Abstract
Abstract: :
Purpose: To evaluate retrospectively the effects of LASIK flap thickness in the correction of myopic astigmatism. Methods: Patients with low to moderate myopia with astigmatism up to –3.75 diopters were included in the study. The eyes were divided into two groups based on flap thickness, with 171 eyes having flap thickness less than 126 microns and 171 eyes having flap thickness greater than or equal to 126 microns. Six–month data were analyzed with regard to spherical power, spherical equivalent, astigmatism power, astigmatism axis, uncorrected visual acuity, and vector astigmatism change. Results: Mean change in total spherical correction 6 months after surgery for eyes with LASIK flap thickness less than 126 microns was –3.79 ± 1.90. For flap thickness greater than or equal to 126 microns, the difference was –2.94 ± 1.99 (p=0.0001). Mean change in spherical equivalent 6 months after surgery for eyes with LASIK flaps less than 126 microns was 4.11 ± 1.90 diopters compared to 3.19 ± 2.01 for flaps greater than or equal to 126 microns (p=0.00003). Mean change in astigmatism magnitude 6 months after surgery for eyes with LASIK flaps less than 126 microns was 0.65 ± 0.80 diopters compared to 0.50 ± 0.71 for flaps greater than or equal to 126 microns (p=0.08). Mean change in astigmatism axis 6 months after surgery for eyes with LASIK flaps less than 126 microns was 33.02 ± 82.4 degrees compared to 17.51 ± 81.5 degrees for flaps greater than or equal to 126 microns (p=0.07). Mean change in uncorrected visual acuity (LogMAR) for LASIK flaps less than 126 microns was 1.36 ± 0.42 compared to 1.10 ± 0.55 for flaps greater than or equal to 126 microns (p=0.000002). Mean vector–corrected astigmatism change was 1.04 ± 0.75 diopters for LASIK flaps less than 126 microns compared to 0.94 ± 0.67 diopters for flaps greater than or equal to 126 microns (p=0.2). The mean change in axis for vector–corrected surgically–induced astigmatism at 6 months after surgery was 1.17 ± 52.6 degrees for flaps less than 126 microns compared to 1.94 ± 51.4 degrees for flaps greater than or equal to 126 microns (p=0.89). Conclusions: There was no significant difference in myopic astigmatism correction based on the thickness of the LASIK flap at 6 months after surgery.
Keywords: refractive surgery: LASIK • cornea: clinical science