Intraocular pressure during corneal flap preparation: comparison among four femtosecond lasers in porcine eyes.

Abstract

PURPOSE: To compare the course of intraocular pressure (IOP) during corneal flap preparation using four different femtosecond lasers in porcine globes. METHODS: Forty-eight (12 in each group) enucleated globes were successfully cannulated through the optic nerve. Intraocular pressure was measured continuously through the cannula during a normal lamellar flap creation (regular procedure) using four femtosecond lasers (IntraLase, Abbott Medical Optics; VisuMax, Carl Zeiss Meditec AG; Femtec, Technolas Perfect Vision; and Femto LDV, Ziemer Ophthalmic Systems AG). In an additional measurement (worst-case procedure), the patient interface was pressed against the globe with increasing force until the applanation maneuver was automatically aborted by those devices capable of doing so. RESULTS: During the regular procedure, the maximum IOP reached was 135±16 mmHg when using the Intra-Lase, 65±20 mmHg with the VisuMax, 205±32 mmHg with the Femtec, and 184±28 mmHg with the Femto LDV. During the worst-case procedure, a maximum IOP of 260±53 mmHg was reached with the IntraLase, 105±13 mmHg with the VisuMax, and 248±51 mmHg with the Femtec. CONCLUSIONS: There is considerable variation in IOP among the tested femtosecond lasers during a regular lamellar flap creation and during the worst-case procedure. The VisuMax femtosecond laser seems to cause the lowest IOP rise in both settings.