The Myth of Blue Light & Eye Strain
I get a consistent trickle of advertisements hoping to sell me blue light glasses to protect my eyes from my screens.
They usually look something like this:
400,000 eyes saved from blue light?!
Unfortunately, this claim is exquisite quackery.
I’ll start to deconstruct the myth of blue-light-induced eye strain by quoting directly from the American Academy of Ophthalmology’s Statement on this topic. *Ahem*
“Digital eye strain is not caused by blue light.” (Porter & Gregory, Blue Light and Digital Eye Strain 2020)
You really can’t ask for a more straightforward statement from a more credible institution.
While one (statistically underpowered) study did in fact correlate the use of blue light filter glasses with reduced symptoms of eye strain, [1] many more show no benefit on those symptoms or on long-term markers of ocular health. [2, 3] A systematic review of the literature came to the same conclusion: there is no evidence for blue-light glasses benefitting the eye health of computer users. [4]
So, now you know — if anyone tries to sell you glasses in order to protect your eyes from blue light, you can justifiably suspect they’re a quack. As much as I love quack-slaying, though, I think it’s a useless endeavor unless you follow the criticism up with something constructive. (In fact, one of my biggest pet peeves is when “science people” merely myth-bust without steering the conversation towards a conclusion that helps us figure out what to actually do or not do.)
The Actual Cause of Digital Eye Strain
The thing you should know about digital eye strain is that it is real — it’s just that blue light isn’t the causal mechanism. As Porter and Gregor (cited above) put it, “the symptoms of digital eye strain are linked to how we use our digital devices, not the blue light coming out of them.”
The actual sources of eye strain from digital devices (aka computer vision syndrome) are (1) reduced blinking and (2) focal fatigue (i.e. staring at an object 1–2 feet from your face for too long). [5, 6]
To address these problems, ophthalmologists propose the “20–20–20 Rule,” which is to look at an object about 20 feet away, for 20 seconds, for every 20 minutes of working on a screen.
That concludes the main point of this article, but for the curious, I’ll acknowledge that the rabbit hole with blue light goes deeper. On one hand, multiple studies show that humans and animals flourish when exposed to blue-wavelength-rich light during the day. [7, 8, 9, 10] This makes sense because it’s exactly the type of light the sun emits, and life on earth has had plenty of billions of years to adapt to the sun’s presence.
However, some research shows potential neurotoxicity and retinotoxicity associated with exposure to blue light. [11, 12]
I’d still advise getting plenty of bright light exposure during the day, be it from the sun (wear sunscreen please) or artificial sources, and to avoid light pollution after sunset. I’ll follow up on this if my position on this changes in light of new data.
I’ve published a companion piece to this article: The Actual Use Case for Blue Light Glasses.
