Orthokeratology (ortho-k), involves the use of specially designed rigid gas-permeable (RGP) contact lenses to alter the shape of the cornea in order to reduce or correct myopia, hyperopia, and astigmatism. It has been practised in the USA for 35 years, but the results were quite variable and unpredictable. However, in the last ten years new technology has become available to accurately map the corneal shape and manufacture lenses that will achieve a controlled and precise reduction in the eye’s optical imperfection. In addition, new developments in lens materials have been made that enable safe overnight wear to be possible. The technique of Ortho-k is now a safe, viable and reversible alternative to refractive surgery. The cornea, whilst being mouldable, always returns to its original shape if lens wear is stopped. For this reason, lenses are always worn nightly, or alternate nights after the ideal corneal shape has been achieved in order to retain the effect.
The main purpose of Ortho-K is to be free of both spectacles and contact lenses for the majority, or more typically, all waking hours. The freedom from any artificial aid appeals to spectacle and contact lens wearers and is ideal for sportspeople, those who work in dusty or dirty environments or people who find spectacles and conventional contact lenses inconvenient. In addition, those who need to have a certain degree of uncorrected vision to satisfy their employers or a licensing body (e.g. pilots, police) can also be helped by Ortho-K. Most patients wear the lenses overnight and remove them on awakening, although some patients wear them solely during the day.
One of the ideal situations for Ortho-K is for the child or teenager with early myopia. Not only does it have all the advantages outlined above, but multiple scientific studies performed in the USA, Asia and even here in Australia have all shown very similar trends in myopia control, supporting what optometrists have been witnessing in their patients for many years; a definite slowing in the progression of myopia.
NO. The procedure works best up to a maximum of 4.50 dioptres of myopia and 2.00 D of astigmatism. New lenses are now also being trialled for the correction of moderate amounts of hyperopia. Prescriptions above this may be reduced, but total correction is not usually possible. In addition there are several unknown factors for each individual; the complexity of the corneal shape and the response of the cornea itself. Thus the speed of corneal moulding from one individual to the next will vary. Whilst the success rate is very high, total success cannot be guaranteed due to these factors.
The initial assessment appointment includes a full eye examination and computerised corneal topographical mapping. This gives the optometrist a chance to assess both the general condition and health of the eyes and also to determine the likely effect of the procedure in that individual. Ortho-K contact lenses, made from highly oxygen permeable rigid material, are then fitted using the results of the corneal map to gently reshape the cornea towards less curvature. These will be worn for an initial trial and the response evaluated. This will typically take place overnight with a review the next morning. The effect should be a reduction of the initial prescription with improvement in the unaided eyesight. The corneal health will be carefully evaluated to ensure that it is not compromised. Only when the patient demonstrates an excellent response to the orthokeratology trial will the treatment programme commence.
Once a patient has shown the appropriate response to a trial, custom made lenses will be ordered. After these lenses have been fitted at a subsequent appointment, the patient will start to wear the lenses on a regular basis, typically overnight. For the first two to four weeks the vision may not be sufficiently good for all day-to-day activities. In these circumstances, daily disposable soft contact lenses will be worn during the day. After the first month, excellent vision and comfort are normally maintained whilst wearing Ortho-K lenses. Occasionally more than one set of lenses are required to effect the desired change.
As most of the visual changes occur rapidly in the first few weeks, fairly frequent examinations and possible lens changes need to take place then. Stabilisation procedures then follow at a slower pace over the next few weeks. The programme length varies between 1 and 2 months depending upon the degree of visual error. The fees for orthokeratology treatment include all visits in the first year.
The final wearing time depends on many variables, but the treatment aim is good unaided vision most or all waking hours, with lenses being worn overnight or part of each day only. Some patients will be able to wear their lenses every second night.
The procedure will involve several appointments and may require multiple lens changes. Ortho-K practitioners have undergone specialised training in the procedure and require technologically advanced equipment to perform the procedure. For these reasons, the initial costs of Ortho-K are greater than conventional contact lens correction but less than refractive surgery. Once the treatment is complete, the on-going costs are significantly less than the costs of disposable contact lenses, since the life of the lenses may be up to two years. The exact fee level will depend on your prescription and the complexity of your individual case. You will be provided with a detailed quote before your treatment program is commenced.