Blue light can have harmful effects on the eyes

Visible light is more complex than you might think. Stepping outdoors into sunlight; flipping on a switch indoors; turning on your computer, phone or other device – all of these result in your eyes being exposed to a variety of 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 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. 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 benefits and dangers. Sunlight is the main source of blue light, and being outdoors is where most of us get most of our exposure to it. But there are also manmade, indoor sources of blue light, including fluorescent and LED lighting and flat-screen televisions.

Notably, the screens of computers, smartphones and other digital devices emit significant amounts of blue light. The amount of HEV light these devices emit is 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.

Anterior structures of the adult human eye 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, macular degeneration and can effect your circadian rhythms.

There are 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 more information about Merrimack Vision Care, call 424-0404 or visit