People who want to wear contact lenses should attend an eye test and fitting at an opticians or optometrists, according to J&J.
This involves measuring the eye and this data is used to prepare the prescription that can then be used to order contact lenses online.
J&J likened the process to being fitted with a new pair of shoes and pointed out that if contact lenses are not properly fitted then they can feel just as uncomfortable as wearing a size too big or small.
Interestingly, J&J also notes people who want to wear contact lenses for cosmetic reasons only - such as to make their eyes a different colour - should also be fitted with contact lenses.
As medical devices, contact lenses can be bought with a valid, written prescription.
While the NHS suggests an eye examination at least once every two years, J&J recommends one every year.
Coloured contact lenses can also be bought cheaply online, for people who need vision correction as well as those who want to use them as a fashion accessory.
by Emily Tait