Eye strain: Do you really need blue light-filtering lenses for your glasses?
We’ve read about how blue light is harmful to your eyes and disrupts sleep – but do you actually need to wear these or does the problem lie elsewhere?
With many of us glued to screens day in and day out, you might have already read plenty about the impact blue light has on your eyes – how it can give you digital eye strain, disrupt your sleep rhythms and cause skin to age prematurely because of UVA exposure.
So we’re guessing when you were getting new prescription glasses, it wasn’t hard for your optician to upsell blue light-filtering lenses. After all, it seems like a no-brainer to say “yes”.
But do you actually need these special lenses, which cost several hundreds of dollars? It would seem that’s not the case.
The American Academy of Ophthalmology (AAO), for instance, has noted on its website that it does not recommend the lenses “because of the lack of scientific evidence that blue light is damaging to the eyes”.
Dr Foo Li Lian, an associate consultant with the Singapore National Eye Centre’s (SNEC) Myopia Centre, also held the same view: “Currently, there is no concrete evidence in the medical literature to suggest any benefit for the eye from the blocking of blue light”.
A study on 120 participants, published this February in the American Journal Of Ophthalmology, further supported that stance. In it, the blue light-blocking lenses were not found to “alter signs or symptoms of eye strain with computer use relative to standard clear lenses” – even after the participants had completed a two-hour computer task.
WHAT EXACTLY IS BLUE LIGHT?
Of all the colours on the visible light spectrum, why single out blue light in the first place?
The shorter the wavelength, the more powerful the light is, according to Healthline website. And as it turns out, blue light’s waves are only slightly longer than ultraviolet (UV) waves, which experts have always warned about their damaging effects on the eyes and skin. In fact, the website noted that blue light is “only slightly less powerful” than UV waves.
There is no concrete evidence in the medical literature to suggest any benefit for the eye from the blocking of blue light.
The wavelengths of visible light range from 380nm (or nanometers) on the high-energy blue end to about 700nm on the low-energy red end of the spectrum. Those special lenses that you pay a small fortune for, supposedly filter out light “at about 400nm to 500nm of the electromagnetic spectrum”, said Dr Foo.
Blue light, like the other colours of visible light emitted by the sun, is all around you. Indoors, sources of blue light include fluorescent, incandescent light bulbs as well as devices that use light-emitting diodes (LED) such as the screens of laptops, handphones and tablets as well as flat-screen televisions.
WHAT’S THE DAMAGE THEN?
If you’re talking about skin damage caused by blue light, we have a report pertaining to that here. But what about blue light purportedly causing computer eye and a messed-up sleep cycle?
As it turns out, digital eye strain (which includes symptoms such as sore, tired, burning, itching, watery or dry eyes, or blurred or double vision) is more likely due to the prolonged staring at digital screens than the blue light, according to the AAO.
Simply put, you end up blinking less, which leads to eye strain.
And while there is blue light coming from your screen, it is a small amount and has “never been shown to cause any harm to our eyes”, according to the AAO website. Furthermore, there is no detection of UVA or UVB radiation (the most harmful part of light) emitted by any screen, as concluded by a study reprinted by the National Library of Medicine.
So, there is no need to wear blue light-filtering lenses when doing computer work then?
“These lenses have yet to be proven effective or beneficial in any way. Good eye-care habits such as taking periodic breaks as well as reading under adequate lighting conditions would be more beneficial in avoiding eye strain or fatigue,” said Dr Foo.
Here are some tips from the AAO to help alleviate computer eye strain:
- Position your eyes about an arm's length from the computer screen, gazing slightly downward.
- Take regular breaks using the 20-20-20 rule: Every 20 minutes, shift your eyes to look at an object at least 20 feet (about 6m) away for at least 20 seconds.
- Use artificial tears to refresh dry eyes.
- Adjust your room lighting and increase your screen's contrast to reduce eye strain. Use a matte screen filter if needed.
- Give your eyes a break by wearing glasses if you usually wear contact lenses.
WHAT ABOUT SLEEP DISRUPTION?
Much has been said about blue light interfering with sleep by making your body react as if it’s exposed to sunlight. As a result, your brain stops producing the sleep hormone melatonin and you feel as awake as if you’ve just had coffee.
However, Dr Foo highlighted that there is no “concrete evidence” to date that shows the benefit of blocking out blue light to improve sleep quality – although she acknowledges that there have been studies that associate “exposure to blue light with melatonin secretions and possible sleep cycle disruptions”.
If you have difficulty falling asleep, there is no harm in limiting your screen time to one to two hours before bed, suggested the AAO. When using your device at night or in dim rooms, switch to night mode to minimise blue light exposure.
Night mode does this by using a black background with white or coloured text, or shifting lighter colours towards pink and red instead of blue. As a result, the contrast between your screen and your room is less stark, there is reduced glare and your eyes are less strained.