Frequent use of eye-drops could damage eyes and might even cause complete loss of vision, the Hong Kong Association of Private Eye Surgeons (HKAPES) warned.

HKAPES said most eye-drops contained preservatives that were harmful to eyes. If they were used frequently - over six times a day - preservatives' residues could accumulate and cause chronic irritation and even infection of the cornea and permanent loss of vision.

A survey, conducted by the University of Hong Kong, found that most people were ignorant of the risk.

Nearly 70 percent of the 518 polled (aged between 20 and 50) knew preservatives in eye-drops were harmful but had no idea that they were contained in most eye-drops.

HKAPES President John Chang said preservatives, especially detergent, could lead to blurred vision and lengthen the period of recovery after an eye surgery.

Contact-lens users could also be at risk because the lenses act as a reservoir for the chemicals.

Only a few of the respondents (17 percent) used eye-drops after consulting an ophthalmologist. Most preferred buying it in pharmacies.

"When buying eye-drops, people should consider the composition, dosage and the side-effects," Chan said.

People are advised to visit an ophthalmologist every other year, according to HKAPES.

(China Daily/Agencies August 4, 2005)