Yohko Murakami1, Edward E Manche. 1. Department of Ophthalmology, Stanford University School of Medicine, Stanford, California 94304, USA.
Abstract
PURPOSE: To prospectively compare intraoperative subtraction pachymetry flap thickness measurements and postoperative anterior segment optical coherence tomography (AS-OCT) flap thickness measurements in eyes that had laser in situ keratomileusis (LASIK) flap creation with a femtosecond laser or a mechanical microkeratome. SETTING: Stanford Eye Laser Center, Stanford University School of Medicine, Stanford, California, USA. DESIGN: Comparative case series. METHODS: Each patient received wavefront-guided LASIK using an Intralase femtosecond laser in 1 eye and a Hansatome mechanical microkeratome in the fellow eye. Flap morphology was assessed with an ultrasound pachymeter intraoperatively and an AS-OCT system postoperatively at 1 year. RESULTS:Thirty-six eyes (18 patients) were enrolled. Intraoperative subtraction pachymetry consistently underestimated mechanical microkeratome flap thickness compared with postoperative AS-OCT (P<.001). There was no significant difference between intraoperative subtraction pachymetry and postoperative AS-OCT measurements for femtosecond flaps (P=.38). The overall mean variation in flap thickness (ie, mean deviation from targeted flap thickness) was 2.6 μm (range 3 to 11 μm) with the femtosecond laser and 14.2 μm (range 17 to 52 μm) with the mechanical microkeratome (P<.001). Postoperative AS-OCT measurements showed femtosecond flaps had a planar configuration and mechanical microkeratome flaps had a meniscus-shaped configuration. CONCLUSIONS: The femtosecond laser created more uniformly planar flaps than the mechanical microkeratome as measured by intraoperative subtraction pachymetry and postoperative AS-OCT. Postoperative AS-OCT measurements varied less than intraoperative subtraction pachymetry measurements for mechanical microkeratome flaps. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.
RCT Entities:
PURPOSE: To prospectively compare intraoperative subtraction pachymetry flap thickness measurements and postoperative anterior segment optical coherence tomography (AS-OCT) flap thickness measurements in eyes that had laser in situ keratomileusis (LASIK) flap creation with a femtosecond laser or a mechanical microkeratome. SETTING: Stanford Eye Laser Center, Stanford University School of Medicine, Stanford, California, USA. DESIGN: Comparative case series. METHODS: Each patient received wavefront-guided LASIK using an Intralase femtosecond laser in 1 eye and a Hansatome mechanical microkeratome in the fellow eye. Flap morphology was assessed with an ultrasound pachymeter intraoperatively and an AS-OCT system postoperatively at 1 year. RESULTS: Thirty-six eyes (18 patients) were enrolled. Intraoperative subtraction pachymetry consistently underestimated mechanical microkeratome flap thickness compared with postoperative AS-OCT (P<.001). There was no significant difference between intraoperative subtraction pachymetry and postoperative AS-OCT measurements for femtosecond flaps (P=.38). The overall mean variation in flap thickness (ie, mean deviation from targeted flap thickness) was 2.6 μm (range 3 to 11 μm) with the femtosecond laser and 14.2 μm (range 17 to 52 μm) with the mechanical microkeratome (P<.001). Postoperative AS-OCT measurements showed femtosecond flaps had a planar configuration and mechanical microkeratome flaps had a meniscus-shaped configuration. CONCLUSIONS: The femtosecond laser created more uniformly planar flaps than the mechanical microkeratome as measured by intraoperative subtraction pachymetry and postoperative AS-OCT. Postoperative AS-OCT measurements varied less than intraoperative subtraction pachymetry measurements for mechanical microkeratome flaps. FINANCIAL DISCLOSURE: Neither author has a financial or proprietary interest in any material or method mentioned.