By Nigel Little 

Ortho-k lenses  are small custom-designed contacts worn overnight while sleeping which correct short-sightedness by gently flattening the surface of the eye utilising the pressure provided by closed eyelids during sleep. The miniscule flattening effect which occurs is sufficient to ensure that light enters the eye at the correct angle so it focuses directly on the retina rather than in front of it which is why distant objects appear blurry to short-sighted people. And the eye's ‘muscle memory' means this flattening lasts for over 24 hours so the ortho-k lens wearer enjoys perfect natural vision from when the lenses are removed in the morning until they are reinserted at night.

Given that the benefit of wearing overnight ortho-k lenses  is the same as that achieved by corrective eye surgery methods such as LASIK - but without any surgery - and the fact that unlike laser surgery it is fully reversible, there is now a growing recognition that this is an attractive risk-free alternative for achieving natural daytime vision. Its emergence as a treatment for short-sightedness comes at a time when questions are being asked about the long term effectiveness of laser surgery and the true nature of risks associated with it. Indeed, as reports, one of the first ophthalmologists to provide laser surgery in Taiwan some 20 years ago has now declared he will no longer perform the procedure because of his concerns about the treatment.

Cai Ruifang, an adjunct professor at Taipei Medical University recently said that a dozen or so middle-aged patients, who underwent the surgery more than ten years ago, are now suffering from a significant decrease of visual acuity. As such, it indicates that the procedure may not provide a permanent correction for short-sightedness which for younger patients may mean that repeat surgical procedures are required to maintain full vision as they age. Given that, for a small percentage of patients, laser surgery can result in side effects such as dry eye, post-operative glare and diminished night vision, the requirement to have repeat treatments to maintain full vision could increase the risk of such side effects occurring. In these circumstances, ortho-k lenses clearly offer an attractive alternative to laser surgery.


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