Comparison of laser in situ keratomileusis flaps created by 3 femtosecond lasers and a microkeratome

Purpose: To evaluate the thickness and side-cut angle of laser in situ keratomileusis (LASIK) flaps created by 1 of 3 femtosecond lasers or a microkeratome using Fourier-domain optical coherence tomography (OCT).

Setting: Department of Ophthalmology, Institute of Vision Research, Yonsei University College of Medicine, Seoul, Korea.

Design: Comparative case series.

Methods: Flap creation for bilateral LASIK was performed using an IntraLase (femtosecond group 1), VisuMax (femtosecond group 2), or Femto LDV (femtosecond group 3) femtosecond laser or an M2 microkeratome. Flap thickness was determined at 14 points. The side-cut angle was measured in 4 directions at the margin interface. Measurements were taken 2 months postoperatively using an RTVue Fourier-domain OCT device and integrated software.

Results: Femtosecond group 1 comprised 50 eyes; femtosecond group 2, 40 eyes; femtosecond group 3, 64 eyes; and the microkeratome group, 52 eyes. Eyes in femtosecond groups 1 and 2 had relatively even flap configuration. Flaps in femtosecond group 3 and the microkeratome group had a meniscus shape. Flaps in femtosecond group 1 had the least difference between the mean peripheral and the central flap thickness (P<.001). The greatest flap thickness predictability (measured versus intended thickness) was in femtosecond group 3 (P<.001). Flaps in femtosecond group 1 had a side-cut angle closest to 90 degrees (P<.001).

Conclusions: Flap morphology differed according to the system used. The 3 femtosecond laser systems appeared to be superior to the microkeratome system generally. The 3 femtosecond laser systems also produced different flap configurations depending on their individual mechanisms.