Blue light is emitted from all handheld electronic devices as well as desktop and laptop computers and televisions. It is the shortest wave length light in the visible spectrum and causes significant damage to many parts of the eye seriously impacting present and future vision capacity. Damage from blue light from smartphones is particularly important because smartphones are often used in dim light and are used close to the eyes. Unlike ordinary computer vision fatigue, damage from blue light is serious, cumulative and irreversible.
How blue light exposure harms the eye
The shortest wavelengths of light, UV and blue light directly cause damage to the macula, retina and photoreceptors. The retina contains cells which are impacted by blue light in both the photoreceptors and the pigmented layer (RPE). Photoreceptors contain photo-pigmented cells which change and trigger other functions when they are struck by a photon of light. In the RPE pigmented cells absorb light and perform a number of functions. Both types of cells are vulnerable to blue light damage. 1
Blue light damages rods and cones
Recent research using mice has helped to explain just how and why the eye is damaged by blue light. Mice that were exposed to high levels of blue light displayed the following characteristics:
- massive irreversible cell death, identified as shrinkage of protein, DNA & RNA in cells in both the inner and outer layers of photoreceptors (rods and cones) in the retina.2
- leaking and rupture of fine capillaries in retina cone photoreceptors
- edema, or swelling of the retina
- development of cystoid spaces (cysts) further indicating edema
- changes in expression of certain proteins
- inner blood-retinal barrier damaged
In humans this translates to wide-spread leaking and rupture of tiny blood vessels in the photoreceptor level of the macula, in turn damaging the remainder of the macula – expressed in a number of vision conditions such as macular degeneration, choroid neovascularization, macular edema, retinitis pigmentosa, macular pucker, Stargardt’s, rod-cone dystrophy, and diabetic retinopathy.
Blue light damage triggered by rod cell protein
There’s a light-sensitive protein called rhodopsin which is found in photoreceptor rod cells which supports vision in dim light. Rhodopsin levels are low in bright light and high in dim light. This protein triggers retinal damage by blue light during dim lighting conditions.3 Furthermore, rods are more sensitive to blue light than cones, exacerbating the problem.4 This is the reason that it is important to not use computers or smartphones emitting blue light during dim light conditions.
Blue light damage to pigmented layer (RPE)
Retinal pigment epithelium is a single-cell layer within the retina that provides nourishment to the photoreceptor cells and protects the division between the retina and the rest of the eye. It contains pigmented granules that absorb scattered light; it secrets a number of signaling photochemicals; it forms an immune-safe barrier between the photoreceptors and blood vessels; and it is an essential part of the vision process.
Blue light damages the RPE. Just how blue light damages the RPE is somewhat obscure but it is clear that such damage does occur and that filtering (such as with amber glasses) prevents such damage.5
Blue light and eye cancer
Blue light is associated with significantly increased rates of cell division (mitosis) implicating it in uveal cancers. In some animal models, blue light was found to markedly increase the rate of cancer cell proliferation. In other animal studies where no uvea melanomas previously existed, exposure to blue light supported development of such cancers. Blue light has also been found to stimulate the development of DNA lesions, especially in the presence of free radicals.6
Blue light in low-light conditions
The damaging effects of blue light are more serious in low-light conditions. The reason is simple. In low light conditions the pupil enlarges to take in more light, and consequently the retina receives a larger dose of blue light. This is one reason to not use computers, smartphones and handheld devices (and TVs!) without other sources of light in the room.
Blue light damage in children
Children under aged 1-9 are particularly vulnerable to damage to the retina’s RPE and photoreceptor cells from blue light emitted by computers, smartphones and other handheld devices. This creates a dilemma for parents who find that providing children with handheld devices makes for peace in the family during long road trips, at the restaurant and other places where children get impatient with adult activities.
Until about age 9, young children’s eyes have not fully developed the protective pigment to help filter harmful blue light. Babies have little, if any, melanin pigment in their eyes. The only pigment in eyes is brown melanin. Whether we have blue, green, hazel or brown eyes simply depends on how much melanin is present – not whether there is blue pigment instead of brown pigment.7 Melatonin is important for filtering out blue light and when there is little or no melatonin, then blue light is more dangerous.
Additionally, in young children blue light appears to retard the development of retinal nerve cells.
For this reason it is very important that you restrict the use of handheld devices in young children. It is even more important that you restrict the use of such devices in dim light –the car at night time, the bedroom before lights out. Similarly it is very important that you make sure your children consume plenty of fresh fruits and vegetables with plenty of important carotenoids that help protect the eyes from blue light damage.
Blue light damage in people with blue eyes
For the very same reason that young children are more susceptible to damage from blue light adults with paler eyes are more vulnerable. People with blue eyes are the most vulnerable to damage from blue light; people with green eyes are slightly less vulnerable; those with hazel colored irises are less at risk; and people with brown eyes are the least at risk. This is why blue eyes are considered a risk factor for conditions such as cataracts and macular degeneration.
Blue light flicker phenomenon
One symptom of computer vision syndrome is caused in part by the blue light component of the visible light spectrum. Due to blue light’s short-wavelength nature it “flickers” more easily than longer, weaker wavelengths.8 Such flickering, not superficially noticeable, creates glare, reduces visual contrast, affects vision acuity and causes general eye strain, headaches and fatigue. This is yet another reason to take care with the number of hours you sit in front of your computer.
Blue light and sleep
The pineal gland secretes the hormone melatonin which is the body’s biochemical signal of biological darkness: in other words, that you are ready for sleep. Blue light suppresses production of melatonin9 to a surprisingly profound degree.10 If you are exposed to blue light right before bedtime (e.g. checking your email one more time) it throws off the internal rhythm that allows you to get adequate sleep. Nearly 3/4 of children now use some sort of electronic device in their bedroom. The use of these devices markedly impacts sleep quality which in turn contributes to social adjustment problems, behavioral problems in school and at home, and, surprisingly, weight gain.
Interestingly, researchers have found the delivering blue light directly to the hypothalamus, the part of the brain tied to sleep, causes animal subjects to briefly awaken.11
While most research on the effects of smartphones on sleep and circadian rhythms have involved children and teens, adults are also adversely impacted. One Flemish study of more than 800 adults, 50% of whom owned smartphones and 60% of whom used their smartphone during the night. Night time phone use and texting at night markedly increased how long it took to fall asleep and markedly decreased the quality, duration, and efficiency of sleep.
- In younger adults it was tied to more fatigue and later rise time
- in older adults it was associated with shorter sleep duration and earlier rise time.12
Similarly, it has been found that sleeping in a room that is not dark also has the effect of disrupting sleep or making it less effective in reducing fatigue and alleviated accumulated stress of the day. Exposure to light in the room during sleep at night reduces melatonin production by 50% in most studies.
How to protect the eyes from blue light damage
Nutritional support from Carotenoids
A recent in-vivo study found that certain nutrients directly protect the eye against the damaging effects of blue light. Carotenoids in bilberry and loganberry as well as N-Acetyl-l-cysteine (NAC, a potent antioxidant) were tested for their protective capacity. Bilberry has long been recognized for its vision-supporting capacity. It contains 15 different anthocyanins, and has strong antioxidant properties, inhibits blood clotting, improves circulation and blood vessel integrity, and reduces inflammation. Similarly, Loganberry contains trans-resveratrol and proanthocyanidins with strong antioxidant properties.
Cultures of photoreceptor cells were exposed to strong blue light, some of which had been pretreated with one or more of these three powerful antioxidants. Such pretreatment markedly reduced blue light damage by inhibiting a number of stress-response enzymes, proteins and other biochemicals which give rise to increased levels of free radicals that in turn cause cell death and the formation of special cells that surround and isolate cells slated for destruction.13
The amino acid taurine helps protect the photoreceptors through a process called rhodopsin regeneration. Rhodopsin is found photoreceptors at levels ten times greater than other amino acids.14,15 In its antioxidant capacity taurine also provides free radical fighting protection, especially for patients with diabetic retinopathy.16
Other important carotenoid antioxidants include lutein, zeaxanthin, meso-zeaxanthin and astaxanthin.
See our nutritional recommendations for computer eye strain.
Replacement lenses implanted during cataract surgery have for some time been designed to block UV radiation. Newer generations of such lenses also block blue light.17
Wear UV resistant sunglasses when you are outside. Favor sunglasses that are amber-tinted, reducing blue light, rather than grey, green or bluish lenses. Investigate glare screens for your desktop, laptop and hand-held displays that reduce blue light. Limit exposure to bluish (e.g., LED, florescent) based light but instead look for lighting options that simulate daylight with broad spectrum color.
Follow the 20-20-20 rule. Every 20 minutes that you use the computer or any electronic device, look at least 20 feet away for at least 20 seconds. This gives the tiny muscles in your eye a chance to relax.
- Jennifer J. Hunter, et al, The susceptibility of the retina to photochemical damage from visible light, Progress in Retinal and Eye Research, January 2012. ↩
- P. Geiger, et al, Blue light-induced retinal lesions, intraretinal vascular leakage and edema formation in the all-cone mouse retina, Cell Death & Disease, November, 2019. ↩
- C. Grimm, et al., Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching, Investigative Ophthamology & Visual Science, February, 2001. ↩
- S. Anstis, Why hearts flutter: Distorted dim motions, Journal of Vision, March 2015. ↩
- T. Narimatsu, et al, Blue light-induced inflammatory marker expression in the retinal pigment epithelium-choroid of mice and the protective effect of a yellow intraocular lens material in vivo, Experimental Eye Research, March 2015. ↩
- Patrick Logan, et al, Evidence for the Role of Blue Light in the Development of Uveal Melanoma, Journal of Ophthalmology, April, 2015. ↩
- Tamekia Reece, When Do Babies’ Eyes Change Color, Parents Magazine (online), December, 2015. ↩
- Where is Blue Light Found, bluelightexposed.com, https://www.bluelightexposed.com/#where-is-blue-light-found, December, 2015. ↩
- Joshua J. Gooley, et al, Exposure to Room Light before Bedtime Suppresses Melatonin Onset and Shortens Melatonin Duration in Humans, Journal of Clinical Endocrinology & Metabolism, December, 2010 ↩
- G. V. Vartanian, et al, Melatonin Suppression by Light in Humans Is More Sensitive Than Previously Reported, Journal of Biological Rhythms, August, 2015. ↩
- John Colapinto, Lighting the Brain, The New Yorker, May, 2015. ↩
- L. Exelmans, Bedtime mobile phone use and sleep in adults, Social Science & Medicine, December, 2015. ↩
- Kenjirou Ogawa, et al, Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro, BMC Complementary and Alternative Medicine, April, 2014. ↩
- The role of taurine in osmotic, mechanical, and chemical protection of the retinal rod outer segments, Petrosian AM, Haroutounian JE, Advances in Experimental Medicine & Biology 1998. ↩
- Taurine interactions with chick retinal membranes., Lopez-Colome AM et al, Journal of Neurochemistry, May, 1980. ↩
- X. Yu, et al. Dietary taurine supplementation ameliorates diabetic retinopathy via anti-excitotoxicity of glutamate in streptozotocin-induced Sprague-Dawley rats. Neurochemistry Research, March 2008. ↩
- Ibid, Logan, 2015 ↩