A technology used in optics that is able to determine and measure high order aberrations. These aberrations directly relate to an individual's quality of vision.

Conventional eye examinations can detect two types of error on the cornea - spherical (myopia and hyperopia) and cylindrical (astigmatism). Wavefront diagnostic can detect an infinite set of ocular aberrations called The Zernike polynomials, but in ophthalmology discussion has generally been limited to the first 15 or so.

The wavefront sensor system includes a fixation target, an input laser beam that generates a point light source, a wavefront sensor that measures the slope of the exiting wavefront, and software that will determine the characteristics of the excimer ablation.

The visual fixation target assists the patient in maintaining view, direction and accommodation during the wavefront measurement. While the patient fixates, a laser beam is shined into the eye. The light is reflected from the retina back through the pupil, and the wavefront of the light leaving the pupil is relayed to the wavefront sensor. The wavefront gets distorted by the refractive properties in the human eye.

When the laser beam enters the eye, it has a flat wavefront. In theory, a perfect human eye would reflect back a beam with its wavefront still flat. But in a normal human eye — after the beam of light has travelled through an imperfect crystalline lens, an irregular cornea and the other ocular media — the flat wavefront has become irregular. Think of a square grid being projected in and a wavy grid reflecting out. Detailed Custom Wavefront Lasik Information.