title: Evaluation of corneal changes after myopic LASIK using the Pentacam®.
abstract: BACKGROUND
  In this study, we used a Pentacam® device to evaluate the corneal changes that occur after laser-assisted in situ keratomileusis (LASIK).
  
  
  METHODS
  Our study included 60 eyes of 32 patients. All patients were treated for myopia and myopic astigmatism using LASIK. The eyes were examined preoperatively and 3 months postoperatively using a Pentacam to assess corneal changes with regard to curvature, elevation, and asphericity of the cornea.
  
  
  RESULTS
  A statistically significant decrease in mean keratometric power of the anterior corneal surface (P = 0.001) compared with its pre-LASIK value was detected after 3 months, but there was no significant change in keratometric power of the posterior surface (P = 0.836). Asphericity (Q-value) of the anterior and posterior surfaces increased significantly after LASIK (P = 0.001). A significant forward bulge of the anterior corneal surface 4 mm and 7 mm from the central zone was detected 3 months post-LASIK (P = 0.001 for both), but there was no significant increase in posterior elevation at 4 mm and 7 mm from the center (P = 0.637 and P = 0.26, respectively). No cases of post-LASIK ectasia were detected. Correlation between different parameters of the corneal surface revealed an indirect relation between changes in pachymetry and anterior corneal elevation at 4 mm and 7 mm from the central zone (r = -0.27, P = 0.13, and r = -0.37, P = 0.04, respectively), and a direct proportion between changes in pachymetry and mean keratometric power of the anterior and posterior corneal surfaces (r = 0.7, P = 0.001 and r = 0.4, P = 0.028, respectively).
  
  
  CONCLUSIONS
  LASIK causes significant changes at the anterior corneal surface but the effect is subtle and insignificant at the posterior surface.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, El-Minya University, Egypt.
authors.forename: Yehia M
authors.initials: YM
authors.lastname: Khairat
authors.forename: Yasser H
authors.initials: YH
authors.lastname: Mohamed
authors.forename: Ismail Ano
authors.initials: IA
authors.lastname: Moftah
authors.forename: Narden N
authors.initials: NN
authors.lastname: Fouad
keywords: LASIK; Pentacam®; corneal asphericity; corneal elevation; laser-assisted in situ keratomileusis
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