Study on the Corneal Higher-Order Aberrations and Correlation in Patients with Different Degrees of Myopia Suitable for Wavefront-Guided FS-LASIK

Background: Individualized corneal refractive surgery requires an understanding of the basis of higher-order aberrations before surgery. To investigate the characteristics and distribution of anterior surface wavefront aberrations in patients suitable for corneal refractive surgery. Methods: A total of 121 myopic patients (121 eyes, 18 - 45 years old) who underwent corneal refractive surgery were recruited from January to May 2016 at Affiliated Hospital, Yanbian University. Patients were randomly selected by the Pentacam anterior segment analysis system with a spherical equivalent (SE) of -0.25 to -10.00 D. The corneal anterior aberrations (total higher-order aberration;spherical aberration;Coma;Trefoil) and Q and K values were detected, and a correlation analysis of the relevant parameters was carried out. Results: The root-mean-square (RMS) of the third to sixth order aberrations of the corneal anterior wavefront aberrations at a 6 mm analysis diameter showed a decreasing trend in patients suitable for the corneal refractive surgery, and the RMS of the third order aberrations accounted for 62.92% of the total HOAs. The coma ratio (coma/total cornea higher-order aberrations) was increased with the increasing diopters, while the spherical aberration ratio (spherical aberration/total cornea higher-order aberrations) was not changed. In addition, the spherical aberration was 0.203 ± 0.082 μm (range: 0.061 to 0.503 μm), and the Q30 was -0.19 ± 0.03 (range: -0.58 to 0.31). There were significant differences in the coma aberrations of preoperative corneal anterior surface (3, 1) between the low, middle and high myopia groups (P = 0.013). The spherical equivalent was positively correlated with the corneal coma of the anterior corneal surfaces (R =?-0.241, P = 0.009), and the Q value was positively correlated with the total higher-order aberrations (R = 0.326, P Conclusions: Individual wavefront aberrations on the anterior surfaces of the cornea are comparatively different, and the Zernike coefficients are related to the degree of myopia. Spherical aberrations are the most overriding aberrations of the cornea.

Repeatability and reproducibility of corneal higher-order aberrations measurements after small incision lenticule extraction using the Scheimpfug-Placido topographer

Background:To evaluate the precision of corneal higher-order aberrations measurements after small incision lenticule extraction(SMILE)using the Sirius Scheimpfug-Placido topographer(CSO,Italy).Methods:Seventy-fve eyes from 75 postoperative subjects were included in this prospective study.Three consecutive corneal aberrometric measurements were obtained with the Scheimpfug-Placido topographer by two experienced operators to assess intra-and inter-observer reproducibility.The within-subject standard deviation(Sw),test-retest repeatability(TRT)and the intraclass correlation coefcient(ICC)were calculated.Results:For intraobserver repeatability of anterior and total corneal aberrations,all ICCs were more than 0.922,except for trefoil(0.722 to 0.768).The ICCs of total root mean square(RMS),coma Z(3,±1),and spherical aberration Z(4,0)were over 0.810 while higher-order RMS,trefoil Z(3,±3),and astigmatism II Z(4,±2)were below 0.634 for posterior corneal surface aberrations.All Sw values for all types of aberrations were equal to or below 0.07μm.Regarding interobserver reproducibility,all TRT values were no more than 0.12μm,0.05μm,and 0.11μm for anterior,posterior,and total corneal aberrations,respectively.The ICC values ranged from 0.875 to 0.989,from 0.686 to 0.976 and over 0.834 for anterior,posterior,and total corneal aberrations,respectively.Conclusions:The repeatability of measurements of anterior and total corneal aberrations with the Sirius system in corneas after SMILE surgery was high,except for trefoil.There was some variability in posterior corneal aberrometric measurements.High reproducibility of corneal aberrometric measurements was observed between measurements of both examiners,except for trefoil,with poor to moderate reproducibility.

Characteristics of corneal aberration in patients with bilateral keratoconus and unilateral corneal Vogt’s striae

AIM:To assess the corneal high-order aberration(HOA)and its correlation with corneal morphological parameters in patients with bilateral keratoconus(KCN)and unilateral Vogt’s striae.METHODS:A total of 168 eyes of 84 patients with KCN,whose corneas had definite signs of unilateral Vogt’s striae,were enrolled.Corneal HOA and morphological parameters were measured using Pentacam HR.RESULTS:The corneal morphological parameters between KCN eyes with and without Vogt’s striae were evidently different(P<0.001).The 3rd coma 90°,4th spherical aberration,5th coma 90°,root-mean-square(RMS)(total),and RMS(HOA)in the front,back surfaces and total cornea in KCN eyes with Vogt’s striae were significantly higher than those in KCN eyes without Vogt’s striae(P<0.001).In KCN eyes with Vogt’s striae,the 3rd coma 90°and 4th spherical aberration in the front surface and total cornea were negatively correlated with flat keratometry value(K1),steep keratometry value(K2),mean keratometry value(Km),maximum keratometry value(Kmax),anterior corneal elevation(ACE),and posterior corneal elevation(PCE;P<0.05).The 3rd coma 90°,4th spherical aberration in back surface and RMS(total),RMS(HOA)in the front,back surfaces,total cornea were positively correlated with K1,K2,Km,Kmax,ACE,and PCE(P<0.05).CONCLUSION:Corneal HOA especially vertical coma and spherical aberration may increase when Vogt’s striae appeared in KCN eyes.The scale of increase is significantly related with changes in corneal shapes.

Efficacy of custom-made soft keratoconus lenses on corneal aberrations and photic phenomena in patients with keratoconus:a corneal topography imaging based study

AIM:To evaluate the efficacy of custom-made soft keratoconus(KC)lenses on corneal aberrations and photic phenomena in two different optical zones in patients with KC.METHODS:Sixty eyes of 42 patients with KC were examined at baseline and after fitting HydroCone(Toris K)soft silicone hydrogel lenses.Best spectacle-corrected visual acuity(BSCVA)and contact lens-corrected visual acuity(CLCVA)were recorded.Lower-and higher-order corneal aberrations(LOAs and HOAs)were measured with and without Toris K lenses and compared in central 4.5 mm and 7 mm zones.Mesopic pupil diameter and subjective photic phenomena were also assessed.RESULTS:Mean CLCVA was significantly improved compared to BSCVA(P<0.0001).Corneal curvature and refractive measurements were found to be significantly reduced by the use of Toris K lenses,except for posterior corneal curvature values.In the 4.5 mm central optical zone,all wavefront aberrations decreased significantly after lens fitting(P<0.0001).In contrast,in the 7 mm(peripheral)optical zone,values for HOAs,spherical and residual aberrations,and optical path differences were increased,while LOAs,trefoil,and quadrifoil coefficients were decreased.The rate of photic phenomena was significantly higher in participants with a pupil size>6.00 mm(85.7%).CONCLUSION:Toris K lenses provide good visual results and a significant reduction in central corneal aberrations in patients with KC but could cause an increase in peripheral aberrations.This practical and nonsurgical approach appears to be an effective method for the visual management of KC.

Ocular higher-order aberrations and mesopic pupil size in individuals screened for refractive surgery

AIM: To study the distribution of ocular higher-order aberrations(HOAs) and mesopic pupil size in individuals screened for refractive surgery. · METHODS: Ocular HOAs and mesopic pupil size were studied in 2 458 eyes of 1 240 patients with myopia, myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, hyperopic astigmatism and compound hyperopic astigmatism using the Zywave aberrometer (Busch& Lomb). All patients had correctable refractive errors without a history of refractive surgery or underlying diseases. Root-mean-square values of HOAs, total spherical aberration, total coma and mesopic pupil size were analyzed. Ocular HOAs were measured across a ≥ 6.0 mm pupil, and pupil size measurements were performed under the mesopic condition. · RESULTS: The mean values of HOAs, total spherical aberration and total coma in the myopic group were 0.369 μm, ±0.233, 0.133±0.112μm and 0.330±0.188μm, respectively. In the hyperopic group the mean values of HOAs, total spherical aberration and total coma were 0.418μm±0.214, 0.202±0.209μm and 0.343±0.201μm, respectively. Hyperopes showed greater total HOAs (P <0.01) and total spherical aberration (P <0.01) compared to myopes. In age-matched analysis, only the amount of total spherical aberration was higher in the hyperopic group (P =0.05). Mesopic pupil size in the myopic group was larger (P ≤0.05). · CONCLUSION: The results suggested that significant levels of HOAs were found in both groups which are important for planning refractive surgeries on Iranians. There were significantly higher levels of total spherical aberration in hyperopes compared to myopes. Mesopic pupil size was larger in myopic group.

Analysis of ocular structural parameters and higher-order aberrations in Chinese children with myopia

BACKGROUND Myopia and high myopia are global public health concerns.Patients with high myopia account for 0.5%-5.0%of the global population.AIM To examine diopters,axial length(AL),higher-order aberrations,and other ocular parameters in Chinese children with myopia,to analyze the influence of structural parameters associated with myopia on visual quality,and to provide a theoretical basis for the prevention and treatment of childhood myopia and high myopia.METHODS This study included 195 children aged 6–17 years with myopia.The AL was measured with an ultrasonic ophthalmic diagnostic instrument,and the aberrations,corneal curvature(minimum K1,maximum K2,and average Km),central corneal thickness,anterior chamber depth,and anterior chamber angle were measured using a Sirius three-dimensional anterior segment analyzer.Using a standard formula,the corneal radius of curvature R(337.3/Km)and AL/R values were obtained.RESULTS The diopter of high myopia compared with low-middle myopia was correlated with age and AL(r=-0.336,-0.405,P<0.001),and AL of high myopia was negatively correlated with K1,K2,and Km(r=-0.673,-0.661,and-0.680,respectively;P<0.001),and positively correlated with age and the anterior chamber depth(r=0.214 and 0.275,respectively;P<0.05).AL/R was more closely related to diopter than AL in children with myopia,and 94.4%of children with myopia had an AL/R of>3.00.CONCLUSION The ocular structural parameters of children change because of different diopters.AL/R is more specific and sensitive than AL in evaluating the refractive status of myopia in children.An AL/R of>3.00 may be used as a specific index of myopia in children.There are differences in AL/R between high myopia and low-middle myopia,which can be used for the classification of ametropia.The degree of myopia has a certain influence on higher-order aberrations.

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.

Evaluations of wavefront aberrations and corneal surface regularity in dry eye patients measured with OPD Scan Ⅲ

AIM: To compare the wavefront aberrations and corneal surface regularity between dry eye(DE) patients and normal subjects and assess its diagnostic performance for DE measured with OPD Scan-Ⅲ.METHODS: Fifty right eyes of 50 DE patients and 31 right eyes of normal subjects were included.The examinations for ocular surface including logarithm of the minimum angle of resolution best-corrected distance visual acuity(logMAR BCVA) the ocular surface disease index(OSDI), tear film break-up time(TBUT) and corneal fluorescein staining(CFS).OPD Scan-Ⅲ was used to measure anterior corneal aberrations including total corneal aberrations, high order aberration(HOA), coma, trefoil, spherical aberration(SA), standard deviation of corneal power(SDP), surface regularity index(SRI) and surface asymmetry index(SAI).Statistical analysis were assessed with nonparametric tests and Spearman’s correlations.All parameters were also analyzed for sensitivity, specificity, and receiver operating characteristics(ROC) curves.RESULTS: Wavefront aberrations parameters including total corneal aberrations, HOA, coma, trefoil, and SA in DE group were significantly higher than those in normal group(P<0.001).Corneal surface regularity parameters including SRI and SAI in DE group were significantly higher than both in normal group(P<0.05).All the wavefront aberrations parameters had significant correlations with ocular surface parameters(P<0.05).The logMAR BCVA had positive correlations with SAI and SRI(all P<0.001).CFS scores had positive correlations with SAI and SRI(all P<0.001).All the wavefront aberrations parameters showed good diagnosis sensitivity and specificity, however, the corneal regularity parameters showed only good specificity but poor sensitivity.The cut-off value selected for trefoil in diagnosis DE showed the highest area under the curve(AUC, 0.921) values as compared to the other parameters with sensitivity of 0.955 and specificity of 0.867.CONCLUSION: Wavefront aberrations and corneal surface regularity are increased in DE patients and also correlated with ocular surface parameters.Wavefront aberrations parameters have potential to be indicators to diagnosis and monitor DE.

Efficacy, safety, predictability, aberrations and corneal biomechnical parameters after SMILE and FLEx: Metaanalysis

AIM： To identify possible differences of efficacy, safety predictability, higher-order aberrations and cornea biomechnical parameters after small-incision lenticule extraction（SMILE） and femtosecond lenticule extraction（FLEx）.· METHODS： A systematic literature retrieval was conducted in Medline,Embase and the Cochrane Library up to October, 2015. The included studies were subject to a Meta-analysis. Comparison between SMILE and FLEx was measured as pooled odds ratio（OR） or weighted mean differences（WMD）. Of 95% confidence intervals（CI） were used to analyze data.·RESULTS： A total of seven studies were included Firstly, there were no differences in uncorrected distance visual acuity（UDVA） 20/20 or better（OR, 1.37; 95% CI0.69 to 2.69; P =0.37） and log MAR UDVA（WMD,-0.02;95% CI,-0.05 to 0.01; P =0.17） after SMILE versus FLEx We found no differences in corrected distance visua acuity（CDVA） unchanged（OR, 0.98; 95% CI, 0.46 to 2.11;P =0.97） and log MAR CDVA（WMD,-0.00; 95% CI,-0.01 to 0.01; P =0.90） either. Secondly, we found no differences in refraction within ±1.00 D（OR, 0.98; 95% CI0.13 to 7.28; P =0.99） and ±0.50 D（OR, 1.62; 95% CI0.62 to 4.28; P =0.33） of target postoperatively. Thirdly for higher-order aberrations, we found no differences in the total higher-order aberrations（WMD,-0.04; 95%CI,-0.09 to 0.01;P =0.14）, coma（WMD,-0.04; 95% CI,-0.09 to 0.01; P =0.11）, spherical（WMD, 0.01; 95% CI,-0.02 to0.03; P =0.60） and trefoil（WMD,-0.00; 95% CI,-0.04 to0.03; P =0.76）. Furthermore, for corneal biomechanica parameters, we also found no differences（WMD, 0.08;95% CI,-0.17 to 0.33; P =0.54） after SMILE versus FLEx.·CONCLUSION： There are no statistically differences in efficacy, safety, predictability, higher-order aberrations and corneal biomechnical parameters postoperative between SMILE and FLEx.

Evaluation of corneal parameter changes under different accommodative stimuli with Scheimpflug imaging-based tomography

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal population.METHODS:Prospective,non-randomized,comparative study including 27 healthy subjects(54 eyes),including emmetropia(13 eyes),myopia(17 eyes),hyperopia(4 eyes)and astigmatism(20 eyes)groups.In all cases,a complete eye examination was performed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the Pentacam AXL system.The investigation was structured in 2 phases:repeatability analysis and characterization of accommodation-related corneal changes in healthy populations.RESULTS:In the repeatability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of parameters acceptable.The group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax;P<0.05),whereas in the astigmatism group,significant changes were not only observed in the position of Kmax,but also in minimum corneal thickness(MCT),corneal spherical aberration,and total and low order aberration root mean square(all P<0.05).Likewise,a significant difference was found in the displacement of the X position of Kmax with+2.00 D and-3.00 D in the myopia group(P=0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the position vector of Kmax in the emmetropia group(P<0.05).No significant changes were found between accommodative stimuli in the displacement of coordinates of MCT(P≥0.109).CONCLUSION:The position of Kmax and MCT in healthy corneas can change significantly when presenting different accommodative stimuli using the accommodation mode of the Pentacam system,with different trends in these accommodation-related corneal changes between refractive errors.Likewise,the consistency of the measurements obtained with Scheimpflug has been confirmed.

Changes in corneal curvature and aberrations after cataract surgery

Background:Surgically induced astigmatism(SIA)and corneal high-order aberrations(HOAs)are the two main causes of poor visual quality after cataract surgery.Changes in the parameters of corneal HOAs after cataract surgery and their effects on and relationships with changes in corneal curvature have not yet been reported.This study aimed to explore changes in anterior,posterior and total corneal curvature,astigmatism and HOAs after microincision cataract surgery.Methods:Sixty-one age-related cataract patients(61 eyes)were included in this prospective study.The total,anterior and posterior corneal astigmatism and corneal HOAs were analyzed by anterior segment optical coherence tomography(AS-OCT)and iTrace before,one day,one week and three months after 2.2 mm temporal microincision coaxial phacoemulsification to evaluate the changes in anterior,posterior and total corneal curvature,astigmatism and corneal HOAs.Results:The mean J0 and J45 values of anterior,posterior and total corneal curvature obtained by ASOCT showed no statistically significant difference between preoperatively and any postoperative followup.SIA occurred on the anterior,posterior and total corneal surfaces and showed no statistically significant difference at any postoperative follow-up.No significant changes in 3rd-order oblique trefoil,vertical coma or 4th-order spherical aberrations were observed after surgery except for a significant increase in horizontal coma at postoperative day 1(POD1).Conclusions:There were no significant changes in corneal curvature after 2.2 mm temporal microincision coaxial phacoemulsification,and the corneal HOAs were not changed significantly except for the increase in horizontal coma at POD1,which may be one of the main reasons of poor visual quality at POD1 in some cataract patients who have good uncorrected or corrected distance vision.

Personalized aspheric intraocular lens implantation based on corneal spherical aberration: a review

With the evolution of cataract surgery from visual rehabilitation to refractive surgery, aspheric intraocular lenses(IOLs) are being increasingly used in the field of ophthalmology. This increased use can be attributed to negative or zero spherical aberrations with unique optical designs, which counteract some of the positive spherical aberrations of the cornea. These alterations reduce the total spherical aberration of human eyes and improve the visual acuity in patients with cataract postoperatively. At present, various types of aspheric IOLs are used worldwide. Although the implantation of aspheric IOL is beneficial to the patients who need correction of spherical aberrations, much controversy is still associated with ocular residual spherical aberrations that facilitate the best visual quality for patients postoperatively. In order to provide reference for future clinical work and scientific research, this report reviews the relationship between the ocular residual spherical aberration of human eyes and visual quality.

Optimal incision sites to reduce corneal aberration variations after small incision phacoemulsification cataract surgery

AIM： To analyze the effect of steep meridian small incision phacoemulsification cataract surgery on anterior,posterior and total corneal wavefront aberration.· METHODS： Steep meridian small incision phacoemulsification cataract surgery was performed in age-related cataract patients which were divided into three groups according to the incision site： 12 o＇clock, 9o＇clock and between 9 and 12 o＇clock（BENT） incision groups. The preoperative and 3-month postoperative root mean square（RMS） values of anterior, posterior and total corneal wavefront aberration including coma,spherical aberration, and total higher-order aberrations（HOAs）, were measured by Pentacam scheimpflug imaging. The mean preoperative and postoperative corneal wavefront aberrations were documented.·RESULTS： Total corneal aberration and total lower-order aberrations decreased significantly in three groups after operation. RMS value of total HOAs decreased significantly postoperatively in the 12 o＇clock incision group（P 〈0.001）. Corneal spherical aberration was statistically significantly lower after steep meridian small incision phacoemulsification cataract surgery in BENT incision group（P 〈0.05） and Pearson correlation analysisindicated that spherical aberration changes had no significant relationship with total astigmatism changes in all three corneal incision location.·CONCLUSION： Corneal incision of phacoemulsification cataract surgery can affect corneal wavefront aberration.The 12 o＇clock corneal incision eliminated more HOAs and the spherical aberrations decreased in BENT incision group obviously when we selected steep meridian small incision. Cataract lens replacement using wavefront-corrected intraocular lens combined with optimized corneal incision site would improve ocular aberration results.

Analysis of Corneal Spherical Aberration in Patients before and after Phacoemulsification

Purpose:To investigate the distribution and changes in corneal four-order spherical aberration Z40 in patients with age-related cataract before and after phacoemulsification,and to direct the application of aspherical intraocular lens (IOL)in PHACO combined with IOL implantation.Methods:A total of 155 eyes in 93 patients with age-related cataract were included.All patients received a comprehensive ophthalmologic examination.Corneal Z40 at a pupil diameter of 6 mm was measured by using a Scheimpflug photography system (Pentacam) preoperatively and 3 months postoperatively.Results:The mean corneal Z40 before and after the PHACO at a diameter of 6 mm was(0.294 ±0.138)μm and(0.271 ± 0.130)μm,respectively,with statistical significance(P<0.05, t =4.384).There was no significant difference between male (n=45, 76 eyes) and female patients (n=48,79 eyes) regard- ing corneal Z40 (t=-0.418,P=0.676).The corneal Z40 for patients (35 eyes) aged from 50 to 59 years was (0.238±0.104) μm preoperatively;(0.308 ±0.104)μm for 60 to 69 years; (0.332±0.151)μm for 70 to 79 years; and (0.307±0.164) μm for 80 to 89 years.A significant difference in Z40 was observed among different age groups.A linear positive correlation was noted between corneal Z40 and ages (r=0.203,P<0.003). Conclusion:The corneal Z40 varied significantly among cataract patients. Patients' corneal Z40 , which should be considered when choosing aspherical IOL, increases slightly with age.Thus,customized aspheric IOLs are needed.

Effect of incision types for Artisan phakic intraocular lens implantation on ocular higher order aberrations

AIM： To evaluate the effect of incision types for Artisan phakic intraocular lens （PIOL） implantation on ocular higher-order aberrations （HOAs）.METHODS： A retrospective review was conducted of the patients who had undergone Artisan PIOL implantation for the correction of myopia and followed up for at least 6mo. Patients are classified into 2 groups considering the incision type： cornea group with patients undergone clear corneal incision; sclera group with patients undergone sclera tunnel incision. All patients with postoperative astigmatism of under 1 diopter （D） were included to minimize the effect of residual astigmatism on postoperative HOAs. Visual acuity, special equivalents, astigmatism, predictability （±1 D from target refraction）, HOAs （coma, trefoil, spherical aberration）, and corneal endothelial counts were analyzed preoperatively and 6mo postoperatively.RESULTS： At the postoperative 6mo, all patients of both groups achieved uncorrected visual acuity of 16/20 or better, and significantly decreased the spherical equivalents compared with preoperative values. The predictability of refractive correction was 96% in the former, and 94% in the latter. Unlike the sclera group, preoperative astigmatism decreased significantly in cornea group at postoperative 6mo. The HOAs increased significantly at postoperative 6mo compared to the preoperative values in both groups, and the root mean square （RMS） total and trefoil wavefront aberration of cornea group were significantly higher than those of sclera group.CONCLUSION： Although corneal incision significantly reduces preexisting astigmatism, the postoperative 6mo of total RMS and trefoil aberration change may deteriorate the visual quality after Artisan PIOL implantation.

Symmetrical femtosecond laser arc incision in correcting corneal astigmatism in cataract patients

AIM:To evaluate the effect of symmetrical arc incision correcting corneal astigmatism in femtosecond laserassisted phacoemulsification(FLACS).METHODS:This study enrolled patients with cataract combined with regular corneal astigmatism of>0.75 D,who underwent FLACS.Symmetrical arc incision was set at 8 mm diameter and 85%depth.The follow-up time was 3-24mo(4.92±3.49mo).Pentacam recorded the corneal astigmatism and higher-order aberration at pre-operation and post-operation.The changes in corneal astigmatism were analyzed by Alpins method.The correlation of astigmatism type,age,corneal horizontal diameter,corneal thickness,arc incision length,and correction index(CI)was analyzed,and the residual corneal astigmatism was compared with the residual whole eye astigmatism.RESULTS:Totally 79 patients(102 eyes)were enrolled,10 patients had corneal epithelial injury,1 patient occurred corneal epithelial hyperplasia.The corneal astigmatism was 1.23±0.38 D pre-operation,and decreased to 0.76±0.39 D post-operation(t=10.146,P=0.000).Corneal high-order aberration was 0.17±0.08μm pre-operation and 0.24±0.11μm post-operation(t=-5.186,P=0.000).The residual corneal astigmatism and residual whole eye astigmatism were no significant difference(t=-0.347,P=0.729).Using Alpin’s method,the following were determined:target-induced astigmatism(TIA)=1.23±0.38 D,surgeryinduced astigmatism(SIA)=0.77±0.45 D,difference vector(DV)=0.77±0.39 D,and CI=0.54±0.28.Age,astigmatism size,corneal horizontal diameter,corneal thickness,and arc incision length were not correlated with CI.The CI for against the rule astigmatism(ATR)was better than that for with the rule astigmatism(WTR;P=0.001).CONCLUSION:Femtosecond laser-assisted astigmatic keratotomy has better CI of ATR,but increase higher-order corneal aberration.CI is not ideal,it’s not a perfect choice if we pursue ideal correction effect.

EFFECT OF SHORT-TERM SOFT CONTACT LENS WEAR ON HUMAN OCULAR ABERRATIONS

Objective To evaluate the effect of short-term soft contact lens （SCLs） wearing on human ocular aberrations （ HOA ）. Methods This prospective study included 50 eyes of 50 young volunteers wearing SCLs for 1 month. The ocular aberrations were measured by Allegretto Wavefront Analyzer. The root-mean-square （RMS） values of the general （RMSG） , higher-order （RMSH） , first to sixth order （ RMS1 to RMS6） and aberration coefficients were analyzed. Results There were no significant differences in the mean values of RMSG, RMSH, RMS1 to RMS6 （ P 〉 0. 05 ） and changes of absolute values of aberration coefficients between baseline and various visits after SCLs discontinuation. However, at d I after the discontinuation of SCLs, changes in coefficient values of the third-order aberrations （ C6 to C9 ） were slightly higher than others, and C7 was the highest. The increase factors of RMS values were higher at 1 week and lower at the 2 week visit after SCLs discontinuation. The uniformity of dominating type in HOA and the corneal topography form was both about 60% after discontinuation of SCLs. The corneal thickness increased after SCLs wear and gradually decreased to baseline until 1 month discontinuation of SCLs. Conclusion The effect of short-term SCLs wear on human ocular aberrations is slight but profound. A month or more wait should be allowed before the short-term SCLs wearers are scheduled for wavefronted-guided LASIK.

波前像差引导的LASIK与SMILE手术对屈光不正患者视觉质量及泪膜稳定的影响

目的 探究波前像差引导的准分子激光原位角膜磨镶术(WF-LASIK)与飞秒激光小切口角膜基质透镜取出术(SMILE)手术对屈光不正患者视觉质量及泪膜稳定的影响。方法 选取2020年1月-2023年1月我院诊治的屈光不正患者60例(120只眼)作为研究对象。根据手术方式不同分为WF-LASIK组(30例,60只眼)与SMILE组(30例,60只眼),比较2组裸眼视力、屈光度、视觉质量、泪膜稳定及并发症。结果 经重复测量方差分析:两组裸眼视力、球镜、柱镜、等效球镜的时间效应有统计学意义(P<0.05),且WF-LASIK组术后1、3mo裸眼视力高于SMILE组(P<0.05);两组球差、水平彗差、垂直彗差、总高阶像差、泪膜破裂时间、泪液分泌试验的时间效应、组间效应及交互效应均有统计学意义(P<0.05),且WF-LASIK组术后1、3mo球差大于SMILE组(P<0.05),水平彗差、垂直彗差、泪膜破裂时间、泪液分泌试验低于SMILE组(P<0.05)。两组并发症总发生率比较无统计学意义(P>0.05)。结论 屈光不正患者通过WF-LASIK与SMILE手术均能获得良好视力效果,其中WF-LASIK手术在视觉质量方面具有较明显优势,SMILE手术在泪膜稳定性方面具有明显优势。

Changes in higher-order aberrations after central corneal regularization-a comparative two-year analysis of a semi-automated topography-guided photorefractive keratectomy combined with corneal cross-linking

Background:The optical quality in progressive keratoconus deteriorates due to ectasia and distortion of the corneal shape and optics.While corneal cross-linking(CXL)aims at stopping disease progression,"CXL-Plus"combines CXL with excimer laser ablation to improve visual function.Central corneal regularization(CCR)represents a therapeutic excimer laser modality specifically designed to smoothen the ectatic corneal shape and to reduce higher-order aberrations(HOA).We set out to compare CXL-Plus,consisting of CXL combined with CCR,with CXL by itself for patients with progressive keratoconus.Methods:Retrospective 2-year matched group analysis of patients who either underwent CXL-Plus{n=28)or CXL as a sole procedure(n=28)for progressive keratoconus.Main outcome parameters were HOA,visual function and tomographic results 12 and 24 months postoperatively.Results:After 12 months,the total HOA root mean square wavefront error was reduced from 0.79±0.30 to 0.40±0.19 pm(CXL-Plus;P<0.0001)and changed from 0.71±0.28 to 0.73±0.36 pm(CXL;P=0.814).Uncorrected distance visual acuity improved from 0.70±0.35 to 0.36±0.29 logMAR(CXL-Plus;P=0.0002)and from 0.65±0.39 to 0.46±0.37 logMAR(CXL;P=0.067),translating to gains of three or more lines in 50%(CXL-Plus)and 36%(CXL)of patients.The steepest keratometry value(Kmax)regressed by 5.84 D(CXL-Plus;P<0.0001)and 0.66 D(CXL;P=0752).For none of the investigated parameters a statistically significant change could be shown between 12 and 24 months.Conclusions:CXL-Plus in the form of a CCR reduces HOA and Kmax more effectively than CXL as a sole procedure.

近视患者角膜生物力学参数与像差的相关性分析

目的探讨近视患者角膜生物力学参数与全眼像差、角膜前表面像差的相关性。方法选取95例(190眼)近视患者作为研究对象,测量全眼像差、角膜前表面像差,记录总像差均方根(RMS)、总高阶像差均方根(RMSh),测量角膜生物力学参数[中央角膜厚度(CCT)、眼内压(IOP)、校正Goldman眼压(IOPg)、角膜补偿眼压(IOPcc)、角膜黏滞阻力(CH)、角膜阻力因子(CRF)]。比较不同近视程度患者的角膜生物力学参数和总RMS、总RMSh,采用Pearson相关分析法分析角膜生物力学参数与全眼、角膜前表面高阶像差(彗差、球差)的相关性。结果95例患者左眼、右眼的角膜前表面像差(总RMS、总RMSh)均大于全眼像差,差异有统计学意义(P<0.05);高度近视患者全眼、角膜前表面的总RMS均高于中度、低度近视患者,且中度近视患者高于低度近视患者,差异有统计学意义(P<0.05)。相关性分析结果显示,IOP与低度、中度近视患者的全眼和角膜前表面球差均呈强正相关(P<0.01),与高度近视患者的全眼球差呈强正相关(P<0.01);IOPg与低度、中度、高度近视患者的全眼球差均呈强正相关(P<0.01),与中度近视患者的角膜前表面球差呈强正相关(P<0.01);IOPcc与低度、中度近视患者的全眼球差呈正相关(P<0.05);CRF、CH均分别与低度、中度近视患者的全眼和角膜前表面球差呈正相关(P<0.05),与高度近视患者的全眼球差呈正相关(P<0.05)。结论近视患者的全眼像差通常小于角膜前表面像差,IOP、IOPg、IOPcc均与全眼球差存在相关性,且低度近视患者角膜生物力学参数与高阶像差的相关性强于中度、高度近视患者。