Changes in posterior corneal elevation after laser in situ keratomileusis enhancement

PURPOSE: To evaluate changes in posterior corneal elevation using the Pentacam topographer (Oculus) in patients having laser in situ keratomileusis (LASIK) enhancement. SETTING: Private practice, Chevy Chase, Maryland, USA. METHODS: The Pentacam device was used to evaluate the changes in posterior corneal elevation above the best-fit sphere before LASIK enhancement and after LASIK enhancement in 24 eyes. The change in posterior corneal elevation in eyes for which pre-primary LASIK data were available was also evaluated. RESULTS: After LASIK enhancement, the mean change in posterior corneal elevation was 5 microm. The mean posterior corneal elevation was 12 +/- 7 microm before LASIK enhancement and 16 +/- 6 microm after enhancement; the difference was statistically significant (P = .004). In eyes for which pre-primary LASIK data were available, the mean change in posterior corneal elevation after primary LASIK was 2 microm. The mean posterior corneal elevation was 11 +/- 5 microm before LASIK enhancement and 11 +/- 7 microm after enhancement. CONCLUSIONS: There was a statistically significant difference in posterior corneal elevation between before LASIK enhancement and after LASIK enhancement. However, the change in posterior corneal elevation was much smaller than previously reported values and below the sensitivity of the Pentacam topographer.