UNTIL recently, cataract children had to rely on contact lenses or glasses with coke-bottle-like lenses, but now there is another option - an ''intra-ocular lens'' implant. Less than half the size of a 10-cent coin, intra-ocular lens implants following the surgical removal of cataracts have been the preferred treatment for adults for many years, but they have only recently been considered for infants. The new programme at the Prince of Wales Hospital started in April and surgeons have implanted the lenses in eight infant eyes, according to Chinese University's ophthalmology lecturer Dr Dennis Lam. Improvements in surgical techniques during the past few years and the development of smaller ''baby'' lenses with a special ''bio-friendly'' coating have made it all possible. ''We've been following the international scene, and while there's still some controversy about implanting intra-ocular lenses in infants, we're now giving parents a choice,'' said Dr Lam, who recently presented his findings at an international cataract surgery conference in Hong Kong. Most cataracts (when the lens of the eye becomes cloudy) are a result of ageing but some are a result of injury, and those occurring in infancy are due to faulty development of the lens. Cataract babies needed to be treated properly, Dr Lam said. If their vision was not corrected, the brain would not receive sufficient visual stimulation and the visual pathways would not develop, leading to ''lazy eyes'' and a lifetime of poor visual acuity. The traditional options - contact lenses and coke-bottle glasses - for cataract babies have not been satisfactory, according to Dr Lam. Some babies cannot tolerate contact lenses, and parents complain they are inconvenient - cleaning the lenses, putting them in and taking them out. The coke-bottle glasses were not really feasible, Dr Lam said. There is a lot of visual distortion - as the world is being magnified about 30 times. And, they do not really fit infants; the glasses are simply too big. Implanting an intra-ocular lens in a baby's eye, however, is not without problems. ''The infant's eye is very small, and the operation is technically much more difficult and complicated than in an adult,'' Dr Lam said. And, babies are more likely than adults to have a bad reaction to the lens itself. As infants are incapable of doing what the surgeon says, the operation has to be done under a general rather than local anaesthetic, and this carries an added risk. ''Infants' eyes are still growing, so calculating the power of the lens is difficult,'' Dr Lam said. ''You can't get a perfect match, it has to be a compromise. Later in life, the child may need glasses.'' The youngest infant given an intra-ocular lens implant in Hong Kong to date was three months old, said Dr Lam, but a leading American ophthalmologist had implanted a lens in a 17-day-old infant. Intra-ocular lens implantation was more cost-effective than contact lenses, he said. While the operation time is doubled - one hour compared to 30 minutes - the one-time payout for an intra-ocular lens is US$100 to US$200 (about HK$770 to HK$1,520); contact lenses would cost much more over a lifetime. For the moment, Dr Lam is letting parents weigh up the pros and cons of intra-ocular lens implants versus contact lenses or glasses. He expects to be able to give a firm recommendation in six to 12 months' time after keeping an eye on his early cases.