Wearing cosmetic contact lenses without the advice of an optometrist can damage the eyes, the Consumer Council said yesterday. The council received a case handled by Polytechnic University's optometry clinic in which a young woman, who wore coloured lenses, was diagnosed with hypoxia (lack of oxygen) to the eye, which can cause corneal damage. She had been wearing the lenses she bought on the internet for a year. At a press conference yesterday, council spokesman Ambrose Ho said cosmetic contact lenses were usually made with only one corneal curvature, unlike lenses that correct the vision. 'It is important to let an eye-care professional check the corneal curvature. If the lenses are too tight or loose they can cause adverse reactions in the eyes,' Mr Ho said, adding that factors such as lens materials, colour concentration, thickness and tint of the lens could also affect the oxygen permeability of cosmetic lenses. Mr Ho said users should get a proper prescription if they wanted to wear contact lenses. 'But this doesn't happen if one buys cosmetic contact lenses via the internet.' Users are advised to stop wearing contact lenses and seek professional advice if there is redness, swelling, pain or blurred vision. 'Lenses must be properly cleaned and disinfected to minimise the chance of getting infections which may, in the worst scenario, result in a corneal ulcer,' Mr Ho said.