AIM: To explore the long-term efficacy of Q-factor guided laser epithelial keratomleusis(LASEK )for myopia and astigmatism with positive Q-factor.

METHODS: There were 158 eyes which were myopia and astigmatism with positive Q-factor taken in two groups randomly: 86 eyes accepted Q-factor guided LASEK as observation group and 72 eyes accepted routine LASEK as control group. The difference between the two groups about all data was similar. The uncorrected visual acuity(UCVA)and the best corrected visual acuity(BCVA)as well as diopter, ocular tension, corneal topography, Keratometry value K, aspherical factor Q, Higher-order aberrations(HOA), corneal thickness by ultrasound and, contrast sensitivity(CS), Haze were examined and compared before and after surgery. All the cased were followed up for 14d, 1, 3, 6, 12mo. And there were no statistical difference among the data before surgery.

RESULTS: After 12mo there were no statistical difference between the two groups about UCVA and BCVA. But the safety index of observation group was 1.10, that of control group was 1.07. The validity index of observation group was 1.06, that of control group was 0.99. The HOA of observation group was 0.45±0.17μm, and that of control group was 0.72±0.25μm, there was statistically significant difference(t=-8.193,P=0.000). Q factor of observation group was 0.41±0.17, that of control group was 0.77±0.22, there was significant difference(t=11.377,P = 0.028). The contrast sensitivity of 3mo post surgery of patients in the observation group returned to the level of before surgery. But in the control group the contrast sensitivity of the patients did not returned until 6mo.

CONCLUSION: Q-factor guided LASEK for myopia and astigmatism with positive Q-factor is stable, safe and effective. The operation allow for reducing the high order aberrations, maintaining the most asphericity of cornea, saving more in corneal tissue, which cause faster recovery of contrast sensitivity, less haze and better visual quality.