The number which is most familiar to people when we discuss vision is 20/20.  This is so much so that there is a television show with this title.  20/20 simply means being able to see at 20 feet what a "normal person" can see at 20 feet.  There is a line on the eye chart which signifies this level of vision.  Therefore 20/40, the minimum vision to drive, is that vision which can be seen at 20 feet that a "normal person" could see if they were farther away, in fact twice as far at 40 feet.  While this is important, and a standard measure of vision, it does not explain all of what is important in vision.  For instance, it says nothing about near vision, and in older patients, presbyopia or difficulty seeing at near is a consideration.  Also it does not describe the "quality of vision" such as the ability to see in the dark, or in difficult lighting conditions.  It also does not give any indication of depth of focus or color vision.

Vision correction procedures have become more sophisticated over the years since first introduced in the mid 1990's.  One of the biggest changes is the ability to correct subtle changes in vision known as aberrations, and also our understanding as to minimizing the creation of new aberrations in returning the vision to 20/20.  The most significant of these aberrations is spherical aberration, and it means that the eye has a different focus depending on the size of the pupil in most simple terms.  The older generation lasers flatten the cornea, but can significantly increase spherical aberration.  Now we have what is termed prolate optimized treatments.

Prolate is the shape that makes the eye work best.  It is the shape of predators like eagles that must be able to see their prey from great distances.  Oblate is the opposite and is less ideal for clarity of vision although still works fairly well.  Many patients are still treated with these older style lasers today with good results.  Early lasers and some that are still used today create an oblate shape to the eye.  Prolate ablations, minimize an increase in spherical aberration, and produce the most natural vision regardless of the exact visual acuity, such as 20/20.  At Dishler Laser Institute, we currently only use "prolate optimized" lasers for correction of near sightedness, far sightedness and astigmatism.

At the Dishler Laser Institute, we use two different laser systems, both of which produce prolate optimized custom laser vision correction.   These include the Zeiss Mel 80 and the Wavelight Allegretto lasers.  Both are the latest FDA approved lasers and the only two platforms designed specifically to produce a prolate shape with control of spherical aberration. 

While no laser can prevent the aging of the eye, or presbyopia, by having a prolate shape, these lasers are less likely to diminish near vision in the process of improving distance vision.  The patient wants to have his or her vision improved with the least side effects and to have it restored to a natural type of vision.  These modern lasers have the greatest chance of accomplishing this goal and for this reason we use them exclusively at our center.  This is why we perform wavefront imaging of all patients prior to their procedure to match the treatment in a custom  manner to each individual patient's needs.