Intraoperative optical coherence pachymetry during laser in situ keratomileusis--first clinical experience.

Abstract

To investigate intraoperative optical coherence pachymetry during laser in situ keratomileusis (LASIK). In an initial clinical evaluation, three patients with myopia and myopic astigmatism were studied. Corneal thickness was assessed with optical pachymetry based on low-coherence interferometry during LASIK. The attempted mean spherical equivalent refraction was -5.70 +/- 2.00 D with a mean calculated stromal ablation depth of 95 +/- 18 microm. Intraoperative optical coherence pachymetry was reproducible in all patients during the different stages of LASIK, demonstrating a mean flap thickness of 141 +/- 30 microm with a residual corneal stroma of 274 +/- 24 microm at the end of the laser ablation. The immediate postoperative corneal thickness revealed marked swelling. This initial clinical evaluation proved that intraoperative optical coherence pachymetry may be an important safety feature for monitoring flap and residual stromal thickness during LASIK. It may be particularly helpful in the effort to avoid iatrogenic corneal ectasia in patients with thin corneas, higher refractive corrections, and LASIK enhancements.