(also referred to as Ortho-K, Overnight Vision Correction and Corneal Refractive Therapy) is a process normally worn only at night, to improve vision through the reshaping of the cornea. This method can be used as an alternative to eyeglasses, refractive surgery or for those who prefer not to wear contact lenses during the day.
Mechanism:
It is presumed that the lenses used in orthokeratology reshape the cornea by moving the epithelial cells that cover the surface of the cornea. Some studies indicate that the epithelial cells are compressed in some areas as well as relocated.A common misconception in design is that the lens "presses" on the cornea, thus flattening the eye. In fact, the belief is that the forces generated by the reverse curve cause the redistribution of the epithelial cells, and not pressure on the eye. Properly designed lenses do not touch the user's cornea.
Overnight orthokeratology is for procedures up to -6.00 of myopia and up to -1.75 dioptres of astigmatism.
In the United Kingdom the procedure is offered primarily for myopic correction up to -5.00 dioptres and up to -1.50 dioptres of astigmatism. Fitting evidence for the leading lens designs indicates that procedures undertaken within these parameters have the highest probability of success.
In countries like South Africa, Australia and Taiwan, practitioners using the GOV Orthokeratology system have achieved successful fits as high as -10.00D of myopia and +5.00D of hyperopia.
Not every patient within these parameters will be suitable for the procedure and, for example, conditions such as flat or steep corneas may result in the procedure being less successful.
Contact your optometrist for details regarding the orthokeratology procedure and your eligibility for the procedure.
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