A Comparative Study Of Anterior Segment Parameters And Ocular Aberrations Before And After SMILE And FS-LASIK

PurposeThe purpose of this paper is to evaluate and compare the corneal aberration,Ocular aberration,corneal central thickness?CCT?,mean Keratometricvalue?Km?,corneal densitometry?CD?,Q-value of Small incision lenticule extraction?SMILE?and Femtosecond laser in situ keratomileusis?FS-LASIK?.MethodsA prospective study.From January 2018 to August 2018,the patients who accepted corneal refractive surgery voluntarily in our hospital were selected,and the results of the examination were in accordance with the indication of SMILE and FS-LASIK.The patients continued to undergo corneal refractive surgery at least 3 months after operation.There were 90 cases?90 eyes?in SMILE group,including 56 males,34females and 90 females in FS-LASIK group,including 45 males and 45 females.The age is from 18 to 40 year.According to the spherical aberrations?SE?,SMILE and FS-LASIK groups were divided into three groups:the low myopia group??-3.00D?,the moderate group?-3.00D--6.00D?and the high myopia group??-6.00D?,30 cases in each group.All patients received Q-value,corneal aberration,Km,CCT,CD and ocular aberration before and after operation.Man-Whitney,Friedman,kruskal-Wallis,Paired-Samples T Test and One-Way ANOVA were used to analyze the collected date.Results1.The Q-value of anterior corneal surface changed from negative to positive.Thechanges of SMILE and FS-LASIK in 6-8mm anterior corneal surface were statistically significance(F_{post3m-6mm,7mm,8mm}=110.01,74.90,31.75,P<0.05),and SMILE was change less than FS-LASIK.There was no significant difference in 9mm anterior corneal surface.The Q-value of the posterior corneal surface tends to change positively in 6-8mm areas,but there was no significant difference in 9mm area.The changes of SMILE and FS-LASIK in the 6mm area of the posterior corneal surface were statistically significance?F=4.26,P=0.04?,and the changes of the other areas were similar.The Q-value of anterior corneal surface decreased with the decrease of degrees,while The Q-value of the posterior corneal surface had no significant difference between different degrees?P>0.05?.2.There was no significant difference in CD before and after surgery in the posterior layer(?²_SMILE=4.45,P=0.22;?²_FS-LASIK=2.77,P=0.43),but there were significant differences in other layers and ranges?P<0.05?.Comparing the changes of CD of SMILE and FS-LASIK at different time points,there were significant differences in the range of6-10 mm?Z=-3.64,P<0.01?at 3 months after operation,and there was no significant difference in other ranges and layers?P>0.05?.There was no statistical significance in CD between different degrees?P>0.05?.3.The absolute values of corneal aberration Z7?vertical coma?,Z8?horizontal coma?,Z12?primary spherical aberration?,Z13?X-direction secondary astigmatism?and HOAs?root mean square of higher-order aberrations?increased.The changes of SMILE and FS-LASIK in Z12 and HOAs were statistically significant(F_{post-1w,1m,3m?Z12?}=66.89,68.07,64.58,P<0.05;F_{post-1w,1m,3m?HOAs?}=66.89,68.07,64.58,P<0.05),and FS-LASK was change greater than SMILE.In SMILE,there was statistical significance in Z7,Z12 and HOAs between different degrees?F=13.95,10.41,16.29,P<0.05?.In FS-LASIK,there was statistical significance in Z12 and HOAs between different degrees?F=50.45,37.93,P<0.05?.4.In ocular aberration,the absolute values of Z7 and HOAs increased,while the absolute values of Z6 decreased.SMLE and FS-LASIK had significant difference in the changes of HOAs in the first week after operation?F=41.25,P<0.01?,but there was no statistical significance in the rest of the time.And SMLE and FS-LASIK had no statistical significance in other ocular aberration.In SMILE,HOAs has statistical significance between different degrees?F=3.98,P=0.02?.In FS-LASIK,there was statistical significance in Z7 and HOAs between different degrees?F=5.73,5.55,P<0.05?.5.Km and CCT decreased significantly after operation.There was significant difference between SMILE and FS-LASIK in the change of Km and CCT(F_{post-1w,1m,3m?Km?}=48.17,33.52,28.43,P<0.05;F_{post-1w,1m,3m?CCT?}=26.07,25.38,52.94,P<0.05).In Km,the change of SMILE was less than that of FS-LASIK.In CCT,the change of SMILE was greater than that of FS-LASIK.In SMILE,there was no significant difference between 1 month and 3 month after operation(P_Km=1.00;P_CCT=1.00).CCT in FS-LASIK had no significant difference between 1month and 3 month after operation?P=0.05?,Km in FS-LASIK had significant difference between 1 month and 3 month after operation?P<0.05?.There were significant differences in Km and CCT between different degrees(F_SMILE=119.73,111.82,P<0.05;F_FS-LASIK=119.40,76.98,P<0.05),and the amount of change decreased with the decrease of degrees.Conclusions1.Both SMILE and FS-LASIK caused the increase of corneal HOAs?root mean square of higher-order aberrations?,Z7?vertical coma?and Z12?primary spherical aberration?of corneal aberration,and FS-LASIK change greater than SMILE.2.SMILE and FS-LASIK can decrease the absolute value of Z6?y-trefoil?in ocular aberration.3.The changes of Km and Q-value of anterior corneal surface in SMLE were less than those in FS-LASIK.The change of Km and Q-value of anterior corneal surface was related to the preoperative diopter.4.Both SMLE and FS-LASIK cause the decrease of corneal densitometry,and the two surgical methods have similar effects on the total corneal densitometry.The change of corneal densitometry has nothing to do with the preoperative diopter.5.The change of CCT in SMILE was larger than that in FS-LASIK.6.SMILE can restore stability faster than FS-LASIK.