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.

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.

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.

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.

Comparison of higher-order aberrations and contrast sensitivity between Tecnis Z9001 and CeeOn 911A intraocular lenses:a prospective randomized study

Background The advent of wavefront technology in the past five years has provided some insight into the optical outcomes of cataract surgery. The Tecnis Z9001 intraocular lens （Tecnis IOL, AMO） with a modified prolate anterior surface was claimed to reduce or even eliminate ocular spherical aberration to improve the visual quality. The purpose of this study was to determine whether Tecnis IOLs can improve the quality of vision as evaluated by measuring visual acuity, wavefront aberration, and contrast sensitivity. Methods In an intraindividual prospective study, 20 patients with bilateral cataract were randomly assigned to receive a modified prolate anterior surface IOL （Tecnis Z9001, AMO） in one eye and a biconvex spherical surface IOL （CeeOn 911A, AMO） in the other. After 3 months, the following were investigated： best corrected visual acuity, pupil diameter, photopic and mesopic contrast sensitivity, and wavefront aberration of the whole eye （ocular）, cornea, and internal plane. Results The differences in the best corrected visual acuity and pupil diameter between the two groups were not statistically significant. Negative 4th-order spherical aberration （Z4^0） was found in the Tecnis group, whereas positive Z4^0 found in the CeeOn group for the internal and ocular plane. Statistically significant differences were found at the ocular higher-aberrations between the two IOLs. Contrast sensitivity testing showed significantly better results in the Tecnis group at visual angles higher than 1.0 degree under photopic conditions and at visual angles higher than 1.6 degree under mesopic conditions both without glare and with glare in comparison with the CeeOn group. Conclusions The Tecnis Z9001 IOL with a modified prolate anterior surface produces negative spherical aberration and consequently reduces the higher-order aberrations in pseudophakic eyes. This leads to enhanced contrast sensitivity and improved functional vision compared to conventional spherical IOLs.

Laboratory evaluation of higher-order aberrations and light scattering in explanted opacified intraocular lenses

Background:Intraocular lens(IOL)calcification is a serious condition that can only be treated by removing the clouded lens.Since explantation bears the risk of complications,it is often deferred until the patient finds the symptoms intolerable.Usually,as the IOL opacifies,visual acuity is minimally affected early on.In this study,we assessed the impact of IOL opacification on optical quality.Methods:We analyzed ten opacified explanted IOLs(Oculentis GmbH).Wavefront aberrations were obtained with a SHSOphthalmic device(Optocraft GmbH),which features a Hartmann-Shack sensor.The root mean square(RMS)of higher-order aberrations(HOAs)was compared.The effect of calcification on image quality was assessed through the Strehl ratio(SR).We detected light scattering with a C-Quant(Oculus GmbH)and expressed it as a straylight parameter.Results:At 2 mm,3mm and 4 mm,the mean RMS(±standard deviation)was 0.033μm(±0.026μm),0.044μm(±0.027),and 0.087μm(±0.049),respectively.The mean SR value was 0.81±0.15 at 3 mm,with four IOLs showing a nearly diffraction-limited performance,but in two explants,opacification precluded reliable measurements.Increased straylight was found in all opacified IOLs with a mean value of 150.2±56.3 deg^(2)/sr at 3 mm.Conclusions:We demonstrated that IOL opacification induces HOAs.However,the RMS remained low,which resulted only in a slight reduction of the SR-derived optical quality.On the other hand,we found a severe straylight elevation in the opacified lenses,which may result in dysphotopsia,such as glare,and subjective complaints,despite good visual acuity.

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.

Orthokeratology with increased compression factor in adolescent myopia control:a 2-year prospective randomized clinical trial

AIM:To explore the long-term efficacy,safety,and optical mechanism of orthokeratology with increased compression factor in adolescent myopia control.METHODS:A prospective,double-masked,and randomized clinical trial was performed from May 2016 to June 2020.Subjects aged between 8 and 16y,with myopia(-5.00 to-1.00 D),low astigmatism(≥-1.50 D)and anisometropia(≤1.00 D),were stratified into low(-2.75 to-1.00 D)and moderate(-5.00 to-3.00 D)myopia groups.Then they were randomly assigned to wear either increased compression factor(ICF;1.75 D)orthokeratology or conventional compression factor(CCF;0.75 D)orthokeratology.The data were recorded including axial length(AL),spherical equivalent(SE),best corrected visual acuity(BCVA),near visual acuity(NVA),corneal staining(using Efron grading scales),corneal hysteresis(CH),corneal resistance factor(CRF),higher-order aberrations(HOAs,expressed as root mean square,RMS_(h)),and subfoveal choroidal thickness(SFCh T)in the 2-year followup period.Pearson's correlation coefficient was conducted to analyze the association between the changes in AL and RMS_(h),SFCh T.RESULTS:At the 2-year visit,there were no statistical differences in all the parameters between the ICF group and the CCF group in low myopia subjects(P>0.05).For the moderate myopia subjects,the ICF group had shorter AL elongation(0.23±0.08 vs 0.30±0.11 mm,P=0.015),higher RMS_(h)(1.94±0.50 vs 1.65±0.51μm,P=0.041),and higher SFCh T(279.04±35.72 vs 254.08±29.60μm,P=0.008)than those in CCF group.The change in AL was negatively correlated with RMS_(h)(r=-0.687,P<0.001)and SFCh T(r=-0.464,P=0.013).CONCLUSION:ICF orthokeratology can control the progression of moderate myopia more effectively,which might be related to greater RMS_(h) and SFCh T.

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.

Comparative study of objective visual quality between FS-LASIK and SMART in myopia

AIM:To compare the changes in the objective visual quality of patients with low and moderate myopia postoperatively after transepithelial photorefractive keratectomy using the smart pulse technology(SMART)and femtosecond laser in situ keratomileusis(FS-LASIK).METHODS:Corneal higher-order aberrations(HOAs),horizontal coma,vertical coma and spherical aberration were measured using Pentacam,and cutoff for modulation transfer function(MTF cutoff),objective scatter index(OSI)and Strehl ratio(SR)was measured using an optical quality analysis system(OQAS-II),before and after operation at 1,3,and 6 mo,and data were analyzed by repeated measurement two-way analysis of variance.RESULTS:The difference in uncorrected distance visual acuity between SMART and FS-LASIK was statistically significant only 1 wk postoperatively.Approximately 86.36%and 80.69%of patients with spherical equivalent(SE)in±0.50 D were observed in the SMART and FS-LASIK groups,respectively.No significant difference was observed in SE between the two groups(P=0.509).The HOAs increased postoperatively compared with those before surgery in both groups(P<0.05).No significant difference in HOA,corneal horizontal coma,spherical aberration,ΔHOA,Δhorizontal coma,andΔspherical aberration were observed between the two group(P>0.05).Corneal vertical coma andΔcorneal vertical coma in the FS-LASIK group were higher than those in the SMART group(P<0.05).The OSI of both groups at 1 mo after surgery was higher than that before surgery(P<0.05).At 3 and 6 mo postoperatively,the OSI in the FS-LASIK group was slightly higher than that in the SMART group(P=0.040 and 0.047,respectively).At 6 mo after surgery,the MTF cutoff was statistically significant different between the two groups(P=0.026).No significant difference in SR between the FS-LASIK and SMART groups was observed at 1,3,and 6 mo postoperatively(P>0.05).CONCLUSION:The HOAs increase and visual quality is delayed in both groups postoperatively,and the long-term objective visual quality after SMART is slightly better than that after FS-LASIK.

Comparison of the femtosecond Laser and mechanical microkeratome for flap cutting in LASIK

· AIM: To compare refractive results, higher-order aberrations(HOAs), contrast sensitivity and dry eye after laser in situ keratomileusis(LASIK) performed with a femtosecond laser versus a mechanical microkeratome for myopia and astigmatism.·METHODS: In this prospective, non-randomized study,120 eyes with myopia received a LASIK surgery with the Visu Max femtosecond laser for flap cutting, and 120 eyes received a conventional LASIK surgery with a mechanical microkeratome. Flap thickness, visual acuity, manifest refraction, contrast sensitivity function(CSF) curves,HOAs and dry-eye were measured at 1wk; 1, 3, 6mo after surgery.·RESULTS: At 6mo postoperatively, the mean central flap thickness in femtosecond laser procedure was113.05 ±5.89 μm(attempted thickness 110 μm), and148.36 ±21.24 μm(attempted thickness 140 μm) in mechanical microkeratome procedure. An uncorrected distance visual acuity(UDVA) of 4.9 or better was obtained in more than 98% of eyes treated by both methods, a gain in log MAR lines of corrected distance visual acuity(CDVA) occurred in more than 70% of eyes treated by both methods, and no eye lost ≥1 lines of CDVA in both groups. The difference of the mean UDVA and CDVA between two groups at any time post-surgery were not statistically significant(P 】0.05). The postoperative changes of spherical equivalent occurred markedly during the first month in both groups. The total root mean square values of HOAs and spherical aberrations in the femtosecond treated eyes were markedly less than those in the microkeratome treated eyes during 6mo visit after surgery(P 【0.01). The CSF values of the femtosecond treated eyes were also higherthan those of the microkeratome treated eyes at all space frequency(P 【0.01). The mean ocular surface disease index scores in both groups were increased at 1wk, and recovered to preoperative level at 1mo after surgery. The mean tear breakup time(TBUT) of the femtosecond treated eyes were markedly longer than those of the microkeratome treated eyes at postoperative 1, 3mo(P 【0.01).·CONCLUSION: Both the femtosecond laser and the mechanical microkeratome for LASIK flap cutting are safe and effective to correct myopia, with no statistically significant difference in the UDVA, CDVA during 6mo follow-up. Refractive results remained stable after 1mo post-operation for both groups. The femtosecond laser may have advantages over the microkeratome in the flap thickness predictability, fewer induced HOAs, better CSF,and longer TBUT.

准分子激光人眼像差矫正系统的研究

准分子激光人眼像差矫正系统旨在实现个体化切削,它不仅能进行正常的角膜屈光矫正,减少高阶像差,而且可以有效的克服传统准分子激光手术引起的球差、彗差以及其他高阶像差而导致的夜间视力下降、光晕、眩光及偏心切削等并发症。准分子激光人眼像差矫正系统包括主观式像差仪进行波前像差的测量、准分子激光系统进行像差矫正两大部分。描述了人眼波前像差的概念、成因以及表示的方法和测量技术;研究了准分子激光人眼像差矫正系统的原理;阐述了准分子激光飞点扫描、主动眼球跟踪、激光的恒能和闭环控制、激光脉冲光斑直径和均匀控制等关键技术。研究成果可直接用于准分子激光人眼像差矫正系统,目前正在进行临床实验,取得了良好效果。

Factors affecting single-step transepithelial photorefractive keratectomy outcome in the treatment of mild,moderate,and high myopia:a cohort study

AIM:To investigate the effect of preoperative factors on visual acuity,higher-order aberrations(HOAs),and index of success for spherical change(S.IOS)after transepithelial photorefractive keratectomy(t-PRK)for treating different grades of myopia.METHODS:This was a retrospective one-armed cohort study where patients with high,moderate,or mild myopia treated with single-step t-PRK using Amaris 500 Hz excimer laser were evaluated for visual acuity,refractive status,corneal topography,HOAs,S.IOS,and mean efficiency and safety index before and 6 mo after surgery.RESULTS:A total of 154 eyes of 77 patients with mild(n=59),moderate(n=83),and high(n=12)myopia were reviewed.The efficiency and safety indices for vision recovery by single-step t-PRK were 98%and 100%,respectively.The achieved spherical equivalent(SE)was within 1 diopter(D)in 151(98%)eyes.The median of the S.IOS was 1.18[interquartile range(IQR)1.0,1.4].The change in S.IOS was significantly correlated with age(P=0.007),6.5 mm ablation zone(Mann-Whitney U test,P<0.01),and mild and moderate grade of myopia(Kruskal–Wallis test,P<0.001).Trefoil aberration,spherical aberration,and aberration coefficient types of HOA increased significantly(Wilcoxon test,P<0.001)6 mo post-surgery.There was a significant correlation between spherical aberration and aberration coefficient HOAs by myopia grades(P<0.05).CONCLUSION:Single-step t-PRK has promising short-term outcomes for refractive corrections and vision improvement to treat all three grades of myopia.

Evaluation of Clinical Outcomes after LASIK for the Correction of Myopia Using the Advanced Customvue Excimer Laser Platform

-Purpose: To evaluate early visual, refractive and aberrometric outcomes after wave front-guided LASIK for the correction of low to moderate myopia and myopic astigmat is musing the excimer laser platform Advanced Custom Vue. Methods: A prospective, non-comparative study in 100 myopic eyes of 50 patients evaluating LASIK results over a period of 3 months. Main outcome variables included visual acuity, refraction, total higher-order aberrations (HOAs), spherical aberration (SA) and coma-like aberration. The surgery was performed using the VISX STAR S4 (Johnson and Johnson Vision) excimer laser and a wave front-guided ablation designed according to the iDesign aberrometer data (Johnson and Johnson Vision). Results: Mean preoperative sphere decreased from -4.07 ± 1.78 D to 0.32 ± 0.30 D at 3 months after surgery. Mean preoperative cylinder was reduced from -1.09 ± 0.88 D to -0.26 ± 0.28 D after the complete follow-up. Postoperative uncorrected distance visual acuity (UDVA) was 0.00 logMAR (20/20) or better in 100% of eyes, and 65.3% of eyes reached an UDVA of -0.20 logMAR (20/12.5) or better (p < 0.05). For a 6-mm pupil, the root mean square (RMS) for total ocular HOAs increased with surgery by 0.03 μm (p = 0.050), whereas the coma-like RMS increased by 0.05 μm (p < 0.001). The change in spherical aberration was +0.08 μm (p < 0.001). Conclusion: Wavefront-guided LASIK using the new generation excimer laser platform Advanced Custom Vue is safe and effective for treating myopia and myopic astigmatism, minimizing the postoperative level of HOAs.

Improving iconic memory through contrast detection training with HOA-corrected vision

Iconic memory and short-term memory are not only crucial for perception and cognition,but also of great importance to mental health.Here,we first showed that both types of memory could be improved by improving limiting processes in visual processing through perceptual learning.Normal adults were trained in a contrast detection task for ten days,with their higher-order aberrations(HOA)corrected in real-time.We found that the training improved not only their contrast sensitivity function(CSF),but also their iconic memory and baseline information maintenance for short-term memory,and the relationship between memory and CSF improvements could be well-predicted by an observer model.These results suggest that training the limiting component of a cognitive task with visual perceptual learning could improve visual cognition.They may also provide an empirical foundation for new therapies to treat people with poor sensory memory.

人工泪液对干眼症患者眼像差及角膜地形图的影响

目的观察干眼症患者滴用人工泪液后眼像差和角膜地形图的改变。方法对18例（30只眼）干眼症患者滴用人工泪液前、用药后即刻和用药10min后进行眼像差和角膜地形图的测量，分析指标为像差均方根值（RMSg），垂直慧差（C7），水平慧差（C8），球差（C12），角膜表面规则性指数（SRI）和角膜表面不对称指数（SAI），采用重复测量方差分析方法对数据进行分析，以P〈0．05认为差异具有统计学意义。结果用药后即刻测得的RMSg、C7、C8、C12、SRI和SAI值较用药前明显下降（P≤0．01），指标在用药10min时仍然维持稳定。结论人工泪液可以改变干眼症患者角膜表面的不规则性参数，从而通过改变RMSg、C7、C8、C12、SRI和SAI值来改善其光学视觉质量。

光学治疗区偏心对角膜塑形镜配戴后角膜高阶像差及眼轴发育的影响

目的：研究角膜塑形镜戴镜后光学治疗区偏心状态对近视儿童角膜高阶像差及眼轴发育的影响。方法：前瞻性临床研究。选取8．14岁接受角膜塑形术的近视儿童20例（40眼），测量戴镜前，戴镜后1周、6个月及1．5年角膜地形图、角膜高阶像差和眼轴。比较角膜塑形镜戴镜后光学治疗区不同偏心状态各时间点角膜高阶像差的变化，分析戴镜后光学治疗区偏心状态与眼轴变化值的相关性。采用重复测量方差分析、Pearson相关性分析和配对t检验进行数据分析。结果：角膜塑形镜戴镜后光学治疗区中心主要呈颞下方向的中度偏心（0．5-1．0mm），各时间点偏心距离差异无统计学意义。角膜塑形镜戴镜后角膜总高阶像差、总三阶像差、总彗差均较术前显著增加（F=4．491、5．297、2．927，均P〈0．05）。戴镜后1．5年，偏心距离与角膜各像差变化值无相关性。戴镜后1．5年，眼轴较戴镜前显著延长（t=-0．725，P〈0．05），但眼轴变化值与偏心距离不相关。结论：角膜塑形镜戴镜后光学中心偏心距离在戴镜后1周达到稳定并可引起戴镜后早期角膜高阶像差增加，但在戴镜1．5年后光学治疗区中心偏心程度对眼轴发育无影响。