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Wavefront LASIK Technology

About Visual Aberrations

Several types of visual imperfections, referred to as lower- and higher-order aberrations, exist within the eye. These imperfections can affect both the sharpness (acuity) and quality of vision.

Lower-order aberrations commonly measured and treated with LASIK include:

Higher-order aberrations cannot be corrected with glasses, contact lenses or LASIK treatments. In fact, some researchers have found that such imperfections may actually be increased by conventional (non-customized) laser eye surgery.

About Wavefront LASIK Technology

Wavefront LASIK technology measures aberrations in your eyes. A perfect wavefront is completely flat. When light rays enter the eye and pass through the different structures inside, the wavefront surface changes, taking on a shape unique to that eye. These variations are called wavefront errors.

The wavefront technology’s software performs complicated measurements and presents a visual representation of how light is bent by your eye for the surgeon to evaluate. Data from this process is transferred to the laser and used by your surgeon to create a treatment plan for your refractive error including both low and higher-order aberrations. Treating a LASIK laser eye surgery patient with the information taken from the wavefront analyzer can result in greater clarity of vision and fewer complaints of glare or night halos.

How Does the Wavefront LASIK Technology Work?

Most laser manufacturers use wavefront analyzers that are based on Hartmann-Shack aberrometry. A specially designed lenslet array, the Hartmann-Shack sensor, measures the change in the wavefront of light as it passes through your visual system.

The Hartmann-Shack aberrometry method maps both lower- and higher-order aberrations by:

  • Projecting waves of light into a patient's eye
  • Mapping and recording the waves that bounce back out of the eye

Uncorrected Aberrations

A diagram of uncorrected aberrations.

Corrected Aberrations

 A diagram of corrected aberrations.

Zernike Polynomials

One way the Wavefront laser eye surgery data is analyzed is by using Zernike polynomials, also called modes. Each mode describes a certain three-dimensional surface and the Zernike polynomials correspond with ocular aberrations. For instance, second-order Zernike polynomials represent the conventional aberrations such as defocus and astigmatism. Zernike polynomials above the second order represent the higher-order aberrations that are suspected of causing night glare and halos. Zernike polynomials help to simplify the Wavefront technology used in laser eye surgery by combining all aberrations into one simple map. This is called Zernike decomposition.

Zernike Polynomials Shapes

A diagram showing Zernike Polynomials Shapes including: sphere, cylinder, tilt, spherical aberration, coma and higher astigmatism.

Eye care professionals are given information through conventional refraction in diopters as well as in Zernike form. The data is processed and presented in a fashion similar to a topographical map and can easily be read by doctors.

This map is then transferred to the laser, enabling the surgeon to address the patient's unique visual requirements.

For more information on Wavefront laser eye surgery technology, visit our TLC LASIK blog.

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