Only if you do not look after your contact lens correctly. This is why you have to ensure that the contact lens is completely sterile before you put it in your eye. Bacteria need three things to live; food, water and warmth, which can all be found in your eye if the bacteria are present on your contact lens! Soft lenses are filled with water so these organisms can therefore survive in them and in your contact lens storage case. If you use your contact lens solutions correctly, and follow the advice of your Optometrist/Ophthalmologist, there is very little risk of infection. The importance of contact lens hygiene cannot be stressed enough.