Posterior corneal surface changes after refractive surgery

Ophthalmology. 2001 Aug;108(8):1415-22. doi: 10.1016/s0161-6420(01)00634-0.


Objective: To determine the frequency of changes in posterior corneal surface after laser in situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Design: Nonrandomized, comparative trial.

Participants: Ninety-five eyes (71 patients) that underwent PRK (n = 45) or LASIK (n = 50).

Controls: Twenty nonsurgery eyes were used to validate the method of analysis of the posterior corneal curvature (PCC). Seventy nonsurgery eyes were used for comparisons.

Methods: Float, apex-fixed best fit corneal curvature (ABC), and posterior elevation difference were evaluated in 20 elevation topography maps at 6 zone diameters (3-7 and 10 mm) and at two time points. Corneal elevation maps before and after PRK or LASIK were analyzed by the ABC and float methods and compared with a nonsurgery group.

Main outcome measures: Posterior corneal curvature change (mm) was classified as flattening, steepening, or no change.

Results: Flattening of more than 0.12 mm was found in 22.2% of eyes (n = 10) in the PRK group, a change of +/-0.12 mm was found in 53.3% of eyes (n = 24), and steepening of more than 0.12 mm was found in 24.4% of eyes (n = 11) using the float method and in 28.9% of eyes (n = 13), 35.6% of eyes (n = 16), and 35.6% eyes (n = 16), respectively, using the ABC method. In the LASIK group, the float method registered flattening in 20% of eyes (n = 10), no change in 52% of eyes (n = 26), and steepening in 28% of eyes (n = 14), whereas the ABC method registered flattening in 30% of eyes (n = 15), no change in 40% of eyes (n = 20), and steepening in 30% of eyes (n = 15). The nonsurgery group showed a similar change in PCC at two different time points similar to that of the PRK and the LASIK groups.

Conclusions: The differences observed in the PCC after PRK or LASIK were not statistically significantly different from those observed over time in the nonsurgery control group.

Publication types

  • Clinical Trial
  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anterior Chamber / pathology*
  • Cornea / surgery*
  • Corneal Topography*
  • Female
  • Humans
  • Keratomileusis, Laser In Situ*
  • Lasers, Excimer
  • Male
  • Myopia / surgery*
  • Photorefractive Keratectomy*