How does Ortho-K slow down the progression of myopia?
New research indicates that one of the causes for the progression of shortsightedness is peripheral retinal blur. This new theory states that while glasses and daytime contact lenses focus the central vision, they do not focus the peripheral vision very well. While the visual system is still developing (up to age in early 20s), the eye grows to try to improve focusing. The amount of growth of the eye is determined by the clarity perceived in the peripheral retina. With glasses the peripheral retina is blurred, since only the central retina is focused correctly. This results in excessive growth of the eye and further progression of shortsightedness in people prone to this.
Ortho-K lenses reshape the front surface of the eye to form the correct shape for clear focusing onto both the peripheral and the central retina. Glasses and normal contact lenses cannot do this. For this reason it is believed that the progression of shortsightedness is slowed by using orthokeratology.
Can Orthokeratology Make a Long-Term Difference to Children's Vision?
It has been shown that children who have had Ortho-K, have significantly reduced progression of myopia compared to myopic children who did not have ortho-k.
Significant myopia progression can be reduced by performing ortho-k during the ages when the fastest progression is occuring. Ortho-K is an alternative method to try to slow myopia progression in children.
The aim is to wear ortho-k lenses until the age when myopia progression has become insignificant. Some people may continue ortho-k after this as a means of vision correction.
Is Ortho-k like braces for the eyes?
Orthokeratology is sometimes referred to as braces for the eyes. This is partially correct as the lenses do change the surface shape of the front of the eye. However, the change with orthodontic braces for teeth is permanent, whereas it is reversible with ortho-k. Ortho-k lenses redistribute the corneal epithelial cells, leaving the rest of the cornea mostly unchanged. This is why the vision correction effect lasts only a few days. The corneal epithelium returns to its normal distribution once ortho-k is ceased.
Is OrthoK like wearing tight shoes?
Practitioners who do not perform ortho-k sometimes give the incorrect analogy that the slowing of myopia progression with ortho-k is like wearing tight shoes to stop the feet from growing. This is incorrect as lenses placed at the front of the eye cannot physically stop the whole eye from growing longer.