ORTHO K FOR MYOPIA CONTROL
近視控制角膜矯視鏡
How does Ortho-K slow short-sightedness progression?
HYPEROPIC DEFOCUS
To understand how Ortho-K lenses work to reduce your child's myopia progression, it's important to first understand the concept of hyperopic defocus.
With regular glasses and contact lenses, light is not focused uniformly across the entire surface of the retina, the light-sensing cells at the back of the eye. While central straight ahead vision is clear, peripheral light rays are focused beyond the plane of the retina instead of on it, which causes blur for that particular part of the eye. This is termed hyperopic defocus. This defocus in the peripheral retina is a stimulus for the eye to grow longer in a growing child or adolescent. When the eye grows in length, in a process called axial elongation, the eye becomes more myopic and leads to an increase in the child's short-sightedness prescription. This eye growth also leads to increased eye health risks. 
With regular glasses, peripheral image is focused beyond the eye. This is a stimulus for the eye to grow longer, which makes the myopia increase.
THE ORTHO-K EFFECT
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Ortho-K lens treatment effectively refocuses peripheral light rays from beyond the retina to the surface of the retina, reducing the hyperopic defocus and peripheral blur, which in turn reduces the growth signal and slows axial elongation of the eyeball.
How an Ortho-K lens achieves this is by creating a circular 'multifocal' shape effect on the surface of the eye, the cornea. When Ortho-K restores vision by flattening the central zone of the cornea, a redistribution of cells causes the peripheral areas of the cornea to become thicker. The thickened peripheral cornea bends light more, reducing the hyperopic peripheral defocus. So Ortho-K treatment for children simultaneously achieve two objectives: (1) Correction of their blurred distance vision, and (2) Reduces myopia progression and eye growth. 
The images below show the real-life eye surface shape changes produced with Ortho-K vision treatment, demonstrating the central flattening of the cornea to correct vision and the peripheral corneal changes for myopia control.
With our fully customised Ortho-K technology we can design your child's lenses to optimise the myopia control effect. Also note that these eye surface changes are temporary and reversible, that if the Ortho-K treatment is discontinued for several weeks the eye surface will return to its original shape. |
Ortho K overnight treatment achieves vision correction as well as myopia control due to a 'multifocal' treatment effect on the eye surface.
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See below for other myopia control treatments.
© 2019 The Myopia Clinic | Eyecare Concepts | Kew East Melbourne
