| Objective To compare one-year results of optical quality and ocular scattering between small incision lenticular extraction(SMILE)and off-flap epipolis laser in-situ keratomihusis(off-flap Epi-LASIK)by the OQAS double-pass system and i-Trace aberrometer.Methods In this retrospective case-control study,103 eyes of 52 patients underwent SMILE,and 86 eyes of 43 patients underwent off-flap Epi-LASIK.There were no significant differences between the 2 groups in age,spherical equivalent(SE),uncorrected visual acuity(UCVA),best corrected visual acuity(BCVA)and pupil diameter.Visual acuity,SE,contrast sensitivity(CS),modulation transfer functions(MTF),wavefront aberrations,objective scattering index(OSI),MTFcutoff frequency(MTFcutoff),Strehl ratio(SR),OQAS values(Ovs)at contrasts of 100%,20%and 9%and patient satisfaction were evaluated 1-year postoperatively.Results(1)There were no significant differences in UCVA during the 1-year follow-up between the 2 groups,except for the postoperative 1 day and 1 week which UCVA of the SMILE group was significantly better than that of the Epi-LASIK group(P<0.05).At 1-year postoperatively,the frequency with which the SMILE and the Epi-LASIK groups achieved postoperative UCVA of ≥1.0 or ≥0.8 and the frequency with which the groups maintained their preoperative BCVA,gain 1 or 2 lines,lost 1 line were not statistically different from each other.(2)At 1 year,the mean SE in the SMILE and Epi-LASIK group was-0.11±0.39D and-0.13±0.47D,respectively.There were no significant differences between the frequency of eyes within ±0.5D or within ±1.0D of the intended refractive target between the 2 groups.But the frequency with which the SMILE group attained a cylindrical refractive error within ±0.5D was obviously higher than that in the Epi-LASIK group(P<0.05).(3)There were no statistical differences in the CS with or without glare between the 2 groups except that the CS with glare at low spatial frequency(3,6 c/d)in the SMILE group was significantly higher than that in the Epi-LASIK group(P<0.05).(4)Total order aberrations,lower-order aberrations,higher-order aberrations,spherical aberrations,coma and trefoil aberrations with 4.0-mm pupils were not statistically significant between the 2 groups.But with 6.0-mm pupils,higher-order aberrations and spherical aberrations of the SMILE group were significantly lower than those of the Epi-LASIK group(P<0.05),no statistical difference were found in the residual aberrations between the 2 groups.(5)There were no statistical differences in the MTF with 4-mm pupils at all spatial frequency between the 2 groups.But the MTF were significantly higher in the SMILE group than that in the Epi-LASIK group with 6-mm pupils at low and high spatial frequency(5,20,25,30 c/d)(P<0.05),no statistical difference were found in the MTF at residual spatial frequency between the 2 groups.(6)At 1 year postoperatively,the mean OSI in the SMILE and Epi-LASIK group was 0.939±0.416 and 0.998±0.422,respectively.There were no significant differences between the 2 groups.MTFcutoff,SR,OV100%,OV20%and OV9%of the SMILE group were slightly higher than those of the Epi-LASIK group,whereas no significant difference was noted between the 2 groups.(7)There were no statistically significant differences in the mean satisfaction score between the groups at postoperative 1 year.Patients in the SMILE group reported the score of the glare and dry eye was significantly better than the eyes treated with Epi-LASIK(P<0.05).Conclusion(1)Both SMILE and Epi-LASIK perform good safety,efficiency,stability and predictability for the treatment of myopia,but SMILE has a better correction of the astigmatic error.With 4.0-mm pupils,SMILE produces similar optical quality to Epi-LASIK.With 6.0-mm pupils,SMILE shows better visual quality than Epi-LASIK.(2)At 1-year postoperatively,the average OSI in both groups was similar to the normal value range,so scattering is not the main factor that influences the visual quality.In eyes with low scattering,i-Trace aberrometer and the Optical Quality Analysis System(OQAS)provided similar estimates of the visual quality.(3)I-Trace aberrometer could measure wavefront aberrations rapidly and specify them accurately,OQAS could measure the intraocular scattering directly and analyze optical quality quantitatively,carrying more accurate retinal image information.Cooperating with each other,they can provide more complete and comprehensive visual quality. |
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