Love that iPhone or iPad or other phone or tablet or computer display? Long term, the blue light from cell phones and tablets and computer displays might have serious implications, and that’s no laughing matter, even if it takes 50 years for it to happen. It is particularly concerning since children from a very young age stare at cell phone or tablet screens for many hours. Excessive blue light is also linked to eyestrain and various health problems.
Observation: the Mac Pro 5K display can be run extremely bright, and looks to contain a lot of blue light.
Macular degeneration (retinal cell death) has been linked to blue light (380nm to 500nm). The term HEV (high energy visible) might also be heard. A sampler:
- Ultra-violet and Blue Light Aggravate Macular Degeneration
- Macular Degeneration Linked to Sunlight and Low Antioxidants
- Ensuring safety in LED lighting
- LED lighting and macular degeneration (all)
- A ban on screens in bedrooms may save kids’ sleep
- Effects of blue light on the circadian system and eye physiology
- Blue light exposed
To be clear, there is no scientific evidence yet that blue LED light will cause macular degeneration (leading to loss of vision) the same way sunlight does. It is a matter of intensity, duration of exposure, and almost certainly a complex interplay of personal factors (overall health, diet, genetics, etc).
LED (or solid-state) lighting sources are designed to emit all energy within the wavelength range of human vision, making LEDs the most energy-efficient commercially manufactured light. However, many current “white-light” LED designs emit much more blue light than conventional lamps, which has a number of health implications, including disruption of circadian rhythms (Holzman 2010).
The most popular LED lighting product, a phosphor-conversion (PC) LED, is an LED chip that emits blue light, which passes through a yellow phosphor-coating layer to generate the ultimate white light (Spivey 2011). Although the white light generated from LEDs appears normal to human vision, a strong peak of blue light ranging from 460 to 500 nm is also emitted within the white light spectrum; this blue light corresponds to a known spectrum for retinal hazards (Behar-Cohen et al. 2011). Some epidemiological studies have suggested that short-wavelength light exposure is a predisposing cause for age-related macular degeneration (AMD) (Wu et al. 2006). Animal models have also been used to determine that excessive exposure to blue light is a critical factor in photochemical retinal injury targeting photoreceptors and the retinal pigment epithelium (RPE) (Hafezi et al. 1997).
Things are often more complicated; tangled up in all this is the age factor: too little blue light can also be a problem, and age can be a mitigating factor of sorts because the lens of the eye yellows with age (yellow filters out blue). But if the damage accrues from youth to middle age, the yellowing lens is not of much help:
With age, the lens becomes more yellowish, and thus, the spectrum of blue light transmission dramatically decreases through the years. It is suspected that one reason older individuals experience sleep problems is the lack of blue light during the daytime.
Spectral transmission graphs
The closer the light wavelength is to ultraviolet (UV), the more damaging it becomes in general. This is true in general for skin cancer or killing viruses in water or degradation of plastics or paint or anything over time (just find any can or bottle that has been sitting in the sun for a long time). That’s because shorter wavelengths contain much higher energy levels (go beyond UV to X-Rays and killer gamma rays).
To assess UV/violet/blue exposure with a sunglass or contact lens, one would need a spectral transmission chart. Yet when I request spectral transmission charts no vendor has them, even first-class sunglass vendors like REVO. Statements like “blocks blue light” are presumably true, but ought to be backed up by hard 3rd-party evidence, that is, a spectral transmission chart showing just what is blocked—and this varies by the tint and coating of the lens used. Accordingly, I hope to actually measure the spectral transmission of sunglasses that I actually wear sometime soon.
The link between blue light and macular degeneration
Some cases of age-related macular degeneration may arise from a combination of low plasma levels of antioxidants and exposure to blue light from the sun, a multinational European study suggested.
The combination more than tripled the risk of the eye disease among individuals with the lowest combined levels of antioxidants, Astrid E. Fletcher, Ph.D., of the London School of Hygiene and Tropical Medicine, and colleagues reported in the October issue of Archives of Ophthalmology.
I’ve also spoken to an optometrist who regularly snapshots the retinas as part of eye exams, and he states (for my eyes and in general) that he has not observed any change in retina health in recent years. Thus theoretical lab tests are no subsitute for real-world scientific evidence as per retinal cells in human eyes, particularly given outdoor light exposure. That said, many of us spend many hours staring at bluish LED displays (cell phones, tablets, computer displays) and/or under LED or CFL lighting in the home or office.
The blue light from LEDs is now associated with retinal cell death. How much is too much is as yet unknown, but the evidence leaves little doubt that blue light kills retinal cells:
The relation between macular degeneration-retinal damage and exposure to light has been known since the middle of the 20th century. Nevertheless, in the last 5 years, the advent of new technology LED along with its massive use in screens of electronic devices (smartphones, tablets, laptops…) has made phototoxicity the main field of our research.
The studies conducted by the Complutense University of Madrid have shown that LED devices emit 5 times more toxic light than light reflected by paper or emitted by the older-style CRT monitors.
In-vitro experiments in which human donated retinal pigmentary epithelium cells were exposed to 36-hour circadian cycles of direct LED light of different intensities have been forceful: without protection, cell death amounted to 93%. However, when a protective element was placed between the cells and LED light, the survival rate of cells increased by 90%... Dr Sánchez-Ramos acknowledges that it may take another 10-15 years for research to demonstrate conclusively that LED light causes macular degeneration in the same way that sunlight does.
Nowadays, there's an increase in the use of digital devices and modern lighting—such as LED lights and compact fluorescent lamps (CFLs)—most of which emit a high level of blue light. CFLs contain about 25% of harmful blue light and LEDs contain about 35% of harmful blue light. Interestingly, the cooler the white LED, the higher the blue proportion. And by 2020, 90% of all of our light sources are estimated to be LED lighting. So, our exposure to blue light is everywhere and only increasing... Who's going to need the most protection? Those who have high exposure to white LED or fluorescent light bulbs in offices and homes, frequent users of LED computer monitors, tablets, or smart phones, and those at risk for AMD, particularly those at high risk, (those with family history, smokers, etc.).
Assessing the risks, protection
Given the lack of nailed-down scientific evidence, one has to make a personal assessment weighing the factors. But there are reasonable precautions to take, even ignoring the macular degeneration theory—sunglasses and blue-light-cut eyeglasses in particular.
Many companies are pushing solutions such as eyeglasses with blue-light-cut coatings, so the vested interests involved need to be considered. That said, blue light filtering eyeglasses might reduce eyestrain and this is easy enough to assess for anyone working at a computer for hours every day. Such solutions are thus appropriate to try, particularly if there is any evaluation period offered.
In my personal case, 10-12 hours daily computer usage seems to put me at high risk, which concerns me greatly. However, I don’t know how much blue light my LED computer displays emit, and I have no basis for knowing whether the risk is zero or something very significant.
Nor do I understand if configuring my NEC professional displays to run slightly warm (yellow) would reduce the risk (I would expect it would).
While I wear UV-blocking contact lenses* as well as sunglasses when outdoors, it’s not clear to me that my contact lenses block blue/violet light at all as when using a computer display. If they did so effectively, it would interfere with my assessment of color balance for photographs. So I suspect that I have no protection for computer work using just contact lenses.
* The Accuvue web site states that “UV-absorbing contact lenses are NOT substitutes for protective UV-absorbing eyewear such as UV-absorbing goggles or sunglasses because they do not completely cover the eye and surrounding area”.
I do a lot of cycling, and high quality sunglasses are very important to me. Hiking at extreme altitude is also considerations. At the least, high quality sunglasses are no-brainer for both comfort and eye protection. See my experience report with the Revo Guide S sunglasses at WindInMyFace.com.
Change the display
Professional displays offer the option of custom calibration, so that a display can be set to, say, 5000°K instead of the typical 6500°K. This is one solution that should greatly reduce the amount of blue light.