Optische Online-Pachymetrie bei Laser-in-situ-Keratomileusis

PURPOSE: Currently the microkeratome incision and the ablation depth are unpredictable in laser in situ keratomileusis (LASIK). Online optical coherence pachymetry is a high-resolution and non-contact method, which enables the corneal thickness changes to be monitored intraoperatively. METHOD. In 12 patients undergoing myopic LASIK, online optical coherence pachymetry with a wavelength of 1310 nm and a measurement frequency of 74 Hz was studied. The central corneal thickness changes were determined continuously. RESULTS: Online optical coherence pachymetry enabled intraoperative visualization and assessment of the central corneal thickness, the flap thickness after the microkeratome pass, the time-resolved ablation and the residual stromal thickness. Intraoperatively the mean flap thickness was 113+/-31 microm and the residual stromal thickness was 277+/-49 microm. The optically determined ablation depth was 116+/-30 micro m, which corresponded to 33 microm higher mean values than the nominal ablation depth. CONCLUSIONS: Online optical coherence pachymetry enabled the flap and residual stromal thickness to be measured intraoperatively. Also the individual ablation depth and possible dehydration effects of the cornea were monitored continuously. Thus, online optical coherence pachymetry could contribute to improve the safety standards during LASIK.