Custom Lasik Surgeries
Custom lasik surgeries can also be called wavefront lasik surgeries.These kind of lasik surgeries are done by using a new technology called wavefront analysis which provides further information and details about the cornea and refractive aberrations.
When the light rays enter the eye, they will undergo distortions by irregularities of the lens and cornea, and the final images will be blurred. These distortions are called aberrations.
There are two types of aberrations. The first aberration is called low order aberrations which can be corrected by spectacles, contact lenses and conventional lasik. This type consists of myopia, hyperopia and regular astigmatism.
The second type of aberration is called high order aberrations which can not be corrected by spectacles, contact lenses or conventional lasik. It is also called irregular astigmatism. This type is induced by cornea and crystalline lens and they are consisting of coma, spherical aberration, chromatic aberration, trefoil and others. For some instant, hard contact lenses can partial correct high-order aberrations that are caused by cornea.
Spherical aberration is the one responsible for night vision disturbances and halos while coma is associated with monocular diplopia.
Low order aberration is responsible of 75%-85% of the refractive errors in normal eye while high order aberration is responsible of 10%-15% of the refractive errors.
Standard lasik or conventional lasik will correct only low order aberration and the patient will have visual acuity that can reach 20 20 but this type of correction might induce high order aberrations which will affect the final visual quality and that is why some patients who underwent conventional lasik will sometime complain of glare, ghosting, halos and double vision especially at night.
In custom lasik surgeries, a wavefront measuring device will project beam of lights onto the retina, and the reflected light will pass through the lens and the cornea. These reflected lights will be received on special sensor which will give the surgeon a detailed map about aberrations that are induced by your eye.
This wavefront map will be inserted into special computer program which is connected back to the laser machine that will guide the surgeon to ablate the corneal stroma according to the wavefront error pattern.and correct low order aberrations and also correct, reduce or even prevent the formation of high order aberrations.