One of the medical journals I subscribe to has “Risk Factors” in wearing contact lenses as the leading article this month. They had carried out a large sample of contact lens wearers in the US, asking them about particular risky behaviors and their prevalence was noted as follows:
Sleeping overnight in contact lenses: 50.2 percent
Napping in contact lenses: 87.1 percent
Mixing new solution with old solution in a contact lens case (as opposed to replacing old solution entirely): 55.1 percent
Extending the recommended replacement frequency of lenses: 82.3 percent
Showering in contact lenses: 84.9 percent
Swimming in contact lenses: 61.0 percent
I don’t know about you, but I’m guilty to the lot of them.
You do take your lenses out each night, don’t you? Even with all the advances in lenses, the ophthalmologists still recommend you give the eyes a rest each night. After all, contact lenses are still ‘foreign bodies’.
As you can see (pun intended), it isn’t just a case of bunging some in and forgetting about it. Quite the reverse. With all our organs that can go wrong, did you know that eye problems are some of the commonest reasons for a doctor visit? And for those of you who wear contact lenses (like me) there are even more eye problems for us to get, despite the common use of contact lenses these days.
There are many types of contact lenses, the old hard ones were made of a material called polymethylmethacrylate (PMMA) which is rigid and does not let oxygen through, but the newer ones have a material called siloxane which is gas permeable. These hard lenses are the most trouble free, although the most difficult to look after. Sounds topsy-turvy, I know.
The second type of lens is the soft contact lens, of which there is a “permanent” style and a disposable type. These are made of hydroxymethylmethacrylate (HEMA) which contains between 30-60 percent water and are gas permeable. However, soft disposable lenses give the most problems, but are the easiest to look after, in direct contrast with the hard lenses. Again sounds weird, I know.
The commonest problems with all contact lenses is infection, and since the lens is a foreign body, there is a good reason to get an infection immediately. For those of you who leave your lenses in the eyes overnight, you have an increased risk of infection by a factor of 10. Take them out every night, you have been warned!
Infection is not to be thought of as something that just happens and when it does you just pop in a few eye drops and get better automatically. Bacterial infection can be sight threatening and the cornea (the clear bit in the centre that you look through) can be destroyed in 24 to 48 hours. There is also a parasite that can get into the eye of contact lens users who have rinsed their lens with contaminated water, or who have worn their lenses swimming in contaminated water.
One very common problem is “losing” the lens in the eye, both the hard and soft types. The most important thing to remember is not to panic. The lens cannot go “behind” the eye. It just rolls itself up under the lid. Try to avoid rubbing and it will reappear in an hour or so. Just like the stray dogs in your soi.
The other very common problem is eye irritation. This is caused by material under the lens or damage to the lens itself, such as splitting or tearing. If you take out the lens and you find it breaking up, do not put it back in – you run the risk of damaging the cornea. Do not be like me and wear your “two week” contacts until they fall apart –you are running a risk!
Lens care is the most important feature and you should always wash your hands before removal or insertion. The lens container should be scrupulously clean and the storage/cleaning fluid should be fresh, and never use water.
Look after your lenses, take them out at night, change them frequently and remove them immediately when there is any irritation or redness. “See” you next week!