Blue light

What is it, anyway?

There’s lots of talk out there about blue light: whether it’s harmful or not, and whether you need ‘blue light blocker’ lenses to help prevent eye damage from the blue light emitted by computer, tablet and phone screens. Here, we’ll look at the facts and contradictions, and suggest ways to minimise harm to your eyes.

Put simply, blue light is part of the visible light spectrum – the light we can physically see. (Ultraviolet, or UV, and infrared light are outside the visible light spectrum.) Sunlight is a natural source of blue light. Artificial blue light is emitted from digital screens (TVs, computers, laptops, smartphones and tablets), electronic devices, plus LED and fluorescent lights.

Here’s our quick, up-front conclusion: based on the evidence, we at Dresden don’t believe blue light is, in itself, damaging to your eyes (though it can definitely interfere with sleep by disrupting your circadian rhythms). It’s the amount of time we spend looking at screens – and how we do so – that’s the real problem, and causes digital eye strain. This is a topic worth exploring a bit further.

Blue light: the good and the bad

A particular spectrum of blue light (in the turquoise range) may have some real benefits. Some studies show it does good things for your sleep patterns1, and it may help fight the “winter blues” (there are even lights designed to help based on this exact theory)2. There’s also some evidence blue light could help reduce the development of myopia (near-sightedness)3.

There are also several studies suggesting blue light could be a risk factor for macular degeneration – but it has a far smaller impact than exposure to sunlight, smoking and age4. The American Academy of Ophthalmologists has even said there is no evidence blue light causes any irreversible damage to our eyes5.

But. (Yes, there’s always a but.) Blue light can affect melatonin levels and change your sleep patterns; that’s a well-established fact6. And when it comes to the digital eye strain we get from being glued to our screens, poorer screen contrast due to blue light does make that strain worse.

Symptoms of digital eye strain include:

  • dry, itchy, burning or red eyes
  • blurred vision
  • fatigue
  • headache
  • neck, shoulder and back pain.

High screen time equals eye strain

Australians spent an average of 9.4 hours on devices every day; for office workers, that rate jumps to an average of 11.4 hours7. Altogether, Australians looked at their smartphones more than 440 million times a day, and 75% of them regularly multitask across multiple screens and devices8. Yikes.

In New Zealand, it isn’t much better. On average, Kiwis aged 16-24 years spend 8.9 hours a day engrossed in digital media9. When the Ministry of Health investigated screen use in children, they found 84.3% of kids aged 5-9 watch TV or look at a screen for two or more hours per day; that jumped to 91.5% of kids aged 10-14.10

Canada’s Screen Smart community education initiative says 59% of children aged under two watch television for an average of two hours per day. By graduation, the average teenager will have spent more time watching screens than in the classroom, playing sports or talking with their parents.

No wonder two out of three adults experience digital eye strain11.

Reducing your exposure to blue light

So what can you do about it?

You can easily change your screen settings – of course, there are apps for this. F.Lux (for Windows, macOS, Linux, Android and iOS), Twilight (Android), Nightshift mode (iPhone) and Nightstand mode (Apple watch) all help reduce the amount of blue light emitted.

If you work with computers all day12:

  • Take regular breaks using the 20-20-20 rule: every 20 minutes, look away to something at least 20 feet away, for at least 20 seconds and blink, blink, blink!
  • Consider a matte screen filter to reduce screen glare.
  • Try to position all devices the same distance away from you so you don’t have to constantly change focus.
  • Position devices slightly below eye level as this decreases the amount the eye is open, causing less strain on the tear film that helps minimise dry eyes.
  • Have plants around the office to humidify and detoxify the air.
  • Speak to your optometrist for further advice if you still have sore and dry eyes.
  • If you wear multifocals, and find you need to lift your chin to see the screen when working on a desktop computer, think about lenses designed specially for desktop computer use.

And of course, you can get blue light-blocking glasses. If you’re considering this, ask us at Dresden about our blue coating. We take the same simple, affordable approach as with all our glasses, prescription or sunglasses.

UV light and blue light – they’re different!

Ultraviolet radiation is invisible, so technically it isn’t even light! It comes from sunshine, some lasers, and the likes of welding and tanning devices. There are different classes of UV radiation (you’ve probably heard of UVA and UVB), and some parts of the eye are better at blocking UV than others, but prolonged exposure can cause serious damage to your eyes13.

You can protect against UV by wearing a hat and sunglasses, prescription glasses, or even most contact lenses, which have full UV protection. Dresden sunnies and prescription sunglasses are Category 3, meaning they provide the maximum (100%) possible protection against UV, while also being suitable for driving.

What’s more, our clear lenses also provide great UV protection: our ‘standard’ 1.5 index lenses block out 91% of UV light and our higher-index lenses, such as 1.6 and 1.67, give you 100% UV protection.

Blue light is far less harmful than UV. (Phew!) In most situations, it would take months of continuous exposure to blue light to cause any damage to your eyes. But we’re being exposed to more and more blue light, as computers and digital device displays become ingrained in everyday life. Not just at the office, but for staying connected, entertained and informed, and – for kids – learning at school.

Our final word

So what’s our advice? Excessive, close-up exposure to blue light causes digital eye strain. Blue-light exposure can also mess with your sleep. For these reasons, blue light-blocking lenses can be really helpful.

But UV is your real enemy and causes proven damage. Wearing lenses with 100% UV protection (either clear or tinted) is the protection your eyes need most of all!

Where we got our information

1 Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality, Antoine U Viola, Lynette M James, Luc JM Schlangen and Derk-Jan Dijk, Scandinavian Journal of Work, Environment & Health, Vol. 34, No. 4 (August 2008), pp. 297-306.

2 Philips goLITE BLU

3 Development of eye enlargement of domestic fowl subjected to low intensity light, P. C. Harrison, A. B. Bercovitz, G. A. Leary, International Journal of Biometeorology, December 1968, Volume 12, Issue 4, pp 351–358.

4 Retinal sensitivity to damage from short wavelength light, William T. Ham Jr, Harold A. Mueller & David H. Sliney, Nature volume 260, pages 153–155 (11 March 1976)

5 American Academy of Ophthalmology

6 Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality, Antoine U Viola, Lynette M James, Luc JM Schlangen and Derk-Jan Dijk, Scandinavian Journal of Work, Environment & Health, Vol. 34, No. 4 (August 2008), pp. 297-306.

7 The New Daily

8 Reddy SC et al. Computer Vision Syndrome: a study of knowledge and practices in university students. Nepalese Journal of Ophthalmology 2013; 5(10): 161-168. (found Prevalence 89.9)

9 Stuff website

10 NZ Ministry of Health survey, year ended June 2017.

11 Ernst & Young (2016). Digital Australia. Sydney, NSW. Deloitte (2015). Mobile Consumer Survey – The Australian Cut. Sydney, NSW. Eyes Overexposed: The Digital Device Dilemma, 2016 Digital Eye Strain Report, The Vision Council, US.

12 American Academy of Ophthalmology

13 Ultraviolet Radiation as a Risk Factor for Cataract and Macular Degeneration Roberts, Joan E Ph.D. Eye & Contact Lens: July 2011, Volume 37, Issue 4, p246-249