WHAT IS ORTHO-K?
Evidence in scientific literature suggests that some contact lenses may slow the progression of nearsightedness in some children. Ortho-K or orthokeratology is the reduction, modification or elimination of nearsightedness and mild astigmatism by the custom application of rigid gas permeable lenses during sleep. The lenses are removed in the morning. In some ways, it is similar to the use of dental retainers by an orthodontist to straighten and retain teeth in a specific position. The only difference is that the cornea (front surface of the eye and the clear window we see out of) is highly elastic and fluid and will always return to its original shape. For this reason, the lenses are worn nightly or alternate nights after the ideal corneal shape has been achieved to maintain good vision during the day. The benefit of the cornea being so elastic is that upon discontinuation of wear, the cornea will flex back to its original shape. It is 100% reversible.
WHY HAVE ORTHOKERATOLOGY DONE?
The main purpose of Ortho-K is to reduce the progression of myopia or nearsightedness. Individuals with extremely high myopia/prescriptions have an increased risk of retinal problems, glaucoma and are highly dependent on glasses to see or move around. Orthokeratology allows for stabilization of the prescription and aims to reduce the progression seen with glasses wear and soft contact lens wear.
The secondary purpose is to be free of both contact lenses and glasses during the day. It is ideal for active children, those who can’t keep glasses on their face, sports individuals, swimmers or those who work in dusty and dirty environments where other types of sight correction may be inhibiting. Children can see all day long without glasses or contact lenses.
Individuals with extremely high myopia will notice that the reduction of the error enables them to have improved functional vision when the lenses are removed. Some long term contact lens wearers develop sensitivity to their lenses which results in reduced wearing time or ocular conditions. Ortho-K can solve these problems too.
If you have difficulty in achieving the required visual standard for employment then Ortho-K may help.
IS EVERYONE SUITABLE FOR ORTHO-K? - NO!
The procedure works best up to -5.00 dioptres of myopia and -1.50 dioptres of astigmatism. Errors above this may be reduced but total correction is not usually possible. The procedure also does not work as effectively on very steep or very flat corneas. 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 moulding from one individual to the next will vary. Whilst the success rate is very high, success cannot be guaranteed due to factors outside your optometrists' control.
WHAT DOES THE PROCEDURE INVOLVE?
First an initial assessment appointment which will include a full oculo-visual examination and a computerized corneal topographical scan. This gives your optometrist a chance to both assess the general condition and health of the eyes and also to discuss the likely effectivity of the procedure according to the specifications of the curvature of your eyes.
A pair of trial lenses is calculated and prescribed for overnight wear. Upon successful learning of how to insert and remove the lenses, they will be given for you to sleep in them. The following morning, the lenses will be removed and another assessment and topographical scan is made. If the fit needs to be modified, the measurements of the trial lenses will be utilized to design a second set of trial lenses. The procedure is then repeated. Once your optometrist has established the correct fit that can reduce your myopia to the best achievable point, a pair of customized orthokeratology lenses that are made to your eye’s specifications will be ordered. When these arrive, you will be given the lenses for overnight wear again and return after wearing them for 1-2 weeks nightly to be assessed again. Excellent vision and comfort are normally maintained whilst wearing Ortho-K lenses. You will be assessed after a month to finalize the fit and every 6 months thereafter. These visits are essential in maintaining the health of the eye and the effectivity of the lenses.
This series of Orthokeratology lenses are made from 100% oxygen permeable rigid material which gently shape the cornea towards a more spherical shape. This reduces the myopia and astigmatism whilst dramatically improving unaided eyesight. Most of the visual changes occur rapidly in the first few days and stabilize over the next few months. The fitting program length varies between 2-4 months depending upon the degree of visual error.
When the maximum results are achieved, the final wearing time depends on many variables. The optimum sleep recommended is 6- 8 hours of sleep with the lenses on. Our optimal goal is to be able to maintain the best vision for 48 hours without wearing the lenses.
WHAT ARE THE ADVANTAGES TO ORTHOKERATOLOGY?
- Good vision without contact lenses or spectacles during the day.
- It is not a surgical procedure.
- It is reversible and non-invasive.
- It may stabilize your myopia progression to reduce risks to the retina and glaucoma.
WHAT ARE THE DISADVANTAGES TO ORTHOKERATOLOGY?
- You must be prepared to allow for 4-10 visits over 2-4 months. During that time, you may experience some changing vision but you can wear glasses during this period.
- Retainer lens wear is essential nightly or the cornea will revert to its original shape.
- The degree of success is high but can’t be guaranteed so mild glasses may still be used.
- Although the chance of an eye infection is still very low (about 1 case in 500 years of wear), it is essential that you wash your hands and keep surfaces clean.
- The rate of improvement varies from one person to the next. You must be prepared to follow instructions implicitly for best results.