Don't clean your contact lenses with tap water, and don't swim in swimming pools when you're wearing them.
These two simple rules will help reduce the risk of a special type of infection that can lead to blindness - and which standard contact lens solutions cannot kill.
Researchers have discovered that a high percentage of contact lenses are contaminated with pathogenic amoebae known as acanthamoeba, a common protozoa found in soil and fresh water.
The amoeba can cause infections, and can lead to an eye infection called amoebic keratitis, which can cause blindness. Around 85 per cent of all cases occur in people who wear contact lenses.
The amoeba is found in chlorinated swimming pools and domestic tap water, and so contact lens wearers who either clean their lens in tap water, or who go swimming while wearing them, have a far greater risk of developing the infection.
In one study of 153 contact lens cases from users in Tenerife, researchers discovered that 65.9 per cent were contaminated even though the wearers did not have any signs of infection.
No strains were found in daily lenses, although some were found in monthly and bi-monthly lenses. Those who wore the same lenses for more than two years had the greatest levels of infection.
(Source: Journal of Medical Microbiology, 2008; 57: 1399-1404).