Wearing contact lenses increases the risk of eye infections. Failing to follow the instructions raises that risk considerably.

Here is some helpful advice from The College of Optometrists on good contact lens safety. Its research has highlighted the main risk factors, including:
 

• Patients not caring properly for their lenses.
• Dirty storage cases. 

The two main types of contact lens are rigid gas-permeable or soft. Instructions for using and caring for your lenses will vary accordingly. It is vital that you follow your practitioner's instructions. If you’re using contact lenses for the first time, make sure they're fitted by a registered optometrist, a qualified dispensing optician or medical practitioner.

For lenses that are re-used, rather than worn once and discarded, the following guidance applies:

Disinfection
After removing your contact lenses it is essential that you disinfect them as this prevents harmful organisms building up on the lens. Your practitioner will advise you on the best contact lens system and care regime. This may include additional cleaning procedures, such as rubbing or rinsing.

To disinfect your lenses, soak them in solution in a storage case for a specific amount of time. Never re-use disinfecting solution or top it up – it must be discarded and replaced with fresh solution each time the lenses are stored. Only use the care products recommended by your practitioner, and follow the instructions carefully. 
 
Case care
Rinse your storage case, leave it open to dry after use each day, and replace it monthly. A dirty case is a major source of infection. Clean the storage case each week, using a clean toothbrush and contact lens solution.
 
Daily disposable lenses require no cleaning or disinfection because the lenses are worn only once and thrown away. Do not re-use these lenses because disinfecting solution will not be available and they are unsuitable for repeated use. Even if you wear daily disposables, it is still important to have regular check-ups with your practitioner.
 
Extended-wear lenses are specially designed for overnight wear, and can be worn continuously for up to a month before being discarded. Do not sleep while wearing lenses unless your practitioner advises it. He or she will also advise you on how to look after the lenses if you need to remove them temporarily. You may require more frequent check-ups if you wear this type of lens.       
 
The following tips apply to all types of contact lens:
 
ALWAYS

• Wash, rinse and dry your hands thoroughly before handling your lenses.
• Have an up-to-date pair of spectacles to wear when you need to remove your lenses.
• Replace the lenses at intervals specified by your practitioner.
• Have regular check-ups with your practitioner.
• Seek professional advice if you are having problems with your contact lenses.

Ask yourself these three important questions when wearing your lenses:

• Do my eyes look good?
• Do my eyes feel good?
• Can I see well?

If you cannot answer ‘yes’ to all of these, or you have any other doubts about your contact lenses, remove them immediately and talk to your practitioner.

NEVER

• Go to bed with a painful red eye. Seek advice immediately.
• Bring your lenses into contact with tap water.
• Wet your lenses with saliva.
• Wear your lenses for showering or swimming (unless you use goggles).