It's advice that has been on the various doctor tv shows and made its rounds on the news before, and probably also mentioned to you by your eye doctor if you wear contact lenses.  It's on the news again via the U.S. CDC (Centers for Disease Control and Prevention) and it's good to know if you wear contacts.  The CDC found that in the 1,000+ contact lens-related infections reported to a federal database over the last decade, nearly 20% of those infections resulted in eye damage - either a decline in vision, a scarred cornea, or the need for a corneal transplant.  And 25% of the reported cases involved known risky bad habits.

“Contact lenses are a safe and effective form of vision correction when worn and cared for as recommended,” said Michael Beach, PhD, director of the CDC’s Healthy Water Program, in a press release about the survey. “However, improper wear and care of contact lenses can cause eye infections that sometimes lead to serious, long-term damage.”

(via ABC News: "Mistakes You're Making With Your Contacts")

CDC warns contact lens wearers to avoid these contact lens bad habits to help prevent eye infections and possible permanent damage:

1) Don't sleep in your contacts.  Your eyes need to breathe - the enzymes and antibodies that protect the surface of your eyes require oxygen to fight off germs.

2) Don't handle your contact lenses with dirty fingers - wash your hands before touching your eyes/contact lenses.

3) Don't assume using 'no-rub' contact solution means that you don't need to rub your contacts - you do, to remove germs and protein buildup.

4) Don't reuse your contacts solution in your lens case - after each use rinse out your lens case and let it dry out, and use fresh lens solution next time.

5) Showering/swimming with your contacts in:

The CDC advises keeping your lenses away from water (including pool water) to avoid a rare but potentially blinding infection caused by an amoeba called Acanthamoeba, as well as other types of infections. Bacteria and parasites in water can get caught under your lenses. If you're a swimmer, you may want to invest in prescription goggles.

6) Leaving your lenses in too long.  According to this ABC article:

When you're at home and on weekends, give your eyes a break and wear your glasses, says Berkeley, Michigan-based ophthalmologist Steven Shanbom, MD. In a prior interview with Health, he recommended that lens wearers keep their contacts in for no more than 12-14 hours a day.

(via ABC News: "Mistakes You're Making With Your Contacts")