الفهرس 
Laser in situ keratomelisiusOnly 14 pages are availabe for public view
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Abstract
The excimer laser is used to perform the corneal ablation. Excimer laser emits ultraviolet beam of wavelength 193 nm sufficient to break intermolecular bonds within the cornea (photoablation) with minimal damage to surrounding stromal tissue.
LASIK is now the most popular method for the surgical correction of refractive errors. It preserves Bowman’s layer and the corneal epithelium and result in increased refractive stability, minimal pain and rapid visual recovery.
Regardless of its advantages, it has several complications, intraoperatively mainly due to flap complications and postoperatively whether early or late like nightglare, halos, undercorrection, overcorrection and regression.
Wavefront- guided corneal ablation is designed to correct the traditional sphere and cylindrical error of the eye as well as the HOA. Formulating the ideal shape for the cornea is not dependent on the corneal surface alone but on the aberrations of the whole eye. Such corrections could lead to better vision (supervision).
There are three major types of aberrometry “wavefront analyzer” systems. Hartmann-Shack, Tscherning and Ray-Tracing aberrometer. A raw data is taken from these devices and a mathematical equation called the Zernike polynomial is applied to these data.
The eye’s optical aberrations include: defocus, astigmatism, HOA and chromatic aberrations. Correcting higher order aberration is the aim of wavefront-guided corneal ablation.
It was reported that aberrations are increased after conventional laser therapy. The technology required to achieve aberration-free laser vision correction should consider the following requirements: scanning spot delivering system, eye tracker and the wavefront measurement device.
CONCLUSION
With the aid of wavefront analyzers, wavefront- guided LASIK gave promising results for ammetropic patients, especially for correction of HOA with better postoperative results rather than the conventional LASIK.