Acute corneal endothelial changes after laser in situ keratomileusis

Purpose. To report the acute effects of laser in situ keratomileusis (LASIK ) on the corneal endothelium. Methods. Twenty eyes of 10 consecutive patien ts (mean age, 38.1 +/- 10.84 years) underwent bilateral simultaneous LASIK for myopic astigmatism (spherical equivalent ranging from -1.75 to -7.13 di opters) without any complications, Each eye was evaluated by slit-lamp biom icroscopy and noncontact specular microscopy preoperatively, within 15 minu tes after LASIK and 1 day after surgery. Specular microscopy images were th en analyzed to calculate endothelial cell density (ECD), coefficient of var iation (CV) of cell size, and percentage of hexagonal cells. Results. All c orneas demonstrated marked alterations in endothelial cell morphology by sl it-lamp biomicroscopy within 15 minutes after surgery that resolved by the first postoperative day. Central corneal endothelial analysis by noncontact specular microscopy confirmed pleomorphism with definite loss of hexagonal ity. Mean ECD was calculated to be 2,816.3 +/- 286.02 cells/mm(2) preoperat ively, 2,750.85 +/- 327.95 cells/mm(2) on day 0 (p = 0.395), and 2,810.55 /- 218.48 cells/mm(2) on day 1 (p = 0.461). Mean CV was 32.65 +/- 7.29 preo peratively, 34.4 +/- 6.19 on day 0 (p = 0.412), and 30.9 +/- 5.54 on day 1 (p = 0.067). Mean percentage of hexagonal cells was 63.35 +/- 10.76 preoper atively, 47.55 +/- 9.69 on day 0 (p = 0.000009), and 60 +/- 9.3 on day 1 (p = 0.00003). Conclusion. Qualitative and quantitative changes in endothelia l cell morphology (i.e., decreased endothelial cell hexagonality) demonstra te that LASIK does induce an acute effect on the corneal endothelium that m ay represent transient endothelial cell edema.