Attention: All naughty contact lens wearers! (yes, YOU who leaves them in overnight)

Posted 6 years ago by Hester du Plessis

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Hester du Plessis is OCULA’s newest, internationally renowned optometrist and comes with a boatload of clinical experience. Here, in her first blog, she urges contact lens wearers to take care of their eyes.

Yes, I get it. Wearing contacts is so old hat that it’s almost a given you’re getting complacent.

I mean, when you should have been in bed hours ago and you're really quite tired - the thought of trying to fish that tiny spec of plastic out of your eye is the last thing you feel like doing. So, you could be forgiven for thinking it’s probably easier to just leave it in. One night won't hurt right? WRONG. 

Your eyes breathe. They need oxygen to function. When they're closed, only small amount is being transmitted to your cornea (the clear lens on the front of the eye). When you sleep in your contacts, they cut down the oxygen supply even more. This is prime opportunity for bacteria to make their move. Already suffocating, the cornea has a hopeless chance of defending itself, and what would have been a fairly minor issue in a healthy eye can turn into a sight-threatening infection in the suffocated eye. Once you’ve had a bad infection, the chances of wearing contact lenses after is slim. Best to take them out, ok? 

Right, next on my list. Throw your damn contacts away when you’re supposed to! No, the recommended replacement time is not a fictional date dreamt up by your optometrist to make more money out of you. It’s a medically necessary, scientifically measured stretch-of-time and it MATTERS. I know, that was a little dramatic. But bear with me, and I’ll tell you why I’m so passionate about it.

As I touched on before, the front of the eye is protected by a clear tissue layer (the cornea) that not only acts as a protective window but is responsible for most of the focussing power of the eyes. As I also mentioned, your cornea has to breathe oxygen to stay clear. By covering this window with a contact lens, the oxygen supply is dramatically reduced. So to counteract this, modern contact lenses have tiny holes throughout - a bit like a honeycomb matrix - to allow oxygen to pass through.

Contact lens manufacturers know how long the contact lens will last before all these holes close up, either by degeneration or from the sticky bits in your tears (proteins, mucins, lipids etc). Hence, contact lenses have an expiry date, starting from the time you break open the seal on a new packet (a bit like opening a jar of food). It doesn’t matter how many times you have worn the contact lens, by it’s expiry (14 days for Acuvue Oasys or 30 days for Alcon Night & Day Air Optix) all the the holes have closed up and there is no more oxygen getting through to the cornea.

For every day over the expiry date the contact lens is worn, the cornea is suffocating. You are literally strangling your eyes! A typical trap is to wait to feel when the contact lenses need changing but here’s the catch - you can’t feel the damage happening until it's too late! If anything, your eyes become more desensitised with damage and you’re lulled into a false sense of security.

What’s really happening is - as we mentioned above - you’re increasing your risk of a serious infection. So again opening yourself up to the risk of losing the ability to wear contacts, not to mention your sight. Really not ideal.

Ok, that's enough. I’ll wrap this little rant up with a final few words. These are your EYES people. You only have two! DON'T mess around with your sight. Often, you’ll get away with naughty habits. But it’s a game of Russian Roulette, and when it goes wrong, it really goes wrong. And it DOES happen, I see people all the time with complications stemming from contact lens overuse. Be good to your peepers, your won't regret it!




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