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AIM: To investigate the effect of different preoperative corneal curvature on the size of optical deformation area after femtosecond laser small incision lens extraction(SMILE).METHODS:A prospective study was conducted on 108 consecutive patients who underwent SMILE surgery in our hospital from February 2021 to January 2022. Considering the association between both eyes, only the left eye of each patient was studied. According to the average anterior corneal surface curvature in preoperative, the patients were divided into three groups: Km<42.0D group(n=30), Km>47.0D group(n=26)and conventional corneal curvature group(n=52)with 42.0D≤Km≤47.0D. All patients underwent standardized SMILE surgery, and the laser ablation diameter was 6.5mm. The diameters of optical deformation areas in the three groups were compared at 6mo after operation.RESULTS:There was no significant difference in preoperative data among the three groups except for the mean curvature of the anterior corneal surface(all P>0.05), and there was no significant difference in uncorrected distance visual acuity(UDVA)and subjective refraction at 6mo after operation(all P>0.05). The diameters of the optical deformation zone in the Km<42.0D group, Km>47.0D group and the conventional corneal curvature group were 6.54±0.14, 6.32±0.13, 6.45±0.15mm respectively(F=19.238, P<0.05). The optical area diameter of the group with flat corneal curvature was larger than that of the group with conventional corneal curvature and the group with steeper corneal curvature(P<0.05). The diameter of optical zone in the conventional curvature group was larger than that in the Km>47.0D group(P<0.05).CONCLUSION: When the preset laser cutting diameter is the same, the steeper the corneal curvature before operation, the smaller the diameter of the optical deformation area after operation.
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Objective:To compare the changes in functional optical zone (FOZ) and corneal morphology in myopes between femtosecond small incision laser lenticule extraction (SMILE) and femtosecond laser-assisted in situ keratomileusis (FS-LASIK).Methods:A cohort study was performed.A total of 94 patients (94 eyes) who underwent FS-LASIK or SMILE at Eye Hospital, Wenzhou Medical University from March to December 2021 were enrolled.The selected patients were divided into a SMILE group (46 cases, 46 eyes) and an FS-LASIK group (48 cases, 48 eyes) according to the surgical procedure, and the follow-up period was 6 months.The primary outcome measures were postoperative changes in corneal FOZ and Q-value, and the secondary outcome measures were changes in central corneal thickness (CCT) and mean corneal curvature (Km). Corneal Q-value, horizontal and vertical FOZ diameters, CCT, and Km were recorded before surgery and at 1 day, 1 week, 1 month, and 6 months after surgery using the Pentacam anterior segment analysis system, and the differences in each parameter and the trends of changes between the two groups were compared.This study adhered to the Declaration of Helsinki and was approved by the Ethics Committee of Eye Hospital, Wenzhou Medical University (No.2021-034-k-27). Written informed consent was obtained from each subject.Results:There were statistically significant overall differences in the postoperative horizontal and vertical FOZ diameters between the two groups (horizontal diameter: Fgroup=7.06, P<0.001; Ftime=64.18, P=0.001; vertical diameter: Fgroup=11.08, P<0.001; Ftime=77.14, P<0.001). The horizontal and vertical FOZ diameters were significantly larger in SMILE group than in FS-LASIK group at various postoperative time points, and the differences were statistically significant (all at P<0.001). In the two groups, the postoperative 1-week, 1-month and 6-month horizontal FOZ diameters and the postoperative 1-week and 1-month vertical FOZ diameters were smaller than the postoperative 1-day ones, and the differences were statistically significant (all at P<0.05). There were significant overall differences in Q-values at different postoperative time points between the two groups ( Fgrouup=53.11, P=0.019; Ftime=29.18, P<0.001). The postoperative 1-day, 1-week, and 1-month Q-values of FS-LASIK group were significantly higher than those of SMILE group (all at P<0.05). The postoperative 1-week Q-value was significantly larger than the postoperative 1-day value in SMILE group ( P<0.001). The postoperative Q-values gradually decreased with time in FS-LASIK group, with significant pairwise differences at all adjacent time points (all at P<0.001). There were significant differences in CCT at various postoperative time points between the two groups ( Ftime=21.43, P<0.01). In FS-LASIK group, the CCT was decreased at 1 week than 1 day after surgery and was increased at 6 months than 1 week after surgery, and the differences were statistically significant (all at P<0.05). In SMILE group, the postoperative 1-week, 1-month and 6-month CCT was increased in comparison with the postoperative 1-day value, and the differences were statistically significant (all at P<0.05). There was no significant overall difference in the Km between the two groups ( Fgroup=27.29, P=0.41). There were significant pairwise differences in the Km at different postoperative time points between the two groups (all at P<0.001). The postoperative 6-month Km was smaller than the postoperative 1-day value in SMILE group, and the postoperative 6-month Km was greater than the postoperative 1-day value in FS-LASIK group (both at P<0.05). Conclusions:The FOZ shows a trend of gradual reduction within a month after SMILE and FS-LASIK.The FOZ is larger after SMILE than after FS-LASIK.The morphologic stability of corneal FOZ is better after SMILE than after FS-LASIK.
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AIM: To investigate the short-term visual quality outcomes after femtosecond laser small incision lenticule extraction(SMILE)and evolution implantable collamer lens(EVO-ICL)implantation for the correction of moderate myopia.METHODS: Prospective control study. A total of 51 cases(51 eyes)with moderate myopia who underwent SMILE or EVO-ICL implantation surgery at Weifang Eye Hospital from April 2021 to February 2022 were selected. They were divided into SMILE group(30 patients, 30 eyes)and EVO-ICL group(21 patients, 21 eyes)according to the surgical methods. The changes of visual acuity [uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA)], diopter [spherical equivalent(SE)] and related parameters of optical quality analysis system(OQAS Ⅱ)were observed before surgery and at 1wk, 1 and 3mo after surgery, and the quality of vision(QoV)questionnaire was completed.RESULTS: At 3mo after surgery, the safety index(postoperative CDVA/preoperative CDVA)of SMILE gruop and EVO-ICL group were 1.20(1.00, 1.20)and 1.20(1.00, 1.38), respectively, the efficacy index(postoperative UDVA/preoperative CDVA)were 1.00(1.00, 1.20)and 1.00(1.00, 1.20), respectively, and the percentage of SE within ±0.50D was 87% and 100%, respectively. In SMILE group, the objective scattering index(OSI)was increased after surgery, while modulation transfer function cutoff frequency(MTF cutoff), contrast visual acuity(VA)100%, and VA20% at 1wk and 1mo after surgery, and Strehl ratio(SR)and VA9% at each time point after surgery were all decreased compared with those before surgery(all P&#x003C;0.05). The OSI, MTF cutoff, SR and VA of EVO-ICL group showed no difference at each time point after surgery compared with those before surgery(all P&#x003E;0.05). The most common visual symptoms after SMILE and EVO-ICL implantation were visual haze and halos, respectively.CONCLUSION: Both SMILE and EVO-ICL implantation have good safety, efficacy and predictability in the short term after the correction of moderate myopia. Both groups had visual symptoms after surgery, but the overall satisfaction of patients was high. Furthermore, EVO-ICL implantation has better objective visual quality performance.
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Femtosecond laser small incision lenticule extraction(SMILE)is one of the most advanced corneal refractive operations at present. Different from other traditional corneal refractive operations, SMILE achieves minimally invasive and valveless operation. Therefore, the evaluation of postoperative visual quality of SMILE also has its own characteristics, at present, the latest research at home and abroad has confirmed that the naked eye vision can be significantly improved and the refractive status is stable after SMILE. However, there are different understandings of the objective visual quality indexes and their influencing factors, such as higher-order aberration, modulation transfer function cut off(MTF cut off)and objective scatter index(OSI)after SMILE. This paper reviews the postoperative visual quality and its influencing factors after SMILE to provide clinical help.
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AIM: To analyze the correlation of changes in non-contact intraocular pressure(IOPNCT)and the surgical parameters after femtosecond laser small incision lenticule extraction(SMILE)for high myopia.MOTHODS:A retrospective analysis, the clinical data of 98 patients(196 eyes)with high myopia were operated SMILE in the optometric center of Gansu Provincial Hospital from January 2018 to July 2019 were analyzed. The change of IOPNCT before and after operation was observed, and recorded the optical zone(OZ), lenticule thickness(LT), cap thickness(CT)and residual stromal thickness(RST)and the correlation with the change value of IOPNCT(△IOPNCT, △IOPNCT=IOPpreoperative-IOP postoperative at 6mo).RESULTS:After operation at 1d, 1wk, 1,3 and 6mo, the group of patients with IOPNCT(10.84±2.14,11.00±2.19,10.65±2.43,10.45±2.04,10.61±1.39mmHg)and the preoperative(16.79±1.65mmHg)comparison have a difference(P<0.001).The optical zone and lenticule thickness were positively correlated with △IOPNCT respectively(r=0.1537, 0.8161, all P<0.05). The cap thickness and residual stromal thickness were negatively correlated with △IOPNCT respectively(r=-0.8362, -0.3351, all P<0.0001). Introduce the above related factors into a multiple linear regression analysis model. The regression coefficients of variables are statistical significane. The regression equation was Y=16.189+0.227X1+0.032X2-0.083X3-0.007X4(Y=△IOPNCT, X1=OZ, X2=LT, X3=CT, X4=RST). The equation was statistically significant(F=195.704, P<0.001), and the regression model coefficient of determination R2=0.901.CONCLUSION:The intraocular pressure changes after SMILE with high myopic were correlated with optical zone, lenticule thickness, cap thickness and residual stromal thickness. The regression equation would provide reference to evaluation the real intraocular pressure after SMILE in clinic.
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@#AIM: To explore the changes and influencing factors of effective optical zone(EOZ)after femtosecond laser small incision lenticule extraction(SMILE)in patients with different degrees of myopia.<p>METHODS:Retrospective study. From October 2019 to October 2020, fifty patients(92 eyes)with myopia who underwent SMILE surgery in the Affiliated Eye Hospital of Nanchang University and whose preoperative optical zone diameter was designed to be 6.5mm were selected. According to the preoperative equivalent spherical diopter, the patients were divided into three groups: low myopia group(-0.50D to -3.00D, 18 cases, 34 eyes), moderate myopia group(>-3.00D to -6.00D, 20 cases, 36 eyes)and high myopia group(>-6.00D, 12 cases, 22 eyes). The uncorrected visual acuity, best corrected visual acuity, manifest refraction spherical equivalent, optical zone diameter, corneal Q-value and high-order aberrations(HOA)were collected before and 3mo after operation.<p>RESULTS:The postoperative 3mo EOZ of patients with low, moderate and high myopia were 5.07±0.69, 5.08±0.43 and 4.50±0.58 mm, respectively, and the corneal Q-values were 0.22±0.17, 0.57±0.34 and 0.63±0.73, there were significant differences among the three groups(all <i>P</i><0.05). The diameter of effective optical zones after operation in all three groups was lower than that predicted by 6.5mm before operation(<i>P</i><0.001). There were significant differences in postoperative total HOA, spherical aberration(Z40)and vertical coma(Z3-1)among the three groups(<i>P</i><0.05). The diameter of effective optical zone after SMILE was positively correlated with preoperative manifest refraction spherical equivalent and residual corneal thickness(<i>r</i>=0.357, 0.275,all <i>P</i><0.05), and negatively correlated with central corneal ablation depth and postoperative corneal Q-value(<i>r</i>= -0.316, -0.353, all <i>P</i><0.05). After operation, ΔZ40 was negatively correlated with ΔEOZ(<i>r</i>= -0.336, <i>P</i><0.05).<p>CONCLUSION:The EOZ after SMILE was lower than that expected before operation, and the higher the myopia was, the smaller the optical area was and the more the postoperative corneal spherical aberration increased. In addition, the depth of corneal ablation, residual corneal thickness and aspheric changes of cornea can affect the size of EOZ after operation.
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@#AIM: To present the visual quality and refractive outcomes obtained in small incision lenticule extraction(SMILE)refractive surgeries, and observe the follow-up of patients over 1a period.<p>METHODS: Retrospective comparative analysis of 85 patients(85 eyes)were treated with SMILE between July and December 2019. Pre- and postoperative uncorrected distance visual acuity(UDVA), corrected distance visual acuity(CDVA), spherical equivalent refraction(SE)were all observed, to evaluate the efficacy, safety and predictability after SMILE refractive surgery. Total corneal higher-order aberrations(HOAs), modulation transfer function cut-off(MTF<sub>cutoff</sub>), strehl ratio(SR), and objective scattering index(OSI)were evaluated. <p>RESULTS: One year after SMILE refractive surgery, the efficacy index was 1.08, 84 eyes(99%)reached an UDVA as or over CDVA preoperatively, 22 eyes(26%)gained one line of CDVA than preoperatively. The safety index was 1.04, 59 eyes(69%)of the treated eyes had an unchanged CDVA postoperatively, 24 eyes(28%)gained one line of CDVA, 2 eyes(2%)gained two lines of CDVA. 85 eyes(100%)were all within ±0.50D. The pre-correction is highly related with the actual correction of SE(<i>Y</i>=0.9949<i>X</i>-0.0033; <i>R</i><sup>2</sup>=0.9977). HOA, spherical aberration and coma were increased under pupil diameters of 6mm(all <i>P</i><0.001). Both MTF<sub>cutoff</sub> and SR were higher than that of SMILE preoperatively(<i>P</i><0.05).<p>CONCLUSION: SMILE demonstrated to be safe, effective, and predictable in the treatment of myopia and myopic astigmatism, and good accuracy in correcting medium and low astigmatism. The post-quality of retinal image is better than that of SMILE preoperatively.
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@#AIM: To study the postoperative optical zone decentration and visual quality by taking visual axis corneal reflect point(VACRP)and corneal vertex(CV)as the ablation center, exploring the femtosecond laser small incision lenticule extraction(SMILE).<p>METHODS: Prospective randomized controlled trial. Totally 70 myopic patients(140 eyes)who underwent SMILE surgery in our hospital from May to June 2020 were randomly divided into two groups, 68 eyes of 34 cases took the VACRP as the ablation center(VACRP group), and 72 eyes of 36 cases took the CV as the ablation center(CV group). The visual acuity, refractive diopter, offset from corneal ablation center, and high-order corneal aberrations were observed before and 3mo after surgery. <p>RESULTS: Three months after operation, there was no difference in uncorrected visual acuity, best corrected visual acuity and refractive diopter between the two groups(<i>P</i>>0.05). The ablation center deviation in CV group(0.20±0.13mm)was less than that in VACRP group(0.27±0.14mm, <i>P</i><0.01). The total corneal high-order aberration(totHOA), spherical aberration(totZ40), vertical coma(totZ3-1)and horizontal coma(totZ31)in CV group were lower than VACRP group(<i>P</i><0.05). Three months after operation, the totHOA, total high-order aberration change(ΔtotHOA), totZ40, totZ3-1 in VACRP group were correlated with ablation center deviation(<i>r</i>=0.470, 0.486, 0.254, -0.366, <i>P</i><0.001, =0.001, 0.037, 0.002), totZ31 in CV group was correlated with the ablation center deviation(<i>r</i>=-0.352, <i>P</i>=0.002).<p>CONCLUSION: SMILE surgery can obtain satisfactory uncorrected visual acuity and the same level of refractive diopter with the VACRP and the CV as the ablation center, but taking the CV as the ablation center can reduce the postoperative decentration and high-order corneal aberrations and obtain better visual quality.
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@#AIM: To compare the objective optical quality of high myopic patients between SMILE and V4c ICL implantation.<p>METHODS: This was a prospective control study. Thirty-eight patients underwent SMILE and thirty-two patients underwent V4c ICL implantation with high myopia were chosen for this study. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA)and refractive situation were evaluated preoperatively, at 1wk, 1mo, 3mo and 6mo postoperatively. The objective scattering index(OSI), strehl rate(SR)and modulation transfer function(MTF)cut off frequency were measured by the double-pass optical quality system at the same time.<p>RESULTS: No significant difference of spherical equivalent(SE), UCVA and BCVA was found between SMILE group and V4c ICL implantation group at all time points. At 1wk and 1mo after operation, the OSI values of two groups were significantly higher than pre-operation(<i>P</i><0.01). OSI values of two groups returned to baseline at 3mo after operation. The MTF cut off frequency of both groups decreased significantly at 1wk after operation(<i>P</i><0.05)and recovered to baseline at 1mo after operation, no significant difference was found between two group at all time points(<i>P</i>>0.05).<p>CONCLUSION: Both SMILE and V4c ICL implantation can obtain good visual acuity and objective optical quality.
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@#AIM: To explore the posterior corneal surface height after femtosecond laser small incision lenticule extraction(SMILE)or femtosecond laser <i>in situ</i> keratomileusis surgery(Fs-LASIK). <p>METHODS: A retrospective analysis of 113 cases of patients(226 eyes)with myopia underwent laser corneal refractive surgery in our hospital from January to December 2016 was taken. There were 51 cases(102 eyes)with SMILE and 62(124 eyes)with Fs-LASIK. Postoperative posterior corneal surface height, uncorrected visual acuity, spherical equivalent change, operation safety were analyzed and compared between the two groups.<p>RESULTS: The preoperative posterior corneal surface height had no statistical difference between the two groups(<i>P</i>>0.05). Corneal surface height at 1, 3 and 6mo after operation were significantly higher than those before operation(<i>P</i><0.05), but the differences between the two groups at different time points after operation were not significant(<i>P</i>>0.05). Preoperative uncorrected visual acuity had no statistical difference between the two groups(<i>P</i>>0.05); postoperative uncorrected visual acuity at 1, 3 and 6mo were significantly better than those before operation(<i>P</i><0.05), but the differences between the two groups at different time points after operation were not significant(<i>P</i>>0.05). Preoperative spherical equivalent had no statistical difference between the two groups(<i>P</i>>0.05); postoperative spherical equivalent at 1wk were significantly better than those before operation(<i>P</i><0.05), but the differences between the two groups after operation were not significant(<i>P</i>>0.05). Postoperative incidence of adverse reactions such as corneal edema, corneal infection, diffuse lamellar keratitis and postoperative glare had no statistical difference between the two groups at 6mo after operation(<i>P</i>>0.05).<p>CONCLUSION: SMILE and Fs-LASIK can be safely and effectively correcting visual acuity, but posterior corneal surface partial forward occurred after either operation.