The patient below had myopic iLASIK -8.00 -2.75 x 020 with pre-op pachymetry of 515.  post ablation she has 357 microns of corneal tissue left.  She had her iLASIK in June 2007 and repeated examinations have presented a very stable result.

 

 

When comparing the performance of the 2 systems, there seems to be some points that need to be noted. 

• The K's in the 4.5 mm zone
  • 39.39 D and 38.37 @ 017 with Visante omni
  • 38.2 D and 37.8 D @ 035 with Pentacam
• Minimum Pachymetry
  • 358 microns with Visante omni
  • 369 microns with Pentacam
• Posterior Corneal Curvature
  • The most anterior protrusion is 8.21 microns.  The posterior protrusion of 10 microns or more is considered suspect for ectasia
  • There are 3 spots greater than 10 microns with most marked at 19 microns of anterior protrusion.

When comparing post LASIK cornea, due to the peripheral camera taking the image through the treated optical zone, the Scheimpflug systems do not fully account for magnification / minification changes that are now induced and can create irregularities such as the above.  The two systems have excellent anterior correlation, but split apart of the posterior curvature calculation.