Visible light is much more complex than you might think.

Stepping outdoors into sunlight; flipping on a wall switch indoors; turning on your computer, phone or other digital device – all of these things result in your eyes being exposed to a variety of visible (and sometimes invisible) light rays that can have a range of effects.

Most people are aware that sunlight contains visible light rays and also invisible ultraviolet rays that can tan or burn the skin. But what many don’t know is that the visible light emitted by the sun is composed of a range of different-

colored light rays that contain different amounts of energy.

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.

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. 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 manmade, 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.

Anterior structures of the adult human eye (the cornea and lens) are effective at blocking UV rays from reaching the light-sensitive retina at the back of the eyeball, but not good at blocking blue light. Blue light exposure can cause eyestrain, lead to macular degeneration and can even effect your circadian rhythms and sleep pattern.

There are several filters and coatings that can be added to your lenses to help block harmful blue light. Ask your eye doctor about which type of vision correction and lens features best suit your needs for viewing your computer and other digital devices and protecting your eyes from blue light.

For more information about Merrimack Vision Care, call 424-0404 or visit merrimackvision.com.