Category Archives: Issues in Science

Do you wear contact lenses? I don’t. I don’t know how to order them, how to put them on, or how to clean them. But even though I have little to no knowledge on contact lenses, I do know this: Don’t sleep with them on!

About half of my friends wear contact lenses and at some point, I hear them say “I slept with my contact lenses on last night”. Guaranteed.

The application of a contact lens. Source: Flickr Commons user suanie

At this point, some of you are probably thinking:

“Why do we say this?”

“What’s the reason for taking out contact lenses before bed?”

“What are the proper steps to cleaning them?”

Well, I am here to help answer these questions.

In a recent article published by CBC, ophthalmologist Tim Hillson addresses the fact that contact lenses prevent oxygen flow to the cornea, causing nutrient-providing blood vessels in the eye to expand. This makes the eye prone to infection. Leaving the contact lenses on over night allows bacteria build up that can penetrate the cornea.

There are 3 types of infection to the cornea:

–Acanthamoeba keratitis: A rare infection caused by amoeba, often found in swimming pools, tap water, and hot tubs. May result in blindness.

–Bacterial keratitis: An infection that proceeds rapidly. Caused by common bacteria like staphylococcuss aureus.

–Fungal keratitis: An infection caused by a fungal organism. Usually involves pain in the eye.

Recently, Lian Kao, 23 year-old Taiwanese student became blind due to prolonged application of contact lenses. When I say prolonged – I mean 6 months! Kao did not remove her disposable contact lenses for 6 months straight, and even went swimming with them on. The cause of her blindness is said to be from Acanthamoeba (as described above), where amoeba ate her cornea during the course of 6 months.

An illustration of Amoeba proteus, by Joseph Leidy, 1879 − The organism that caused Lian Kao’s blindness. Rare but dangerous when infected. Source: Wikipedia

Specialists say that the blindness caused by acanthamoeba is an extreme case, but they want the public to “realize the importance of using contact lenses as prescribed”. Well, I guess it is fair to say that Lian Kao learned it the hard way.

So how preventable are these infections? Easy. Just follow these 8 steps regularly.

1. Wash and rinse hands with a mild non-cosmetic soap before handling contact lenses.
2. Dry hands with a clean towel.
3. It is a good idea to keep fingernails short and apply hair spray before you put in your contacts.
4. Put on makeup after the contact lenses are in your eyes, and remove them before you remove your makeup.
5. Always use disinfecting solutions that your eye care professional has recommended. Be aware that some eye products or eye drops are not safe for contact lens users.
6. Never use tap water directly on the contact lenses, or put them in your mouth.
7. Clean each contact by rubbing it gently with your index finger in the palm of your other hand.
8. Clean contact lens case after every use, with either sterile solution or hot tap water and let it air dry. These cases should be replaced every three months.

Here is a video showing the steps, created by FramesDirect.com:

Aside from these steps, I also recommend getting eye exams or check ups regularly. Although you are not guaranteed protection from those nasty infections, just remember, doing something is better than doing nothing.

And again, don’t forget to take them out before going to bed.

-Lilly Inoue