The eyes are especially prone to certain types of oxidative and related damage with ultra violet and blue light from the sun being a primary culprit. Age-related macular degeneration (AMD) is a typical result of the aging process, as is the formation of cataracts. Prevent Blindness America estimates that AMD may affect 13 million individuals in this country. Cataracts impair the vision of roughly 4 million Americans. Some authorities estimate that thirty percent of all adults aged 70 and older suffer from some form of vision impairment. Diet may play a significant role in these age-related degenerations. In one study of 40 to 70 year olds, for instance, those who consumed fewer than 3.5 servings of fruits and vegetables per day had five times the risk for developing one type of cataract and 13 times the risk for developing another type of cataract when compared to those who ate more than 3.5 servings of fruits and vegetables daily.1
Much less well recognized than the threat to the eyes from sunlight is the threat posed by non-solar radiation sources. Is your computer a source of potentially damaging blue light? Yes, it is. Is your TV a potential threat? Yes, it is. How about your smart phone? Yes, it also emits blue wavelengths of light. In fact, many or even most sources of light-emitting diode (LED) white light emit significant amounts of blue light (short-wavelength) that may be harmful to the eyes. Compact fluorescent lamps (CFL) also emit blue light and may be even more health damaging overall due to the spectrum of their light compared to that of the LED as attested by comparisons in animal models.2
LED Light—the Good, the Bad and the Ugly
The LED has many virtues compared with more traditional light sources and one does not need to be an engineer to appreciate this. Who wants to lug around a cathode ray tube in order to watch TV or have a computer monitor? Indeed, are modern portable laptops and smart phones even possible without some version of LED or related technology? Moreover, is it at all likely that sitting in front of, i.e., on the receiving end, of a cathode ray tube can be made safe from the type of radiation that such devices require to activate screens? The answer to these questions and others clearly is “no” in most cases. Modern screen and lighting technologies offer many advantages over those that came before. Nevertheless, these advantages should not blind us to potential problems.
That various wavelengths of ultraviolet light pose risks for cataract formation and macular degeneration, particularly in those over the age of 40, has been known for decades. These wavelengths are not within the visible spectrum leading to a tendency to overlook threats from sources of visible light. In addition to UV radiation, short blue visible light (400–440 nm) is a risk factor for the adult human retina even though this wavelength of light is not essential for sight and not necessary for a circadian rhythm response.3 Many indoor sources of light emit short blue visible rays and the risks become significant after age 50. There even is a name for the retinal damage induced by commercial LEDs, phototoxicity.4
Unfortunately, even teenagers and college students are not immune to exposure to short blue rays, albeit the effects may not show up in the eyes. A study published in 2011 testing responses in young male volunteers found that with five hours of exposure the “spectral profile of light emitted by computer screens impacts on circadian physiology, alertness, and cognitive performance levels.”5 A later study using tablet displays found that melatonin levels (hence sleep and performance dependent upon the natural secretion of melatonin) were not affected by one hour of exposure, but that two hours of exposure led to a significant impact.6 Looking at a variety of studies, it appears that, at least in teenagers and college students, the tipping point of when exposure to screen light becomes significant depends upon the brightness of the screen, other sources of light and related factors with two hours being the shortest exposure that, at least in short-term studies, was clinically meaningful.7,8 Importantly, in a study with teenage subjects which lasted for a week rather than just a day, it was clear that evening exposure to light-emitting diode screens did lead to melatonin suppression in the evening and to undesirable increased vigilant attention and subjective alertness before bedtime.9 In other words, standard teen and college habits of extensive computer use before bedtime does have an impact over the long term.
Of course, computer screens are not the only indoor sources of short blue light. Television screens are sources, smart phones are sources, fluorescent and other backlighting may be sources, and so forth.10 Those of us over the age of 50 already tend to produce less melatonin due to age and, unlike teenagers and college students, short blue light in quantity potentially is a hazard to us in terms of our sight.
Blue Light Solutions
One obvious solution to risks from blue light is the use of lenses and/or contact lenses that filter these wavelengths. Experimental trials have been ongoing for this approach for years and there is no doubt that, assuming that reducing risk is ones only concern, such an approach can help. However, tradeoffs in terms of visual acuity, inconvenience and other such factors make this solution less than idea.
Another solution, one readily available for computer monitors, is software that can be used to shift the light balance from blue to red at night by altering computer settings. Something similar can be accomplished by means of filters to be attached to TV screens. Downsides include screens that are dramatically less bright with white light that is less “white” and blue colors and all colors that depend on blue components, such as green, being less vibrant. As solutions, again, these are not ideal.
Fortunately, there are food/herbal/nutritional supplement solutions that can be quite helpful, at least for the eye protection if not against the impact of too much evening light on melatonin production. Some of these nutritional alternatives were covered in considerable depth in “Focus on the Eyes,” TotalHealth, 2013. In that article many alternatives were outlined, including sources of lutein and zeaxanthin, bilberry extract, grape seed extract, etc.
Lutein and zeaxanthin continue to be the favorites for protection against damage by blue and ultraviolet light.11 New clinical research is expected to be published in the spring of 2016 that will further demonstrate the protective effects of these two carotenoids and demonstrate that, in this case, more really is better. Similarly, current research continues to support the protective effects of bilberry and lingonberry extracts. A recent in vitro trial looked specifically at the protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage.12
As concluded in an earlier article, the eyes are vulnerable organs. The sun is the most familiar threat to the long-term health of the eyes and recent studies have not altered this observation. However, short wave blue light sources, especially the LED, have become pervasive in the modern environment in terms of lighting, computer screens, television monitors, smart phones and so on. Despite the many benefits of these modern light sources, they are not entirely innocuous. Restraint should be exercised in their use, especially in constant close proximity. Fortunately, it remains the case that deterioration can be protected against to a remarkable degree through sound dietary practices and a judicious use of special herbs and other supplements that complement sound nutrition.