الفهرس 
Optical defects of the eyeOnly 14 pages are availabe for public view
 |  | from | 117 |  |  |
| | | from | 117 | | |
Abstract
Wavefront technology is a qualitative measurement of the eye’s imaging quality.
To explain wavefront technology, light rays enter the eye as flat sheets. When the optical system is perfect, it exits the eye as regular flat sheets. When the optical system is imperfect, it exits the eye as irregular curved sheets of light.
The results of wavefront sensors are affected by changes in the eye like the development of cataracts or by pupil dilatation. The wavefront analysis is affected in the different stages of pupil dilatation.
Wavefront is used to provide detailed information about the refractive status of the eye. It is also used for correction of the lower order and higher order optical aberrations of the eye.
Wavefront sensors are based on analysis of the ingoing light rays as in Laser Ray Tracing (LRT) system, Tscherning aberrometry, Spatially Resolved Refractomerter (SRR), or analysis of the outgoing light rays as in Hartmann-Shack (HS) aberrometer.
Zernike polynomials are mathematical equations that describe the row data obtained by the wavefront sensors.
Wavefront provides the whole profile of refraction. So, by using wavefront guided ablation, it is posssible to eliminate the higher order aberrations which affect the quality of vision and achieve what is called the supervision.
In wavefront guided LASIK, the data obtained by the aberrometer are converted into an ablation profile to correct the lower order and higher order aberrations.
Summary
Many companies developed and distributed systems of wavefront guided LASIK as Autonomous, Zeiss / Humphrey, Bausch & Lomb, Nidek, and VISX.
The early results of wavefront guided LASIK show improvement of the eyes over the standard LASIK.
VISX developed the customized contact lenses called PreVue to correct the eye’s higher order aberrations in addition to spherical and cylindrical refractive errors.
The advantages of wavefront guided, ablation include better results, greater predictability, safety, decreased complications, less invasive, useful in post-LASIK patients, and reduced amount of tissue ablation.
There are some limits to wavefront such as the lack to meaure the aberrations of the highly aberrated corneas, it measures only over pupil, and the eye has to be carefully centered during aberrometry and the surgery.