Posterior corneal surface topographic changes after laser in situ keratomileusis are related to residual corneal bed thickness

Ophthalmology. 1999 Feb;106(2):406-9; discussion 409-10. doi: 10.1016/S0161-6420(99)90083-0.


Objective: To determine whether ectasia after laser in situ keratomileusis (LASIK) is related to residual corneal bed thickness.

Design: Retrospective noncomparative case series.

Participants: Thirty-two eyes of 16 patients with refractive errors of -4.00 to -18.00 diopters were examined.

Intervention: LASIK was performed. The topography of the posterior corneal surface was examined with the Orbscan slit scanning corneal topography/pachymetry system.

Main outcome measures: The difference in the elevation of posterior corneal surface regarding the best-fit sphere was measured.

Results: After surgery, mean bulge of 17.2 +/- 7.2 microns was found in eyes with residual corneal bed of 250 microns or greater, whereas 41.0 +/- 22.1 microns was seen in eyes with bed thickness less than 250 microns (t = 4.29; P = 0.000).

Conclusion: Posterior corneal bulge is correlated with the residual corneal bed thickness. The risk of ectasia may be increased if the residual corneal bed is thinner than 250 microns.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cornea / pathology*
  • Cornea / surgery
  • Corneal Stroma / surgery
  • Corneal Topography*
  • Dilatation, Pathologic / etiology
  • Dilatation, Pathologic / pathology
  • Humans
  • Laser Therapy*
  • Myopia / surgery
  • Ophthalmologic Surgical Procedures*
  • Retrospective Studies
  • Surgical Flaps