WASCA stands for Wavefront Aberration Simulated Customised Ablation. It is used prior to Nu-Lasik surgery to measure the aberrations (small imperfections) of the optical system within your eye with great precision.
This resulting measurement is interpreted by the cutting edge software to generate an "ablation profile".
Aberrations occur within all optical systems. They represent distortions in the path of a ray of light. Natural examples of aberrations are the way car and street lights can seem to have a halo, starburst or surrounding fringe around them at night. Aberrations are related to quality of the light which is focused on to the retina and subsequently the quality of vision you experience.
Once measured, the aberration profile is incorporated into the programming of the Excimer laser to deliver you a more precise result and, ultimately, better vision. Improved night vision and reduced glare, in particular.
The addition of WASCA at the Northern Laser Vision Centre has meant that >45% of our patients now see better without glasses after laser vision correction than they could see before surgery with their glasses.
In Optics there is a law of reversibility. In an optical system, this law means that light passing into the eye and focusing on a point should be reflected back out of the system in exactly the way it entered the eye.
WASCA works by projecting a very controlled IR (infra-red) ray of light into the eye, then capturing and recording the light reflected back out of the system. If the optical system within the eye were aberration free, the beam of light would return unchanged.
When WASCA receives the reflected light, it compares it to the original beam. Any variations in the IR beam from its original state represent aberrations induced by the eye. This process is called Wavefront analysis.
The WASCA readings are displayed on a screen, with all the components of the total aberration broken down into their particular areas. The different types of aberrations are shown below.
