One of the most innovative features of the Allegretto Wave is the way it uses wavefront-optimized technology to automatically compensate for the curvature of the cornea. In earlier laser correction systems, the “optical zone,” or area of correction, was centered on the front of the cornea; the result was a flattened circular area that ended with an abrupt edge, causing unwanted side effects like poor night vision, glare, and halos.
Allegretto Wave changes all that. The Allegretto Wave sends extra pulses to the peripheral cornea area in order to compensate for the angle of the laser beam. In this manner, the aspherical shape of the cornea is preserved to a degree that older lasers simply could not achieve. This compensation, combined with the incredibly small, 1mm size of the laser, produces a smooth, effective optical zone that results in what can only be described as high performance vision. link to High Peformance Vision.
Imagine a glass ball. If you took a flashlight and aimed it directly at the top of the ball, the light would form a circular shape on the surface of the ball. If you now aimed the flashlight towards the side of the ball, the light would form an elliptical shape and not seem as bright anymore. This is because the same amount of light is suddenly distributed over a larger area and some of the light is reflected away due to the angled surface of the glass ball.
The illustration below demonstrates the need for additional pulses to the corneal periphery, in order to compensate for the energy lost through reflection. Therefore, the natural cornea shape of each patient can be maintained.