AIM:To compare the difference of actual corneal ablation depth during individual and conventional laser in situ keratomileusis(LASIK).

METHODS: Prospective comparative study. 161 eyes of 87 low and moderate myopia patients accepted refractive surgery with the Technolas 217z100 excimer laser system. Two groups were divided according to the type of operation: conventional LASIK and individual LASIK. The corneal thickness was continuously assessed intraoperatively with online optical coherence pachymetry(OCP). The residual stromal thickness before and after laser ablation were recorded, and then the actual corneal ablation depth was calculated. The values of actual and theoretical ablation depth, and the difference in the two groups were compared.

RESULTS: In conventional-LASIK group, the actual corneal ablation depth and theoretical ablation depth were 94.37±22.76μm and 85.69±21.19μm respectively(P<0.05); In individual-LASIK group, the actual corneal ablation depth and theoretical ablation depth were 90.08±15.98μm and 76.30±13.65μm respectively,(P<0.05). In conventional-LASIK group, the actual corneal ablation depth was increased in 8.68±6.30μm than the theoretical ablation depth. In individual-LASIK group, the actual corneal ablation depth was increased in 13.78±7.63μm than the theoretical ablation depth(P<0.05). The difference in individual-LASIK group was about 5.10±1.10μm thicker than that in conventional-LASIK group.

CONCLUSION: Actual ablation depth was thicker than theoretical ablation depth in both conventional LASIK and individual LASIK. The difference of actual corneal ablation depth and theoretical ablated depth in individual LASIK is more than that in conventional LASIK.