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Objective:To compare the changes of corneal asphericity and higher-order aberrations after smart pulse technology-assisted transepithelial photorefractive keratectomy (Smart) for low and moderate myopia and to investigate the changes in the shape of the front corneal surface in patients with different diopters.Methods:A non-randomized controlled study design was used.Ninety-eight eyes of 54 patients with moderate or low myopia who underwent Smart surgery in Tianjin Medical University Eye Hospital from November 2018 to March 2019 were included.The 41 eyes of 23 patients with low myopia were set as the low-myopia group, and 57 eyes of 31 patients with moderate myopia were assigned as the moderate-myopia group.The Pentacam anterior segment analysis system was used to measure Q value, index of surface variance (ISV), corneal higher-order aberration (HOA), corneal vertical coma (Z 3-1), corneal horizontal coma (Z 31) and spherical aberration (Z 40) before surgery, 1 month and 3 months after surgery.The anterior surface morphology was compared between the low-myopia and moderate-myopia group.Pearson correlation analysis was used to analyze the correlations between measurement parameters.The study protocol was approved by an Ethics Committee of Tianjin Medical University Eye Hospital (No.2019KY-17). Written informed consent was obtained from each patient before surgery. Results:Corneal Q value, ISV, HOA and Z 40 were 0.445±0.191, 26.973±5.611, 0.671±0.142 and 0.384±0.188, respectively, in the low-myopia group at one month after surgery, which were significantly increased than corresponding preoperative values of -0.273±0.817, 13.784±2.376, 0.433±0.687 and 0.231±0.062 (all at P<0.05). Corneal Q value, ISV, HOA and Z 40 were 0.693±0.203, 34.038±5.773, 0.874±0.216 and 0.520±0.129, respectively, in the moderate-myopia group at one month after surgery, which were significantly increased than corresponding preoperative values of -0.309±0.104, 14.838±3.992, 0.409±0.081 and 0.228±0.089 (all at P<0.05). Corneal Q values, ISV, HOA and Z 40 in the moderate-myopia group were higher than those in the low-myopia group at different time points after surgery, showing significant differences between the two groups (all at P<0.05). There was no significant difference in postoperative 1-month and 3-month corneal Z 3-1 and Z 31 between the two groups (both at P>0.05). The results of correlation analysis showed that there were no significant differences in ΔQ value and ΔISV between the two groups, both of which were negatively correlated with spherical equivalent (ΔQ value: low-myopia group: r=-0.364, P=0.044; moderate-myopia group: r=-0.589, P<0.01; ΔISV: low-myopia group: r=-0.298, P=0.039; moderate-myopia group: r=-0.409, P=0.022). ΔQ value and ΔZ 40 were positively correlated in the moderate-myopia group ( r=0.348, P=0.009); there was no significant correlation between ΔQ value and ΔZ 40 in the low-myopia group ( r=0.180, P=0.266). Conclusions:The corneal high-order aberrations and ISV after Smart are increased in comparison with preoperative values in the low-myopia and moderate-myopia eyes, and the corneal Q values change from negative to positive.The effect of Smart on corneal asphericity is less in the low-myopia eyes.
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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 observe the effect of transepithelial photorefractive ketatectomy(TPRK)on corneal curvature, asphericity and aberrations. <p>METHODS: Twenty-nine patients(58 eyes)were enrolled. The 1mm-8mm zone curvature, target curvature and 3mm ring curvature, corneal asphericity(Q value)and corneal aberration was measured and analyzed before and 6mo after TPRK surgery. <p>RESULTS: In the 1mm-8mm zone, the corneal curvature all had significant decrease after TPRK surgery. The curvature 3mm ring after operation was 39.20±1.99D, and the curvature target was 39.51±1.99D. And both values had a significant correlation(<i>r</i>=0.98). The Q values before and after operation were -0.44 to -0.30, 0.34-0.66 respectively <i>(P</i><0.05). The total high-order aberration, spherical aberration and vertical coma of cornea before and after operation were 0.41±0.10, 0.17±0.08, -0.07±0.23 and 0.72±0.23, 0.41±0.17, -0.24±0.32, respectively, and these differences were significant. The pre-and postoperative horizontal coma was -0.03±0.12, and -0.03±0.30 respectively(<i>P</i>>0.05).<p>CONCLUSION: After TPRK operation, corneal curvature decreased significantly, and the change in zone of 3mm was the largest. The Q value, total high-order aberration, spherical aberration and vertical coma increased significantly after TPRK operation.
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@#AIM: To investigate and compare the effect of femtosecond laser-assisted <i>in situ</i> keratomileusis(FS-LASIK)and small incision lenticule extraction(SMILE)surgery on anterior corneal asphericity.<p>METHODS: There were sixty eyes of 60 patients in FS-LASIK and SMILE group respectively from November 2016 to September 2017. The Q-values of anterior corneal surface for different diameters(6, 7, 8 and 9mm)and corneal aberrations were measured with Pentacam before and 3mo after operation.<p>RESULTS: The Q-values of anterior corneal surface between FS-LASIK and SMILE were no significant differences. After 3mo operation, the values increased significantly; and the post-operative Q-values of 6mm in group SMILE was significant lower than group FS-LASIK(0.47±0.32 <i>vs</i> 0.89±0.43,<i>P</i><0.05). The higher aberration and spherical aberration in FS-LASIK and SMILE were no significant differences before surgery; after 3mo operation,there were no significant difference between them. However, group FS-LASIK had significant higher spherical aberration than group SMILE(0.43±0.23μm <i>vs</i> 0.31±0.11μm, <i>P</i><0.05).<p>CONCLUSION: FS-LASIK and SMILE cause significant changes of anterior corneal asphericity, Q-values all increased to positive values after surgeries; and there have less changes of Q-value and corneal aberration in SMILE than in FS-LASIK surgery.
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Background Corneal epithelial remodeling will happen after laser refractive surgery,But there have been few studies to evaluate the changes of the corneal epithelial thickness after integrated transepithelial photorefractive keratectomy (TranspRK).Objective This study was to evaluate the changes in epithelial thickness profile within the optical zone and its related factors following TransPRK for myopia.Methods In this retrospective non-randomized controlled study,forty-three patients (43 eyes) who underwent TransPRK with the spherical equivalent refraction-1.25 to-6.25 D from August 2014 to May 2015 in Jinan Mingshui Eye Hospital were included under the informed consent.Epithelial thickness was measured using spectral-domain optical coherence tomography in different corneal zones (central,2 mm;paracentral,2-5 mm,and mid-peripheral,5-6 mm) preoperatively at 1 week and 1,3,and 6 months postoperatively.Correlations between epithelial thickness changes and the amount of correction,optical zone,and Q-value changes (△Q) were analyzed 6 months postoperatively.Results The mean epithelial thickness in the central zone were (53.97±4.33),(51.03 ±4.11),(55.14±5.46) and (56.68 ± 5.09) μm at 1 week,1 month,3 months and 6 months after surgery,respectively.The epithelium were thicker at 3 months and 6 months after surgery compared to preoperative measurements ([52.37±3.42] μm),with significant differences between them (both at P＜0.05).Compared to preoperative values,the epithelial thickness at 6 months after surgery was (3.69 ±4.23),(5.19 ±3.88) and (6.23 ±3.91) μm thicker in the center,paracenter,and midperiphery zone,respectively,with significant differences between them (all at P ＜ 0.01).Epithelial thickness was positively correlated with programmed spherial equivalent correction and △Q (all at P＜0.05).A significant positive relationship was observed between epithelial thickening and ablation depth paracentrally and mid-peripherally (r=0.380,0.383;both at P＜0.05).Significantly negative relationships were observed between epithelial thickening and optical zone at the center,paracenter,and mid-periphery,respectively (r =0.405,0.485,0.384;all at P＜0.05).No correlation betwcen epithelial thickness change and ablation depth at the central zone was detected (P＞0.05).Conclusions The epithelial thickness shows a lenticular change with more thickening mid-Peripherally after TransPRK,which results in increased oblateness postoperatively.Epithelial remodeling may modify the profile after surface ablation.
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Background The measurement of corneal Q value is essential for corneal refractive surgery and calculation of intraocular lens during cataract surgery.Topolyzer was often used for the measurement of Q value,and recently Topcon KR-1W and iTrace were applied in ophthalmology.However,whether the measured values are interchangeable is unclear.Objective This study was to assess the difference and consistency of corneal Q values measured by Topcon KR-1W,iTrace and Topolyzer.Methods Corneal Q values were measured on 100 right eyes of 100 healthy subjects under the approval of Ethic Committee of the Sixth Hospital Affiliated to Shanghai Jiaotong University and informed consent of each subject from November to December in 2014 with Topcon KR-1W,iTrace and Topolyzer.Three valid measurements were obtained for each device,and the average values from each device were calculated.The difference of the outcomes among the instruments was compared by repeated measures analysis of variance (ANOVA),and the consistency among the outcomes from different apparatus was analyzed by Bland-Altman plots.Results The mean corneal Q values were-0.184-±0.112,-0.117±0.167 and-0.269±0.117 from Topcon KR-1W,iTrace and Topolyzer,respectively,with a significant difference among them (P ＜ 0.001).The measured Q value by Topcon KR-1W was 0.085±0.010 larger than that by Topolyzer,and the Q values by iTrace was 0.152± 0.014 larger than that by Topolyzer,while the Q values obtained by Topcon KR-1W was 0.067±0.016 smaller than that by iTrace (all at P＜0.05).The 95％ confidence interval of the values between Topcon KR-1W and iTrace,Topcon KR-1W and Topolyzer,iTrace and Topolyzer were-0.106 to-0.028,0.060 to 0.109 and 0.118 to 0.186,respectively.Bland-Altman plots showed that 6％,6％ and 5％ values were outside of 95％ agreement of limit (LoA) between Topcon KR-1W and iTrace,iTrace and Topolyzer or KR-1W and Topolyzer,respectively,with the maximal differences of 0.28,0.43 and 0.38.Conclusions Corneal Q values measured by Topcon KR-1W and iTrace are larger than those measured by Topolyzer.Due to the poor agreements among the corneal Q values by the 3 kinds of devices,they are not interchangeable in clinical applications for the measurement of corneal Q value.
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The corneal asphericity refers to most normal corneal surface is an aspherical flat oval,which is helpful to improve the visual quality.In most cases,corneal aspherical coefficient Q-value is negative,and different normal Q-value is reported in literatures,corneal Q-value is influenced by many factors,quadrants have great effects on it,the influence of age is weak,there are correlation between myopic degree,ocular axial length,radius of curvature,intraocular pressure and Q-value.The corneal refractive surgery is one of the most important methods to correct refractive errors,but it has negative effects on the corneal asphericity,and then results in glare,visual quality degradation and other issues.Different corneal refractive surgeries would have different effects on the corneal asphericity.Wavefront aberration-guided femtosecond laser in situ keratomileusis(LASIK) surgery and Q-value guide LASIK are superior to standardized LASIK,the change of Q-value after femtosecond lenticule extraction (FLEx) surgery is less than that after wavefront aberration guided LASIK.The influence of femtosecond laser in situ keratomileusis (FS-LASIK) and small incision lenticule extraction (SMILE) on Q-value are rarely reported.In addition,the Q-value changes from negative to positive after corneal refractive surgery of myopia,the variation tendency is opposite after hyperopia surgery.Q-value variation is highly correlated to spherical equivalent,the impact of laser and healing still needs further exploration.In order to further exploring of the corneal asphericity and getting a better effect of surgery,here is a review about normal corneal asphericity and the effects of the corneal refractive surgery on it.
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·AlM: To investigate the distribution and related factors of corneal spherical aberration in the age-related cataract patients, and to provide a scientific basis for the application of aspheric intraocular lens ( lOL ) in cataract surgery patients. · METHODS: Retrospective study of 509 age -related cataract patients of 610 eyes in our hospital. Corneal spherical aberration, corneal curvature, corneal astigmatism and corneal Q -value were examined by iTrace visual function analysis. Statistical software SPSS16.0 was used to analyze statistically. · RESULTS: The range of corneal spherical aberration was 0 ~1.800μm. The mean coefficient of corneal spherical aberration was 0.266 ±0.010μm. Corneal spherical aberration was no significantly correlation with age, corneal curvature, corneal astigmatism ( r =0.71, 0.56, 0.93, P>0.05 ). There was positive correlation between corneal spherical aberration and Q-value ( r=0.086, P=0.03). · CONCLUSlON: Corneal spherical aberration varied greatly among age-related cataract patients.The choice of asphericity intraocular lens should be a matter of personal choice.
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Objective To use Q value method to assess the effect of combination therapy with vitamin E and vitamin C for idiopathic asthenospermia. Methods 76 patients diagnosed as idiopathic asthenospermia by computer-assisted semen analysis according to the WHO criteria were selected at the andrology clinic from August 2012 to November 2013. Malondialdehyde (MDA) concentration was measured by using thiobarbituric acid (TBA) assay. The patients were randomly divided into three groups. Vit C group received vitamin C 200 mg thrice daily, vit E group received vitamin E 100 mg thrice daily , and the combination group received vitamins E and C for 12 weeks. Repeat semen analysis and MDA measurement were conducted after treatment, and the Q value which evaluated whether a synergistic interaction existed was calculated. Results MDA concentration decreased in all the groups, with the lowest concentration in the combination group. While all the groups achieved improvement in term of progressive motility , with the combination group presented far more better than the other two groups , exhibiting a synergistic interaction, with a Q value of 1.18. Conclusion Combination therapy with vitamin E and vitamin C has a marked internal synergistic effect on antioxidation in the treatment of idiopathic asthenospermia.
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Background Aspheric intraocular lens (IOL) is designed to reduce the spherical aberration of the eye after cataract surgery and to obtain better visual quality.However,the selection of a personalized aspheric IOL is a problem to be solved.Objective This study was to compare the wavefront aberration and quality of vision of patients between the implantation of negative spherical aberration IOL and non-aberration IOL,and to investigate the relationship between corneal Q values and postoperative spherical aberration.Methods One hundred and four eyes of 90 patients with age-related cataract were randomized into two groups.Fifty-two eyes of 46 patients who received a Tecnis Z9001 IOL implantation were assigned as the negative spherical aberration IOL group and 52 eyes of 44 patients who received Akreos AO IOL without aberration were assigned as the non-aberration IOL group.The preoperative corneal Q values were measured and the mean Q value(Q)was computed.Then the patients in the two groups were further divided into 2 subgroups,respectively,based on their Q values were over or below (Q）.The corneal Q values,root mean square(RMS) of ocular spherical aberration,coma and total higher-order aberrations(HOAs) for 5 mm diameter pupil,scotopic contrast sensitivity with or without glare at 6 mm pupil diameter were measured 3 months after surgery.Results The pre-and post-operative corneal Q values were insignificantly changed (t =1.447,P =0.151).The spherical aberration in the negative spherical aberration IOL group was(0.059-±0.047)μm,and that in the non-aberration IOL group was(0.110±0.066)μm,with a statistically significant difference between them (t =-4.567,P=0.000).Scotopic contrast sensitivities at intermediate and high frequencies were significantly better in the negative spherical aberration IOL group than in the non-aberration IOL group (t =2.495,t =2.359,P ＜ 0.05).There was no significant difference in coma and HOAs between the two groups after operation (P ＞ 0.05).Weak positive correlations were seen between the pre-and post-operative corneal Q values and spherical aberration in the two groups(r=0.277,0.292,0.285,0.325,all at P＜0.05).However,no significant differences were found in spherical aberration,contrast sensitivity and scotopic contrast sensitivity between the different subgroups (P ＞ 0.05).Conclusions Negative spherical aberration IOL has lower spherical aberration and better scotopic contrast sensitivity than non-aberration IOL.The results suggest that it may be not enough to choose the corneal Q value only as the single reference criterion for selection of aspheric IOL.
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Background Nowadays,customized ablation is widely used in the excimer laser corneal refractive Burgery.And the Q-value guide LASIK is one of the research hotspots. Objective Present study was to evaluate and compare the effectiveness of Q-value guide LASIK and standardized LASIK for myopia.Methods A systematic literature retrieval from 2003 through 2010 was conducted in the MEDLINE,CNKI,Cochrane Library,EMBASE.The literature examine possible difierences in uncorrected visual acuity(UCVA),Q-value,higher order aberrations(HOAs),and spherical equivalent(SE) between Q-value guide LASIK and standardized LASIK for correcting myopia.Statistical analysis was performed using a Review Manager 5.0 software.The data was extracted,and the methodological quality was evaluated by two reviewers independently.The quality of included literature was scored according to the Jadad Scale. Results A total of 14 studies involving 1617 patients(2956 eyes)was included in the meta-analysis.Of these fourteen studies,six studies were randomized trials and the other eight studies were retrospective cohort studies.According to the Jadad Scale,2 studies scored 3 points,and the other 12 studies scored 1～2 points.The results showed that the Q-value guide LASIK group had a better postoperative effectiveness in uncorrective visual acuity(UCVA)(WMD=0.04.95% CI 0.00 to 0.08,P<0.05).Q-value(SMD=-1.52,95% CI -2.23 to-0.81,P=0.00),total HOAs (SMD=-1.63,95% CI-2.57 to-0.69,P<0.05) and spherical-like aberrations ( SMD =-1.49,95% CI-2.22 to-0. 76,P<0. 00) after surgery. However, the number of eyes achieved UCVA≥20/20 ( OR= 1.16,95% CI 0. 61 to 2. 19,P=0. 65) ,coma-like aberrations (SMD=-1. 02,95% CI-0. 36to 0.11,P=0.29) and SE (WMD=0.10,95% CI-0.11 to 0.31,P=0.34) after surgery were comparable.Conclusion The effectiveness of Q-value guide LASIK is superior to standardized LASIK for treatment of myopia.High-quality clinical randomized-controlled study should be performed to further evaluate the comparable outcome of Q-value guide LASIK with standard LASIK.
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Phakic intraocular lens implantation(PIOL)is one of the primary surgery fashions for correcting high myopia.The evaluation of visual quality following the surgery,including visual activity,contrast sensitivity,aberration and corneal Q value,is very important.Researches showed that the visual quality of patients after tradition laser in situ keratomileusis(LASIK)decreased because of the alteration of corneal aspherieity by laser excision cornea；while compared with LASIK,implantation of implantable contact lenses(ICL)is popular due to its excellent safety,effectiveness,reversibility and fewer complication.The visual quality after ICL is also superior than that of LASIK.Therein,the surgical project will furthermore be recommend for the high myopia patients.The purpose is to find the optimal strategy for the high myopia patients to get the best visual quality.
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Background Laser in situ keratomileusis (LASIK) is frequently performed to reduce or eliminate myopic refractive error.Some patients complain of a loss of visual function after surgery even when they have 20/20 visual acuity.One of the reasons is the change of asphericity of the cornea.Objective This study attempts to investigate the short-term changes of the anterior and posterior corneal asphericity after LASIK.Methods One hundred and seven myopic eyes of 54 subjects with the equivalent spherical diopter of -1.30 to -7.50 D who have received LASIK were enrolled in this prospective study.The Q-values of the posterior corneal surface for different corneal diameters (6mm,7mm,8mm and 9mm) were measured with Pentacam preoperatively and 1 month postoperatively.The correlations between Q-value,Q change (△Q),and the mean preoperative spherical equivalent refraction (SE),central corneal thickness (CCT),central ablation depth (AD) and residual bed thickness were investigated.Written informed consents were obtained from all the subjects prior to the clinical trial.Results The Q-values of the anterior and posterior corneal surfaces gradually decreased to negative values with the increase of corneal diameter in myopic eyes.Weak correlations were found between the asphericity of the anterior and posterior corneal surfaces from diameters of 6mm,7mm,8mm and 9mm (r=0.227,0.288,0.303,0.389;P=0.019,0.003,0.002 and 0.000,respectively).No statistically significant correlation was found between Q-value and the diopter of refractive error (P＞0.05).Both the anterior and posterior corneal Q-values varied toward the positive direction except that in the 9mm area of the posterior corneal surface at postoperative 1 month(t=-1.495,P=0.138).The increase of the anterior corneal asphericity (△Q) was more obvious than that of the posterior corneal surface and showed a positive correlation with ablation depth and a negative correlation with residual bed thickness.However,no statistically significant correlation was seen between △Q and these two parameters in the posterior corneal surface (P＞0.05).Conclusion The shape of the anterior and posterior corneal surface shows more prolateness as the increase of corneal diameter in myopic eyes.Both the anterior and the posterior corneal surfaces have an oblate shift within the ablation zone 1 month after LASIK.
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Objective To observe the distribution of cornea Q value in adult myopia,and its relationship with age,sex,eye and refraction.Design Prospective case series.Participants Consecutive 510 patients (1020 eyes) of myopia of adults.Methods Cornea Q values were obtained with OrbscanⅡz Anterior Segment Analysis System in all subjects of adult myopia.Normal distribution test of Q value and correlation analysis with sphere,cylinder,sex,and age were performed.Main Outcome Measures Q value of cornea,corre- lation coefficient.Results In 1020 eyes of adult myopia,the mean Q value was-0.27?0.16 (range from-0.86 to 0.25) with near nor- mal distribution.The difference of Q value between right eyes and left eye was not statistically significant (P=0.675).The Q value be- tween male (-0.26?0.15) and female(-0.27?0.17) was not statistically difference(P=0.697).No significant relation was found Q value with either sphere (r=0.057,P=0.068) or cylinder (r=0.044,P=0.156).Mean Q value of below 20 years old was maximal,-0.24,while over 40 years old was minimal,-0.36,and the difference were statistically significant (P=0.000).Conclusions Q value of cornea has negative shift with the increase of age,especially in over 40 years old.Q value of cornea has no relationship with left or right eyes,sex and refraction,but it is highly customized.