Blue Light Glasses: What you need to know
Blue light glasses are all the rage. As an eye doctor, I have been able to make prescription blue light glasses for a while now. More and more companies are making blue light glasses for people that don’t have a glasses prescription. Before you buy your very own pair, here is what you need to know about blue light and blue light glasses.
In this blog post, I will cover
How blue light affects your sleep and wake cycle.
Data about "blue-light hazard" and how much blue light exposure we get in a day.
High-quality science about blue-light blocking glasses.
You might be wondering you should get blue light glasses to protect your eyes. If you're anything like me, you're using your cell phone and your computer all day, every day. We have to use our computer for school or work, and when we're not using our computer, we're using our phone. Then when we get home, we like to watch a movie or maybe a couple of shows on Netflix to unwind before bed. Our homes have been switched so that our light bulbs are all using LED, which emits blue light. It's pretty reasonable to be concerned that this might be hurting your eyes.
Even though we're surrounded by technology that gives off blue light, the most important source of blue light is the sun. (just one more reason why you should always use sunglasses when you're outdoors).
Let's get into how blue light affects our sleep and wake cycles. Our eyes have this type of cell called the melanopsin expressing ganglion cell. And that cell is supposed to tell our body when it's daytime and when it's nighttime. Melanopsin-expressing cells are most sensitive to, you guessed it- blue light. The thinking is that by using a screen or watching tv before bed, we're artificially telling our body that it's still daytime. This makes it hard for us to fall asleep, or we don't get a restful sleep.
A group took people with difficulty sleeping and gave those people amber-coloured lenses (1). These aren't the clear lenses with the blue-filtering glare coating like we're usually talking about. They are actually orange-coloured lenses that block all of the blue light that comes through them. The study found that people that use those lenses for three hours before bed for two weeks reported an improvement in the quality of their sleep and an improved ability to fall asleep. They also gave people clear lenses with blue-blocking anti-glare coatings (kind of like what you see online or get from your optometrist office). They found that those lenses used before bed made no difference to a person's sleep quality or their ability to fall asleep. In short, the amber-coloured lenses really helped, and the clear lenses with the blue-blocking glare coating probably didn’t.
Blue light can cause damage to the back of the eye. The point where blue light will start to cause some toxicity in the retina and in the surface of the eye is called "Blue-Light Hazard. The International Commission on Non-Iodizing Radiation Protection found the specific amount of blue light exposure that causes damage. If you had more than this amount, there would be damage inside the eye from the blue light, and if you were under this amount, there would be no damage to the eye caused by blue light.
A different group added up all of the blue light exposure that a person gets in a day in an extreme scenario (2). For example, this person who uses their phone all morning, uses their computer all day at work, works under led light bulbs, and then goes home uses their cell phone or watches tv all the way up to bedtime. They found that if you added up all of that blue light exposure, you only got about 10% of the harmful amount. This means that we can rest assured that the amount of blue light that we receive on a day-to-day level will not cause us any harm.
Just because blue light doesn't cause us harm doesn't mean that it can't make our eyes feel tired. Some authors suggested that blue light from the computer screen can cause computer vision syndrome, a.k.a. digital eye strain (3). Digital eye strain is a common thing that I see in the clinic these days with the work from home movement due to the coronavirus pandemic.
Another group took people that suffered from computer vision syndrome (4). They gave half of them clear lenses with a regular anti-glare coating and half of them clear lenses with a blue-blocking anti-glare coating. They made them do a computer task and measured the patient's eye strain and different tests about eye fatigue. They found that the participants that got the regular anti-glare coating had the exact same amount of eye fatigue and strain as the group that got the blue-filtering coating. In other words, the blue filtering coating did not cause any protection from the digital eye strain symptoms. These results lead us to think that there might be something else- not the blue light- but something else that causes fatigue when we use the computer. As we all know, when we have a long day on the computer, our eyes feel tired, they can feel blurry, and the vision can go in and out.
In my experience with people that have blue light filtering coatings, it's about 50/50 if a person noticed any benefit. Half of the people that got it really found it helpful. The other half didn't find it so helpful. It's tough to know who's who.
The critical thing to know about this is that there's definitely no harm in blue light glasses. So, if you're interested, it definitely won't hurt, but I just can't promise that it will definitely help.
I have three main takeaways from today's blog:
Blue light definitely affects our ability to sleep, and amber-coloured lenses may help us. More practically, the most important thing is to reduce our screen time before bed to fall asleep and have a good quality sleep.
Our daily exposures from our screens, computers, and cell phones don't cause any damage to your eyes.
Blue light glasses might help, they also might not, but they definitely won't harm.
If you’ve tried out blue light glasses, I would love to know what you think! Send me a DM on instagram @theeyestudioyxe or email email@example.com. Be sure to subscribe to my YouTube Channel, so you don't miss any future info!
Burkhart Kimberly & Phelps James R.(2009)AMBER LENSES TO BLOCK BLUE LIGHT AND IMPROVE SLEEP: A RANDOMIZED TRIAL,Chronobiology International,26:8,1602-1612,DOI: 10.3109/07420520903523719
O'Hagan JB, Khazova M, Price LL. Low-energy light bulbs, computers, tablets and the blue light hazard. Eye (Lond). 2016;30(2):230-233. doi:10.1038/eye.2015.261
Lawrenson JG, Hull CC, Downie LE. The effect of blue-light blocking spectacle lenses on visual performance, macular health and the sleep-wake cycle: a systematic review of the literature. Ophthalmic Physiol Opt. 2017 Nov;37(6):644-654. doi: 10.1111/opo.12406.
Singh S, Downie LE, Anderson AJ. Do Blue-blocking Lenses Reduce Eye Strain From Extended Screen Time? A Double-Masked Randomized Controlled Trial. Am J Ophthalmol. 2021 Feb 12;226:243-251. doi: 10.1016/j.ajo.2021.02.010. Epub ahead of print. PMID: 33587901.