Comparison of real-time intraocular pressure during laser in situ keratomileusis and epithelial laser in situ keratomileusis in porcine eyes

PURPOSE: To compare real-time intraocular pressure (IOP) between laser in situ keratomileusis (LASIK) and epithelial LASIK (epi-LASIK) in porcine eyes during flap creation using a microkeratome or an epikeratome, respectively. SETTING: Vissum Madrid, Madrid, Spain. METHODS: In this prospective study, a Moria microkeratome was used in 1 eye (LASIK group) and an Epi-K epikeratome in the other eye (epi-LASIK group) to create a lamellar corneal flap and an epithelial flap, respectively, in freshly enucleated porcine eyes. The IOP changes during the procedures were recorded by direct cannulation using a reusable blood pressure transducer connected to the anterior chamber. RESULTS: Each group comprised 17 eyes. In the LASIK group, the mean IOP was 113.65 mm Hg +/- 10.78 (SD) during suctioning and 112.35 +/- 11.51 mm Hg during cutting phases. The mean duration of the phases was 9.00 +/- 1.46 seconds and 6.06 +/- 1.14 seconds, respectively. In the epi-LASIK group, the mean IOP was 92.57 +/- 20.86 mm Hg during suctioning, 82.09 +/- 20 mm Hg during cutting, and 67.28 +/- 13.49 during low vacuum. The mean duration of the phases was 25.88 +/- 1.96 seconds, 33.82 +/- 2.81 seconds, and 29.71 +/- 3.29 seconds, respectively. The IOP values were significantly different between the 2 groups (all comparisons P<.05). CONCLUSION: Real-time IOP measured during suctioning and flap creation by direct cannulation of the anterior chamber in freshly enucleated porcine eyes showed a significant increase in IOP during LASIK and epi-LASIK; the increase was lower in the epi-LASIK group.