by Susan Cheong
New specialised othokeratology contact lenses may correct common problem known as presbyopia. Photo: Mary Thorman
Contact lenses worn only while sleeping may soon give some people with poor vision the chance to see close objects clearly again.
A research study recently conducted by the University of New South Wales has found othokeratology contact lenses can correct presbyopia, a natural aging process that affects most people in their 40s and 50s.
Orthokeratology, otherwise known as ortho-k, is a treatment that involves wearing specialised rigid contact lenses to gently reshape the cornea – the front surface of the eye – to temporarily correct vision.
The lenses are individually fitted and worn overnight to give people corrected vision during the day. To maintain the optical effect, the lenses need to be worn every night, as the vision will start to revert after a day.
Professor Helen Swarbrick, of the School of Optometry and Vision Science at the University of New South Wales, says the research adopts the commonly used correction technique of mono-vision, where one eye is corrected for near vision and the other eye for distance vision with orthokeratology to successfully correct presbyopia.
“I found it absolutely fabulous,” says Vanessa Honson, a participant of the research study. “I found that I could read nearly everything in any light and when going to the shops, I didn’t have to put my glasses on.”
However, Professor Swarbrick says the mono-vision technique does not work for everybody as some people may find it difficult to adapt to this type of vision.
Orthokeratology lenses have already been proven to successfully correct myopia in adults and, more recently, in potentially halting the development of myopia in children. Professor Swarbrick says the idea was to fit these lenses to children when they first showed signs of short sightedness to stop it from progressing.
“It is more than a cosmetic advantage. It is a real public health advantage particularly in parts of Asia where there is such a high prevalence of myopia in children,” she says.
Dr Gavin Boneham, President of the Orthokeratology Society of Oceania, says people who do a lot of contact and water sports will find ortho-k lenses particularly beneficial, as they provide a trouble-free way of seeing clearly without glasses or lenses.
He says most people adapt to the lenses very well.
“When I first put the lenses on, I was aware something was there but it wasn’t painful,” says Tess Mallos, another participant of the research study. “But now, it’s so comfortable that I don’t even notice it.”
The ortho-k lenses are made out of special material to allow sufficient oxygen to the eyes whilst they are closed to ensure good eye health. However, the ideal candidate will need to have good ocular and general health.
“The risk of wearing any contact lens is an eye infection. But as long as you wash your hands and look after the lenses, the chances of getting an eye infection is fairly low,” says Dr Boneham.
Ms Mallos is yet to experience any problems from her lenses.
“I’ve had no problems with it,” she says. “It’s the last thing I do before I go to bed. I pop them in and it’s really quite easy cleaning and storing them in the morning.”
Dr Boneham says there is a relatively low drop out rate of 0.5 per cent for ortho-k lens users in Australia.
“It’s definitely a freeing experience. You’re not caught out in any situations where you can’t see something and that is a great advantage,” Vanessa Honson says.
For more information on orthokeratology lenses or to find a trained practitioner, visit http://www.osa.net.au/