Corneal flap thickness in laser in situ keratomileusis using the Summit Krumeich-Barraquer microkeratome

Abstract

Purpose: To evaluate the thickness of corneal flaps created by the Summit Krumeich-Barraquer microkeratome (SKBM) (Alcon Surgical) and identify factors that may influence flap thickness. Setting: SSK Ankara Eye Hospital, Ankara, Turkey. Methods: Seventy-eight eyes of 50 patients who had laser in situ keratomileusis with the Asclepion-Meditec MEL 70 G-Scan excimer laser and the SKBM were prospectively evaluated. Preoperatively, the central corneal thickness, keratometry, visual acuity, and manifest refraction were measured. The microkeratome with the suction ring designed to create 160 μm thick and 9.0 to 9.5 mm diameter flaps was used in all eyes. Stromal bed thickness was measured with the Pachette ultrasonic pachymeter (DGH Technology, Inc.) after the flap was lifted. Flap thickness was calculated by subtracting the central stromal bed thickness from the preoperative central corneal thickness. Results: The mean preoperative central corneal thickness was 546.7 μm ± 31.9 (SD), the mean manifest refraction spherical equivalent was −6.8 ± 3.4 diopters (D), and the mean corneal refractive power was 42.9 ± 1.5 D. The mean corneal flap thickness created by the microkeratome was 154.9 ± 19.3 μm (range 101 to 202 μm). There was no correlation between corneal flap thickness and the degree of myopia (P = .151) or the corneal refractive power (P = .257). There was a linear relationship between flap thickness and the preoperative central corneal thickness (P = .000). A posterior corneal stroma thicker than 250 μm was preserved in 87 eyes (98.9%). Conclusions: The SKBM produced corneal flaps that were consistently close to the intended thickness. Corneal flap thickness did not appear to be influenced by the degree of myopia or the corneal refractive power; however, there was a linear relationship between flap thickness and the preoperative central corneal thickness.