How to prevent eye strain from computer screens is a critical question for the more blue light sensitive. Science suggests that blue light emitted by computer screens (and other energy saving light sources) is a frequent cause of visual stress. Solution: a blue light filter. Yet, if you decide to get one, the options may be overwhelming. Most blue light filters tend to sell themselves as the solution to any blue light associated condition: eyestrain, insomnia, AMD, etc. Yet there are significant differences in how they filter blue light, and by how much. The inevitable result is confusion not only among users but also among eye care professionals. Below you may learn how to prevent eye strain and with which blue light filter.

Contents:
what are the symptoms of eye strain
are you more blue light sensitive
causes of eye strain
why computer light causes eye strain
how blue light filters help prevent eye strain
how to compare different blue light filters
should you always block 100% of blue light
the different options of blue light filters available online and their effectiveness
how can you know which blue light filter will help you prevent your eye strain


Updated: October 20, 2017. This post was originally published on July 30, 2015, and has been completely revamped and updated for accuracy and comprehensiveness.

Disclaimer: I am NOT a vision scientist nor a physician but a more computer glare and light-sensitive person. Hence, my interest in how to prevent eye strain with blue light filters. If you wish to add or discuss something below, please, do write about it in comments or send me a note for the benefit of other readers.

Disclosure: GLARminŸ earns a small commission (at no additional cost to you) if you use the links labeled (commission link) and purchase a product. Thanks for supporting GLARminŸ!


 

What are the symptoms of eye strain?

Scientists suggest the following: eyestrain, tired eyes, sore eyes, dry eyes, watery eyes, irritated eyes, contact lens problems, blurred vision, slowness of focus change, double vision, presbyopia, neck pain, back pain, and shoulder pain [Computer Vision Syndrome: A review (2015)].

But, if you don’t identify with any of the above and you spend considerable time with digital screens, you might also consider reviewing the terminology ordinary people use when searching for solutions to their eye strain. (In case you thought you were alone: there are 1-10 million computer eye strain related searches each month on Google alone).

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Are you more blue light sensitive

If you are not more sensitive to blue light you don’t need to worry about how to prevent eye strain caused by it.

Many people do not experience eye strain (or other issues) because of blue light and report no benefits of blue light filters. They dislike blue light filters because they distort color. Remember, you can’t block blue light and see it too. Moreover, apparently their acuity gets worse. Obviously, for these people the negative effects of blue light, if any, are not sufficiently important (see below what explains these differences).

If you are experiencing computer eye strain and you have already eliminated other possible causes, such as for example glare and reflections on your screen, you might be among the more blue light sensitive.

The simplest way to find out if you are more blue light sensitive might be with fire. If you find glare (contrast in brightness) disturbing, but you can stare into a flame – in otherwise complete darkness – without any pain, chances are you are more blue light sensitive. This is because light emitted by a normal flame from a candle, match, wood, emits almost no blue light (see spectral power distribution of a candle below).

Candle spectral power distribution

Then, there are a couple of slightly more sophisticated methods.

 

Use a free app to test blue light sensitivity

If you don’t know whether computer blue light could be causing your eye strain see: Are you sensitive to light … or just blue light? The guide explains how you can use a free blue light filter app to test your blue light sensitivity. It’s easy!

 

Or a blue light filter test kit

You can also test your eyes’ sensitivity with a blue light filter Tester with 8 different blue light filters:

Blue light filter Tester S

This option will give you more information about your sensitivity and suggest the best suited blue light filter for it.

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What causes computer eye strain

Intense use of the eyes is the generic cause of eye strain – or asthenopia – in a person with normal vision. Activities that likely cause eye strain are extended periods of driving, reading, writing, sewing, … and of course, the use of digital screens. Secretaries, accountants, bookkeepers, draftsmen, are some obvious jobs with a greater risk of eye strain [Is all Asthenopia the Same? (2003)]. But as we are becoming increasingly digitized (at work and otherwise) the experience of computer eye strain is starting to affect everyone.

Moreover, digital screens bring about a host of new challenges for our eyes (see article: What causes computer vision syndrome).

 

How blue light causes computer eye strain

On average computer screens tend to emit blue light with much greater intensity than other, longer wavelengths of visible light. This is because the predominant color in most GUIs is white. To make it worse, white is often combined with blue.

Yet, blue light disturbs our sharp vision because of blue light scatter, chromatic aberration, and because the spot of our precision vision is not sensitive to blue light but to longer wavelengths (green and red).

And sharp vision is what we use for screen-based activities. Therefore, computer eye strain develops.

Unless our natural blue light filter – macular pigment – blocks enough blue light to prevent it.

Or we use external/artificial blue light filters.

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How to compare different blue light filters

The only way to compare blue light filters is based on their spectral transmission/transmittance. It describes uniquely a filter’s transmission properties by telling you what percentage of light passes through the filter for all different wavelengths.

Spectral transmission may be given in a table or plotted in a graph – spectrogram (click to see an example). A table normally has two columns. The first column contains wavelength data in nano meters (nm) with % transmission in the second column.

Often, only data for visible light wavelengths are shown, i.e. from ~380nm – ~750nm.

The image below explains how to read a spectrogram:

Blue light filter - how to interpret spectrograms

Spectral transmission curve describes what proportion of each light wavelength the filter lets through (% Transmission) and what proportion it blocks (100%-% Transmission).

Blue light filters should be compared across the entire visible spectrum, but particularly on the interval from 400-500nm, which are considered to be the blue light wavelengths. (If your problem is insomnia, you might have to go a bit higher – to about 550nm).

Put simply: filters with a lower curve from 400-500nm transmit less blue light, or the same thing said differently, block more blue light.

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Should you always block 100% of blue light?

No. Blue light is not bad.

Throughout evolution people were exposed to blue light emitted by the Sun. Our body needs and uses blue light’s oscillating intensity (high during the day and low or none at night) to regulate various biological and behavioral processes and function properly [Measuring and using light in the melanopsin age (2013)].

The photoreceptors principally responsible for this regulation are most sensitive to blue light. However, they are placed all over the retina except its center, where our sharp vision takes place. Therefore, on the one hand it is good and normal, that your eyes get full spectrum light from the Sun, including blue light.

On the other hand, #as shown above#blue-light-eyestrain#, our central vision must be shielded from blue light for maximum acuity and eye comfort. It is therefore unfortunate (for those with less effective macular pigment) that digital screens display images by emitting lots of blue light.

Hence, if your eye strain is really bad, you might consider blocking all blue light up to 500nm or even higher. However, if you do that during the day, you should also make sure you take brakes outside, to expose your eyes to all the benefits coming to us via sunlight.

However, even to carry out long lasting computer tasks, blocking 100% of blue light with artificial filters might be an overkill. Your macular pigment already filters some blue light, but you don’t know how much. Is your MPOD hi, low, somewhere in between, or irregular? Unfortunately having it measured is not an easily accessible option. But, you can get an idea with one of the methods suggested above, particularly with GLARminŸ Tester.

(In case you are reading this for reasons other than eye strain, there is a subtle difference between blue light-induced insomnia, migraines, AMD, etc. and eye strain. You can read about it in How to pick the best blue filter for your light sensitivity problem.)

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The 10 blue light filters to prevent eye strain

Below you may find a list of blue light filters divided into three sections: the natural solution, software, and physical blue light filters. As suggested #above#, the natural solution – our macular pigment – is superior, as long as its MPOD is high enough.

A good software blue light filtering solution may provide superior viewing comfort than a physical filter by preserving contrast better. A physical blue light filter always reduces contrast. It also produces internal and surface reflections of light, even when it includes an anti-reflective (AR) coating.

The downside of software solutions is that they can never reduce blue light emissions to 0, which physical filters can.

If you find the choices and the spectral transmission data information overwhelming consider reading first the post: How to pick the best blue filter for your light sensitivity problem.

The list below includes only blue light filters for which data about their spectral transmission is available because if not, you don’t really know what exactly you are getting. And, if you try a no-spectrogram filter and it doesn’t help you, you won’t know what to try next. Thus you miss an opportunity to learn something about your eyes. Moreover, you might simply conclude that blue light filters don’t work for you, which may or may not be true!?

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Macular pigment: our natural blue light filter

Macular pigment, its advantages, and interpersonal variability have been #suggested above#. For more info see Less light sensitivity, computer eye strain: BlueLight filtering diet.

The shape of macular pigment spectral transmission curve shows our natural blue light filter blocks blue light considerably between 430-490nm (maximum at ~460nm). This could be a good indication of where and by how much we need to block blue light with external filters, to prevent eye strain.

macular pigment as blue light filter spectrogram

This curve is for MPOD score at 0,5. MPOD score ranges from 0 (blocks least blue light) to 1 (highest blue blocking capacity). This means that for MPOD scores higher than 0,5 the curve would be lower than the one in the image, while for lower scores the curve would be higher. Source: fluxometer.

If supplementation appeals to you more than eating a bucket of green, leafy vegetables a day, see the article on best eye supplements containing all three macular pigment carotenoids – lutein, zeaxanthin, and meso-zeaxanthin. (If interested, see also a summary of my experience with macular pigment supplements).

Note that the effect is not immediate – supplementation might show results in 8-12 weeks, and your MPOD might plateau in 6-12 months.

Moreover, some people appear to be genetically pre-conditioned to lower MPOD or irregular macular pigment shape.

You may buy macular pigment supplements from Amazon US (commission link); or Amazon UK (commission link).


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Software blue light “filtering” solutions

Strictly speaking, software solutions do not filter blue light. Instead, they reduce screen’s blue light emissions by altering the colors displayed by your digital screen. In most cases, the reduction of blue light cannot be 100%, because the software is restricted by the limitations imposed by the hardware.

Color distortion depends on how much blue light you’ll want to take out. Colder colors – white, blue, green – are transformed into warmer, yellow-ish colors.

 

Blue light filter apps

Preserving contrast is a very important feature/advantage of a blue light filtering app because low contrast reduces readability thus causing computer eye strain.

There are two different approaches used by blue light filtering apps: Color transform approach is superior because the alternative, transparent overlay, reduces contrast far more.

You may easily recognize which approach an app is using by looking at what it does to black. Color transform leaves it unchanged because black has the lowest possible blue light content. Overlay approach, on the other hand, makes black look lighter (usually yellowish or reddish) thus reducing the contrast between black and other colors unnecessarily.

There are two blue light filter apps that use color transform approach:
f.lux – free; designed principally to help with blue light induced insomnia; for Windows, Mac, Linux, and iPhone/iPad and Android
Iris (commission link) – freemium; designed to prevent computer eye strain and insomnia; for Windows, Mac, and Linux (Iris for Android uses transparent overlay approach due to system’s limitations).

Essentially they both do the same thing – i.e. reduce the amount of blue light emitted by your screen. Therefore they may both be used for both eye strain and insomnia. However, there are some differences such that if your principal goal is to avoid computer eye strain you might find Iris more suitable. In terms of preventing insomnia they are very similar (for a full review see Best blue light filter apps for visual comfort: Iris & f.lux).

Spectral power distribution (SPD) of screen emissions at different f.lux settings are available at fluxometer.com. SPDs in the case of Iris are similar for the same CCT settings.

For example reductions in blue light emissions running f.lux/Iris are:
– 70-80% (varies from screen to screen) when running at 2700K CCT (correlated color temperature)
– 94-98% when running at 1200K
See spectrograms below – click to enlarge – the first is with f.lux off, i.e. 6500K, second at 2700K, and third at 1200K)

Blue light filter app efficiency NO FLux Spectrographic analysis Blue light filter app efficiency FLux at 2700K Spectrographic analysis Blue light filter app efficiency FLux at 1200K Spectrographic analysis

As set by default, f.lux will run at 6500K during the day (no blue light reduction) and closer to 2700K at night. That might be fine if your problem is insomnia. To prevent eye strain, it is preferable to set f.lux/Iris to a lower CCT setting day and night.


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DIY blue light filter app: Change screen colors

Changing text and especially background color is a free and easy DIY version of a (color transform) blue light filter app. Changing background and text color is a good option if you mostly read of the screen, edit text or work with spreadsheets.

The advantage is that you can select any color you want and control the contrast level.

Disadvantage: Not everything will appear as one would like to – particularly some buttons on web pages might be hidden or text on them invisible.

Depending on your background/text color choice and digital screen model it may “filter” up to 75-95% of blue light as compared to black text on white background (estimates based on LEDMuseum and f.luxometer data).

You may find detailed instructions on how to change background color and text color in:
Windows 7, Adobe Acrobat, Firefox, Chrome, Internet Explorer, etc…
Windows 10

Choosing background color well is key to reducing blue light emissions of your digital screen; see Least likely colors to cause computer eye strain.


 

Bluelight filter app & color change

You can combine the two approaches, thus filtering blue light with the app and also being able to choose the colors your screen displays. Remember that the app will distort your colors, so if you care a lot about the exact colors displayed, you should set the app to the desired setting first and carry out color changes with the app running.


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Physical blue light filters

As commented, a major drawback to physical blue light filters is that they always reduce contrast, however, this doesn’t seem to bother everyone. Contrast reduction is significantly lower with filters/lenses that have an Anti-Reflective (AR) coating.

Blue light filtering capacity of physical filters depends principally on filter’s tint color and its darkness (in some cases blue blocking coating or certain materials within the lens). The most common blue light filtering tints are yellow (amber), orange and red:
Red tinted filters may block all light except red, so blue will be blocked entirely. Subsequently their overall, visual light transmission is the lowest and color distortion the greatest.
– Filters tinted yellow tend to block the least blue light, but provide greatest visual light transmission and lowest color distortion.
Amber/orange filters are somewhere in between.
(If interested, play with different filter tints to see how their color affects spectral transmission here or here).

Also, it is wise you check return policy before ordering a blue light filter you haven’t used yet. You can’t really know if it will work until you try it. Also, use this table compare filters based on transmission of blue light.

 

Blue blockers – computer glasses

There are tons on the market. However you’ll see your choices greatly reduced if you need prescription (Rx), or anti-reflective (AR) coating, or care about the style of computer glasses frames. If on top of that you care about spectral transmission (as you should) you may be left with just handful or, sadly, in the worst case, no choices.

All this info has been pulled together in this article on computer glasses with known filter specs (spectrograms included) – in the image below you might recognize some of the featured brands (links to online stores that sell them are provided, where available).

Best blue blocking computer glasses


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Glasses with FL-41 blue light filtering tint

Some people find relief from blue light filters with very particular spectral transmission characteristics. FL-41 tint was originally designed to reduce eye strain from fluorescent lights. Later it was also found to help many people with migraines and some Benign Essential Blepharospasm symptoms [Diagnosis, Pathophysiology, and Treatment of Photophobia (2016)].

These are among the more expensive blue light blocking glasses. The vendors themselves admit that while they work great for some people, they don’t produce desired effects with others, or produce negative side effects, for example nausea. Testing the tints with the blue filter Tester before ordering FL-41 glasses might save you time and money (particularly if you need prescription glasses).

 

Axon Optics FL-41 glasses and contacts

Disclosure: I’ve tested a pair of glasses with indoor tint, courtesy of Axon Optics: The glasses are very high quality. For me other blue light filters appear more suitable, which, however, doesn’t mean you shouldn’t try FL-41 tint. I don’t suffer from Migraines nor Blepharospasm, and there is much praise by happy customers out there.

Axon indoor tint spectral transmission properties available here (similar to GLARminŸ Tester Filter 6).

– blue light filtered: ~50% (indoor lens)
– visual light transmission: ~60% (indoor lens), ~20% (outdoors lens)
– UV absorption: 100%

Sources: Axon Optics (private communication), f.luxometer

You may purchase Axon Optics FL-41 glasses, fit-overs, and soft contact lenses from Axon Optics (commission link):
several frame models available including wrap-arounds with a removable inner gasket which contours to the exact shape of your face to keep any unwanted light out
– you can also send in your own frame and have regular or prescription Rx FL-41 tint lenses fitted.



 

TheraSpecs FL-41 glasses

Along with Axon Optics (above), TheraSpecs is another vendor that offers quality FL-41 tint on their migraine relief and fluorescent light sensitivity eyeglasses [Diagnosis, Pathophysiology, and Treatment of Photophobia (2016)].

TheraSpecs Indoor Lens spectrogram available here – similar to GLARminŸ Tester Filter 4

– blue light filtered: ~70% (indoor lens)
– visible light transmission: ~43% (indoor lens)
– UV absorption: 100%

You can buy TheraSpecs’ many frame designs including fit-over glasses from Amazon (commission link) or directly from TheraSpecs online shop



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Blue blocking screen filters

There are many screen protectors claiming impressive blue blocking properties. However, meaningful spectral transmission characteristics are available only for a handful of them.

Data on all screen filters has been collected as long as they provide some minimal spectral transmittance data. Where available spectrograms are included (see brands included in the image below).

Best blue light screen filters Reduced

The above mentioned article also explains how you can make your own, DIY screen filter for under $10: huge selection of filters and known spectral transmittance for all!


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Fit-overs and Clip-on Flip-ups that filter blue light

For those who wear prescription glasses it sometimes makes sense to use blue blockers that fit over prescriptions.

Axon (commission link) and TheraSpecs fit-overs with their FL-41 tint were already mentioned above.

Uvex fitovers with amber or orange lens are an inexpensive (under $10) option:

Uvex Fit-Overs Blue light filter Amber Orange lens

UVEX Amber lens spectrogram:
– blue light filtered ~ 55%
visible light transmission: 90%
– UV absorption >= 99.9%

UVEX SCT-Orange lens spectrogram:
– blue light filtered >= 98%
visible light transmission: 45%
– UV absorption >= 99.9%

Source: Uvex

You may buy Uvex Amber or Orange fit-overs from Amazon (commission link).



 

Cocoons fit-overs with yellow (lemon) or orange lens (available in various designs and sizes):

Yellow (lemon) lens:
blue light filtered 40% (100% up to 470nm) – source: Cocoons
visible light transmission: 86%
– UV absorption: 100%

Orange lens:
blue light filtered 100% up to 520nm
visible light transmission: 34%
– UV absorption: 100%

You may buy yellow or orange Cocoons fitovers from Cocoons.


 

NoIR might have the greatest selection of blue blocking tints. It also has several fit-over frames.

NoIR just updated their site and it is truly great. Each lens tint comes with a spectrogram and all the different frames available for that tint. Exemplary!

You may shop their blue blocking Fit-overs and Clip-on Flip-ups at NoIR online store.


 

Cocoons SideKick clip-on flip ups with yellow or orange lens:

Cocoons SideKicks clip-on yellow orange lens blue light filter

Yellow (lemon) lens:
blue light filtered 40% (100% up to 470nm) – source: Cocoons
visible light transmission: 86%
– UV absorption: 100%

Orange lens:
blue light filtered 100% up to 520nm
visible light transmission: 34%
– UV absorption: 100%

You may buy Cocoons SideKick clip-on flip ups in three sizes (M, L, XL) from from Cocoons.


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How can you know which blue light filter will work for you

Having reviewed the all the options above, you might feel overwhelmed. Over the last two years many people wrote to me asking more or less: so which one will work for me? Unfortunately, nobody can tell you that. You have to try and see what works for you.

To help find the answer that question more quickly and inexpensively, I recently made available GLARminŸ Tester, a blue light filter test kit, to help you find the optimal blue light filter for your eyes. It has:
– 8 blue light filters with different spectral transmission characteristics
a comprehensive table of all marketed blue light filters (with available spectrograms). They are ordered from blocking more blue light to less and grouped based on spectral transmission similarity to the 8 Tester Filters

The Tester can be worn over prescriptions.

Blue light filter Tester S

 

Ps: If you found this post 10 blue light filters to relieve computer eye strain, help sleep better, etc. useful, please consider LIKING, REBLOGGING, and/or SHARING it below.

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