AIM: To observe the predictability of corneal flap creation with the VisuMax femtosecond laser and preliminarily analyze the factors correlated to the thickness and diameter of the flap.

METHODS: This retrospective case series study included 300 eyes of 150 consecutive patients. The eyes were assigned to two groups according to intended flap thickness, 100μm(204 eyes)and 110μm(96 eyes), which created with the VisuMax femtosecond laser. Intended flap diameters were 7.9mm and 8.3mm. Difference analysis of flap diameter and intended diameter as well as flap thickness and intended thickness were made. The data were analyzed with SPSS to sum up a multiple stepwise regression formula that could express their quantitative relationship.

RESULTS: The 100μm flap group had an average flap thickness of 103.11±4.07μm, while for the 110μm group the average flap thickness was 113.35±5.71μm. The difference between right and left eyes was not statistically significant(t_100μm =-0.901, t _110μm=-0.490; P>0.05). Corneal flap thickness was not related to flap diameter(r=0.003, 0.018; P>0.05), preoperative patient age(r=0.022, 0.050; P>0.05), corneal thickness(r=0.051, 0.101; P>0.05), keratometric value K(r=-0.048, -0.136; P>0.05)or intraocular pressure(r=-0.113, 0.047; P>0.05). Preoperative corneal keratometric value K was positively correlated with corneal flap diameter(r=0.359, 0.532; P=0.01, 0.007<0.05).

CONCLUSION:The LASIK flap creation with the VisuMax femtosecond laser has relatively good predictability. There is no influencing factor for flap thickness.