European Academy of Orthokeratology and Myopia Control
How Do We See?
Light rays enter the eye through the cornea, pupil and lens. The cornea is the clear, round dome covering the iris, the colored ring in the center of the eye, and the pupil, the black circle in the middle of the iris. The light rays then pass through the vitreous, a clear, gel-like substance that fills the middle of the eye, and are focused on the retina, a light-sensitive tissue lining the back of the eye.

The macula is a very small area at the center of the retina that gives us our fine, pinpoint central vision. The area of retina surrounding the macula gives us our peripheral — or side — vision. The retina converts light rays into impulses that are sent through the optic nerve to your brain, where they are recognized as images.

By helping to focus light as it enters the eye, the cornea and the lens both play important roles in giving us clear vision. In fact, 70% of the eye's focusing power comes from the cornea and 30% from the lens.
What Is Orthokeratology?
In the most basic of terms Overnight Orthokeratology or Ortho-k is the science of changing the curvature or shape of the cornea to change how light is focused on the retina at the back of one's eye.

Think of the cornea as the eye's equivalent of a watch crystal. It is a clear, dome shaped structure that overlies the colored iris. Its tissue is most similar to clear, wet skin; and like skin it is very pliable. Because the cornea separates the eye from air and the rest of the outside world and because it has a curvature that bends light towards the back of the eye, it is responsible for most of the eye's corrective power and contributes to various conditions such as nearsightedness (myopia), farsightedness (hyperopia), and the blur of astigmatism.

When you choose Ortho-k a few key tests must be performed. Chief among these tests is the determination that your eyes are healthy. The Orthokeratologist will examine the retina and also the health of the outside of the eye.The other key procedure is the mapping of your cornea. To do this an instrument called a Topographer is used. Just like a topographical map of a camping area show hills, plains, and valleys; the topography of the eye shows your doctor exactly how your cornea is shaped.The information from your corneal mapping plus the size of your cornea and the prescription needed to correct your vision are all used to design the retainer lenses (corneal molds) needed to create the Ortho-k effect.
On the day you pick up your Ortho-k retainer lenses you will be instructed in how to insert, remove, and take care your vision retainers.The fit of your retainers will be evaluated and you will be scheduled to be seen after your first night of wear. On day 1, your doctor will re-evaluate your fit and newly corrected vision and another mapping of your cornea will be performed.
Throughout your initial fitting period, your Orthokeratologist will monitor your corneal health and the effectiveness of treatment. At certain times your retainer lens fit may be modified to achieve your goals.

Orthokeratology can produce results in a surprisingly short period of time. The length of treatment to achieve your goals can vary from patient to patient. Factors which can affect the speed of treatment include:
  • your initial prescription
  • corneal rigidity
  • tear quality and quantity
  • your expectations
We advise patients that they may need to use their retainers every night to maintain their newly corrected vision although some patients are able to vary their wearing time to once every two to four nights. The reason for this is due to the flexibility of your cornea.