Advances in Laser Vision Correction Precision with Wavefront Measurements
Reviewed by Brad Spagnolo, M.D.
for LASIK Laser Eye Surgery
Laser Vision Correction of nearsightedness or myopia, farsightedness or hyperopia and astigmatism using Laser Eye Surgery such as LASIK has emerged as a precise way correct vision problems. In fact, the precision with which eyeglass and contact lens prescriptions can be corrected with Laser Vision Correction has changed considerably since its introduction in 1995.
Prior to having Laser Vision Correction it is critical to have a thorough eye examination and consultation at which time the eye surgeon can determine if you are indeed a good candidate for LASIK, PRK, Epi-LASIK or near vision Monovision LASIK. During the Laser Vision Correction examination it will be important to have an accurate measurement of your prescription. Typically, measurement of your prescription, called refraction, is performed on an either or both an automated instrument called an "autorefractor" as well as an instrument called a "phoroptor"-which is the test where you are asked "which is better, 1 or 2?". Measuring your refraction using the conventional methods such as these ONLY PRODUCES A MEASUREMENT OF THE COMMON VISION PROBLEMS OF NEARSIGHTEDNESS, FARSIGHTEDNESS AND ASTIGMATISM.
These common vision problems are the result of "Low Order Aberrations". Low Order Aberrations that cause the typical blurring of vision can be corrected with eyeglasses or contact lenses or by conventional Laser Vision Correction using LASIK, PRK or Epi-LASIK. However, even with the best glasses and contacts may people still complain about their night vision and don’t like to drive at night. One of the reasons for poor night vision is that tiny imperfections, or aberrations above and beyond nearsightedness, farsightedness and astigmatism may also exist and disturb your vision. These tiny aberrations include chromatic aberration, spherical aberration, diffraction, curvature of field, coma, trefoils, and quadrifoils-and are collectively known as “High Order Aberrations”. These aberrations, which cannot be corrected with glasses or contacts, can cause disturbing problems like halos and glare and disturb your night vision.
High Order Aberrations often involve night vision and the reduced clarity caused by imperfect vision in low light.
The first step in achieving greater vision correction precision with Laser Vision Correction is to not rely solely on the "refraction" test, but to include measurements taken with an instrument called an Aberrometer as this provides a more precise and accurate assessment of all the optical imperfections found in the eye’s optical system so that they can then be corrected. The Aberrometer uses a method called "Wavefront Mapping". Wavefront Mapping technology was originally pioneered in the field of astronomy and physics to aid in reducing "aberrations" or imperfections in the multiple lenses of telescopes. Now we can actually use it right in the offices of eye doctors in order to obtain the most precise measurements of your prescription.
By using Wavefront Mapping to evaluate the measurements of your prescription for Laser Vision Correction, we can actually use those more precise measurements to plan and calculate the actual prescription to be treated during your Laser Eye Surgery procedure. Using these measurements of even tiny aberrations helps the eye surgeon provide you with the best possible results.