The Truth about Wavefront Custom LASIK

Dr. Michael Grimmett, FDA consultant, questioning representative of laser manufacturer during review of clinical trials for wavefront-guided custom LASIK: " I just had an observation and would like to hear if you have a comment. You may have none. There may be no answer. I found it curious that despite a very comprehensive analysis and sophisticated technology, that the patients that were unsatisfied or extremely unsatisfied approximated 9 percent."

In spite of the marketing hype, there are substantial barriers to achieving better vision from LASIK than with glasses or contact lenses. FDA-required clinical trials of custom wavefront LASIK demonstrate that patients' quality of vision is worse after LASIK, even with the latest custom wavefront technology.

From the FDA website:

Q: How does wavefront (custom) LASIK compare to conventional (older technology) LASIK?

A: Wavefront adds an automatic measurement of more subtle distortions (called higher order aberrations) than just nearsightedness, farsightedness, and astigmatism corrected by conventional LASIK. However, these "higher order aberrations" account for only a small amount (probably no more than 10%) of the total refractive error of the average person's eye. Conventional LASIK increases higher order aberrations. Although wavefront-guided treatments attempt to eliminate higher order aberrations, results from the clinical studies have shown that the average aberrations still increase, but less than they do after conventional LASIK. In a few studies comparing wavefront-guided LASIK to conventional LASIK, a slightly larger percentage of subjects treated with wavefront LASIK achieved 20/20 vision without glasses or contact lenses compared to subjects treated with conventional LASIK... Source

34 Challenges for Excimer Laser Technology to Achieve Super-Vision

    Ocular challenges

  • Changes in wavefront with age
  • Changes in wavefront during accommodation
  • Effect of pupil size on higher-order aberrations
  • Biomechanical differences among corneas before surgery
  • LASIK flap biomechanics
  • Changes in tear film
  • Changes in corneal thickness after laser surgery
  • Changes of wavefront during cycloplegia
  • Variation of ablation rate in the different depths of the cornea
  • Variation in corneal thickness in different meridians
    Uncontrolled optical changes during the healing process

  • Corneal epithelium wound healing
  • Corneal collagen wound healing
  • Effect of corneal biomechanics after surgery
    Technological limitations of surgical equipment

  • Eye positioning during preop measurement and laser treatment
  • Accuracy of laser ablation
  • Microkeratome accuracy and profile
  • Tracking the location of the laser beam
  • Decentration
  • Accuracy of wavefront sensors
  • Computer programs for the laser
  • Accuracy of the laser
  • Consistency of one laser
  • Chromatic aberrations not detected by aberrometers
  • Location and shape of wavefront measurement
  • Possible cortical, neural impact on vision
    Uncontrollable surgeon variables
  • Dryness of the ablation surface
  • Environmental issues during surgery
  • Retinal problems of aberration-free optics
  • Possible worsening of visual performance with inaccurate surgery
  • Effect of enhancement procedures on the wavefront
  • Positioning of the flap after ablation
  • Flap edema after ablation
  • Ill fit of curvature of flap and bed after ablation
  • Irreversible procedure
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