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

Abstract

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.

Online optical coherence pachymetry to evaluate intraoperative ablation parameters in LASIK

“…As reported previously [27][28][29]31], online OCP was reliable, easy to perform, and did not affect the LASIK procedure. Online OCP provided intraoperative noncontact and continuous measurements of the changes of the central corneal thickness and several ablation parameters during LASIK.…”

“…Although, in this clinical study, a high pulse-to-pulse stability was noted, compared to polymethylmethacrylate (PMMA) ablation studies in corneal tissue, a greater measurement error must be considered [11,12,28], and the measured ablation values were higher than calculated. Also, with intraoperative contact ultrasound [8,13,21,22] and optically [4,26,29,31], significantly more tissue was ablated intraoperatively than predicted. The average differences between the calculated and measured myopic laser resection have been shown to range between 25 and 40 μm [8,22,26,29,31].…”

“…The technical details of this system have been described previously [27][28][29]31]. The most important features of online OCP for this study allowed continuous measurement of the central cornea during the LASIK procedure and the ablation phase in realtime without disturbing the procedure itself [29,31]. The quantitative changes of the ablation depth were assessed after lifting the flap at the beginning of the ablation process and immediately after completion of the ablative correction.…”

“…The measured preoperative fluence ranged from 0.3 to 0.6 μm per pulse at a repetition rate of 200 Hz. All patients underwent an identical standardized surgical procedure and postoperative treatment, as described previously [27,[29][30][31].…”

“…Recently, we presented a high-resolution and noncontact intraoperative monitoring of the central corneal thickness changes by integrating optical coherence pachymetry (OCP) into an excimer laser in experimental [28] and clinical studies [27,29,31]. These studies revealed that online OCP allowed continuous measurement of the intraoperative corneal changes, such as the flap and the residual stromal thickness, with a high reproducibility.…”