With Star Wars: The Force Awakens fresh in our minds, most of us see “dark side” and think lightsabers and Darth Vader. But did you know that light also has a dark side? What we know as “light” is actually just energy travelling in waves – a small portion of which our eyes are able to detect, allowing us to see. Light is divided into colors by wavelength – short wavelength visible light is blue while long wavelength visible light is red. All the other colors we see fall between the two. Since shorter wavelength = higher energy, blue light has the most energy of any visible light. If you go one step shorter than blue light on the wavelength spectrum you get ultraviolet light. Most of us are aware of the effects of ultraviolet light – it causes sun tans, sunburns, skin cancer, premature aging of skin, cataracts and other growths on the front of the eyes. Ultraviolet light is strong enough to kill bacteria and disinfect surfaces. Most of us, however, are not nearly as familiar with the harmful effects of blue light.
Everyone likes a beautiful blue sky or crystal clear blue water. But, the reason these things appear blue is the same reason blue light produces so much glare. Namely, blue light scatters most easily when coming into contact with a particle. The scattering of light contributes to glare, loss of clarity and loss of contrast when viewing things with high amounts of blue light (like computer and smartphone screens). As harmful as UV radiation is the great majority of it is absorbed by the lens and never reaches the delicate sensory tissue known as the retina. Blue light, on the other hand, is not absorbed at all before it reaches the retina. Thus, all of the energy of blue light (and remember, it’s the highest energy visible light there is!) reaches and then is absorbed by the retina. Studies have shown that the energy carried by blue light is enough to damage our retinal cells. There is evidence that prolonged exposure to blue light contributes to aging changes in the retina, the most serious of which is called macular degeneration. Macular degeneration is the leading cause of sight loss in those over age 74. Studies have shown those that spend more than 3 hours per day outdoors are 10 times more likely to develop macular degeneration due to the photostress bright light causes on the retina over time.
Recently there has been concern that smartphone and tablet screens may be harmful because they are held close to the eye and emit significant amounts of blue light. What makes these particularly problematic is that most of us are on them from basically the moment we wake up until right before we go to bed. Because this type of blue light exposure is new territory for mankind we really don’t know what the long term effects of this will be on the health of the eyes. Besides eye health concerns, blue light also influences melatonin release – which is important in regulating our sleep cycle. When we are exposed to blue light melatonin production is turned off and our brain thinks it is daytime. Thus, computer and smartphone use prior to bedtime can decrease both your ability to fall asleep and the quality of sleep once you do. Since our bodies need sleep to function properly, a decrease in either quantity or quality can contribute to a host of health problems over time.
The good news is that we have ways to decrease one’s blue light exposure. We now offer lenses that reflect or absorb from 30% to over 90% of blue light while maintaining relatively normal color vision (unlike the blue blockers of old many of you may remember). There are also supplements that have been shown to help protect the retina against the type of damage caused by blue light. These supplements, such as macuhealth, contain the macular pigments lutein, zeaxanthin and mesozeaxanthin. When it comes to blue or ultraviolet light prevention is key, so be sure to protect your eyes! And may the force be with you!
–Dean Amundsen, O.D. & Andrew Wilson, O.D.