A Simple Analytic Approximation for the Refracted Field at Gaussian Beam Incidence upon a Boundary of Absorbing Medium

An approximate analytic model is presented to describe spatial structure of refracted electromagnetic field arising at oblique incidence of a Gaussian beam on a plane boundary of an absorbing homogeneous medium. The analytic solution is obtained by asymptotic approximation of a Fourier field integral under the condition of great beam width in comparison with a wavelength (the geometrical-optics approximation). This model can be used also for approximate simulation of refracted field in the cases of beam incidence near the critical angle on transparent or absorbing (amplifying) refracting medium, if one artificially introduces the additional absorption (amplification), whose value is proportional to the ratio of the wavelength and the effective beam width. It is shown that the analytic model reflects the general features of refracted field at total internal reflection.

Propagation characteristics of converted refracted wave and its application in static correction of converted wave

Three-component seismic exploration through P-wave source and three-component geophone is an effective technique used in complicated reservoir exploration. In three-component seismic exploration data processing,one of the difficulties is static correction of converted wave. This paper analyzes propagation characteristics of non-converted and converted refracted waves,and discovers a favor-able condition for the formation of converted refracted wave,i.e. the velocity of overlaying medium S wave is much lower than that of underlying medium S wave. In addition,the paper proposes the static correction method of converted wave based on PPS converted refracted wave,and processes the real three-component seismic data with better results of static correction of converted wave.

One-year results for myopia control of orthokeratology with different back optic zone diameters: a randomized trial using a novel multispectral-based topographer

AIM:To present the 1-year results of a prospective cohort study investigating the efficacy,potential mechanism,and safety of orthokeratology(ortho-k)with different back optic zone diameters(BOZD)for myopia control in children.METHODS:This randomized clinical study was performed between Dec.2020 and Dec.2021.Participants were randomly assigned to three groups wearing ortho-k:5 mm BOZD(5-MM group),5.5 mm BOZD(5.5-MM group),and 6 mm BOZD(6-MM group).The 1-year data were recorded,including axial length,relative peripheral refraction(RPR,measured by multispectral refractive topography,MRT),and visual quality.The contrast sensitivity(CS)was evaluated by CSV-1000 instrument with spatial frequencies of 3,6,12,and 18 cycles/degree(c/d);the corneal higher-order aberrations(HOAs)were measured by iTrace aberration analyzer.The one-way ANOVA was performed to assess the differences between the three groups.The correlation between the change in AL and RPR was calculated by Pearson’s correlation coefficient.RESULTS:The 1-year results of 20,21,and 21 subjects in the 5-MM,5.5-MM,and 6-MM groups,respectively,were presented.There were no statistical differences in baseline age,sex,or ocular parameters between the three groups(all P>0.05).At the 1-year visit,the 5-MM group had lower axial elongation than the 6-MM group(0.07±0.09 vs 0.18±0.11 mm,P=0.001).The 5-MM group had more myopic total RPR(TRPR,P=0.014),with RPR in the 15°–30°(RPR 15–30,P=0.015),30°–45°(RPR 30–45,P=0.011),temporal(RPR-T,P=0.008),and nasal area(RPR-N,P<0.001)than the 6-MM group.RPR 15–30 in the 5.5-MM group was more myopic than that in the 6-MM group(P=0.002),and RPR-N in the 5-MM group was more myopic than that in the 5.5-MM group(P<0.001).There were positive correlations between the axial elongation and the change in TRPR(r=0.756,P<0.001),RPR 15–30(r=0.364,P=0.004),RPR 30–45(r=0.306,P=0.016),and RPR-N(r=0.253,P=0.047).The CS decreased at 3 c/d(P<0.001),and the corneal HOAs increased in the 5-MM group(P=0.030).CONCLUSION:Ortho-k with 5 mm BOZD can control myopia progression more effectively.The mechanism may be associated with greater myopic shifts in RPR.

A robust triaxial localization method of AE source using refraction path

Acoustic emission(AE)localization algorithms based on homogeneous media or single-velocity are less accurate when applied to the triaxial localization experiments.To the end,a robust triaxial localization method of AE source using refraction path is proposed.Firstly,the control equation of the refraction path is established according to the sensor coordinates and arrival times.Secondly,considering the influence of time-difference-of-arrival(TDOA)errors,the residual of the governing equation is calculated to estimate the equation weight.Thirdly,the refraction points in different directions are solved using Snell’s law and orthogonal constraints.Finally,the source coordinates are iteratively solved by weighted correction terms.The feasibility and accuracy of the proposed method are verified by pencil-lead breaking experiments.The simulation results show that the new method is almost unaffected by the refraction ratio,and always holds more stable and accurate positioning performance than the traditional method under different ratios and scales of TDOA outliers.

Prevalence of visual impairment and estimation of refractive errors among school children in Kakamega,Kenya

AIM:To investigate the prevalence of visual impairment(VI)and provide an estimation of uncorrected refractive errors in school-aged children,conducted by optometry students as a community service.METHODS:The study was cross-sectional.Totally 3343 participants were included in the study.The initial examination involved assessing the uncorrected distance visual acuity(UDVA)and visual acuity(VA)while using a+2.00 D lens.The inclusion criteria for a subsequent comprehensive cycloplegic eye examination,performed by an optometrist,were as follows:a UDVA<0.6 decimal(0.20 logMAR)and/or a VA with+2.00 D≥0.8 decimal(0.96 logMAR).RESULTS:The sample had a mean age of 10.92±2.13y(range 4 to 17y),and 51.3%of the children were female(n=1715).The majority of the children(89.7%)fell within the age range of 8 to 14y.Among the ethnic groups,the highest representation was from the Luhya group(60.6%)followed by Luo(20.4%).Mean logMAR UDVA choosing the best eye for each student was 0.29±0.17(range 1.70 to 0.22).Out of the total,246 participants(7.4%)had a full eye examination.The estimated prevalence of myopia(defined as spherical equivalent≤-0.5 D)was found to be 1.45%of the total sample.While around 0.18%of the total sample had hyperopia value exceeding+1.75 D.Refractive astigmatism(cil<-0.75 D)was found in 0.21%(7/3343)of the children.The VI prevalence was 1.26%of the total sample.Among our cases of VI,76.2%could be attributed to uncorrected refractive error.Amblyopia was detected in 0.66%(22/3343)of the screened children.There was no statistically significant correlation observed between age or gender and refractive values.CONCLUSION:The primary cause of VI is determined to be uncorrected refractive errors,with myopia being the most prevalent refractive error observed.These findings underscore the significance of early identification and correction of refractive errors in school-aged children as a means to alleviate the impact of VI.

Two different autorefractors for vision screening in children and adolescents

AIM:To compare the consistency of two autorefractors(Tianle RM-9000 and Topcon KR-800)for school-age myopia children,and to provide a basis for largescale data analysis and comparison.METHODS:The refractive error in 909 subjects(age 4–18y)were measured using both autorefractors without cycloplegia.The data were analyzed using Fourier decomposition and the correlation coefficients,intraclass correlation coefficients(ICC),and Bland-Altman limits of agreement(LoA)for each parameter were calculated.RESULTS:There was a strong correlation between the spherical equivalent(SE),sphere diopter(DS),and cylinder diopter(DC)readings of the Tianle RM-9000 and those of the Topcon KR-800,with correlation coefficient values of 0.98,0.98 and 0.83 and ICC values of 0.99,0.99 and 0.93,respectively.However,the correlation coefficients and ICC values of J0 and J45 were unreliable(R=-0.004,-0.034;both ICC<0.10).Bland-Altman analysis revealed that SE,DS,and DC measured by the Tianle RM-9000 were significantly biased toward myopia compared with the Topcon KR-800,and the mean differences were-0.072,-0.026,-0.091 D,respectively(all P<0.01).The minimum absolute value of the difference within the 95%LoA for SE,DS,and DC was 0.63 D,0.50 D,0.62 D,respectively;all these values were in the clinically acceptable range.For J0 and J45,the mean differences were close to zero(P=0.43,0.84);however,the 95%LoA were relatively wide(J0 SD:0.53;95%CI:-1.00,1.10;J45 SD:0.52;95%CI:-1.00,1.00).CONCLUSION:The two autorefractors are consistent with each other,as the differences in SE,DS,and DC were within the clinically acceptable range.Readers can compare the data measured by either device in different studies and use the two devices in the same study to generate a dataset that can be analyzed together.However,the J0 and J45 vectors are unreliable and should not be used to assess astigmatism.

Fabrication of UV-Curing Linalool-Polysiloxane Hybrid Films with High Refractive Index and Transparency

In this article,a series of high refractive indices(1.50-1.53)thiol phenyl polysiloxane(TPS)were synthesized via hydrolytic sol-gel reaction.The Fourier transform infrared spectra(FT-IR)and nuclear magnetic resonance spectra(NMR)results showed that TPS conformed to the predicted structures.Natural terpene linalool was exploited as photocrosslinker to fabricate UV-curing linalool-polysiloxane hybrid films(LPH)with TPS via photoinitiated thiol-ene reaction.LPH rapidly cured under UV irradiation at the intensity of 80 mW/cm^(2) in 30 s,exhibiting good UV-curing properties.The optical transmittance of LPH in the wavelength of 300-800 nm was over 90%,exhibiting good optical transparency.The water contact angle and water vapor permeability results showed that the introduction of phenyl groups enhance the hydrophobicity and water vapor barrier properties of LPH.The results indicated the potential of LPHs in the applications of optical functional coatings.

Retinoscopes:Past and present

BACKGROUND Retinoscopy is arguably the most important method in the eye clinic for diagnosing and managing refractive errors.Advantages of retinoscopy include its noninvasive nature,ability to assess patients of all ages,and usefulness in patients with limited cooperation or communication skills.AIM To discuss the history of retinoscopes and examine current literature on the subject.METHODS A search was conducted on the PubMed and with the reference citation analysis(https://www.referencecitationanalysis.com)database using the term"Retinoscopy,"with a range restricted to the last 10 years(2013-2023).The search string algorithm was:"Retinoscopy"(MeSH Terms)OR"Retinoscopy"(All Fields)OR"Retinoscopes"(All Fields)AND[(All Fields)AND 2013:2023(pdat)].RESULTS This systematic review included a total of 286 records.Publications reviewed iterations of the retinoscope into autorefractors,infrared photo retinoscope,television retinoscopy,and the Wifi enabled digital retinoscope.CONCLUSION The retinoscope has evolved significantly since its discovery,with a significant improvement in its diagnostic capabilities.While it has advantages such as non-invasiveness and broad applicability,limitations exist,and the need for skilled interpretation remains.With ongoing research,including the integration of artificial intelligence,retinoscopy is expected to continue advancing and playing a vital role in eye care.

Pattern of Eye Diseases among Tea Workers

Background: Bangladesh’s tea industry is essential to the country’s economic expansion. Since tea workers in Bangladesh are marginalized within our community, they have limited access to comprehensive eye care services. Productivity and well-being are cornerstones of comprehensive health care strategy. Ocular disorders are influenced by life expectancy, sociodemographic status, and the epidemiological transition. In this context, the state of ocular health and the many eye illnesses remain to be significantly addressed. Purpose: To evaluate the pattern of eye diseases among tea workers in a tea estate of Bangladesh. Methods: This cross-sectional observational study was carried out in Halda Valley Tea Estate, Nazirhat, Fatickchari, Chattogram, Bangladesh, under the supervision of the Department of Community Ophthalmology, BSMMU, following ethical clearance and approval by the IRB board of BSMMU. With informed written consent and approval from the authority of the tea estate, a total of 110 tea workers were recruited. Socio-demographic characteristics, ocular findings, and patterns of eye diseases were determined and recorded. Results: The mean age of the study participants was 39.60 ± 11.63 years. The maximum (58.1%) study participants were 31 - 50 years old, female (64.5%), illiterate (82.7%), and tribal (71.8%) indigenes. Eye diseases were found in 94.5% of workers. Presbyopia (28.2%), cataracts (27.3%), and refractive error (26.4%) were the most common. Tea workers with eye diseases were significantly older than those who did not have any eye diseases (40.20 ± 11.57 vs. 29.17 ± 7.31 years, p Conclusion: A significant number of tea workers had eye diseases, of which presbyopia, cataracts, and refractive error were the most common.

Enhanced Harris Hawks Optimization Integrated with Coot Bird Optimization for Solving Continuous Numerical Optimization Problems

Harris Hawks Optimization(HHO)is a novel meta-heuristic algorithm that imitates the predation characteristics of Harris Hawk and combines Lévy flight to solve complex multidimensional problems.Nevertheless,the basic HHO algorithm still has certain limitations,including the tendency to fall into the local optima and poor convergence accuracy.Coot Bird Optimization(CBO)is another new swarm-based optimization algorithm.CBO originates from the regular and irregular motion of a bird called Coot on the water’s surface.Although the framework of CBO is slightly complicated,it has outstanding exploration potential and excellent capability to avoid falling into local optimal solutions.This paper proposes a novel enhanced hybrid algorithm based on the basic HHO and CBO named Enhanced Harris Hawks Optimization Integrated with Coot Bird Optimization(EHHOCBO).EHHOCBO can provide higher-quality solutions for numerical optimization problems.It first embeds the leadership mechanism of CBO into the population initialization process of HHO.This way can take full advantage of the valuable solution information to provide a good foundation for the global search of the hybrid algorithm.Secondly,the Ensemble Mutation Strategy(EMS)is introduced to generate the mutant candidate positions for consideration,further improving the hybrid algorithm’s exploration trend and population diversity.To further reduce the likelihood of falling into the local optima and speed up the convergence,Refracted Opposition-Based Learning(ROBL)is adopted to update the current optimal solution in the swarm.Using 23 classical benchmark functions and the IEEE CEC2017 test suite,the performance of the proposed EHHOCBO is comprehensively evaluated and compared with eight other basic meta-heuristic algorithms and six improved variants.Experimental results show that EHHOCBO can achieve better solution accuracy,faster convergence speed,and a more robust ability to jump out of local optima than other advanced optimizers in most test cases.Finally,EHHOCBOis applied to address four engineering design problems.Our findings indicate that the proposed method also provides satisfactory performance regarding the convergence accuracy of the optimal global solution.

Multi-Strategy Boosted Spider Monkey Optimization Algorithm for Feature Selection

To solve the problem of slow convergence and easy to get into the local optimum of the spider monkey optimization algorithm,this paper presents a new algorithm based on multi-strategy(ISMO).First,the initial population is generated by a refracted opposition-based learning strategy to enhance diversity and ergodicity.Second,this paper introduces a non-linear adaptive dynamic weight factor to improve convergence efficiency.Then,using the crisscross strategy,using the horizontal crossover to enhance the global search and vertical crossover to keep the diversity of the population to avoid being trapped in the local optimum.At last,we adopt a Gauss-Cauchy mutation strategy to improve the stability of the algorithm by mutation of the optimal individuals.Therefore,the application of ISMO is validated by ten benchmark functions and feature selection.It is proved that the proposed method can resolve the problem of feature selection.

Prevalence of refractive errors in children of Puerto Rico

AIM:To determine the prevalence of refractive error in 5-to 17-year-old schoolchildren in Puerto Rico.METHODS:A quantitative descriptive study of 2867 children aged 5 to 17y from all seven educational regions of Puerto Rico was conducted from 2016–2019.Refractive error was determined via static and subjective refraction.Children with distance acuity≤20/40 or near visual acuity≤20/32 had a cycloplegic refraction.Data analysis included descriptive statistics,correlation coefficient,Kruskal-Wallis,Chi-square,and t test calculations.RESULTS:Twenty percent of the children had a spherical equivalent refractive error≤-0.50 D,3.2%had a spherical equivalent≥+2.00 D,and 10.4%had astigmatism≥1 D.There was a statistically(but non-clinically)significant myopic change in spherical equivalent refractive error with age(P<0.001).The prevalence of myopia increased with age(P<0.001)but not hyperopia(P=0.59)or astigmatism(P=0.51).Males had a significantly higher hyperopic spherical equivalent than females(P<0.001).Females had a higher prevalence of myopia(P<0.001)than males,but there was no difference in the hyperopia(P=0.74)or astigmatism prevalence(P=0.87).CONCLUSION:The prevalence of a spherical equivalent equal to or less than-0.50 D(myopia,20.7%)is one of the highest among similar-aged children worldwide.Further studies should explore the rate of myopia progression in children in Puerto Rico.Individual children must be monitored to examine the need for treatment of myopia progression.

Predictive methods for density and refractive index of naphthenic lubricating oils during solvent extraction process

Lubricating oils are usually produced by solvent extraction to separate aromatics in order to achieve the desired specifications and better quality products.Among the different properties of lubricating oils,density and refractive index are some of the most important properties which can both be used for petroleum fluid characterization.Predictions of density and refractive index for naphthenic oils during solvent extraction by DMSO obtained by the pseudo-component approach and the quadratic correlation were both examined.The pseudo-component approach is a method to predict density and refractive index from composition while the latter merely relates density to refractive index.Results indicated that the predictions yielded by the pseudo-component method were in good agreement with experimental data for naphthenic oils.And the use of a function of refractive index(FRI_(20))as a pseudo-component property remarkably improved n_(20)predictions for the naphthenic mixtures.However,the density and refractive index predictions obtained by the quadratic correlation exhibited significantly higher de-viations for naphthenic oils than those for paraffinic oils.Thus a new modified correlation of the same functional form was proposed for naphthenic oils.The modification significantly improved predictions for naphthenic oils,which presented similar accuracy as the pseudo-component approach.And the previous correlation was still used for paraffinic oils.Additionally,effect of temperature on density and refractive index of naphthenic oils was examined.Results showed that the modified quadratic correlation was accurate for describing the relationship between density and refractive index of naphthenic oils at 20-90℃.The temperature dependence of density and refractive index for the raffinates and the extracts could be accurately described by the thermal coefficients for saturates and aromatics,respectively.Regarding the refractive index variation of the extracts with temperature,the empirical equation was proved to be a better option compared with the method using the thermal coefficient for aromatics.

Postoperative efficacy,safety,predictability,and visual quality of implantable collamer lens implantation versus small incision lenticule extraction in myopic eyes:a Meta-analysis

AIM:To compare the postoperative efficacy,safety,predictability,and visual quality of implantable collamer lens(ICL)implantation versus small incision lenticule extraction(SMILE)in myopia eyes.METHODS:Pub Med,EMBASE,Web of Science,Cochrane Library and several Chinese databases were searched at May 2021 to select relevant studies in comparison of clinical outcomes between ICL implantation and SMILE for myopia.The primary outcomes were efficacy,safety,and predictability.And the secondary outcomes were postoperative higher-order ocular aberrations(HOAs),modulation transfer function cutoff frequency(MTF),objective scatter index(OSI),contrast sensitivity and a quality of vision(Qo V)questionnaire.RESULTS:A total of 1036 eyes from 10 studies,of which 503 eyes underwent ICL implantation and 533 eyes underwent SMILE,were enrolled in this Meta-analysis.Pooled results revealed that ICL group had a better safety index and post-corrected distance visual acuity(CDVA)(P=0.007,<0.00001,respectively),and a lower percentage of eyes with a postoperative CDVA lost 1 line(P=0.007)than the SMILE group.No significant differences were found in comparison of the other primary outcomes.In the longterm follow-up(>6mo),ICL group had a lower total HOA,coma,and spherical aberration than SMILE group(P=0.003,<0.00001,0.04).Yet higher trefoil was found in ICL group at 6mo after surgery(P=0.003).Additionally,ICL group also had a higher MTF value(P=0.02),and a higher contrast sensitivity score for spatial frequencies of 1.5,6,and 12 cpds(P=0.02,0.005,0.02,respectively).And it also had a lower score of bothersome in Qo V questionnaire than SMILE group(P=0.003).CONCLUSION:ICL implantation and SMILE have similar and comparable outcomes in term of the efficacy and predictability for correcting high myopia.However,ICL group is relatively safer and also has better visual quality in comparison of SMILE group.

Long-term observation on safety and visual quality of implantable collamer lens V4c implantation for myopia correction:a 5-year follow-up

AIM:To elucidate the safety and visual quality of implantable collamer lens with central hole(ICL V4c)implantation for correcting moderate and high myopia for at least 5y.METHODS:This retrospective study was conducted on 58 patients(114 eyes)who were followed up for at least 5y after ICL V4c implantation.The observation was done before and on 1d,1mo,1 and 5y or more after the surgical procedure.The visual acuity,subjective refraction,intraocular pressure,vault,axial length,central hole position,pupil diameter,visual quality,and adverse events were analyzed.The visual quality includes aberration,the modulation transfer function cutoff frequency(MTF cutoff),objective scattering index(OSI),Stroller's ratio(SR),and visual quality questionnaire.RESULTS:The average follow-up period was 69.25±3.80mo(range 60–82mo)and the preoperative spherical equivalent(SE)was-8.66±1.97 D.At 5y after operation,the safety index was 1.01±0.02 and the efficacy index was 0.99±0.42 and SE was-0.65±0.63 D.The 59.6%of the eyes achieved an uncorrected distance visual acuity of 20/20,76.3%of the eyes had SE within±1.0 D at the last visit.The axial length increased by 0.29±0.71 mm 5y after the surgery(t=-3.843,P<0.001).The mean vault at the last follow-up was 510.59±245.61μm.The central hole was on the temporal side in 80 eyes(84.2%).The visual quality questionnaire showed that 98.2%patients were satisfied with the surgical procedure.Adverse events occurred in 4 eyes(3.5%),including the posttraumatic toric ICL rotation(2 eyes),iris incarceration(1 eye),and posttraumatic ICL displacement(1 eye)at the last follow-up.CONCLUSION:Long-term ICL V4c implantation is safe,effective,and stable for correcting moderate and to high myopia,and the visual quality with patients is excellent and satisfactory,but the progression of axial length still needs attention after surgery.

Observation of peripheral refraction in myopic anisometropia in young adults

AIM:To investigate the differences in retinal refraction difference values(RDVs)of adult patients with myopic anisometropia compared with those without myopic anisometropia,and to investigate the relationship between ocular biometric measurements and relative peripheral refraction.METHODS:This clinical observation study included 130 patients with myopia(-0.25 to-10.00 D)between October 2022 and January 2023 aged between 18 and 40y.The patients were divided into anisometropia(n=63;difference in binocular anisometropia≥1.00 D)and non-anisometropia(n=67;difference in binocular anisometropia<1.00 D)groups accordingly.Ocular biometric measurements were performed by optical biometrics and corneal topography to assess the steep keratometry(Ks),flap keratometry(Kf),axial length(AL),corneal astigmatism(CYL;Ks-Kf),surface regularity index(SRI),surface asymmetry index(SAI),and central corneal thickness(CCT).The RDV was measured at five retinal areas from the fovea to 53 degrees(RDV-0-10,RDV-10-20,RDV-20-30,RDV-30-40,and RDV-40-53),the total RDV(TRDV)of 53 degrees,and four regions,including RDV-superior,RDV-inferior,RDV-temporal,and RDV-nasal.An analysis of Spearman correlation was carried out to examine the correlation between RDV and the spherical equivalent(SE)and ocular biological parameters.RESULTS:Within RDV-20-53,both groups showed relative hyperopic defocus,and the increase in RDV corresponds to the increase in eccentricity.In the myopic anisometropia group,the TRDV,RDV-20-53,RDV-superior,and more myopic eyes had significantly higher RDVtemporal values than less myopic eyes.(P<0.05).In the non-anisometropia group,there was no significant difference in the RDV between the more and less myopic eyes at different eccentricities(P>0.05).There was a negative correlation between SE and TRDV(r=-0.205,P=0.001),RDV-20-53(r=-0.281,-0.183,-0.176,P<0.05),RDV-superior(r=-0.251,P<0.001),and RDV-temporal(r=-0.230,P<0.001),a negative correlation between CYL and RDV-10-30(r=-0.147,-0.180,P<0.05),and a negative correlation between SRI and RDV-0-20(r=-0.190,-0.170,P<0.05).AL had a positive correlation with RDV-20-30(r=0.164,P=0.008)and RDV-temporal(r=0.160,P=0.010).CONCLUSION:More myopic eyes in patients with myopic anisometropia show more peripheral hyperopic defocus.Diopter and corneal morphology may affect peripheral retinal defocus.

Effectiveness and the nomogram of small incision lenticule extraction in the correction of myopic anisometropia in adults

AIM:To evaluate the safety,effectiveness,and predictability of small incision lenticule extraction(SMILE)for the treatment of anisometropia,and to explore the personalized design scheme of SMILE in correcting adult myopia anisometropia based on the nomogram.METHODS:It’s a prospective cohort study.Patients with anisometropic myopia of refractive difference≥2.0 diopters(D)who underwent SMILE between September 2020 and March 2021 were enrolled.Clinical features and visual function were assessed preoperatively and at 1wk,1,3,and 6mo after the operation.The examination included tests for uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA),refractive errors,effectiveness index(preoperative CDVA/postoperative UDVA),safety index(postoperative CDVA/preoperative CDVA),nomogram and stereoscopic function.Paired t-test,Wilcoxon signed-rank test and repeated-measures analyses of variance were used for continuous variables,and Pearson Chi-squared test was used for categorical variables.RESULTS:The study involved 45 consecutive patients(average age:25.0±6.9y;82 out of 90 eyes underwent SMILE,while 8 eyes were not operated).The average preoperative spherical equivalent(SE)was-4.74±0.22 D.Six months after surgery,the effectiveness index was 1.05±0.12,and the safety index was 1.09±0.11.Seventy eyes(85.4%)exhibited SE correction error within±0.5 D.The percentage of eyes with Titmus stereoscopic function equal to or less than 200”significantly increased from 55.6%preoperatively to 88.9%postoperatively(P<0.05).There was statistically significant difference between higher myopia eyes and contralateral eyes in average nomogram value/spherical refraction ratio.CONCLUSION:SMILE is safe,effective and predictable in correcting myopic anisometropia,and it improves stereoscopic visual function of anisometropia patients.The precise and individualized design of the nomogram is a vital element to ensure the balance of both eyes after SMILE.

Bibliometric analysis of research relating to refractive cataract surgery over a 20-year period:from 2003 to 2022

AIM:To investigate the research trend on refractive cataract surgery,compare the contributions of different countries,institutions,journals,and authors in the past 20y,and explore its potential research hotspots.METHODS:All publications were extracted relating to refractive cataract surgery from 2003 to 2022 from Web of Science.Document types were limited to original articles and reviews,and the language was limited to English.Quantitatively and qualitatively of the publications were analyzed through Microsoft Excel and GraphPad Prism.VOSviewer and CiteSpace were used for bibliometric and visualized analysis.RESULTS:A total of 2090 publications were enrolled.The United States contributed the most publications(434,20.8%),followed by China(345,16.5%)and England(163,7.80%).Publications from the United States were cited more frequently(9552 citations)with the highest H-index of 48.China ranked second in the total number of publications,the papers were not cited that frequently(3237 citations),and the H-index ranked sixth(H-index=29).Journal of Cataract and Refractive Surgery published the most papers(333,15.9%),and the University of London had the highest number of publications(75,3.59%).Dick HB from Germany published the most papers.Corneal astigmatism-related research,cataract surgery methodrelated research,postoperative visual-quality relate to research,and postoperative complications-relate research are the hotspots in this field.The most significant limitation was that the database was updated frequently and the latest publications were not included.CONCLUSION:The bibliometric analysis shows a brief summarization of the contribution of the authors,institutions,countries,and journals.Corneal astigmatism,cataract surgery method,postoperative visual-quality and postoperative complications related researches have become the emerging hotspots,which can give a direction in the future researches.

A 3-month comparison study of subjective and objective visual quality of small incision lenticule extraction and transepithelial photorefractive keratectomy in patients with low and moderate myopia

AIM:To compare the subjective and objective visual quality between small incision lenticule extraction(SMILE)and transepithelial photorefractive keratectomy(t PRK)in patients with low and moderate myopia.METHODS:Patients undertaking SMILE or t PRK for the correction of low and moderate myopia were consecutively recruited in this prospective cohort study with a 3-month follow-up period.Objective evaluation[visual acuity test,manifest refraction,wavefront aberrations,the total cut-off value of the total modulation transfer function(MTFcut-off),and Strehl ratio(SR)]and subjective evaluation of visual quality(quality-of-life questionnaire)were conducted before surgery and at days 1,7,30,and 90 after surgery.RESULTS:A total of 47 patients(94 eyes)with SMILE and 22 patients(22 eyes)with t PRK were enrolled.The uncorrected visual acuity(UCVA)was better in SMILE patients on day 7 after surgery(1.13±0.13 vs 0.99±0.17,t=4.85,P<0.001)but was comparable at days 30 and 90.At day 90,the SMILE group had a lower spherical equivalent(SE)than the t PRK group(0.04±0.31 vs 0.19±0.43,t=2.08,P=0.042).Total higher order aberrations(HOAs)were induced in both surgical types,which were more evident in the t PRK group with 3-mm pupil diameter(0.16±0.07 vs0.11±0.05,t=4.27,P<0.001)and 5-mm pupil diameter(0.39±0.17 vs 0.36±0.11,t=2.33,P=0.022).The MTFcut-offand SR showed a trend of improvement in both SMILE and t PRK patients but were statistically better in the SMILE group with both pupil diameters.There was a significant improvement of contrast sensitivity(CS)over baseline levels at the spatial frequency of 18 cycles/degree(c/d)in the SMILE group(F=2.72,P=0.033)and at 3 c/d(F=3.03,P=0.031),12 c/d(F=3.72,P=0.013),and 18 c/d(F=4.62,P=0.004)in the t PRK group.The subjective quality of life questionnaire showed a steady improvement in the SMILE group(F=8.31,P<0.001)but not the t PRK group.CONCLUSION:SMILE and t PRK are both safe and effective ways to correct low and moderate myopia.A generally better and quicker recovery of visual quality favors the application of SMILE in qualified patients.

Axial length,vitreoretinal pathology,and anterior chamber depth can predict postoperative refractive outcomes in phacovitrectomy/silicone oil removal

AIM:To evaluate the postoperative refractive prediction error(PE)and determine the factors that af fect the refractive outcomes of combined pars plana vitrectomy(PPV)or silicone oil removal(SOR)with cataract surgery.METHODS:The study is a retrospective,case-series study.Totally 301 eyes of 301 patients undergoing combined PPV/SOR with cataract surgery were enrolled.Eligible individuals were separated into four groups according to their preoperative diagnoses:silicone oil-filled eyes after PPV(group 1),epiretinal membrane(group 2),macular hole(group 3),and primary retinal detachment(RD;group 4).The variables af fecting postoperative refractive outcomes were analyzed,including age,gender,preoperative best-corrected visual acuity(BCVA),axial length(AL),keratometry average,anterior chamber depth(ACD),intraocular tamponade,and vitreoretinal pathology.The outcome measurements include the mean refractive PE and the proportions of eyes with a PE within±0.50 diopter(D)and±1.00 D.RESULTS:For all patients,the mean PE was-0.04±1.17 D,and 50.17%of patients(eyes)had a PE within±0.50 D.There was a significant difference in refractive outcomes among the four groups(P=0.028),with RD(group 4)showing the least favorable refractive outcome.In multivariate regression analysis,only AL,vitreoretinal pathology,and ACD were strongly associated with PE(all P<0.01).Univariate analysis revealed that longer eyes(AL>26 mm)and a deeper ACD were correlated with hyperopic PE,and shorter eyes(AL<26 mm)and a shallower ACD were correlated with myopic PE.CONCLUSION:RD patients have the least favorable refractive outcome.AL,vitreoretinal pathology,and ACD are strongly associated with PE in the combined surgery.These three factors affect refractive outcomes and thus can be used to predict a better postoperative refractive outcome in clinical practice.