AIM: To assess posterior corneal stromal interface(PCSI)quality after FS200 femtosecond laser(FSL)lamellar cuts were applied in different patterns in cats.

METHODS: A total of 20 fresh cat eyeballs were randomly separated into 4 groups: Group A, the routine(control)group, cuts were made using a suction ring and complete corneal applanation within an approximate diameter of 13 mm; Group B, no suction ring was used, but complete corneal applanation was performed using an approximate diameter of 13 mm; Group C, a suction ring was used, and corneal applanation was performed using an approximate diameter of 8 mm; and Group D, no suction ring was used, and corneal applanation was performed using an approximate diameter of 8 mm. Scanning electron microscopy(SEM)images of the resulting PCSI were graded for ridges and roughness using a subjective 5-point grading scale.

RESULTS: Photography performed using a slit lamp microscope showed that the best PCSI was achieved in Group D, and the worst group was Group A. SEM images(×30 magnification)indicated that the macroscopic interface quality was significantly different between Group D and Group A(P=0.007), between Group D and Group B(P=0.007), and between Group D and Group C(P=0.016). Other SEM images obtained at ×100 magnification indicated that the grades for the microscopic surface quality between Group D and Group A(P=0.01)and between Group D and Group B(P=0.016)were significantly different. The grades of the other groups were not significantly different.

CONCLUSION: The quality of PCSI on the cat corneas can be partially improved if the deformation of the extruded corneal stroma is slight without using suction ring or an excessive corneal applanation scope by the applanation cone.