Changes in higher order aberrations after wavefront guided FS-LASIK for myopia combined with moderate to high astigmatism

AIM: To assess the changes in higher order aberrations after wavefront guided femtosecond laser assisted laser <i>in situ</i> keratomileusis(FS-LASIK)for moderate to high astigmatism. <p>METHODS: Eighty-eight eyes of 50 myopia patients with moderate to high astigmatism were included in this prospective study. There were 51 eyes with moderate astigmatism(≥-1.50D and <-3.00D)and 37 eyes with high astigmatism(≥-3.00D). All patients underwent wavefront guided FS-LASIK. Uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA), keratometry, central corneal thickness(CCT)and higher order aberrations(HOAs)were evaluated before operation and 3mo postoperatively. <p>RESULTS: At the 3mo after operation, the mean UDVA of all eyes was above 20/20, better than before operation(<i>P</i><0.05), but CDVA remained unchanged(<i>P</i>=0.36)and no eyes lost ≥2 lines of CDVA. Mean astigmstism of 85 eyes(97%)was reduced below -1.00D, mean astigmatism of 70 eyes(80%)was reduced below -0.50D(<i>P</i><0.05). The average corneal curvature was flatter by 3.81±1.97D and CCT was reduced by 78.66±37.22μm, postoperatively(<i>P</i><0.05). Coma and trefoil aberrations remained unchanged(<i>P</i>=0.078, 0.065). The spherical aberration, secondary astigmatism and the HOA root mean square(RMS)increased from 0.19±0.06, 0.05±0.02 and 0.42±0.12, preoperatively to 0.32±0.17, 0.26±0.08 and 0.78±0.28(<i>P</i><0.05), postoperatively. <p>CONCLUSION: Wavefront-guided FS-LASIK is a safe and effective option for the patients with moderate to high astigmstism although parts of HOAs increased