AIM:To analyze corneal flap thickness of laser in situ keratomileusis(LASIK) by Hansatome microkeratome and Amadeus II microkeratome.METHODS:Totally 50 patients(100 eyes) were divided into two groups randomly.The LASIK procedures were performed with Hansatome microkeratome using a 160μm head in group 1 and Amadeus II microkeratome using a 140μm head in group 2.The preoperative central corneal thickness and the stromal bed thickness after the flap was lifted were measured by ultrasound pachymetry.All patients were performed LASIK on right eye firstly and then left eye.The actual corneal flap thickness created by two different microkeratomes and the difference between the left and right eye of patients by the same microderatome were compared.RESULTS:The mean actual corneal flap thickness created by Hansatome and Amadeus II were 98.70±18.04μm(range from 67 to 158μm) and 110.60±16.47μm(range from 69 to 171μm),respectively.The difference between these two kinds of microkeratomes was statistically significant(P= 0.001).In the Hansatome group,the flap thickness in the right eye and left eye were 104.40±18.78μm and 93.00±15.61μm(P=0.01),while in the Amadeus II group,the flap thickness in the right eye and left eye were 115.12±18.74μm and 105.20±12.29μm(P=0.024).The corneal flap thickness of left eye was thinner than the right eye in each groups and the difference between two groups was statistically significant.CONCLUSION:The corneal flap thickness created by microkeratome was different from the expected value.Intraoperative measurement of corneal flap thickness was important for LASIK surgery.