An "eagle eye" PROLATE Cornea instead of a frog eye OBLATE Cornea!

The Intralasik Wavefront Aspheric (WFA) algorithm or treatment uses two separate personalised approaches for vision correction. Zyoptix Wavefront established in 2001 and refined over the last 8 years have provided exceptional outcomes from treatments customised to each individual eye.  Aspheric is another personalised treatment that endeavors to preserve the original prolate shape of the cornea being treated.  Like for instance a Zeiss Aspheric lens in a high-end camera, visual quality is optimised to avoid blur and improve clarity.  This treatment has been demonstrated by Centre for Sight and others to be of benefit.

Now a combination of Wavefront and Aspheric is available and using two individual personalised approaches, visual outcomes are enhanced.

What is the benefit of an Aspheric treatment?

The normal cornea is Prolate which means it is Steeper in the centre and flatter towards the sides.  On corneal topographic maps read by surgeons the colors are warmer (reds, oranges and yellow) in the centre and cooler (greens and blues) in the periphery.   The benefit of a Prolate cornea is sharper definition with less blur.  Aspheric treatments using the Technolas Perfect Vision Zyoptix technology uses the preoperative corneal shape and attempts to maintain a level of asphericity i.e. steep in the centre and flatter in the periphery.

Laser eye surgery increases spherical aberration.  This results in blur especially in dim light conditions and patients can sometimes report halos and poor night vision.  There are three mechanisms postulated for an increase in spherical aberration and these are summarised in fig 1.

Laser treatment results in an oblate cornea and light rays can land up falling on the retina outside the point of focus and produce a blur.

A prolate cornea on the other hand results in all rays falling on the same spot and as a result there is no surrounding blur. An Aspheric treatment results in a more prolate cornea.

Wavefront Treatments

These treatments treats high order aberrations (HOA) which if present can lead to visual degradation.  However can also induce spherical aberration and blur.

Wavefront Aspheric Treatments

This combines both treatments providing the best of both.  These treatments often result in vision that is better than vision with contact lenses and glasses prior to surgery and within a month of treatment (Centre for Sight experience)

This cornea is OBLATE (flat centrally and steep peripherally). This type of shape can produce blur with light rays falling outside the fovea or central receiving area on the retina.

Note warmer color centrally – this is a PROLATE shape and will provide much higher definition vision with less blur. 

 IntraLASIK Zyoptix→