You can reduce computer eye strain and light sensitivity with diet! Light sensitivity and computer eye strain may be due to low macular pigment, your natural bluelight filter. Nearly 80% of Americans have this condition! Research shows that low macular pigment is associated with lower threshold of light sensitivity or discomfort glare (Enhancing performance while avoiding damage: A contribution of macular pigment; 2013). Moreover, since glare is a known computer eye strain cause (Computer vision syndrome: A review; 2014) low macular pigment, i.e. lower threshold to glare, may make you more prone to computer eye strain. Luckily macular pigment bluelight filtering capacity can be improved with appropriate fruit and vegetable diet or dietary supplements (Lutein and zeaxanthin dietary supplements raise macular pigment density and serum concentrations of these carotenoids in humans; 2003).
Light sensitivity: Intrapersonal variability in discomfort glare threshold
Light sensitivity (photophobia) appears to be a behavioral mechanism that protects the macula, the region of the retina, which is the most important for our visual performance (Enhancing performance while avoiding damage: A contribution of macular pigment; 2013). Glare and brightness lead to visual discomfort: photophobia or discomfort glare (The Visual Effects of Intraocular Colored Filters; 2012). It is manifested in an aversive instinctive reaction to strong light, i.e. squinting, blinking, or an impulse to look away (Action spectrum for photophobia; 2003).
If light sensitivity is a good thing, then you probably wonder:
- why other people don’t find exposure to a certain level of light brightness (or glare) as disturbing as you do, and
- why other people don’t experience computer eye strain often working in computer lighting and screen brightness conditions you find unbearable?
Recent research suggests that one possible cause (perhaps the most common one) for intrapersonal variation in light sensitivity threshold is due to important variations in macular pigment optical density (MPOD), i.e. its blue light filtering capacity (Macular pigment optical density and photophobia light threshold; 2006).
Computer eye strain and MPOD score variability hypothesis
Given the apparent absence of research on macular pigment bluelight filtering capacity and its influence on computer eye strain I contacted Dr. Stringhan, a vision scientist investigating macular pigment, particularly in its relation to glare and light sensitivity. (Coincidentaly he is currently conducting a study on MPOD and its influence on computer eye strain, so in a few months we’ll know more on the subject). Here are the conclusions of our exchange of ideas:
- Glare is a commonly recognized cause of computer eye strain (Computer vision syndrome: A review; 2014), though not the only cause of comptuer eye strain, nor the most important one (other causes).
- Given macular pigment bluelight filtering (glare and light sensitivity reducing) function it seems reasonable to expect that low MPOD, i.e. low macular pigment bluelight filtering capacity, is a risk factor for developing computer eye strain.
- People with significantly low MPOD would be at an especially high risk of developing computer eye strain, because of their low discomfort glare threshold (greater light sensitivity).
Low macular pigment optical density score and computer eye strain stated differently:
You have low MPOD and hence low threshold to discomfort glare. This means that you are particularly sensitive to blue light which produces discomfort glare at low intensity levels (Retinal sensitivity to damage from short-wavelength light; 1976).
When you use digital display devices you expose your eyes to high blue light intensity relative to other colors in the visible spectrum (see below – source fluxometer – spectral readings for many other devices available – you might find yours among them). Note that the sun’s light is much more intense (~360 – 1000 times) but more evenly spread throughout the visible spectrum. (Caution: the scale on the vertical axis varies – click on images to see detail).
Digital device blue light’s intensity is not high enough to make you immediately look away, probably not even high enough to cause damage to the photoreceptors in your macula – age related macular degeneration, AMD (The Visual Effects of Intraocular Colored Filters; 2012). If, however, your macular pigment is low, blue light intensity may be high enough to gently irritate your neurophysiological protective mechanism that mediates visual discomfort. This gentle irritattion goes on for hours, days, … years! (Remember that during this time your macular pigment likely continues to wear out). Sooner or later you start feeling the accumulated irritation in a form of chronic computer eye strain.
In the meanwhile people with higher macular pigment bluelight filtering capacity never notice any eye strain, or if they do it is due to other computer eye strain causes, which, by the way, may also contribute to your computer eye strain.
Disclaimer: My interest in vision science comes from my problems with light sensitivity (photophobia), discomfort glare, and computer eye strain. This post was motivated by my recent discovery of the research on macular pigment, its bluelight filtering function and the huge intrapersonal variability in its bluelight filtering capacity.
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Macular pigment, our intraocular bluelight filter
Blue light is also called High Energy Visible (HEV) light. It carries more energy than other visible wavelengths and is thus able to penetrate deeper into the eye and cause damage to the photoreceptor layer of the eyes’ retina, i.e. age-related macular degeneration – AMD (The Visual Effects of Intraocular Colored Filters; 2012). Hence the need for a bluelight filter.
Macular pigment (the yellow spot found in the inner layers of the central retina) protects the most photosensitive portion of the eye where the light is focused and vision is sharpest, the macula.
Macular pigment’s function is to protect biological tissue, i.e. the photosensors behind it. It does so in two ways: acting as an anti-oxidant and by selectively absorbing/filtering bluelight (The Visual Effects of Intraocular Colored Filters; 2012). Macular pigment’s anti-oxidant function is very important for the long-term health of our vision as it helps prevent AMD. The same solutions (provided below) that increase macular pigment’s bluelight filtering capacity also build its anti-oxidant power (more information here).
Macular pigment, as a bluelight filter, absorbs light almost exclusively in the blue region of the spectrum.
With peak absorbance at ~460nm, it matches peak intensity wavelength of white sunlight (Influence of the dietary carotenoids lutein and zeaxanthin on visual performance: application to baseball; 2012).
Moreover, macular pigment’s absorbance band coincides with the blue light part of the spectrum (~400-530nm). This is where bright white light (from the sun, artificial lighting or digital displays) carries most of its energy (Macular pigment and its contribution to visual performance and experience; 2010).
It’s been shown that blue light provokes discomfort glare (photophobia) at substantially lower intensity levels than other, longer wavelength lights (Retinal sensitivity to damage from short-wavelength light; 1976).
Variability in macular pigment bluelight filtering capacity
Macular pigment optical density (MPOD) – a measure of macular pigment’s quality as a bluelight filter – varies significantly – by the factor of 10! – from person to person (Individual variations in the spatial profile of human macular pigment; 1997). It is normally depleted with ageing when not replenished through adequate diet – mostly fruits and vegetables.
Variable bluelight filtering capacity means that macular pigment’s effectiveness in reducing light sensitivity (and in visual acuity improvement, detail enhancement, contrast enhancement, and protection from age related macular degeneration – AMD) also varies significantly between different people (Macular pigment and visual performance in glare: benefits for photostress recovery, disability glare, and visual discomfort; 2011. Glare disability, photostress recovery, and chromatic contrast: relation to macular pigment and serum lutein and zeaxanthin; 2013).
Moreover, the effect of low discomfort glare (photophobia) threshold to blue light tends to be exaggerated in people with low macular pigment bluelight filtering capacity (Action spectrum for photophobia; 2003).
As summarized in the image below a surprising majority of people have suboptimal macular pigment bluelight filtering capacity. A healthy macular pigment should filter 80% of blue light or more. However, only one person out of five has macular pigment capable of that (The Visual Effects of Intraocular Colored Filters; 2012).
How can you know if your macular pigment bluelight filtering capacity might be low
While it is best to have your MPOD measured, there is also a a free blue light filter app that can help you check if you might have low macular pigment bluelight filtering capacity. This post explains how you can do it. If by turning the app on you feel a great relief, you are more likely to have lower MPOD.
Fruit and vegetable diet increases Bluelight filtering capacity of macular pigment
External bluelight filters such as tinted glasses or filters covering your digital display (here a list of 10 external bluelight filters) are a quick solution for light sensitivity, i.e. low macular pigment bluelight filtering capacity (Influence of the dietary carotenoids lutein and zeaxanthin on visual performance: application to baseball; 2012). They might help you reduce your computer eye strain, although most external filters increase the risk of other (non-bluelight) computer eye strain causes: contrast reduction and reflections.
Over the longer-term the bluelight filtering (and anti-oxidant) function of your macular pigment is best improved through fruit and vegetable diet (or macular pigment dietary supplements) because the carotenoids absorbed from food into our macular pigmentare anti-oxidants and protect your macula fromdegenerative processes (Macular pigment and its contribution to vision; 2013). No external bluelight filter can do that!
Bluelight filtering diet that contains macular pigment forming carotenoids, lutein and zeaxanthin, has high content of egg yolk, fruits, and vegetables. A good rule of thumb is to look for fruits and vegetables that are yellow, orange or leafy green (dark): corn, parsley, spinach, orange peppers, kiwi, pumpkin, oranges, basil, kale, leek, etc. For more information on foods rich with macular pigment carotenoids lutein and zeaxanthin along with exact quantities/concentrations contained check NutritionData or click on the tables below.
- Xanthophyll (lutein, zeaxanthin) content in fruits, vegetables and corn and egg products; 2010
- Dietary sources of lutein and zeaxanthin carotenoids and their role in eye health; 2013
- Fruits and vegetables that are sources for lutein and zeaxanthin: the macular pigment in human eyes; 1998
Note: BlueLight filtering carotenoids (lutein, zeaxanthin and meso-zeaxanthin) are lipid/fat-soluble (not water), therefore you should take carotenoid rich foods or supplements with your fattiest meal.
BlueLight filtering dietary supplements
Recent research favors supplements containing meso-zeaxanthin in addition to lutein and zeaxanthin
Improvements in macular pigment optical density have been detected as early as two weeks into daily supplementation and MPOD appears to plateau in about one year in most people (Macular pigment and visual performance under glare conditions; 2008. Augmentation of Macular Pigment Following Supplementation with All Three Macular Carotenoids: An Exploratory Study; 2010. Sustained supplementation and monitored response with differing carotenoid formulations in early age-related macular degeneration; 2015).
Optimal visual function and protection of the eye is achieved when the three macular pigment carotenoids (lutein, zeaxanthin and meso-zeaxanthin) work together.
Until recently it was believed that supplementing lutein and zeaxanthin was sufficient because (according to the predominant hypothesis) lutein is bioconverted into meso-zeaxanthin within the macular pigment. However, recently this theory is being challenged. It appears that a sizeable proportion of the population cannot convert lutein into meso-zeaxanthin (see an 8 min video on macular pigment, its functions, deficiencies and treatment by a leading macular pigment scientist).
For these people fruit and vegetable diet rich in lutein and zeaxanthin won’t be sufficient. They also need meso-zeaxanthin.
Meso-zeaxanthin is extremely important because it has the highest antioxidant potential and is highly concetrated at the center of macular pigment (see image above), protecting the portion of the macula that is subjected to most stress from light (Distribution of Lutein and Zeaxanthin Stereoisomers in the Human Retina; 1997). It has been shown that some people can only achieve a typical central peak (where meso-zeaxanthin dominates) when supplemented with all three macular carotenoids (Macular carotenoid supplementation in subjects with atypical spatial profiles of macular pigment; 2012).
Therefore, to be safe, vision scientists recommend supplements containing all three macular carotenoids, including meso-zeaxanthin, to achieve normal macular pigmnet density distribution within the retina, and hence optimal vision, macular health, and visual comfort / light sensitivity.
You may buy supplements containing all three macular pigment carotenoids – lutein, zeaxanthin, and meso-zeaxanthin at Amazon: US/Canada-based readers (commission link); UK/EU-based readers (commission link).
After you’ve tried bluelight filtering diet or supplements, do come back and let us know how it’s going!
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