Wavefront Diagnosis – Higher Order Aberrations

Wavefront-Optimized LASIK Surgery Wavefront technology has long been used by astronomers as a tool to adjust their telescope optics. It helps to eliminate any aberrations (irregularities) caused by the Earth's atmosphere.

Use of wavefront technology by ophthalmologists is a fairly new application. Ophthalmologists use it to diagnose the eye's microscopic irregularities so that they can be corrected by laser vision surgery. The diagnosis is done in a visit separate from your actual surgery and your eye surgeon will use the data gathered to plan your customized vision correction.

Traditional vs. Custom LASIK

When LASIK is done after a Wavefront diagnosis, it is called Custom LASIK, as opposed to Traditional LASIK. Diagnosis for Traditional LASIK is done the same way it is done for glasses or contact lenses, using a phoropter. A phoropter is the floor-standing device with many lenses and as you sit looking with one eye through the aperture at the vision chart, your doctor switches lenses, asking you which one gives you clearer images.

Diagnosis for Traditional LASIK detects only the three Lower Order Aberrations (LOA): myopia, hyperopia, and astigmatism. Since treatment is based only on that data, it corrects only those three conditions, and does not correct the Higher Order Aberrations (HOA). Custom LASIK corrects both LOA and HOA.

Custom LASIK has that name because your vision correction is so customized by the Wavefront diagnosis that nobody in the entire world will ever have the same treatment. In fact, each of your eyes will be given different treatments, because every human eye is unique.

How Wavefront Diagnosis is Done

It is a quick and painless procedure. The term Wavefront refers to the front edge of a beam of light as it passes into your eye from the Wavefront diagnostic system.

The light starts out with a smooth front end;
It travels through a series of light-refracting eye structures (cornea, lens, internal eye fluids) and arrives at the retina;
The smooth front end is now a little distorted by the microscopic irregularities of your eye structures;
It reflects back from the retina to the Wavefront system and is recorded as it re-enters the system;
The Wavefront system’s software configures that distorted front end as a colored 3-D map and displays it on the monitor.

Higher Order Aberrations

The two 3-D maps of your eyes show your eye surgeon exactly what has happened to the diagnostic light beam as it entered and exited your eye. From that, he can tell exactly what irregularities in your eye are interfering with your vision and he can then plan your LASIK vision correction.

While there are only three LOAs, there are over 60 HOAs. Some common examples are:

Halos around light sources
Starburst shapes around light sources
Ghosting (a faint second image)

There are others with names like Coma, Trefoil, and Quadrafoil, and many more with no names that are expressed mathematically. Many of them are related to low-light conditions.

By correcting your eyes’ HOAs as well as the LOAs, Custom LASIK gives you both better vision quantity (clear at more distances) and better vision quality (good night vision). Wavefront diagnosis can be done for other laser vision correction procedures also – PRK, IntraLase, iLASIK, LASEK and Epi-LASIK.

Wavefront-Based Eyewear

Now that HOAs can be diagnosed, there is research being done on how glasses and contact lenses could be designed using Wavefront data. The Tecnis® Intraocular Lens has a design based on Wavefront data collected from about a thousand eyes. It enables that IOL to provide better night vision than other IOLs.

If you are interested in laser vision correction, please contact an experienced ophthalmologist in your area to schedule a Wavefront diagnosis and determine if you are a good LASIK candidate.