Comparison of visual quality after laser in situ keratomileusis flap creation with a femtosecond laser and a mechanical microkeratome

Abstract

Objective To compare and analyze the higher-order aberrations (HOA),contrast sensitivity (CS) and CS under the glare after FEMTO LDV femtosecond laser flap and mechanical microkeratome Hansatome flap in laser in situ keratomileusis (LASIK).Methods This was a prospective clinical controlled study.Ninety-two eyes of 46 patients were treated with FEMTO LDV as the observation group,and 104 eyes of 52 patients were treated with Hansatome as the control group.Wavefront-guided LASIK (Zyoptix) was performed on each of these eyes after the flap preparation.HOA,CS and CS under the glare were evaluated before surgery and 1 week,1 month,3 months after treatment.Data were analyzed using chi-square test,ANOVA,independent t test.Results At 1 week after the surgery,59/92(64.1％) patients in the observation group had uncorrected visual acuity (UCVA) levels reaching or surpassing the preoperative best corrected visual acuity (BCVA),while in the control group,this rate was 76/104(73.1％).At 1 month after the surgery,the rate of UCVA≥preoperative BCVA was 82/92 (89.1％) in observation group and 96/104 (92.3％) in control group.At 3 months after the surgery,the rate of UCVA≥preoperative BCVA was 86/92(93.5％) in observation group and 96/104(92.3％) in control group.The two groups were not significantly different after the surgery (x2=1.423,1.112,0.183,P＞0.05).The refraction was +0.49±0.24 D in the observation group and +0.35±0.32 D in the control group at 1 week after surgery,while at 3 months,it was +0.10±0.18 D in the observation group and-0.14±0.22 D in the control group.The differences between the 2 groups were insignificant (t=0.566,1.178,P＞0.05).Higher-order aberration.At 1 week and 3 months,the HOA and coma in the observation group were all lower than in the control group (t1w=-2.422,-2.295,t3m=-1.957,-1.926,P＜0.05).There were no difference in spherical aberration and trefoil between the 2 groups (t1 w=-1.395,-0.779,t3m=-1.205,-0.922,P＞0.05).The 2 groups photopic CS was not significantly different after the surgery.The observation group mesopic CS decreased to the lowest level at 1 week postoperation,and returned to preoperative level at 1 month after operation.At 1 month and 3 months,the CS were higher than preoperation at 3.0,18.0 c/d (F=3.602,3.216,P＜0.05).At 1 week after surgery,the mesopie CS of the observation group was better than the control group at 6.0 c/d (t=2.326,P＜0.05).The 2 groups mesopic CS was not significantly different at 1 month and 3 months after operation.At 1 week after surgery,the photopic CS under the glare stimulus of the observation group was significantly higher than the control group at 3.0,12.0 c/d (t=2.173,2.327,P＜0.05).At 3 months,the medium to low spatial frequencies (1.5,3.0,6.0 c/d) the mesopic CS of observation group was higher than the control group (t=2.428,2.416,2.507,P＜0.05).Conclusion Patients undergoing femtosecond laser-assisted LASIK have better quality of vision after surgery than hansatome patients. Key words: Femtosecond laser; Keratomileusis,laser in situ; Aberration; Contrast sensitivity ; Glare