I have heard horror stories in the news of bacteria eating the eye through contact lens wear! Is this true?!
It is true that acanthamoeba keratitis (a very specific type of ulcer that forms on the cornea) is a serious condition that can severely damage the eye very quickly, but it is rare, so therefore it appears in the news when it does occur. 85% of cases of acanthamoeba keratitis are caused via contact lens wear, and there are other organisms which can cause unpleasant corneal ulcers in the same way. All need immediate treatment to prevent long term scarring.
So how is it caught?
Acanthamoeba, and many of the other ulcer causing organisms, live in water. So via swimming pools, showers, tap water etc we often come into contact with them, but it is only when they infect the cornea that major problems occur. Contact lenses should never be worn if they could be exposed to water, nor should they be handled in bathrooms. It is also why contact lenses and their cases should only be washed in specified solution.
Why does it cause a problem with contact lenses?
Contact lenses are designed to work with the eyes, to interact with tears so they don't dry out, and to allow oxygen through to the eye. Therefore lens materials are made to absorb all manner of things, and if acanthamoeba gets into a contact lens on the eye it finds itself in perfect growing conditions - light, warm, moist, and with available nutrients from your tears. As the lens is in close contact with the cornea, it's easy for infection to start.
This is one of the reasons why patients are given specific wearing times for their lenses, so if you are told to dispose of your lenses after a month, it is because it cannot be guaranteed to stay free of bacteria after that time. When you dispose of your lenses dispose of the case and solutions too, to ensure you're using the most sterile products possible - even if you have some left!
So how do I know if I have an eye infection?
Usually the symptoms are severe and easily felt. There is often sudden pain and discomfort which intensifies within a day, and if associated with contact lens wear discomfort intensifies when the lens is removed and the bacteria attack the dense network of nerves that fill the cornea. Often there is sensitivity to light, and the eye will become bloodshot and watery. These are all signals from the eye that there is something seriously wrong.
What should I do?
As it is a severe condition, if you experience these symptoms you should see an Optometrist immediately. The GP may be able to help, but most do not have the equipment to make a full diagnosis. There is a simple phrase to remember regarding contact lenses - if in doubt, keep them out! If you feel they're not quite right, remove the lenses and come in as soon as possible. Always keep up to date specs in case of such emergencies.
If I have an ulcer - what then?
You will have to dispose of the current set of lenses, solutions and case. You will probably have to go to the hospital eye department, to be prescribed antibiotics. They will test the bacteria to confirm acanthamoeba or anything else. if caught early it will heal without problems, but serious infections, left untreated, will scar the cornea permanently.
My Optometrist is always very serious about what I can and can't do with my lenses. I'm sure I'll be fine!
Unfortunately there are many people who don't follow their wear regimes. Your optometrist tells you what you should do to avoid infections. You may have been fine for years, but it only takes one infected drop of water to change that. You may think it sounds over-cautious, but the guidelines are there for your protection and benefit.
Is that why I need regular check ups, even if my sight stays the same?
Yes. Your vision may be stable but the way your eye interacts with your lenses may change. The lens may give good vision and feel fine, but may be causing unseen damage that leaves you more vulnerable to infections like acanthamoeba. This is why people are often discourged from buying lenses online, as they miss out on regular checks that ensure their eyes are still coping with their contact lenses.