Customized Wavefront Guided LASIK with Zyoptix

1
Customized Wavefront Guided LASIK with Zyoptix
?
Jonathan M. Davidorf, MD (Davidorf Eye Group
Los Angeles, CA)
Entered vs. Achieved Spherical Equivalent
METHODS As part of an ongoing nonrandomized,
unmasked, prospective study of seventy-five
myopic eyes were treated with lasik using
Zyoptix. Preoperatively, patients had complete
ophthalmologic examinations, including manifest
and cycloplegic refractions, undilated and
dilated wavefront measurements (Zywave), corneal
topography/pachymetry (Orbscan II-Z), and mesopic
pupil size measurement. Patients with a history
of prior ocular surgery or with poorly controlled
medical problems were excluded from the study.
Treatment plans were calculated
preoperatively using the Zylink software version
2.38. All eyes were targeted for best possible
uncorrected distance vision. The information
from the Zyoptix workstation was brought to the
excimer laser on a floppy disk and the data then
transferred to the laser. Lamellar flaps were
created using the BD K-3000 or K-4000
microkeratome (Becton Dickinson) with an intended
flap thickness between 90 and 140 microns. When
appropriate, bilateral simultaneous lasik was
performed. The spot scanning excimer laser, the
Bausch Lomb Technolas 217-Z, was used in all
cases. Optical zone sizes from 6.0 to 6.5 mm
were used depending on the amount of correction,
mesopic pupil size, and corneal thickness.
Postoperatively, patients underwent additional
Zywave testing at the one to three month
interval. Only undilated Zywave measurements
were performed postoperatively. Uncorrected
distance visual acuity, loss of best spectacle
corrected visual acuity, and RMS values derived
from Zernicke polynomials from Zywave maps to
measure HOAs were evaluated. Data was entered
into an Excel spreadsheet and the Students
t-Test used to determine statistical significance.
RESULTS

• BACKGROUND
• Wavefront guided customized lasik procedures are
  designed to correct both lower order (sphere and
  cylinder) and higher order optical aberrations
  (HOAs). Zyoptix is the customized, wavefront
  guided platform for the Bausch Lomb Technolas
  217-Z excimer laser. The system incorporates a
  Hartmann-Shack aberometer (Zywave) and topography
  data (Orbscan II-z). The Hartmann-Shack
  aberrometry data from the Zywave is combined with
  the Orbscan data to generate the custom treatment
  plans.
• While there are factors extraneous to the excimer
  laser ablation profile (such as flap creation,
  wound healing, laser centration, and ocular
  surface abnormalities) in LASIK that influence
  postoperative HOAs, wavefront guided custom
  treatments attempt to minimize the induction of
  laser induced HOAs.1 The purpose of this study
  is evaluate the efficacy and effect on higher
  order aberrations in myopic eyes undergoing lasik
  with Zyoptix software version 2.38.

Higher Order Aberrations (RMS - m)
Graph of the spherical equivalent entered
into the zyoptix treatment versus the
postoperatively achieved manifest spherical
equivalent (preoperative minus postoperative
spherical equivalent refraction)
Discussion Wavefront guided custom lasik with
Zyoptix demonstrated excellent efficacy regarding
lower order aberrations as manifest by over 80
of eyes realizing 20/20 or better uncorrected
visual acuity. All eyes had best spectacle
corrected visual acuity of 20/20 or better
preoperatively and postoperatively. The Entered
vs. Achieved graph of spherical equivalent shows
a tight data series with an R2 of 0.97. Nomogram
refinements solely based on spherical equivalent
could be expected to further improve the
uncorrected visual acuity data. Examining
the effect of treatment on HOAs, there was no
significant change in the mean RMS values at 5mm
from the preoperative levels (p 0.65). There
was, however, a statistically significant
increase in mean RMS values at the 6 mm zone (p
0.05). The main limitation of this study is the
relatively small sample size and the lack of
comparison of the effects on HOAs of Zyoptix
lasik treatments compared to conventional
treatments.
OBJECTIVE
The Bausch Lomb Technolas 217-Z Excimer
Laser

• CONCLUSIONS
• Lasik with Zyoptix demonstrated
• excellent efficacy and safety
• little effect on HOAs at a 5 mm zone
• an increase in HOAs at a 6 mm zone

Postoperative Uncorrected Visual Acuity
To study the effect on HOAs using custom
wavefront guided lasik with the Bausch Lomb
217-Z excimer laser for lasik (Zyoptix).
Sample preoperative Zywave maps
Demographics

• References
• Bühren J, Kohnen T. Factors affecting the change
  in lower-order and higher-order aberrations after
  wavefront-guided laser in situ keratomileusis for
  myopia with the Zyoptix 3.1 system. J Cataract
  Refract Surg. 2006321166-1174.

For additional information please
contact Jonathan M. Davidorf, MD Davidorf Eye
Group www.davidorf.com
The Zyoptix Dual Workstation (Zywave and Orbscan
II-Z)