There are so many things in our lives that can cause cancer and/or cause our bodies harm. Some of us just live our lives not knowing what those things are, or just not wanting to know. One thing that I knew was bad but didn't know how or why, contact lenses. I wear contacts and decided that I should do some research on how they affect my eyes.
In 2006 there was an outbreak of an eye infection in Singapore, that was related to a cleaning product by Bausch & Lomb. This infection, Fersarium Keratitis, is known to cause blindness and/or scar tissue. To read more about this: http://drbenkim.com/blog/2006/05/potential-dangers-of-contact-lenses.html
Contact lenses can cause dangers to the eyes, but if properly cleaned and worn the risk of infection is lowered. Our eyes are not something to mess around with. I personally never thought too much about how dangerous putting something in my eye could be, but now that I think about it and have done some reading, our eyes are super sensitive and they are not something I want to have get infected and damaged.
There are things that contact wearers can do: make sure that the contacts are made to allow adequate oxygen flow, clean them properly, follow instruction from the doctor, don't be cheap-put a new pair in when it's time, and just be aware. Do the research and ask questions to find out what contacts are right for you, I know I am going to!
These sites offer information on infections, Q&A, and preventative measures.