Moorfields has noticed an increase in severe contact lens related corneal infections and ulcers. In the worst cases this can lead to permanent blindness and or severely reduced vision necessitating a corneal transplantation. Simple hygiene rules can prevent serious contact lens related infections. You should never use tap water to clean your lenses and never swim or sleep with your lenses in. Moorfields Eye Hospital recently produced the following video on how to use contact lenses safely.