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Growing interest in Orthokeratology

Orthokeratology is the science, and art, of using rigid gas permeable contact lenses for the temporary reshaping of the anterior corneal surface.

This process is also sometimes referred to as corneal moulding, although in reality the fundamental shape of the cornea is not altered. Rather, it is a phenomenon restricted to the surface and superficial tear layer of the eye. It is usually done to correct myopia, and less commonly hyperopia.

Myopia is now recognised as a serious public health issue, and is often described by experts and the media as an epidemic. Increasingly among children, genetic factors are combining with the ever-growing use of electronic devices at close range. When coupled with a lack of outdoor and physical activity, the issue of myopia is increasingly pertinent.

Despite all this, involvement in the practice of orthokeratology (Ortho-k) has only seen a limited increase. This is unusual, because Ortho-k contact lenses can play an important part in combating this threat to public health.

Ortho-k lenses have a come a long way over the years. Initially, their design concentrated on the central flattening effect. George Jessen was the first to publish research on Ortho-k in the early 1960s, however his early approach was met with limited and variable success. The Ortho-k revolution truly began during the late 1980s and early 1990s, with designs using so-called reverse geometry proving to be far more effective.

More recently, studies into the prevention and slowing of myopia have noted the optical benefit from the mid-peripheral steepening afforded by the return curve of reverse geometry contact lenses. Effectively, the use of Ortho-k lenses has been resulting in myopic peripheral defocus, an optical outcome that has been shown to be effective in slowing or halting increases in the eye’s axial length. Dr Earl Smith of the University of Houston has done a lot of outstanding work in this regard.

"With Ortho-k being both clinically effective and professionally satisfying, why is there such a small number of practitioners taking up the field?"

Most commonly, successful Ortho-k contact lenses are worn overnight, leaving the wearer with good to excellent vision throughout the following day, freeing them from the need for spectacles or other contact lenses.

While Ortho-k is not the only myopia control measure available, it shows a high percentage of success. It is only matched by some recent special anti-myopia design soft multifocal contact lenses; along with a pharmacological approach that principally involves the use of atropine. Other attempts with standard multifocal soft lenses, special spectacle designs and the application of binocular vision training, have been less rewarding.

Carl Zeiss

With Ortho-k being both clinically effective and professionally satisfying, why is there such a small number of practitioners taking up the field?

Principally, today’s universities find it difficult to accommodate all possible topics into an ophthalmic curriculum. Courses already teach contact lens fundamentals, but adding in rigid gas permeable lenses followed by less common specialty categories such as Ortho-k, modern mini sclerals and hybrid lenses often prove to be too much. There is also the learning curve in practices. Once graduated, many early optometrists find fitting contact lenses a real challenge to their confidence levels. For many, Rigid Gas Permeable and Ortho-k lenses are even more challenging.

Confidence can only be gained through hands on work, preferably with the guidance of a knowledgeable mentor. This makes finding an opportunity for experience and coaching crucial to new Ortho-k practitioners.

In order to encourage new recruits into the ranks of Ortho-k practitioners, and also build practitioner confidence, the Orthokeratology Society of Oceania conduct Ortho-k and rigid contact lens workshops around Australia and New Zealand. Anyone interested in an introduction to the field should consider taking a good look at what OSO has to offer.

Finally, in the myopia context Ortho-k comes with the challenge of prescribing and instructing children on how to use the lenses. While this may seem like a daunting task to some, intelligent young prospective contact lens wearers with very motivated parents can overcome these challenges without undue effort.

Professionally Ortho-k is a very rewarding field, and I encourage anyone interested to take a look at the opportunities available.

Name: Ian G. Sim
Qualifications: B.Optom
Workplace: Private practice, and Ophthalmology Eye Clinic, Royal Perth Hospital
Position: Contact lens optometrist
Special interests: Acanthamoeba corneal infections, origins of contamination, the treatment success and outcomes.
Location: Perth
Years in the profession: 54 years


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