Analysis of Microkeratome Assisted Corneal Flap Thickness in Laser in Situ Keratomileusis Using Anterior Segment Optical Coherence Tomography.

Abstract

Purpose:To evaluate corneal ap thickness with Moria M2 microkeratome in Laser in situ keratomileusis (LASIK) using Anterior segment optical coherence tomography (AS-OCT). Methods: 170 eyes of 85 patients underwent LASIK using VISX Star S4 Excimer Laser System. The Moria M2 single-use head 90m microkeratome was used to create nasal hinged corneal aps. The right eye (RE) was operated rst followed by the left eye (LE), using the same blade. Flap thickness was analyzed using AS-OCT. Statistical Analysis: SPSS Software for Windows (version 18.0, SPSS, Inc). Results: The mean spherical equivalent (MSE) was - 4.17 diopters (D) + 2.5(range: -12.5 to + 2.375 D), preoperative keratometry was 44.02 +1.58D (range 40.19-48.95D), and corneal thickness was 535.62 ± 34.6 m (468-661m) in all eyes. The mean corneal ap thickness was 117.80 ± 9.12m (96 -138m), 112.98 ± 9.86m (93-142m), and 115.35 ± 9.7m (93-142m) in the RE, LE, and both eyes respectively. There was a negative signicant relationship between MSE and the ap thickness (p<0.001). Females had thinner aps as compared to males (p=0.013). There was a weak positive correlation between the pre-operative pachymetry and ap thickness (p=0.039). No signicant relationship was found between preoperative keratometry, age and ap thickness. RE had a thicker ap than the LE which was statistically signicant (p<0.001). Conclusions:The aps created using Moria M2 90 microkeratome were thicker than intended and reproducible. Preoperative keratometry and age did not inuence ap formation. Thick corneas had thicker aps and vice versa. Higher refractive errors and re-use of blades cause thinner aps.