Efficacy of scleral buckling for the treatment of rhegmatogenous retinal detachment using a novel foldable capsular buckle

●AIM:To evaluate the effectiveness and safety of scleral buckling for the treatment of rhegmatogenous retinal detachment(RRD)using a novel foldable capsular buckle(FCB).●METHODS:This was a series of case observation studies.Eighteen patients(18 eyes)who visited our ophthalmology department between August 2020 and August 2022 and were treated for RRD with scleral buckling using FCB were included.The procedure was similar to conventional scleral buckling,while a balloon-like FCB was placed onto the retinal break with balanced salt solution filling for a broad,external indentation instead of the silicone buckle.The retinal reattachment rate,best corrected visual acuity(BCVA),intraocular pressure(IOP),refractive dioptre and astigmatism degree,and complications were evaluated and recorded.●RESULTS:There were 7 males and 11 females aged 19-58y.The average time course of RRD was 12d,ranging from 7-20d.The retinal break was located in the superior quadrants in 8 eyes and in the inferior quadrants in 10 eyes,with macula-off detachments in 12 eyes.The patients were followed-up for at least 6mo.The final retinal reattachment rate was 100%.The BCVA was significantly improved compared with the baseline(P<0.05).There was no significant change in refractive dioptre or astigmatism degree at each follow-up(all P>0.05).Three patients had transiently high IOPs within one week after surgery.Mild diplopia occurred in 5 patients after surgery and then disappeared after the balloon fluid was removed.●CONCLUSION:The success rate of FCB scleral buckling for RRD is satisfactory.This procedure can be expected to be applied in new,uncomplicated cases of RRD.

Endophthalmitis secondary to globe penetration from hydrogel scleral buckle

Dear Sir,Iam Dr Katrina A.Mears,from the Department of Ophthalmology and Visual Sciences,University of Iowa Carver College of Medicine,200 Hawkins Drive,Iowa City,Iowa,USA.I wish to present a case of endophthalmitis secondary to globe penetration from a hydrogel scleral buckle which,to the best of our knowledge,is the first reported case

Transcapsular scleral fixation of the standard capsular tension ring and in-the-bag intraocular lens implantation for severely subluxated lenses

AIM:To present a technique of transcapsular scleral fixation of the standard capsular tension ring(CTR)through equatorial capsulotomy and in-the-bag intraocular lens(IOL)implantation in subluxated lenses.METHODS:This retrospective consecutive case series included patients with subluxated lenses by more than 180 degrees who underwent lens extraction,transcapsular scleral fixation of the standard CTR through equatorial capsulotomy,in-the-bag IOL implantation and with at least 6mo follow-up.Preoperative and postoperative best corrected visual acuity(BCVA),intraocular pressure(IOP),complications,and postoperative IOL tilt and decentration were recorded.RESULTS:Nine eyes of 7 patients with a mean followup of 11.0±3.7mo were included in this study.The BCVA was significantly improved from 0.64±0.22 logMAR preoperatively to 0.21±0.19 logMAR postoperatively(P<0.001).The IOP was within the normal range postoperatively.The mean tilt of the IOL was 4.30°±2.31°(range,1.0°to 8.9°)and the mean decentration of the IOL was 0.37±0.12 mm(range,0.14 to 0.50 mm).No visually threatened intraoperative and postoperative complications were detected during the follow-up period.CONCLUSION:This is a safe and effective surgical technique for managing patients with severely subluxated lenses.It has achieved favorable outcomes with fewer surgical manipulations and less need for advanced capsular support devices.

Non-contact wide-field viewing system-assisted scleral buckling surgery for retinal detachment in silicone oilfilled eyes

AIM:To evaluate scleral buckling(SB)surgery using a noncontact wide-field viewing system and 23-gauge intraocular illumination for the treatment of rhegmatogenous retinal detachment in silicone oil(SO)-filled eyes.METHODS:Totally 9 patients(9 eyes)with retinal detachment in SO-filled eyes were retrospectively analyzed.All patients underwent non-contact wide-field viewing system-assisted buckling surgery with 23-gauge intraocular illumination.SO was removed at an appropriate time based on recovery.The patients were followed up for at least 3mo after SO removal.Retinal reattachment,complications,visual acuity and intraocular pressure(IOP)before and after surgery were observed.RESULTS:Patients were followed up for a mean of 8.22mo(3-22mo)after SO removal.All patients had retinal reattachment.At the final follow-up,visual acuity showed improvement for 8 patients,and no change for 1 patient.The IOP was high in 3 patients before surgery,but it stabilized after treatment;it was not affected in the other patients.None of the patients had infections,hemorrhage,anterior ischemia,or any other complication.CONCLUSION:This new non-contact wide-field viewing system-assisted SB surgery with 23-gauge intraocular illumination is effective and safe for retinal detachment in SO-filled eyes.

Molecular mechanism of hypoxia and alpha-ketoglutaric acid on collagen expression in scleral fibroblasts

AIM:To investigate the molecular mechanisms underlying the influence of hypoxia and alpha-ketoglutaric acid(α-KG)on scleral collagen expression.METHODS:Meta-analysis and clinical statistics were used to prove the changes in choroidal thickness(ChT)during myopia.The establishment of a hypoxic myopia model(HYP)for rabbit scleral fibroblasts through hypoxic culture and the effects of hypoxia andα-KG on collagen expression were demonstrated by Sirius red staining.Transcriptome analysis was used to verify the genes and pathways that hypoxia andα-KG affect collagen expression.Finally,real-time quantitative reverse transcription polymerase chain reaction(RT-qPCR)was used for reverse verification.RESULTS:Meta-analysis results aligned with clinical statistics,revealing a thinning of ChT,leading to scleral hypoxia.Sirius red staining indicated lower collagen expression in the HYP group and higher collagen expression in the HYP+α-KG group,showed that hypoxia reduced collagen expression in scleral fibroblasts,whileα-KG can elevated collagen expression under HYP conditions.Transcriptome analysis unveiled the related genes and signaling pathways of hypoxia andα-KG affect scleral collagen expression and the results were verified by RT-qPCR.CONCLUSION:The potential molecular mechanisms through which hypoxia andα-KG influencing myopia is unraveled and three novel genes TLCD4,TBC1D4,and EPHX3 are identified.These findings provide a new perspective on the prevention and treatment of myopia via regulating collagen expression.

Sutured scleral fixation of existing subluxated/dislocated acrylic one-piece intraocular lenses

AIM:To evaluate the visual and refractive outcomes in cases after sutured scleral fixation of existing subluxated or dislocated acrylic one-piece intraocular lenses(IOLs).METHODS:This study retrospectively enrolled a consecutive series of patients who underwent a surgery of sutured existing subluxated or dislocated IOLs from October 2018 to June 2020.All patients underwent comprehensive preoperative and postoperative ophthalmologic examination,and data were collected including age,sex,surgical indications,best-corrected visual acuity,refractive error,intraocular pressure.Presence of intraoperative and postoperative surgical complications was documented.RESULTS:A total of 20 consecutive cases were enrolled for analysis with mean final follow-up period 9.8±5.3mo.Visual acuity improved from a mean of 0.35(0.46±0.32 logMAR)preoperatively to 0.61(0.21±0.18 logMAR)at the 3-month follow-up(P=0.002).The mean amount of preoperative keratometric astigmatism and total postoperative refractive astigmatism was-1.24±0.80 diopters(D)and-1.42±0.97 D,respectively.There was no statistically significant difference between preoperative and postoperative astigmatism(P=0.156).The mean IOL-induced astigmatism was-0.23±0.53 D.The mean spherical equivalent at the 3-month follow-up was-0.1±0.94 D.No major complications were noted during the follow-up period.CONCLUSION:Surgical techniques using sutured scleral fixation of existing subluxated or dislocated acrylic one-piece IOLs result in favorable visual and refractive outcomes without major complications.

Analysis of Stability and Large Deflection Buckle of Rolled Strip by Third Power B-Spline Function Method

A new method——the third power B-spline function method is developed to analyse the stability and the buckle of rolled strip under residual stress.The large deflection theory of thin plate is used to calculate the buckle of rolled strip and criterion of critical buckle is given.The computed results tally with those of experiment well,which provides theoretical basis and method for developing the mathematical model of flatness control.

DYNAMIC ANALYSIS OF ARREST OF BUCKLE PROPAGATION ON A BEAM ON A NONLINEAR ELASTIC FOUNDATION BY FEM

Based on the dynamic governing equation of propagating buckle on a beam on a nonlinear elastic foundation, this paper deals with an important problem of buckle arrest by combining the FEM with a time integration technique. A new conclusion completely different from that by the quasi-static analysis about the buckle arrestor design is drawn. This shows that the inertia of the beam cannot be ignored in the analysis under consideration, especially when the buckle propagation is suddenly stopped by the arrestors.

Application of optical coherence tomography angiography in assessment of posterior scleral reinforcement for pathologic myopia

AIM： To investigate the effect of posterior scleral reinforcement （PSR） on circulation of pathologic myopia eyes with posterior staphyloma by optical coherence tomography angiography （OCTA）.METHODS： The study included 30 pathologic myopia eyes with posterior staphyloma which underwent PSR （PSR group） for 6 to 18mo ago, and 30 age and myopia matched eyes without PSR surgery as control group. Macular, choriocapillaris and radial peripapillary capillary （RPC） flow density were measured by OCTA, and the measurements were compared between groups. RESULTS： OCTA found no significant differences in macular flow density between PSR and control groups. For the superficial flow, whole enface flow density （WED）, fovea density （FD）, and parafoveal density （PD） were 46.55%±5.19% vs 47.29%±4.12% （P=0.542）, 31.45%±6.35% vs 31.17%±4.48% （P=0.841）, and 48.82%±5.66% vs 49.21%±4.15% （P=0.756） in PSR and control groups, respectively. For the deep flow, WED, FD, and PD were 52.07%±5.78% vs 53.95%±4.62% （P=0.168）, 29.62%±6.55% vs 29.50%±6.38% （P=0.940）, and 56.93%±6.17% vs 58.15%±5.13% （P=0.407） in PSR and control groups, respectively. The choriocapillary flow density was 61.18±3.25% in PSR group vs 60.88%±2.56% in control group （P=0.692）. Also, OCTA found no significant differences in RPCs flow density between PSR and control groups. The optic disc WED, inside disc flow density and peripapillary flow density were 48.47%±4.77% vs 48.11%±4.57% （P=0.813）, 45.47%±11.44% vs 46.68%±9.02% （P=0.709）, 54.32%±5.29% vs 52.47%±6.62% （P=0.349） in PSR and control groups, respectively.CONCLUSION： OCTA provides a non-invasive and quantitative approach for monitoring macular and papillary blood flow in pathologic myopia. PSR can not improve but may maintain the circulation of pathologic myopia eyes with posterior staphyloma.

Non-linear buffeting response analysis of long-span suspension bridges with central buckle

The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in China. By using a spectral representation method and FFT technique combined with measured data,a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented,in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

Posterior scleral reinforcement for the treatment of pathological myopia

AIM： To investigate the effects of posterior scleral reinforcement（PSR） in the treatment of pathological myopia.·METHODS： The study included 52 eyes in 43 patients with pathological myopia who underwent PSR（PSR group）, and 52 eyes in 36 age- and myopia-matched patients who did not undergo such treatment as control group. Axial length, refraction error, best corrected visual acuity（BCVA）, and macular scans by optical coherence tomography（OCT） were recorded at baseline, 6mo, 1, 3and 5y after the surgery, and the complications were noted.·RESULTS： There were no statistical differences in axial length, refractive error, or BCVA between the PSR group and the control group at baseline. At the end of the follow-up, the mean axial length was 29.79 ±1.26 mm in the PSR group, which was significantly shorter than that in the control group（30.78±1.30 mm）（P 〈0.01）, and the mean refractive error was-16.86 ±2.53 D in the PSR group, which was significantly lower than that in the control group（-19.18 ±2.12 D）（P 〈0.01）. A statistically significant difference in BCVA was found between the PSR group（0.51 ±0.25 log MAR） and the control group（0.62±0.26 log MAR） at the postoperative 5-year follow-up（P 〈0.01）. There were no serious complications during the 5-year follow-up period.·CONCLUSION： PSR can prevent axial elongation and myopia progression in eyes with pathological myopia.

Distribution of bone morphogenetic protein receptors in human scleral fibroblasts cultured in vitro and human sclera

AIM: To investigate the distribution of bone morphogenetic protein receptors (BMPRs) in human scleral fibroblsasts (HSFs) and in human sclera. METHODS: Primary HSFs were cultured in vitro. The mRNA levels of BMP-2 and BMPRs in HSFs were assayed by reverse transcription-polymerase chain reaction (RT-PCR). The protein distributions of BMP-2 and BMPRs in HSFs were further detected by immunocytofluorescence and western blot. Their protein expression was also detected in frozen human posterior scleral sections by immunohistofluorescence. RESULTS: BMP-2 and BMPRs were expressed in both HSFs and human sclera not only at mRNA level but also at protein level. The expressions of BMPRIA and BMPRII were higher than that of BMPRIB in the cytoplasm and cell membrane of HSFs in vitra Western blot further verified the results of immunocytofluorescence. In human sclera, BMP2, BMPR IB and BMPR II were found to be expressed in the cytomatrix of HSF, and weak signal was detected about BMPRIA. CONCLUSION: BMP-2 and all three subtypes of BMPRs were found in HSFs and may play a role in scleral remodeling.

Analytical modeling for rapid design of bistable buckled beams

Double-clamped bistable buckled beams demonstrate great versatility in various fields such as robotics,energy harvesting,and microelectromechanical system(MEMS).However,their design often requires time-consuming and expensive computations.In this work,we present a method to easily and rapidly design bistable buckled beams subjected to a transverse point force.Based on the Euler–Bernoulli beam theory,we establish a theoretical model of bistable buckled beams to characterize their snapthrough properties.This model is verified against the results from a finite element analysis(FEA)model,with maximum discrepancy less than 7%.By analyzing and simplifying our theoretical model,we derive explicit analytical expressions for critical behavioral values on the force-displacement curve of the beam.These behavioral values include critical force,critical displacement,and travel,which are generally sufficient for characterizing the snapthrough properties of a bistable buckled beam.Based on these analytical formulas,we investigate the influence of a bistable buckled beam's key design parameters,including its actuation position and precompression,on its critical behavioral values,with our results validated by FEA simulations.Our analytical method enables fast and computationally inexpensive design of bistable buckled beams and can guide the design of complicated systems that incorporate bistable mechanisms.

Evaluation of functional outcome and stability of sutureless scleral tunnel fixated IOLs in children with ectopia lentis

AIM:To evaluate functional outcome of sutureless scleral tunnel intraocular lens(SSTIOL)in children with crystalline lens subluxation of more than 7 clock hours.METHODS:A prospective interventional study was conducted consisting of 45 eyes of 44 children in age group 6-18 y having>7 clock hours of lens subluxation who underwent lensectomy-vitrectomy followed by SSTIOL implantation.Primary outcome was improvement in best corrected visual acuity(BCVA)and secondary outcomes were assessment of intraocular lens(IOL)tilt using ultrasound biomicroscopy(UBM),mean change in astigmatism at last follow-up of 1 y and associated complications.RESULTS:The mean preoperative and postoperative BCVA was 1.05±0.28 and 0.64±0.45(log MAR)respectively(P=0.001)at last follow-up.The mean astigmatism preoperatively and postoperatively was-4.17±2.69 D and-1.86±1.25 D respectively(P=0.011).Significant IOL tilt(>5 degrees)was present in 5 cases.The mean percentage endothelial loss was 3.65%±1.92%.The most serious complication encountered was retinal detachment seen in 2 cases.CONCLUSION:SSTIOL implantation provides efficient visual rehabilitation in children provided there is stringent case selection.We recommend caution in children having white-to-white distance>12 mm and presence of peripheral retinal degenerations.

Long-term outcome of pathologic myopic foveoschisis treated with posterior scleral reinforcement followed by vitrectomy

AIM: To report the long-term outcome of posterior scleral reinforcement(PSR) followed by vitrectomy for pathologic myopic foveoschisis(MF).METHODS: The records of 27 patients(44 eyes) treated with posterior scleral reinforcement(PSR) followed by vitrectomy for pathologic MF were retrospectively reviewed.The best-corrected visual acuity(BCVA), refractive error, axial length, and spectral-domain optical coherence tomography findings and complications were analyzed.RESULTS: Forty-four eyes of 27 patients were included in this study. The follow-up period was 47.98±18.23mo(24-83mo). The mean preoperative BCVA(logMAR) was 1.13±0.63, and the mean postoperative BCVA was 0.30±0.33at the last visit. There showed a significant improvement in BCVA postoperatively(P<0.001). Postoperative BCVA in 41eyes(93%) was improved compared with the preoperative one. Forty-two eyes(95.45%) got total resolution of the MF after surgery. The remaining two eyes(4.55%) got partial resolution of foveoschisis. The preoperative foveal thickness was 610.45±217.11 μm and the postoperative foveal thickness at the last visit was significantly reduced to 177.64±55.40 μm(P<0.001). The preoperative axial length was 29.60±1.71 mm, and the postoperative axial length was 29.74±1.81 mm at the last visit. There was no significant increase in axial length within 47.98±18.23mo of follow-up(P=0.562). There was no recurrence of foveoschisis or occurrence of full-thickness macular hole during the whole follow-up period.CONCLUSION: For pathologic MF, PSR followed by vitrectomy is an effective procedure to improve the visual acuity and the anatomical structure of macula. It can also stabilize the axial length for a long time.

Influence of central buckle on suspension bridge dynamic characteristics and driving comfort

The central buckle, which is often used in a suspension bridge, can improve bridges' performance in the actual operation condition. The influence of the central buckle on natural vibration characteristics and bridge-deck driving comfort of a long-span suspension bridge is studied by using a case study of Siduhe Suspension Bridge in China. Based on the finite element software ANSYS and independently complied program, the influence of the central buckle on the structure force-applied characteristics of a long-span suspension bridge has been explored. The results show that the huge increases of natural frequencies can result in the presence of central buckles because of the increases of bending and torsional rigidities. The central buckle basically makes the stiffening girders and cables within the triangular area covered as a relatively approximate rigid area. Hence, the central buckle can reduce the torsional displacement of the main girder. However, the increases of bending and torsional rigidities have little influence on the impact factor, which is obtained by using vehicle-bridge coupled vibration analysis. This means that the central buckle has little effect on the comfort indices. In addition, it is found that the central buckle can enhance the bridge deck's driving stability due to the decrease of the torsional displacements of the main girder.

Clinical observation of vitrectomy combined with endolaser photocoagulation at the edge of posterior scleral staphyloma for macular hole retinal detachment in high myopia

AIM: To observe the clinical effect of pars plana vitrectomy(PPV) and silicone oil filling surgery combined with intraoperative posterior scleral staphyloma(PS) marginal retinal photocoagulation in the treatment of high myopic macular hole retinal detachment(MHRD) with PS.METHODS: This was a retrospective clinical study. From May 2017 to March 2020, 62 MHRD patients with PS(62 eyes) were enrolled in the study. Patients were divided into 23 G PPV combined with PS marginal retina intraoperative photocoagulation group(combined group) and conventional surgery group(conventional group), with 31 eyes in each. Triamcinolone acetonide and indocyanine green were used to remove the epiretinal membrane and the posterior macular inner limiting membrane(ILM). In the combined group, 2 to 3 rows of retinal photocoagulation were performed on the edge of the PS. The patients were followed up for an average of 8.34±3.21 mo. The first retinal reattachment rate, macular hole closure rate, Duration of silicone oil tamponade, best corrected visual acuity(BCVA) and average number of operations were observed and compared between the two groups.RESULTS: The first retinal reattachment rates of the eyes in the combined group and the conventional group were 96.7%(29/31) and 67.7%(21/31), respectively(χ~2=6.613, P=0.010). The macular hole closure rates in the combined group and the conventional group were 74.2%(23/31) and 67.7%(21/31), respectively(χ~2=0.128, P=0.721). The Duration of silicone oil tamponade of the patients in the combined group was lower than that of the routine group(t=-41.962, P≤0.001). Postoperative log MAR BCVA values of patients in the combined group and the conventional group were 1.27±0.12 and 1.26±0.11, compared with the log MAR BCVA before surgery, each group was improved(t=19.947, t=-19.517, P≤0.001, P≤0.001). There was no significant difference in the log MAR BCVA between the eyes of the two groups(t=-0.394, P=0.695). The average numbers of operations on the eyes in the conventional group and the combined group were 2.39±0.62 and 2.06±0.25 times, the combined group had fewer operations on average(t=-2.705, P=0.009). CONCLUSION: Intraoperative PPV treatment of MHRD with PS combined with PS marginal endolaser photocoagulation can effectively increase the rate of retinal reattachment after the first operation, reduce the number of repeated operations, and reduce the postoperative duration of silicone oil tamponade.

Influence of rigid central buckle on seismic response of long-span suspension bridges

A rigid central buckle is employed in Runyang Suspension Bridge （RSB） to replace commonly used short suspenders in the main span. Based on the seismic waves with 2% probabilities of exceedance, the nonlinear seismic response time-domain analysis are then conducted and influence of central buckles on seismic response of long-span suspension bridge is specially studied. Analysis resuits show that the central buckle can effectively control the longitudinal floating vibration mode of the deck, and therefore reduce earthquake-excited longitudinal displacement at the end of the deck. However, the central buckle may cause increment of longitudinal displacement at the top of main tower and bending moment at the bottom of the main tower, which should be paid special attention to. Results provide references for anti-earthquake analysis and design of long-span suspension bridges using rigid central buckles.

Electronic,Elastic and Piezoelectric Properties of Two-Dimensional Group-Ⅳ Buckled Monolayers

Electronic, elastic and piezoelectric properties of two-dimensional （2D） group-IV buckled monolayers （GeSi, SnSi and SnGe） are studied by first principle calculations. According to our calculations, SnSi and SnGe are good 2D piezoelectric materials with large piezoelectric coefficients. The values of d11d11 of SnSi and SnGe are 5.04pm/V and 5.42pm/V, respectively, which are much larger than 2D MoS2 （3.6pm/V） and are comparable with some frequently used bulk materials （e.g., wurtzite AlN 5.1pm/V）. Charge transfer is calculated by the L wdin analysis and we find that the piezoelectric coefficients （d11d11 and d31） are highly dependent on the polarizabilities of the anions and cations in group-IV monolayers.

Nonlinear Contact Between Pipeline's Outer Wall and Slip-on Buckle Arrestor's Inner Wall During Buckling Process

In order to theoretically study the buckle propagation of subsea pipelines with slip-on buckle arrestors, a two-dimensional ring model was set up to represent the pipeline and a nonlinear spring model was adopted to simulate the contact between pipeline's inner walls and between pipeline's outer wall and slip-on buckle arrestor's inner wall during buckle propagation. In addition, some reverse springs are added to prevent the wall of left and right sides separating from the inner wall of slip-on buckle arrestors. Considering large deformation kinematics relations and the elastic-plastic constitutive relation of material, balance equations were established with the principle of virtual work. The variation of external pressure with respect to the cross-sectional area of pipelines was analyzed, and the lower bound of the crossover pressure of slip-on buckle arrestors was calculated based on Maxwell's energy balance method. By comparing the theoretical results with experiment and finite element numerical simulation, the theoretical method is proved to be correct and reliable.