May 2011 Issue
Caring for children’s life-long vision
PolyU’s novel contact lenses to slow down your children’s short-sightedness
The ongoing obsession with mobile computing devices such as Kindle and iPad brings extended hours of close-up work that could be stressful for the eyes. Technology revolution may fuel the development of myopia, or shortsightness, a vision problem that has affected a large number of young people in Hong Kong. Recent study has found that over 40 percent of primary school children are short-sighted. Myopia rate grows with school age and by the time they get to the universities, 80 percent of students have to wear glasses or contact lenses. However, there is so far no clinically acceptable method to control the prevalence and progression of myopia.
Therefore, a research team led by Prof To Chi-ho and Prof Carly Lam from PolyU's School of Optometry have invented a new and natural way to improve vision for children and teenagers, which will ultimately help minimize the associated risk of irreversible eye diseases. It is a pair of specially prescribed contact lenses known as "Defocus Incorporated Soft Contact (DISC) Lens", for the myopic sufferers to wear during the day. Unlike the conventional contact lens, these lenses allow the short-sighted children to see clearly while perfecting their vision with a unique formula that preserves the natural focal power of their eyes.
DISC lens works on the natural homeostatic mechanism of the eye, also known as "emmetropization", by which the size of the eyes is regulated by optical inputs from the environment. This lens is a multizone bifocal soft contact lens which simultaneously provides clear vision and constant myopic defocus, a technique whereby images are projected as a blurred image in the front of the retina. This "myopic defocus" helps balance out the negative impact from extensive close-up works that cause accommodative lag in the eyes. By reducing the influence from accommodative lag, the specialized lenses help stop excessive long growth of the eyeball that causes short-sightedness.
"This is because if images are put in front of the retina, it produces optical signals. These translate into biochemical signals," Prof To explained. "The retina recognizes these signals and then transmits biochemical signals like proteins or other small molecules to the eye white, which slows down the growth of the eyes."
DISC lens takes advantages of the natural growth mechanism of the eyes, thus, wearers can avoid any risks from surgery or drugs. In a recent clinical control trial, the first of its kind in the world, has shown that our lens effectively slowed down myopia progression by about 50% for local school children aged from 8 to 13 years old. This marks a significant technological advance in eye care that will certainly benefit millions of children with myopia around the world.
Modern work and lifestyle have forced us to spend long hours in close-up work such as using computer, watching television and reading books, making young people more susceptible to eye fatigue and deterioration in vision. Myopia develops rapidly as children grow, and parents are increasingly concerned. Nowadays, it is very common to find youngsters with high myopia (over 5.00 diopters) in Hong Kong. Similar worrying statistics have been reported in other part of Asia including Singapore, Taiwan and Southern China. People with high myopia are at greater risk of acute eye problems such as retinal detachment or glaucoma, and in severe cases, it may lead to blindness in later life.
As a leading optometry institute in Hong Kong, PolyU is dedicated to vision science for the prevention of visual defects. Our groundbreaking DISC lens now makes effective intervention possible at the first sign of childhood myopia. Prof To stressed, "It is our best defence against many myopia related abnormalities and eye diseases which cannot be cured at present."
"We would like to join forces with a contact lens company to make this available to the public and to increase the dose so that we can get better results. Instead of a 50 percent decrease, we aim to have a 70 to 80 percent decrease or even a reversal of myopia altogether," Prof To added.
This natural, comfortable and effective lens has not only grabbed local media's attention but also international recognition. It has just won a Grand Prize and a Special Gold Medal at the 39th International Exhibition of Inventions of Geneva in April this year.
Professor TO Chi-ho, one of the principal investigators from School of Optometry
Hong Kong school children wore the DISC lens in a recent clinical trial
DISC lens comprises optical zones for correcting refractive error and positive defocus zones for myopia control
Science of eye growth
A novel optical approach - myopic defocus
Grand Prize and Gold Medal with Jury's Commendation at 39th International Exhibition of Inventions of Geneva