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Health, Science

The Shady Truth About Sunglasses: How Safe Are Your Eyes?

This post was chosen as an Editor's Selection for ResearchBlogging.org

Sunglasses

Are your sunglasses ruining your eyes?

Companies are great at selling us things that we don’t really need; but when you’re out shopping for sunglasses then picking the right ones is crucial. Do you skimp and go for cheap ones?

Picking shades with proper UV protection is an absolute must. Wearing poor quality sunglasses could be doing you much more harm than good. But if you thought that splashing out on expensive sunglasses would save your vision, then you’d be wrong. Today’s blog shines some light on the darker side of being out in the sun (with some images that aren’t for the faint-hearted)…

Four Nasty Conditions Bad Sunglasses Could Give You

UV (ultraviolet) light comes from the sun and we cannot see it. It’s well known that too much of it causes skin burns and skin cancer. But did you know that UV light can damage the eyes? A lifetime of wearing poor sunglasses could significantly increase your chances of ending up with one of these nasty conditions:

1. Photokeratitis

Also called ‘sunburn of the eye’, skiers often get this if they don’t wear goggles with UV protection. A few hours after enjoying the sun, the eye gets painful, gritty and vision becomes blurred. You look like you’ve had a pretty heavy night on the town as well:

Photokeratitis: Something best avoided (Source: Pixnet)

Thankfully, with rest and eyedrops, your eyes should be back in normal order after two or three days.

2. Cataracts

The normally clear cornea hazes over to cause a cataract. (Image source: jwgrundy.co.uk)

Cataracts grow slowly over many years, dulling vision and eventually making sight very difficult. Although they can be removed, too much sunlight is one sure-fire way to increase your chances of getting an appointment with an eye surgeon.

3. Pterygium

Yuk! What is that thing attacking my eye?

This exotic-sounding condition looks pretty revolting. UV light can trigger the surface of the eye to grow out of control. Although it isn’t a cancer, it looks unsightly, can be painful and occasionally obscures sight.

4. Macular Degeneration

How the world looks to someone with macular degeneration - Central vision is lost.

The macular is the most sensitive part of the inside of our eye (the retina). Excesses of UV light damages this delicate region and eventually prevents you from seeing clearly.

The Hidden Dangers of Sunglasses

In bright sunlight, your eyes will try to protect themselves from too much UV light getting in by shrinking the size of the pupils.

Small Pupil: The eye protects itself from excess UV light by constricting

But when you put on a pair of sunglasses, light reaching your eyes is darker and so your pupils open up again. If your sunglasses don’t have UV protection then harmful UV light will now be flooding through your – now wide open – pupils into the back of your eyes. If your sunglasses don’t provide UV protection, it would be better if you weren’t wearing them at all!

Dilated pupil. Click to watch animation.

So when you’re out shopping for sunglasses, make sure that they have UV protection. A dark tint or a high price tag is no guarantee of this either. Research has shown that because laws don’t exist yet to enforce it, many expensive brands don’t meet minimum standards for eye protection.

How to Pick Safe Sunglasses

Always make sure European sunglasses have a 'CE' label


Always make sure that sunglasses have a label to prove it meets minimum standards in your country:

  • In the USA, the minimum safe standard is called ANSI Z80.3
  • In Europe, all sunglasses that meet the minimum EN1836 standard carry a ‘CE’ label.
  • In Australia, the standard is AS1067, and all sunglasses sold in Australia are supposed to meet this standard (but check anyway).

When you’re choosing sunglasses, style can make a difference. Large ‘wrap around’ shades generally give the best protection as they block out more UV light from the sides.

Well, yes, they are large, but perhaps not the most practical...

Thanks for reading – your comments and feedback are warmly welcomed!

P.S. For a useful diagram showing UV light penetration in the eye click here

.

Reference:
Dain, S. (2003). Sunglasses and sunglass standards Clinical and Experimental Optometry, 86 (2), 77-90 DOI: 10.1111/j.1444-0938.2003.tb03066.x

The World Health Organization has a page all about the UV effects on the eye here

NASA have published safety advice for observing a Solar Eclipse. The article explains that looking directly at the sun results in extreme damage to the retina due to near-infrared light.

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About Stuart Farrimond

I love writing about science and health subjects. Strange, because I also teach the same things. I trained as a medical doctor before turning my hand to other things. Shortlisted for The Guardian/Observer for Science Writer of the Year 2011 and editor for Guru Magazine I also like to grow large pumpkins...

Discussion

19 thoughts on “The Shady Truth About Sunglasses: How Safe Are Your Eyes?

  1. Simple point but well made. As soon as I saw the title of the post I made the pupil dilation – UV connection but, despite spending loads of time outdoors and often wondering why I’d end up with sore eyes despite sunglasses, I’d never thought of it before!

    Posted by David Robertson | April 26, 2011, 3:05 pm
    • Thanks for commenting David!
      It’s bizare to think that bad sunglasses could be far worse for you than no sunglasses at all…
      I think though that folks ‘Down Under’ are doing it best by trying to legally enforce the rules.

      Posted by Stuart Farrimond | April 26, 2011, 3:25 pm
  2. I’ve got a couple pterygiums (sp) – result of a lifetime in the Tropics. The downside is that I can’t wear contact lenses, the surface of my eye is too rough to allow it.

    Glad I’ve finally found the Dr Stu blog – looking forward to becoming more informed!

    Posted by Alice Jackman | April 30, 2011, 9:32 pm
  3. Overall rather good rundown and caveats, but author didn’t mention the danger of infrared as well. (Near IR around 750-1200 nm, not the long-wave heat rays.) IR rays are more a cause of macular degeneration than UV, because IR penetrates deeper into the eye and retina. (From link here about UV penetration:
    Studies indicate that due to its absorption by various molecules in the cornea and the lens, most UVR never reaches the retina in the normal adult eye. In the case of ambient UVR (i.e., UV-B and UV-A), the shorter wavelengths are absorbed preferentially, with the cornea absorbing most of the radiation below 300 nm, and the lens absorbing almost all of the rest of the UVR below about 370 nm (Merriam, 1996).

    Good sunglasses by definition block IR but labeling about that is not as clear, so you need more research. Green lenses tend to be best because they need to absorb red as well as violet in order to look green, hence they favor the safest, middle part of the light spectrum. Late sun is dangerous because low-angle yellowing admits red and near IR. I would like to see good consistent IR standards all around. One tip: polycarbonate lenses intrinsically block both UV and IR.

    Also, not to confuse with sudden turns but: it’s healthier to get some UV, even in your eyes, than none at all. Just a limited time, make enough vitamin D and some input to retinas or lower mood could result.

    Posted by Neil Bates | May 3, 2011, 6:46 pm
    • Hi Neil!
      Thanks for commenting – some very useful information that is much appreciated! Most research papers focus exclusively on UV radiation, so thanks for bringing up the dangers of near-Infrared light.
      (I have now included a relevant link at the end of the article).
      And yes – great points on the importance of getting sufficient UV light exposure – both for Vitamin D production and to help reduce Seasonal Affective Disorder risk. Spot on!

      Posted by Stuart Farrimond | May 3, 2011, 9:39 pm
  4. Thank you for publishing this. I was unaware of the UV – pupil connection and am glad to know about it. I am an avid sunglass wearer and do not know if my sunglasses protect my eyes as well as i thought. I will be looking into getting a new pair soon. My eyesight is not bad and I plan to keep it that way.

    I love your blogs!

    Posted by Elizabeth Holmes | June 24, 2011, 5:17 am
  5. Hi!
    I was wondering, who’s the model in “The Hidden Dangers of Sunglasses” (hazel eyes owner)?
    Thank you for these awesome articles!

    Posted by beto | August 16, 2011, 12:11 pm
  6. Thank you for sharing this blog. Very helpful. Keep posting like this.

    Posted by Daniel1828 | August 17, 2011, 5:28 pm
  7. Is it true that the eyes pick up the amount of sunlight we are exposed to and then tells the body how much pigmentation to produce ( our natural sun protector)hence if we wear sunnies all the time we are giving the eyes and the body the wrong message

    Posted by Trevor Hatch | November 14, 2011, 8:20 am
  8. Is there any practical way to test it? Because I’m sure a lot of “CE” tags in Europe are fake…

    Posted by Faun | June 8, 2012, 2:27 pm
  9. Wow that was unusual. I just wrote an very long comment but after I clicked
    submit my comment didn’t show up. Grrrr… well I’m not writing all that over again.
    Anyway, just wanted to say great blog!

    Posted by nike free | April 11, 2013, 7:11 pm
  10. you have done a good job, keep it up.

    Posted by Nora | May 28, 2013, 6:19 am
  11. I always thought that sunglasses were a bad idea as I realised that, when my eyes thought it had got darker, my pupils would get large again and could lead to eye damage – thanks for backing up my belief!
    Carol.

    Posted by mountaincoward | August 11, 2014, 12:11 am

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Hospital doctor turned lecturer and science communicator, I love trying to answer life's questions - whether it is how our body works or the best way to dunk a biscuit.... Read more...

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