How to take care of eyes for computer users: Screen cover, App, both…?

Question: Is it your view, that you’re covered, if you have Iris blue light app on every digital screen device – that you don’t need a screen cover – or do you use both? I’m considering Reticare screen cover for both retinal care and insomnia. I am under the impression that it works for both. If you don’t agree, I would love to hear from you.

Answer: What seems best to take care of my eyes may not be the best for you! So, please, don’t take me as an example of anything.

But since you asked, I am very much focused on mitigation/prevention of eye strain. I use an app (f.lux or Iris – depending on which I am testing) and a physical filter (a screen cover or blue blocking glasses – depending on room lighting). Here is a more thorough description of everything I do. (As a positive side effect that also covers retinal care and insomnia :).

However, you should know that my office lighting is very specific (unusual?). Also, I am a moderate-to-bad case of chronic computer eye strain and light sensitivity. As such, I find benefit in using a physical filter in addition to an app.

What is best for you, will also depend on several issues that are specific to you.

Since many other digital device users are wondering how to take care of their eyes, it might make sense to expand on the factors that might influence the decision between screen covers, blue light apps, and other types of blue light filters. Specific detail comparing Reticare and Iris is also provided.


Is there a need for computer users to take care of their eyes?

Everyone whose work, livelihood, and career depend on the intensive use of digital screens should be thinking about how to take care of their eyes in order to prevent computer eye strain, insomnia, and (possibly) age-related macular degeneration (AMD). This advice is from someone who’s suffered the first two. (Your question shows you are being smart about it).

When computer eye strain hits hard one might not be able to stand even a few minutes of screen time and might dread moments spent in offices lit by fluorescent or LED lights. If this happens, the causes are very hard to identify and even harder to treat quickly and effectively. Some of us had to quit a screen-based job and even reconsider our careers because of it. (The consequences of chronic insomnia or AMD may be similar or worse).

Still, there is no need for panic!

Extreme cases of eye fatigue or insomnia caused in part by screen-based work are not that common. Moreover, it has not been demonstrated that AMD could be caused by screen exposure. In fact, based on the weakness of digital screen (blue) light -when compared to the Sun’s- scientists hypothesize (short of evidence) that digital screen blue light CANNOT cause damage to our sharp vision [The Visual Effects of Intraocular Colored Filters (2012)].

However, while we are waiting for more conclusive research findings, it seems better to be safe than sorry.

Still, it seems fair to advise caution because extreme cases -often chronic- of eye strain, photophobia, insomnia, etc. sometimes do happen. I am one, and I get letters from people who have found themselves in a similar situation – in some cases as early as during undergraduate studies. But it is more likely to happen to people in their thirties, forties,… They have likely acquired a high degree of specialization that depends on screen work. Also, they likely have a family that depends on their income. Taking time off and making a career shift in such circumstances is tough.

Also important, digital screen blue light does not seem to be the only cause of eye strain or insomnia, but it does seem to contribute importantly to the problem in those who are predisposed to computer eye strain and light sensitivity. It’s also been found that computer eye strain can negatively affect sleep. In turn, insomnia can negatively affect eye fatigue by not providing sufficient time for our eyes to recover. Hence, both retinal care and digital screen impact on sleep are important.

Disclaimer: My interest in how to take care of eyes for computer users comes from my blue light related problems with light sensitivity (photophobia), discomfort glare, insomnia and computer eye strain. I am not a physician nor a vision scientist.

Disclosure: Some of the links in the article are commission links. You can help sustain GLARminY – at no additional cost to you – by “donating” a small percentage of any product you might buy from Amazon. Thanks for your help!


How to compare blue light filters

What uniquely defines a blue light filter is by how much it reduces the intensity of the different blue light wavelengths: ~400-500nm for computer eye strain and retinal care, ~400-550 for insomnia.

Blocking 100% of blue light might be a safe bet since science can still not tell you what is the best filter for you. But filtering out all blue light might be an overkill for many people. The best way to know what spectral transmission you need is to try on different ones. Here is a handy way to test 8 different filters – or you can also try different settings on a free bluelight app.

Another resource is a table of 80+ blue light filters sorted from stronger to weaker. It shows the range of different spectral filtering properties available in the market.

You seem interested in prevention (assumption based on you not mentioning any existing blue light-related symptoms). This means that you might be OK with a milder reduction of blue light (bottom third of the above-mentioned table). But I could be very wrong.


Reticare screen cover: Reasonable for retinal care & insomnia prevention

Excess blue light seems to be the major concern for the retinal care and insomnia prevention. In that respect, the main advantage of screen covers (or other physical blue blockers) is their ability to filter all blue light. Blue light apps cannot, although they can get close.

However, in the specific case of the Reticare screen filter, 100% blue blockage is not a determining factor, because Reticare is not designed to filter all blue light at any of the blue light wavelengths (at ~440nm it filters the most blue light, some 55-60% – see below).

In general, Reticare screen filter [also available on Amazon (commission link)] could be an excellent option for eye strain, insomnia, and retinal care. Reticare screen cover’s spectral transmission resembles a lot the spectral transmission of our macular pigment:

RetiCare blue light screen protector spectrogram fluxometer

how to take care of eyes for computer users macular pigment spectrogram

This property makes Reticare unique among the screen covers available in the market (and also among other blue light filters). You can see how such a filter should be well suited for people whose macular pigment might not filter all the blue light it should.

Macular pigment is a blue light filter inside our eyes. Its function is to improve acuity and protect our central retinas from blue light. It makes sense that a blue light screen filter designed to achieve the very same goal would have similar spectral transmission properties.

Therefore, Reticare is certainly an interesting option for retinal care and eye strain prevention.

That is as long as we are speaking about prevention. People who have already developed AMD, light sensitivity, or other eye strain symptoms, might need a stronger blue light filter!?

Reticare might also be a good choice to prevent digital-blue-light-induced sleep disorders because it blocks far more blue light up to 520nm than most screen covers in the market. Only LowBlueLights’ screen cover blocks more blue light and might be suitable for those whose sleep might be very sensitive to minimal amounts blue light.

However, a good blue light app can (among other benefits) achieve a similar reduction in blue light as the Reticare screen cover.


Blue light apps

One of the strengths of the better blue light filter apps is that you can choose the level of blue light reduction (see below – source: fluxometer).

The digital screen used for this example is from Retina MacBook Pro 2014 (the effect on other digital screens would be similar). Unfortunately, data for Iris (the blue light app you mention) is not available, but based on my experience with both Iris and f.lux, it seems reasonable to assume the reduction is comparable at similar CCT settings, for example at 2700K, 4100K, …

The first spectrogram below shows spectral power distribution of a Retina MacBook Pro 2014 screen displaying white with NO blue light reduction. Note the typical high peak in the blue region (at about 450nm).

How to take care of eyes for computer users Bluelight app screen cover Retina Macbook Pro 2014 SPD no reticare no flux


The next spectral power distribution reading is from the same screen but with a Reticare screen filter covering it. Note that (as expected based on the Reticare transmission spectrogram above) light intensity is reduced across the entire visible light spectrum (~380-760nm) but by far the most in the blue range. Subsequently, the three peaks (blue, green and red) are about equally strong.

How to take care of eyes for computer users Bluelight app screen cover Retina Macbook Pro 2014 SPD reticare no flux


Below you may examine spectral power distributions of Retina MacBook Pro 2014 with f.lux running at different settings (in the order of appearance: 4100K, 3400K, and 2700K – as denoted by the darker blue buttons at the bottom of each image). Note that at 3400K f.lux already achieves lower blue light emissions than the Reticare screen cover.

How to take care of eyes for computer users Bluelight app screen cover Retina Macbook Pro 2014 SPD no reticare flux at 4100K


How to take care of eyes for computer users Bluelight app screen cover Retina Macbook Pro 2014 SPD no reticare flux at 3400K


How to take care of eyes for computer users Bluelight app screen cover Retina Macbook Pro 2014 SPD no reticare flux at 2700K


Important: the default settings of f.lux or Iris allow more blue light during the day and less in in the evenings (which is fine for insomnia). If you need lower blue light emissions throughout the day (AMD and/or digital eye strain), you have to set up your app appropriately.

Finally, fluxometer also shows spectral power distributions with both f.lux blue light filter app and Reticare screen cover. To see the impact of both, go to fluxometer and click the different buttons for f.lux settings in the row of buttons under the spectrogram.


So, what will it be: a screen cover, a bluelight app, both,…?

The choice of how to take care of your eyes may, in addition to blue light reduction criteria, depend on a unique set of factors. You not only have a unique sensitivity to digital screens but are also using digital devices in unique ways and under unique lighting conditions.

Below is a list of some other issues you might want to consider. In doing so you might have to also look at alternatives to Iris and/or Reticare.


Do you need blue light protection to cure or to prevent

For prevention purposes, it seems that either Iris or Reticare could be fine.

If you are already suffering from a certain blue light related condition the decision will not be as simple because your tolerance to light abuse has dropped significantly. Here are some articles you can look at depending on your condition:
What is the best blue light filter for migraine glasses
Macular degeneration glasses & blue blocking AMD products guide
How to pick the best blue filter for your light sensitivity problem (focus on insomnia, glare/light sensitivity, and computer eye strain)
How to reduce eye strain headache from fluorescent lights


Your blue light sensitivity

Either way, but particularly if you are looking for a cure it might make sense to test your blue light sensitivity to make it easier for you to decide among the many options of blue light filters available in the market.

Blue light filter Tester S

You can also test you blue light sensitivity with a free blue light filter app, f.lux (here are the instructions how you can go about it).

Once you know if you are blue light sensitive and how sensitive you are, you can consult this table to find the most appropriate blue blocking solution.



If (where you normally use digital screens) lighting is aggressive – very bright and high in blue light content, you might consider blue blocking glasses because they protect your eyes from digital screens and from harsh lighting, which is something that screen covers and bluelight apps can’t.

The level of protection from lighting depends also on how tightly the glasses wrap around your face.


Screen brightness level and Veiling glare

The level of screen brightness may condition the choice of a blue light filter. To reduce blue light emissions emitted by darker screens a bluelight app tends to be more appropriate because it is less likely to cause veiling glare than screen covers.

The darker the screen, the more it reflects objects facing it (like a mirror). Seeing reflected images on the screen is particularly notorious with glossy screens – something similar happens if you use a glossy cover.

The article: Do computer glasses protect your eyes from digital screens: Veiling glare problem gives some suggestions as to the appropriateness of screen covers vs. glasses.

Also, if you have a matte screen – a blue light app will generally cause less veiling glare than a screen cover. That is because, unfortunately, many blue blocking screen covers are (fairly) glossy.

Conversely, if you have a glossy screen and veiling glare is bothering you, you should get a matte screen cover. If it doesn’t block (enough) blue light, use it with a bluelight app.


Flicker sensitivity

Low screen brightness may be another source of eye strain for those who are sensitive to flicker.

Flicker sensitivity may be a good reason to use a blue light app. Good blue light apps, such as Iris and f.lux, provide flicker-free brightness control functionality.

The blue emissions control and brightness control can be adjusted independently of each other.

Unfortunately, if (via the app) you “lower brightness too much”, the text to background contrast may drop below the comfortable (non-eye-straining) level.

Also, bluelight apps don’t give you (m)any options in the color for text and background.


Screen background color

Screen brightness can also be reduced using darker background colors (see the How to instructions for Windows 7 & popular applications, browsers, or for Windows 10).

Note that by choosing colors wisely (warm colors) you can also reduce blue light emissions of your screen.

(When I must work in normal lighting conditions – and not in my glare and reflection free office – I cannot use black background due to veiling glare. Hence I use regular black text on off-white background theme with:
– the screen set to full brightness,
– a blue light app at about 2700K and dimmed to about 70-80% brightness, and
– a DIY screen cover (orange – blocks all blue light up to about 490nm).
(The screen cover is glossy because you can’t get matte filter gels, but at 100% screen brightness, the light from the screen is strong enough to eliminate veiling glare).


Other factors

There are several other possible side effects of different filters:
– discomfort in using them,
– some blue blocking tints cause nausea in some people,
– aesthetics,
color distortion, and
refraction– and reflection-related distortions of light passing through any physical filter which reduce acuity, blur vision and often lead to eye strain.
In any of these cases, a bluelight app might be the most appropriate.


One final recommendation: Consider improving your macular pigment

The most important recommendation particularly for retinal care and eye strain is to improve their macular pigment through diet and/or supplementation. It is not an immediate solution but it should work in a matter of a few weeks.

Macular pigment is by far the best blue light filter. Not only because, when not depleted, its spectral transmission properties perfectly match our eye’s needs, but also because:
– it is an anti-oxidant that slows/stops oxidative processes at the macula, i.e. AMD [Effects of the Macular Carotenoid Lutein in Human Retinal Pigment Epithelial Cells (2017)],
– it doesn’t interfere with our low-light vision – it is placed only in front of the photoreceptors for sharp (daytime) vision, and also
– it is natural.


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