smartphones and other digital devices might increase a person’s risk of macular degeneration later in life.

Blue light contributes to digital eye strain

Because short-wavelength, high energy blue light scatters more easily than other visible light, it is not as easily focused. When you’re looking at computer screens and other digital devices that emit significant amounts of blue light, this unfocused visual “noise” reduces contrast and can contribute to digital eye strain. Computer glasses that block blue light may increase comfort.
Therefore, computer glasses with yellow-tinted lenses may increase comfort when you’re viewing digital devices for extended periods of time. Your eye doctor can recommend lenses and filters that protect your eyes from blue light.

Not all blue light is bad.
So, is all blue light bad for you? Why not block all blue light, all the time?
Bad idea. It’s well documented that some blue light exposure is essential for good health. Research has shown that high-energy visible light boosts alertness, helps memory and cognitive function and elevates mood.
Also, blue light is very important in regulating circadian rhythm — the body’s natural wakefulness and sleep cycle. Exposure to blue light during daytime hours helps maintain a healthful circadian rhythm. But too much blue light late at night (reading a novel on a tablet computer or e-reader at bedtime, for example) can disrupt this cycle, potentially causing sleepless nights and daytime fatigue.

Very important: Always make sure you discuss and make decisions about your eye care based upon a formal appointment with your optician.

For more information please call us or visit
KOBRIN & MARTIN OPTOMETRISTS, SANDTON
Tel: 011 884 8413 | kobrinmartin@telkomsa.net