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Orthokeratology may be defined as 'neutralising the eye's power by the programmed application of rigid contact lenses'. On taking the lenses out, the eye retains its 'neutral' strength allowing clear vision for an extended period of up to two or three days depending on the individual.

So what does that mean……? Programmed? Neutralised? Applications?

Yes that might all sound complicated but let me try explain it another way. Something that most people have heard of and can relate to. How about orthodontic treatment for your teeth? You probably know or have heard of this especially if you have teenage children.  In orthokeratology, you wear a retainer lens at night and it fixes your vision. As in orthodontics, you take out the retainer and your vision remains fixed throughout the day. To maintain good day time vision, you need to wear the ‘vision retainer’ at night.

Like orthodontics, orthokeratology has been around a long time - it just not as mainstream. It is totally reversible and a safe process that offers an alternative to other forms of vision correction. Stop wearing the lenses and your eyes return to the normal, pre-treatment prescription in around five days.

It was found that the neutralising process occurred much faster when the lenses were slept in. This resulted in the labels 'accelerated orthokeratology' or ‘overnight vision correction' and you will also find the term 'ortho k'.  All these terms refer to the same process. 

Wearers find overnight orthokeratology more comfortable and altogether more satisfactory than conventional lenses. Many choose this because of dry eye or other comfort related issues present with their existing lenses which doesn't happen with orthokeratology. 

It is a minimally invasive, reversible technique appealing to patients unsure of or unsuitable for refractive surgery or too young to be considered for surgery. Despite its popularity, laser surgery does not always give permanent stability of vision (as well as other risks). Where short sight has started to develop again, satisfactory stabilisation can be provided by orthokeratology where there is no desire for repeat laser surgery. 

Additionally, they appeal to active or professional sportspeople since participation without wearing lenses means there are no issues of lens loss. They are of particular benefit to swimmers and martial arts participants. In the latter case, normal contact lens wearers have had contests stopped because of conventional lens lose during bouts - something that doesn't happen when lenses are only worn at night. 

It is generally considered that orthokeratology is only available for low to moderate short sight with low degrees of astigmatism. While this has been the main area of correction, the last decade has seen the range of correctable prescriptions expanded.  Much higher amounts of astigmatism are also being successfully corrected. This has the greater advantage of providing more stable vision than conventional lenses. 

Possibly the greatest benefit of orthokeratology will be found in its now proven ability to stabilise short sight (control myopia). While not being able to reverse it, the ability to stop a young person at a prescription of -1, -2 or -3 where the prescription is seen to be rapidly changing, is a huge potential benefit given the sight problems that higher levels of short sight bring. 

For the more mundane, not wanting to wear contact lenses full time but not wanting to be known as 'the lady with glasses' has also been cited as a reason for trying orthokeratology. 

But what about safety? You are sleeping in these lenses. Let’s be clear: all contact lenses carry a risk of infection or more. Traditional lenses that are slept in, do have a higher prevalence of infections. However, you need to remember that not only are they slept in for 7 nights or up to 30 nights, but also throughout the waking hours as well. Orthokeratology lenses are worn when sleeping (7-8 hours usually?) 7 nights or less per week. This reduced wearing schedule contributes to fewer complications compared with some traditional contact lenses. Recent research has confirmed these results. Complying with wearing instructions and having access to an eye care practitioner, as required, greatly reduces safety concerns.

Cost - this varies with the specific lens design that is required but there are two options – outright purchase or smaller initial payment followed by monthly DD (includes standard solutions, annual replacement of lenses, follow up appointments and a degree of insurance). This second option is a two year contract but if it just doesn’t work, the lenses are returned and no further monthly payments are due.     

As you may have noticed, annual replacement of lenses was mentioned. Handling, wearing, cleaning lenses results in a degree of wear and tear to the lens surfaces. We are dealing in minute adjustments to the cornea’s surface to make these vision changes possible. Small changes to the lens surface affect these changes over time. This is why manufacturers advocate changing lenses periodically. If you have already researched orthokeratology, you may find opticians suggesting changing lenses every six months. This is the most commonly suggested regime. However, twelve monthly is advocated by others. Personally, I find the determining factor to be the type of lens worn and the how the individual eye reacts to the procedure. Having said that, I do find annual replacement works well for the majority of wearers. Where this is the case, ignoring any initial fitting changes, orthokeratology costs less than wearing good daily disposable lenses.   

To receive further answers to the most common questions about orthokeratology click to receive your free PDF copy of ‘Life Without Lenses – A Complete Guide’.

Colin Tonner MCOptom DipTP is an experienced Optometrist based in Lancashire/Cheshire and can be contacted at The Ortho K Clinic  Tel: 0161 300 6989.