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ORTHOKERATOLOGY

WHAT IS ORTHOKERATOLOGY?

Orthokeratology is the application of individually designed extended-wear rigid gas-permeable (RGP) contact lenses to alter the shape of the cornea in order to reduce myopia (short-sightedness), hyperopia (long-sightedness) and astigmatism.

Orthokeratology is also sometimes called Ortho-K, CRT (Corneal Refractive Therapy), Corneal Moulding, CCC (Corneal Corrective Contacts), VST (Vision Shaping Treatment), GVSS (Gentle Vision Shaping System), EZM (Eccentricity Zero Moulding) or AOK (Accelerated Orthokeratology).

This procedure has been available for nearly 40 years, however, it is only in the last 10 years that it has become a very feasible option for vision correction. Today, with space-age polymers, computerized corneal scanning, and highly sophisticated, truly accurate computerized lathes, the procedure accomplishes vision correction in a matter of days. In addition, new developments in lens materials have made rigid gas permeable contact lenses more permeable to oxygen enabling safe overnight wear. This allows patients to wear lenses overnight while sleeping and to have good vision throughout the day without using lenses or spectacles.

This procedure is effective in both children and adults, freeing them from spectacles and lenses so that they may enjoy a more physically active lifestyle. Current research shows that there is an added advantage in children as it slows down myopic progression.

The Ortho-K technique is a viable and reversible alternative to refractive surgery. The cornea, however, is highly elastic and always returns to its original shape eventually. For this reason, the lenses are worn either nightly, or on alternate nights or for 3 to 5 hours each day once the ideal corneal shape has been achieved.
THE PROCEDURE
The cornea is first measured by a computerized corneal topographer, which measures approximately 15,000 points on the cornea and draws a topographical map in 3-dimensions accurately showing the exact shape of the cornea from centre to edge in all directions. This map is subsequently used to design the person's lens, to determine if the cornea is modified accurately by the lens and to monitor the molding effect over time. The lens works by applying positive and negative pressures to mold the corneal shape to achieve the desired result.


WHY HAVE ORTHO-K DONE?
The main purpose of ortho-k is to free the individual from using contact lenses and spectacles for the majority of, or possibly all, waking hours. This freedom from any artificial aid appeals especially to myopic spectacle and contact lens wearers and is ideal for sportsmen (swimmers, scuba divers, water polo players, boxers etc.); those who work in dusty or dirty environments or people who find spectacles and conventional lenses a nuisance. In addition, ortho-k is also suited to those who need to have a certain degree of uncorrected vision to satisfy their employers or a licensing body, for example, pilots, police, firemen and commandos.

One of the ideal situations for using ortho-k lenses is for a child or teenager with early myopia. Not only does the procedure have all the advantages already given above, but the latest scientific evidence shows that it retards the progression of myopia.

IS EVERYONE SUITABLE FOR ORTHO-K?
No. The procedure generally works best for up to 6.00 diopters of myopia and 2.00 diopters of astigmatism. There are now special lenses that can correct up to 10.00 diopters in certain individuals. Myopes above this limit can still use ortho-k 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 rigidity of the cornea itself. Thus, the speed of corneal molding from one individual to the next will vary. Whilst the success rate is very high, total success for every individual cannot be guaranteed due to these factors.

WHAT DOES THE PROCEDURE INVOLVE?
At the first appointment a full eye examination and computerized corneal topographical scan is performed. This gives us a chance to assess the general condition and health of the eyes and allows us to determine the likely effectiveness of the procedure. If required, a trial fitting will be done, this involves checking the patient in the morning and afternoon of the same day.

A series of ortho-k contact lenses, made from a highly oxygen-permeable rigid material, are then fitted to gently reshape the cornea towards a flatter shape. This reduces myopia and astigmatism whilst dramatically improving unaided eyesight. Excellent vision and comfort are normally maintained whilst wearing these ortho-k lenses.

Most of the visual changes occur rapidly in the first few days. The programme length varies from between 1 and 3 months depending on the degree of visual error. During the first 3 months the patient will have to make 4 to 6 visits to check on their progress. The lenses are worn during sleep for a minimum of 4 hours up to a maximum of 20 hours. This results in good vision for at least all waking hours. Some patients will be able to wear their lenses every second night, and the best case scenario is wearing the lenses every third night.


DOES ORTHO-K HAVE ANY ADVANTAGE OVER LASER SURGERY(LASIK)? YES
  • No ethical surgeon will perform laser surgery for a patient until he or she is at least 18, or more usually 21, years old as the eye is still growing and the myopia will continue to progress.
  • Ortho-k does not cause permanent hazy vision experienced by some patients following laser surgery.
  • Changes in prescription as a person ages can be adjusted without further surgery.
  • The procedure is REVERSIBLE. (Lasik is not!).
  • There is a very thorough understanding and knowledge of the effects of contact lens wear on the cornea because contact lenses have been fitted by optometrists for many years. Lasik's effects are not totally understood.
  • There is no post-operative pain.
  • Ortho-k is significantly cheaper and does not preclude surgery in the future.


WHAT ARE THE ADVANTAGES OF ORTHO-K?
  • Good vision without spectacles or contact lenses during the day.
  • It is not a surgical procedure.
  • It is reversible.
  • It is modifiable.
  • It does not hurt.
  • It may slow down the increase in myopia in children.
  • Using well established contact lens fitting techniques means that there are very few risks.

WHAT ARE THE DISADVANTAGES OF ORTHO-K?
  • You must be prepared for 6 to 8 visits to the optometrist over 12 months.
  • You must continue to wear lenses for short periods of time or the cornea will revert to its original shape.
  • The degree of success is high but cannot always be guaranteed.
  • You must follow instructions implicitly for the best results.

COSTS INVOLVED
The procedure may involve several lens changes. The lenses are manufactured to accuracies far exceeding those for normal contact lenses and with very specialized materials. The price, including all fees for the first year, varies from $1,600.00 to $2,400.00.
 
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