Porcine model to compare real-time intraocular pressure during LASIK with a mechanical microkeratome and femtosecond laser

PURPOSE. To compare real-time intraocular pressure (IOP) during laser in situ keratomileusis (LASIK) in porcine eyes using two types of microkeratomes. METHODS. An interventional, prospective study of two microkeratomes: a Moria 2 (Moria group) and an IntraLase femtosecond laser (IntraLase Corp., Irvine, CA; IntraLase group). These devices were used to create lamellar corneal flaps in freshly enucleated porcine eyes. The IOP changes induced by the procedures were recorded with a reusable blood pressure transducer connected to the anterior chamber by direct cannulation. RESULTS. Seven porcine eyes were studied in each group. The IOP increased during the suctioning phase, reaching a mean of 122.52 +/- 30.40 and 160.52 +/- 22.73 mm Hg during the cutting phase in the Moria group (the total time in this group was 36.42 +/- 7.48 seconds; suctioning required 21.42 +/- 7.48 seconds and the cutting phase, 15 +/- 2.88 seconds). In the IntraLase group, the IOP reached 89.24 +/- 24.26 mm Hg during the suctioning phase and 119.33 +/- 15.88 mm Hg during the intrastromal laser application (the total time was 92.85 +/- 13.49 seconds; suctioning required 40.00 +/- 9.57 seconds and the cutting phase 52.85 +/- 5.66 seconds). Both IOPs during both phases differed significantly between the two groups (P = 0.01 for all comparisons). CONCLUSIONS. Real-time IOP can be measured during LASIK using a transducer connected to the anterior chamber. The results showed a significant increase in IOP during the procedure in both groups, although with the IntraLase the IOP seemed to increase to a lesser extent than with the conventional mechanical microkeratome.