Analysis On The Studies Of Visual Quality After Fine Adjusted-customized Femtosecond Laser Refractive Surgery

Objective: To study the visual quality after three patterns of laser ablation during LASIK with femtosecond laser in patients with myopia and astigmatism.Methods: Total of 71 patients(142 eyes) with myopia and astigmatism were divided into three groups,including group A, B and C. They were treated by different patterns of laser ablation during LASIK with femtosecond laser in our eye optical center of Hunan province hospital. In group A, 26patients(52eyes) were treated by conventional ablation. In group B, 25patients(50eyes) were treated by iris tracing combined with Kappa Angle adjustment ablation. In group C, 20patients(40eyes) were treated by Q-value guided ablation after iris tracing and Kappa Angle adjusting. In preoperative and postoperative(1month, 3 month, 6month), collecting the data of vision, slit lamp, intraocular pressure, refraction and keratometry. The Sirius system was used to measure the topography and corneal high-order aberration(C7, C8, C12, RMSH), corneal aspherical(Q-value), Strehl Ratio(SR). Contrast sensitivity(CS) was assessed at 1month after operation and preoperative. In 3 month postoperative, patients were used visual quality analysis system(OQAS) to measure MTF cut-off frequency. And we also investigated subjective visual quality and satisfaction questionnaire. All the results were deal with medical statistics and analysis accordingly.Results: 1.VA: There were no statistically significant differences in vision ability(VA) between three patterns of lase ablation groups at 1,3 and 6 months after operation(P>0.05). 2. CS: The contrast sensitivity was declined in 1month postoperative compared with preoperative. However, there were no statistically significant differences between preoperative and 1month(P>0.05). 3. Q-value: Three groups of operation can increase corneal aspherical, and changes in group C is smallest than the other groups(P<0.05). 4. Corneal aberration: The higher order aberration(C7, C8, C12, RMSH) were increased postoperative at 1 month, 3 months, 6 months in three groups of ablation modes, and there were statistically significant differences(P<0.05); In group C, coma or spherical aberration and higher-order aberration were smallest increased, the differences were statistically significant(P < 0.05). 5. SR: It was increased postoperative at 1 month, 3 months, 6 months in three groups of ablation modes, and there were statistically significant differences(P > 0.05). 6. MTF cut-off rate: The MTF cut-off rate in group A was 37.01±5.91, group B was 37.41±6.65, group C was 38.17±7.10. The frequency showed as group C > B > group A, but there was no statistically significant difference(F=0.331,P>0.05). 7. Subjective visual quality and satisfaction questionnaire: The questionnaire scores in group A was 80.13±6.99, group B was 81.20±6.22, group C was 87.09±8.08. There were statistically significant differences within different ablation patterns(F=35.643,P=0.000).Conclusion: For patients with myopia and astigmatism, the increases of high-order aberration and changes of corneal aspherical in Q-value guided LASIK with femtosecond laser were less than the non-Q value guided LASIK; The individualized Q-value guided LASIK can obtain better visual quality.