1.Comparison of flap thickness, visual outcomes, and higher order aberrations in eyes that underwent LASIK flap creation using a femtosecond laser versus a mechanical microkeratome
Rachelle C. Perez ; Emerson M. Cruz ; Albert G. Dela Cruz, Jr. ; Robert Edward T. Ang
Philippine Journal of Ophthalmology 2012;37(2):83-90
Objective:
To compare the predictability of flap thickness, visual and refractive outcomes, and higher order
aberrations in eyes that underwent myopic LASIK using either a Technolas femtosecond laser or a Zyoptix XP
mechanical microkeratome for flap creation.
Methods:
The study involved a total of 44 eyes of 22 patients who underwent LASIK. Flap creation was randomized
to using the Technolas femtosecond laser in one eye and Zyoptix XP microkeratome in the contralateral eye. Flap
thickness was measured intraoperatively using ultrasonic pachymetry and postoperatively using the Visante ASOCT. Refractive outcome, visual acuity (VA), higher order aberrations, and contrast sensitivity were compared
between the two groups.
Results:
Twenty-two patients had LASIK for myopia or myopic astigmatism. Using ultrasonic pachymetry
intraoperatively, the mean flap thickness was 134 (±10) um and 124 (±23) um in the femtosecond (FS) and
microkeratome (MK) groups respectively. Comparing the deviation of the actual from the intended flap thickness,
the FS group had statistically lower standard deviation compared to the MK group (p=0.04). Using the AS-OCT,
the mean flap thickness at 3 months postoperatively was 119 (±10.82) um and 123 (±15.77) um in the FS and MK
groups respectively. The difference in standard deviation between the two groups did not reach statistical significance
(p=0.19). The mean spherical equivalent at 3 months was -0.45D (±0.42) and -0.13D (±0.16) respectively. Eightynine percent (89%) of eyes had uncorrected VA of 20/20 or better in both groups. All eyes attained best corrected VA of 20/20 or better in both groups. Differences in total higher order aberrations (p=0.09) and contrast sensitivity
scores (p=0.47) were not statistically different between the two groups.
Conclusion
Flap thickness predictability was better using the Technolas femtosecond laser compared to the
XP microkeratome blade. Visual and refractive outcomes, higher order aberrations, and contrast sensitivity were
comparable between the 2 groups.
Keratomileusis, Laser In Situ
;
Lasers, Excimer