الفهرس 
Application of Wavefront Technology to corneal Ablation; Basic scienceOnly 14 pages are availabe for public view
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Abstract
At the end of the twentieth century, having learned from astronomers the importance of using wavefront analyses to improve the images captured by the telescopic optic systems, vision researchers started to apply these technologies to the study of the human optic system. The first technology was the Hartmann-Shack wavefront sensor, used by astronomers to analyze atmosphere aberrations above a telescope in real time and adapted by vision scientists to measure higher-order aberrations (HOAs) of human eyes.
These naturally occurring higher order aberrations, combined with large increases in the eye’s higher order aberrations induced by refractive surgery can decrease visual performance despite the elimination of spherocylindrical errors.
Wavefront aberration is defined as the deviation between the reference wavefront that comes from an ideal optic system and the wavefront that originates from a measured optical system. It usually refers to monochromatic aberrations.
The shape of the wavefront and its deviations can be characterized mathematically by Zernike polynomials, The unit for wavefront aberration is micron and it is expressed as root mean square (RMS).
Aberrometer or wavefront sensors, are instruments designed not only to refract the eye, measuring sphere and cylinder, but also provide a quantitative analysis of the whole wavefront of reflected light entering the eye and reaching the retina. The Hartmann-Shack aberrometer is the more used one.
Wavefront sensors can be linked to excimer laser systems, making possible wavefront-guided, customized corneal ablations with two specific targets:
1) The correction of all measured pre-existing aberrations (sphere, cylinder, higher-order aberrations), and
2) The noninduction of higher-order aberrations, such as spherical aberration, that have been disclosed to be induced by any laser treatment.
Wavefront sensing devices serve better as guides for customized ablation than do corneal topographers. However, corneal topographers should not be neglected because they give direct information on the shape of the cornea, information that is unavailable from a wavefront sensor. They should therefore be routinely used as a “second opinion” when planning a customized ablation and to see if the desired ablation pattern was achieved.
The purpose of wavefront-guided LASIK is to improve the quality of vision, recent results of patients treated with wavefront-guided LASIK are encouraging.