Korean J Ophthalmol.  2012 Feb;26(1):6-9. 10.3341/kjo.2012.26.1.6.

Posterior Corneal Curvature Assessment after Epi-LASIK for Myopia: Comparison of Orbscan II and Pentacam Imaging

• Byun YS
• Chung SH
• Park YG
• Joo CK

• KMID: 1120174
• DOI: http://doi.org/10.3341/kjo.2012.26.1.6

Abstract

PURPOSE
To compare the changes in posterior corneal curvature using scanning slit topography (Orbscan II) and Scheimpflug imaging (Pentacam) before and after Epi-laser in situ keratomileusis (LASIK) for myopia.
METHODS
In a prospective observational case-series study, 20 myopic patients having undergone Epi-LASIK were examined serially with two different devices, Orbscan II and Pentacam, preoperatively and one month postoperatively. Posterior central elevation (PCE) and posterior maximal elevation (PME) were compared between the two devices, and the changes in parameters after Epi-LASIK were analyzed using a difference map.
RESULTS
All parameters (preoperative and postoperative PCE and preoperative and postoperative PME) that were measured using the Orbscan II were significantly greater compared to those of the Pentacam (for all p < 0.001). PCE and PME were significantly increased one month postoperatively in the Orbscan II measurements (p < 0.05) but were not significantly increased in the Pentacam measurements. Also, DeltaPCE and DeltaPME, in the difference map obtained by each serial scanning, were significantly greater in the Orbscan II measurements than with the Pentacam (p = 0.012, p = 0.016).
CONCLUSIONS
The Pentacam measurements displayed significantly reduced values in all parameters related to posterior corneal elevation compared to those of the Orbscan II. The Pentacam showed no significant change in posterior corneal curvature after Epi-LASIK, based on the difference map.

Keyword

Epi-laser in situ keratomileusis; Orbscan II; Pentacam; Posterior central elevation; Posterior maximal elevation

MeSH Terms

Adult
Corneal Topography/*methods
Female
Humans
Keratomileusis, Laser In Situ/*methods
Male
Myopia/*surgery
Prospective Studies
Treatment Outcome

Figure

• 

  Fig. 1 Intra-device comparison of pre-operative and post-operative values (*p < 0.05). PCE = posterior central elevation; PME = posterior maximal elevation.

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