One-year clinical efficacy evaluation of selective corneal wavefront aberration-guided FS-LASIK correction in patients with high myopia

AIM:To evaluate the effectiveness,safety,predictability,precision and changes of higher-order aberrations(HOAs)on corneal front surface of selective corneal wavefront aberration-guided femtosecond laser-assisted in situ keratomileusis(CW-FS-LASIK)in patients with high myopia 1-year postoperatively.METHODS:Totally 74 eyes of 37 patients with high myopia or myopic astigmatism in both the eyes who underwent the CW-FS-LASIK procedure in Xi’an Gaoxin Hospital from January 2021 to June 2021 were included.The changes of uncorrected distance visual acuity(UDVA),best corrected visual acuity(BCVA),spherical equivalent refraction(SER),astigmatism,HOAs and Strehl ratio(SR)on the anterior surface of the cornea after 1y of the surgery were analyzed.RESULTS:At postoperative 1y,the UDVA(logMAR)of 74 eyes(100%)reached 0 or better,including 0 in 8 eyes(10.81%),-0.1 in 45 eyes(60.81%),and-0.2 in 21 eyes(28.38%).The effectiveness index was 1.29±0.134.There was no decrease in postoperative BCVA compared with preoperative BCVA in all patients.Postoperative BCVA was the same in 44 eyes(59.46%)as preoperative BCVA,increased by 1 line in 23 eyes(31.08%)and increased by 2 lines in 7 eyes(9.46%)compared with preoperative BCVA.The safety index was 1.11±0.159.The estimated corrected SER before surgery was(-7.76±1.21)D,and the actual corrected SER was(-7.83±1.25)D(Y=0.9811X+0.2156,R2=0.9084).There was a high correlation between the estimated corrected SER and the actual corrected SER.The postoperative SER in 74 eyes(100%)was within±0.75 D.The postoperative astigmatism of all was within-0.75 D to 0.Root mean square(RMS)HOAs of spherical aberration and SR within 5 mm of the corneal front surface were all increased compared with those before operation(P<0.01).The total coma,horizontal coma and vertical coma were all decreased compared with those before operation(P<0.01).There was no statistically significant difference in horizontal trefoil and vertical trefoil compared with preoperative ones(P>0.05).CONCLUSION:Selective CW-FS-LASIK for correction of high myopia is effective,safe,predictive,and accurate.For patients with preoperative RMS HOAs over 0.25 defocus equivalent,postoperative coma aberration can be significantly reduced,and SR value can be increased,thus corneal imaging quality can be improved.

Changes in corneal biomechanics and posterior corneal surface elevation after FS-LASIK

AIM:To investigate the changes in corneal biomechanics and posterior corneal surface elevation after femtosecond laser-assisted in situ keratomileusis(FS-LASIK).METHODS:Totally 197 eyes of 100 patients who underwent the FS-LASIK from April 2022 to November 2022 were included.They were divided into three groups according to the ratio of residual corneal stroma thickness/corneal thickness(RCST/CT):Group I(50%≤RCST/CT<55%,63 eyes of 32 patients),Group II(55%≤RCST/CT<60%,67 eyes of 34 patients),and Group III(RCST/CT≥60%,67 eyes of 34 patients).The intraocular pressure(IOP),corneal compensated IOP(IOPcc),corneal hysteresis(CH)and corneal resistance factor(CRF)were measured immediately,1,and 3mo postoperatively by ocular response analyzer(ORA)and the posterior elevation difference(PED)was measured by Pentacam.RESULTS:After operation,IOP,CH,CRF,and PED were statistically different among the three groups(F=12.99,31.148,23.998,all P<0.0001).There was no statistically significant difference in IOPcc among the three groups(F=0.603,P>0.05).The IOP,IOPcc,CH,and CRF were statistical changed after surgery(F=699.635,104.125,308.474,640.145,all P<0.0001).The PED of Group I was significantly higher than that of Group II(P<0.05),and Group II was significantly higher than that of Group III(P<0.05).The PED value of 3mo after surgery decreased in each group compared with 1mo after surgery,but there was no statistical difference(Group I:t=0.82,P=0.41;Group II:t=0.17,P=0.87;Group III:t=1.35,P=0.18).The correlation analysis of corneal biomechanical parameter changes with PED at 1mo and 3mo after surgery showed thatΔIOP,ΔIOPcc,ΔCH,andΔCRF were not correlated with PED value in three groups(P>0.05).CONCLUSION:The smaller the RCST/CT,the greater effect on corneal biomechanics and posterior surface elevation.There is no correlation between changes in corneal biomechanics and posterior corneal surface elevation in the range of RCST/CT≥50%.

Sirius、Oculyzer、AS-OCT和A超测量近视患者角膜最薄点厚度的比较

目的:比较Sirius、Oculyzer、AS-OCT和A超对近视患者角膜最薄点厚度测量结果的差异性、相关性和一致性,为临床的应用提供参考。方法:选取2016-03/04在武警陕西省总队医院眼科近视眼激光部行飞秒激光辅助LASIK患者81例162眼,用Sirius、Oculyzer、AS-OCT和A超四种仪器分别测量以上患者的角膜最薄点厚度,对其进行统计学分析。结果:A超、Sirius、Oculyzer、AS-OCT测量结果分别为537.91±24.12、538.12±22.64、538.20±23.74、527.04±23.11μm(P<0.01)。AS-OCT的测量结果明显小于其他三种方法测量结果,A超、Sirius、Oculyzer之间无差异。将A超、Sirius、Oculyzer、AS-OCT测得的角膜厚度最薄点数值进行两两相关分析,表明四种方法测量角膜最薄点厚度均有高度相关性(r=0.920、0.914、0.951、0.908、0.929、0.919,均P<0.001)。A超分别与Sirius、Oculyzer、AS-OCT测量角膜最薄点厚度在95%CI为-18.77~18.33、-19.79~19.19、-3.79~25.53μm,结合Bland-Altman图,提示Sirius、Oculyzer、AS-OCT分别与A超间均具有较好的一致性。结论:与A超测得的角膜最薄点厚度结果相比,AS-OCT测量的结果偏薄。四种方法测量的角膜厚度最薄点值具有高度的相关性及一致性,但95%的一致性界限较宽,临床使用中两者可以相互参考,不能替换。