SCMP June 23, 2001
Doctors concerned about risks of special lens
Eye doctors fear a surge in cases of corneal ulcers in short-sighted children who wear a certain type of corrective lens.
Two girls went down with the condition last month, bringing to eight the number of corneal ulcer patients using Ortho-K lenses to have been treated by the eye unit at the Prince of Wales Hospital.
Seven were aged nine to 14 and one was an adult. They suffered an average 25 per cent permanent loss of vision.
The lenses supposedly stop short-sightedness from getting serious during adolescence by flattening the cornea and reducing its thickness, said Professor Dennis Lam Shun-chiu, chairman of Chinese University's department of ophthalmology and visual sciences.
One of the girls, 13, was left with permanent scarring of her left cornea and 80 per cent vision loss, said Dr Alfred Leung Tai-shing, an associate professor in the department.
The girl said an optometrist persuaded her to use the lenses. "After wearing them for three years, one day my eye suddenly got red and painful, like having needles stuck in it."
Dr Leung said: "The damage to her eye is irreparable. She is waiting for a cornea transplant to regain better vision which, at best, still could not compare with what it used to be."
He said the risk of infection was at least twice that with normal contact lenses due to their tight-fitting and night-wear properties. This increased the chances of oxygen depletion and abrasion. Allergy and bacterial infection were other complications that could eventually cause ulcers and even blindness.
But optometrist Andy Cheung Moon-kuen, president of the Hong Kong Orthokeratology Association, said more than 60 per cent of 3,000 Ortho-K lens-users in Hong Kong were under 17 and the organisation had received no report of serious eye damage.
He said the lenses were safe if the optometrist or eye doctor followed prescription procedures and the users were healthy.