Half of contact lens solutions fail amoeba test, says council

PUBLISHED : Sunday, 16 July, 1995, 12:00am
UPDATED : Sunday, 16 July, 1995, 12:00am

HALF the territory's contact lens solutions are incapable of killing dangerous micro-organisms that cause serious eye infections.

The Consumer Council yesterday said tests on 16 soft lens solutions revealed eight were ineffective at killing acanthamoeba, an organism which could cause corneal ulcers.

The Chinese University of Hong Kong's Faculty of Medicine tested three types of disinfection systems, including eight chemical disinfection systems, seven hydrogen peroxide systems, and one heat disinfection system.

One contact lens manufacturer, Bausch & Lomb (HK), estimated there were about 265,000 contact lens users in Hong Kong.

'Of the 16 samples of soft lens solution tested, eight could effectively destroy the micro-organism,' the council's Publicity and Community Relations Committee chairman, Sara Ho Suk-ching, said.

Of four brands which claimed to be effective in destroying or removing amoeba, only two were able to substantiate their claims. One could not be verified due to a technical problem in testing.

Although eight other solutions were effective within 24 hours of soaking, the time required by half of these samples exceeded the minimum soaking time recommended by the manufacturers.

But, in a statement, Bausch & Lomb said the report was not comprehensive; the council had shifted the focus from full lens care to only one disinfecting step, it said.

The company said three steps - cleaning, rinsing and disinfecting - were needed to maintain corneal hygiene, but the council had only focused on the disinfection part.

Ms Ho said that just because solutions failed to kill the amoeba within 24 hours, it did not mean they were not up to the required safety standards in other aspects.

'We concentrated on the effectiveness of these solutions in destroying the amoeba. But, in fact, all of these solutions can perform a variety of functions,' she said.

Ms Ho advised consumers to concentrate on total eye-care as preventive measures, to follow the proper procedures as recommended by manufacturers, and to consult optometrists or ophthalmologists when needed.

Team head of the Eye Unit at Prince of Wales Hospital, Dr Dennis Lam Shun-chiu, said amoeba infection was rare, but in the worst case could result in the loss of sight, even the eye itself.

There had been more than 1,000 cases worldwide, and 'over 80 per cent of these cases are related to the wearing of contact lenses,' Dr Lam said.

He said there were four cases in Hong Kong, with two patients receiving cornea transplants.