

Home > Overnight Vision Correction > How it works
How it works
What being 'short-sighted' essentially means is that the image falls short of the retina as the eye is too long. In order for you to be able to see clearly the image needs to fall on the retina, thus in effect this makes the distance seem blurry.
The concept of OVC (also known as Orthokeratology) has been around for years and works by reshaping the cornea. The cornea is the frontal layer of the eye and by gently 'flattening' it, it can enable the image to fall back onto the retina.
In order to create a rigid contact lens that can achieve these effects, we use what is called a computerized Topographer. This provides us with a map of your
cornea, just like you may see the topography of a mountain on a map. This
therefore indicates areas where your cornea is steep and so we can work to
'flatten' such areas. This process is often a little more complex with
astigmatic patients (when your eye is rugby shaped).
The lens is then accurately manufactured on computerized lathes according
to your prescription and the topography of your cornea. After sleeping in the
lens for the first night much of the re-shaping is achieved making your visual
acuity improve significantly. Yet to reap the true benefit of the lenses you
will require wearing them consistently for at least the first week.
Over time, the changes made by OVC may start to reverse back. As a result
of this we will keep in regular contact and continually take maps of your
cornea to ensure the lenses are functioning effectively. After six months we
dispense you with new re-shaped lenses to match your latest refractive
demands.
OVC is a reversible process and so if the contact lenses are not worn for a period of time your vision will return to its previous refraction - this makes the process far less invasive than eye surgery.

Starting with the upper left image, the OVC lenses progressively remould the cornea creating a flattening as shown on the larger image