Biology / Experiment / Health / Science

Blue light danger

There’s a new article in the Guardian here claiming that blue light is dangerous for you, accelerating the risk of a form of blindness called macular degeneration.

Scientists say they have found how blue light from smartphones, laptops and other digital devices damages vision and can speed up blindness.

Research by the University of Toledo in the US has revealed that prolonged exposure to blue light triggers poisonous molecules to be generated in the eye’s light-sensitive cells that can cause macular degeneration – an incurable condition that affects the middle part of vision.

Now, macular degeneration is a major interest for me, since my mother was diagnosed rather younger than is typical, and chances are that I’m at risk too. The article is a little sparse on some details (like the actual title of the study), so I decided to dig into it and see how credible I found it. While I’m at it, I thought I’d also run through why I’m making those decisions — i.e. how I decide what’s a credible source when I’m researching.

It’s best to think first about what macular degeneration is and what causes it. There are two forms of MD: wet and dry. Wet macular degeneration features bleeding into the macular, while dry macular degeneration typically features cellular debris called drusen forming in deposits in the macular. The macular is important for your central vision, and wet MD in particular can quickly lead to legal blindness. It’s typically associated with age, and has various genetic components, but can occur in younger people (like my mother).

The actual study is in Nature (so a very reputable source) and can be found here. The authors have declared no competing interests, and I don’t know anything to the detriment of the Department of Chemistry and Biochemistry at the University of Toledo — but I’m a little concerned that perhaps nobody there is actually a biologist or medical researcher. However, the title doesn’t actually mention macular degeneration: the actual title is ‘Blue light excited retinal intercepts cellular signaling’. So maybe someone’s theorising beyond the data. Next thing to try, in this case, is searching for actual references to macular degeneration in their piece.

Although it’s tagged as being about macular degeneration, the actual text of their report contains the word once, in the introduction. That suggests to me that whatever this study concludes, it might have to do with macular degeneration, but it’s definitely theoretical at this point. No humans have been studied — and indeed, in this case they state that:

Studies in mice have demonstrated that, ATR accumulation and photodegradation leads to diseases such as age related macular degeneration (AMD), Stargardt disease, acute light-induced retinopathy, retinitis pigmentosa and night blindness5.

Not so promising so far for the sweeping conclusion in the Guardian, presenting blue light as a clear and proven risk for macular degeneration. But maybe that conclusion comes out of the paper. I normally begin by reading through the abstract. Chemistry isn’t my area of expertise, so I know that in the full paper there will likely be things I won’t understand — but the abstract should be relatively accessible, and give a good overview. Basically, they state that the interaction between blue light and retinal, a molecule that’s part of a photoreceptor in the mammalian eye, forms a by-product which can eventually lead to cell death.

There’s no mention anywhere in the article of the use of screens which give out blue light, etc. That’s not what’s been tested: instead, it looks like this is a test of a theory that blue light can cause cell death through its effects on retinal. As far as that goes, it’s true. This study alone certainly doesn’t confirm that the blue light from screens is significantly increasing the risk of people developing macular degeneration, though.

Should you be using screens giving out a lot of blue light in the dark? No. We already knew that for other reasons: blue light is linked to low melatonin production, disrupting sleep cycles. Disrupted sleep is linked to all kinds of other problems. And you should always be protecting your eyes from UV light in particular. Is there solid evidence (in that study at least) that there’s some kind of epidemic of damage to the macular due to the use of screens emitting blue light? No. But there is a proven mechanism for it to cause damage, so on those grounds, I would want to study it more and in the meantime, I’ll be turning on blue light filters on my screens (Windows 10 has one built in, as does the Samsung Galaxy S8 and probably many other Android phones)… like I probably should’ve done already.

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