UNSW researchers have found the first scientific evidence that special orthokeratology (OK) contact lenses worn only while you sleep may be able to correct long-sightedness;
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Key Points:
- UNSW researchers have found the first scientific evidence that special orthokeratology (OK) contact lenses worn only while you sleep may be able to correct long-sightedness;
- The pilot study holds future promise of a safe, simple and reversible treatment for the many people with this vision problem (when you can see distant objects clearly but close objects are blurry). In Australia, moderate long-sightedness affects 8% to 10% of the population.
- The finding builds on the team’s earlier studies into the often dramatic and rapid improvements achieved with OK lens therapy for myopia - or short-sightedness. Many myopic people have been able literally to throw away their glasses.
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Background: |
A traditional Chinese remedy for short-sightedness reportedly was to sleep with small sandbags on the eyes.
Australia now plays a leading role in a myopia therapy that uses special orthokeratology (known as OK or ortho-K) contact lenses that are worn during sleep and removed during waking hours.
The rigid polymer lenses are flattened in the centre so that they gently press on the soft surface of the cornea to reshape it and correct its focal length.
Vision begins to change within as little as 10 minutes and many myopic people can see normally - without the need for spectacles -after only a week of wearing OK lenses at night. Some then need only use the lenses every two or three nights to maintain normal vision. Others with a greater degree of myopia need to wear them every night.
The therapy is safe, reversible, highly effective, much cheaper (about $1,200 in total, including consultation and follow-up) than laser surgery (about $5,000 for both eyes). Vision returns to its prior state when users stop wearing OK lenses.
It’s estimated that about two-thirds of myopic people can have their vision problems corrected in this way.
What’s new?
A pilot study by a team led by Dr Helen Swarbrick, a senior lecturer and contact lens expert in the UNSW School of Optometry and Vision Science, now has found evidence that a new “steep” OK lens design may be able to overcome long-sightedness
The study suggests that a steep lens could work by reshaping the wearer’s cornea to alter the eye’s focal length in the opposite way to the effect achieved by using flat lenses to correct short-sightedness (see graphic).
The study involved 10 young adults being fitted with steep OK lenses for four hours. Before-and-after tests showed a significant steepening of the subjects’ corneas and they also reported a small but significant reduction in long-sightedness.
A report on the study has been accepted for publication in the leading US science journal Optometry and Vision Science.
It will be the first research paper in a refereed scientific journal to show the potential for OK lenses to correct long-sightedness.
Dr Swarbrick comments: “Although the study involved only a small number of subjects, it’s very promising that we were able to achieve a measurable change even in such a short time. We now plan to expand on this preliminary study with a more extensive research program starting later this year, with industry backing.”
“It happens so fast it’s amazing”
She began researching OK lens therapy for short-sightedness in 1997 and was “a complete sceptic” at the time but soon became a convert when she saw them in action.
“It happens so fast it’s amazing: even after as little as 10 minutes of OK lens use, some short-sighted people can read unassisted a further two lines down an eight-line eye chart. After one night’s wear, some people can read up to six or seven lines down the chart.
“There’s increasing interest around the world; it’s an amazingly wide field of research and Australians lead the way both in research and in the design and manufacture of OK lenses.”
Fellow UNSW researcher, Ms Nina Tahhan, clinic research manager for the Vision Co-operative Research Centre, recently published a research report on myopic OK lens therapy involving 60 subjects. It confirmed that about three-quarters of the benefit is achieved on the first night alone and that very little further change occurred after the first week.
“People are a bit sceptical about it but I use them myself and I can tell you that I had glasses from the age of 15 and hated wearing them: now, I couldn’t even tell you where my glasses are,” says Ms Tahhan.