Cosmetic contact lenses have become must-have accessories for thousands of adolescents: tiny scraps of coloured plastic that give them the eyes of a cat, or an alien, or the Incredible Hulk.
Put them in and you are guaranteed to be noticed. But the lenses also risk permanently damaging teenagers' eyes, say opticians.
Over the past 12 months, sales of cosmetic lenses - which have no corrective effect on sight, merely change eye colour - have increased fourfold. A total of one million pairs have already been sold by stores such as Argos. Manufacturers say they plan to increase production to 10 million next year, partly by expanding into American markets.
It is a prospect that alarms health experts and on Friday the House of Commons will consider the second reading of a private Bill - promoted by Glasgow MP John Robertson - to outlaw cosmetic lens sales from stores that do not provide eye experts to give advice to customers.
'Real contact lenses can only be sold by opticians who give advice, measure users' eyes so lenses fit properly and show them how to keep their lenses clean,' said Robertson. 'But cosmetic lenses can be sold by anyone. Both types pose the same health problems.'
Opticians say serious infections are triggered when users swap coloured lenses at clubs or parties, or fail to clean them, or keep them in their eyes for several days at a time. The current issue of Eye and Contact Lens publishes a series of alarming case studies of the kind of eye damage that can be caused.
One 14-year-old girl, who bought her coloured lenses in a video rental store, was hospitalised for several days and suffered scarring to her cornea when she picked up an eye infection from her lenses.
A man bought a pair for Halloween and scratched his cornea as he tried to remove one. Another victim regularly slept wearing her lenses and after several months developed ulcers in her eyes. All victims endured considerable pain and discomfort, while their lenses, the journal notes, were all 'purchased without an eye examination, proper fitting or wear and care instructions'.
The General Optical Council said it was 'extremely concerned' about the risks posed by cosmetic lenses. 'People understand the risks posed by corrective lenses because of the advice and care that they get from opticians,' said director of standards Melanie Carter. 'They need to understand that the risks from cosmetic lenses are exactly the same.'
But lens sellers and manufacturers last week rejected accusations that their products are dangerous. Argos said only individuals over 16 could buy cosmetic lenses in their stores while its catalogue suggests purchasers should consult an optician or doctor about their lenses.
In most stores there are no age restrictions on purchasers, though Kashol Pungi of manufacturers Fashion Wear Services said the price of cosmetic lenses - £25 a pair - would probably be enough to deter boys and girls in their early teens. He also said he had received no reports of lenses causing any health problems. 'I would not sell these if I thought they were dangerous,' he added.
But Susan Blakeney of the College of Optometrists disagreed. 'You cannot put any old lens in your eye,' she said. 'People have different-size eyes and if you put in lenses that are too tight you will simply suffocate your eyes. You need to be measured and advised by a professional or you will damage your sight.'
It remains to be seen if such warnings will be effective, however. Robertson admitted his Bill had little chance of success because of parliamentary time constraints
The Department of Health said lenses could not be controlled as medical devices as their use was purely cosmetic. However, a spokesman said it was still hoped that regulations covering their sale would be introduced one day.
