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.

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.

Comparison of scleral buckling using wide-angle viewing systems and indirect ophthalmoscope for rhegmatogenous retinal detachment

AIM：To compare the effects of scleral buckling using wide-angle viewing systems（WAVS） with that using indirect ophthalmoscope for the treatment of rhegmatogenous retinal detachment.METHODS：The study was a retrospective analyses of the medical records of 94 eyes（94 patients） with rhegmatogenous retinal detachment.Among them,47 eyes underwent scleral buckling using WAVS with endoiiluminator（Group W）,and 47 eyes underwent scleral buckling using indirect ophthalmoscope（Group I）.Surgical durations,primary success rate,best-corrected visual acuities（BCVA）,delayed subretinal fluid absorptions and surgical complications were compared between the two groups.RESULTS：At baseline,there were no statistical differences between the two groups in patient＇s age（P=0.997）,gender（P=0.853）,symptom duration（P=0.216）,BCVA（P=0.389）,refractive error（P=0.167）,intraocular pressure（P=0.595）,the number of retinal breaks（P=0.832）,the extent of retinal detachment（P =0.246）,subretinal demarcation line（P=0.801）,and macular detachment（P=0.811）.The follow-up period was 12 mo.The surgical durations in Group W（with or without encircling buckling） were significant shorter than those in Group I（P〈0.001 respectively）.The primary success rate was94.27%in Group W,which was similar to that in Group I（92.38%,P=0.931）.The BCVA in Group W was better than that in Group I（P〈0.001） at 1-month follow-up visit.However,there were no significant differences between the two groups at 3-month（P=0.221）,6-month（P =0.674）,and 12-month（P=0.363） follow-up visits respectively.Delayed subretinal fluid absorptions were more common in Group I than in Group W at 1-month（P=0.045） follow-up visit,but there were no significant differences between the two groups at 3-month（P=0.111）,6-month（P =1.000） and 12-month follow-up visits respectively.CONCLUSION：Scleral buckling using WAVS can be an alternative choose for rhegmatogenous retinal detachment

Predictive factors for postoperative visual function of primary chronic rhegmatogenous retinal detachment after scleral buckling

AIM： To evaluate predictive factors for postoperative visual function of primary chronic rhegmatgenous retinal detachment （RRD） after sclera buckling （SB）. METHODS： Totally 48 patients （51 eyes） with primary chronic RRD were included in this prospective interventional clinical cases study, which underwent SB alone from June 2008 to December 2014. Age, sex, symptoms duration, detached extension, retinal hole position, size, type, fovea on/off, proliferative vitreoretinopathy （PVR）, posterior vitreous detachment （PVD）, baseline best corrected visual acuity （BCVA）, operative duration, follow up duration, final BCVA were measured. Pearson correlation analysis, Spearman correlation analysis and multivariate linear stepwise regression were used to confirm predictive factors for better final visual acuity. Student＇s t-test, Wilcoxon twosample test, Chi-square test and logistic stepwise regression were used to confirm predictive factors for better vision improvement. RESULTS： Baseline BCVA was 0.8313±0.6911 IogMAR and final BCVA was 0.4761 ±0.4956 IogMAR. Primary surgical success rate was 92.16% （47/51）. Correlation analyses revealed shorter symptoms duration （r =0.3850, P=0.0053）, less detached area （r=0.5489, P〈0.0001）, fovea （r=0.4605, P=0.0007）, no PVR （r=0.3138, P= 0.0250）, better baseline BCVA （r=0.7291, P〈0.0001）, shorter operative duration （r=0.3233, P=0.0207） and longer follow up （r=-0.3358, P=0.0160） were related with better final BCVA, while independent predictive factors were better baseline BCVA [partial R-square （PR2） = 0.5316, P〈0.0001], shorter symptoms duration （PR2= 0.0609, P=0.0101）, longer follow up duration （PR2=0.0278, P =0.0477） and shorter operative duration （PR2=0.0338, P=0.0350）. Patients with vision improvement took up 49.02% （25/51）. Univariate and multivariate analyses both revealed predictive factors for better vision improvement were better baseline vision [odds ratio （OR） =50.369, P= 0.0041] and longer follow up duration （OR=1.144, P= 0.0067）. CONCLUSION： Independent predictive factors for better visual outcome of primary chronic RRD after SB are better baseline BCVA, shorter symptoms duration, shorter operative duration and longer follow up duration, while independent predictive factors for better vision improvement after operation are better baseline vision and longer follow up duration.

Pars Plana Vitrectomy versus Combined Scleral Buckling—Pars Plana Vitrectomy for Phakic Rhegmatogenous Retinal Detachment with Inferior Breaks

Aims: To compare the results of pars plana vitrectomy (PPV) and combined scleral buckling—PPV (SB/PPV) in phakic rhegmatogenous retinal detachments with inferior breaks. Methods: Randomized, prospective, clinical controlled trial of forty consecutive phakic eyes with primary rhegmatogenous retinal detachment, associated with inferior breaks and not complicated by proliferative vitreoretinopathy ≥grade C, to either PPV (group 1) or combined SB/PPV (group 2). Results: At 6 months follow up the primary reattachment rate was 100% (20/20 cases) in group 2 and 70% (14/20 cases) in the group 1, the difference being statistically significant (p = 0.027). The best corrected visual acuity improved significantly from a preoperative mean of 1.65 ± 1.13 (Range: 0.6 to 3) to a mean of 0.45 ± 0.11 (Range: 0.3 to 0.6) in the group 2 and in the group 1 improved from a preoperative mean of 2.34 ± 0.92 (Range: 0.48 to 3) to a mean of 0.668 ± 0.20 (Range: 0.48 to 1), the difference between the two groups being statistically significant (p = 0.001). Conclusion: Anatomical and functional success rates are significantly better with the use of a scleral explant during PPV for uncomplicated forms of phakic rhegmatogenous retinal detachments with inferior breaks.

Local dry vitrectomy combined with segmental scleral buckling and viscoelastic tamponade for rhegmatogenous retinal detachment with vitreous traction

AIM:To demonstrate local dry vitrectomy combined with segmental scleral buckling and viscoelastic tamponade for the treatment of partial rhegmatogenous retinal detachment(RRD)with local vitreous traction in patients at high-risk for proliferative vitreoretinopathy(PVR).METHODS:Eleven eyes of 11 patients were retrospectively studied,including 5 retinal dialysis and 6 retinal detachment(RD;5 eyes with peripheral retinal hole and I eye with giant tear).All patients exhibited partial RD and local vitreous traction.Combined local dry vitrectomy without conventional infusion and segmental scleral buckling was performed.Viscoelastic fluid was injected into the vitreous cavity if needed Demographic information,preoperative and post­operative complications,and outcomes were recorded.RESULTS:The mean age of the patients at presentation was 26.55±13.52y.All 11 patients obtained retinal reattachment after a single surgical intervention.Postoperative visual acuities were improved or remained stable in all patients.None of them developed complications,except for temporary mildly increased intraocular pressure in 3 cases.CONCLUSION:Combined local dry vitrectomy and segmental scleral buckling are effective for patients of RRD with local vitreous traction.The technique avoids many complications associated with regular surgery and was minimally invasive to both the external and internal eye.

Scleral buckling combined with internal cyclopexy for severe traumatic cyclodialysis cleft in open globe injuries

This study aimed to evaluate the effect of scleral buckling combined with internal cyclopexy on the treatment of severe traumatic cyclodialysis cleft in open globe injuries(OGIS). This retrospective study recruited 10 patients of 10 eyes. With our surgical intervention, all the 10 eyes achieved retinal and ciliary body anatomic re-attachment. The choroidal ruptures in nine eyes were closed with complete choroidal reattachment. Postoperative best-corrected visual acuity of nine eyes had various improvements. The mean intraocular pressure was increased from 8.9±2.6 mm Hg to 13.4±4.4 mm Hg. Eventually, six eyes underwent silicone oil(SO) removal without complications, two eyes still had SO tamponade and two eyes became SO-dependent eyes. The result shows that internal direct cyclopexy combined with scleral buckling is an effective treatment for severe traumatic cyclodialysis cleft in OGIS.

Size-dependent effect on biaxial and shear nonlinear buckling analysis of nonlocal isotropic and orthotropic micro-plate based on surface stress and modified couple stress theories using differential quadrature method

The size-dependent effect on the biaxial and shear nonlinear buckling analysis of an isotropic and orthotropic micro-plate based on the surface stress, the modified couple stress theory （MCST）, and the nonlocal elasticity theories using the differential quadrature method （DQM） is presented. Main advantages of the MCST over the classical theory （CT） are the inclusion of the asymmetric couple stress tensor and the consideration of only one material length scale parameter. Based on the nonlinear von Karman assumption, the governing equations of equilibrium for the micro-classical plate consid- ering midplane displacements are derived based on the minimum principle of potential energy. Using the DQM, the biaxial and shear critical buckling loads of the micro-plate for various boundary conditions are obtained. Accuracy of the obtained results is validated by comparing the solutions with those reported in the literature. A parametric study is conducted to show the effects of the aspect ratio, the side-to-thickness ratio, Eringen＇s nonlocal parameter, the material length scale parameter, Young＇s modulus of the surface layer, the surface residual stress, the polymer matrix coefficients, and various boundary conditions on the dimensionless uniaxial, biaxial, and shear critical buckling loads. The results indicate that the critical buckling loads are strongly sensitive to Eringen＇s nonlocal parameter, the material length scale parameter, and the surface residual stress effects, while the effect of Young＇s modulus of the surface layer on the critical buckling load is negligible. Also, considering the size dependent effect causes the increase in the stiffness of the orthotropic micro-plate. The results show that the critical biaxial buckling load increases with an increase in G12/E2 and vice versa for E1/E2. It is shown that the nonlinear biaxial buckling ratio decreases as the aspect ratio increases and vice versa for the buckling amplitude. Because of the most lightweight micro-composite materials with high strength/weight and stiffness/weight ratios, it is anticipated that the results of the present work are useful in experimental characterization of the mechanical properties of micro-composite plates in the aircraft industry and other engineering applications.

Buckling Analysis of Tapered Continuous Columns by Using Modified Buckling Mode Shapes

Elastic critical buckling load of a column depends on various parameters,such as boundary conditions,material,and crosssection geometry.The main purpose of this work is to present a new method for investigating the buckling load of tapered columns subjected to axial force.The proposed method is based on modified buckling mode shape of tapered structure and perturbation theory.The mode shape of the damaged structure can be expressed as a linear combination of mode shapes of the intact structure.Variations in length in piecewise form can be positive or negative.The method can be used for single-span and continuous columns.Comparison of results with those of finite element and Timoshenko methods shows the high accuracy and efficiency of the proposed method for detecting buckling load.

Surgical Approaches in Primary Rhegmatogenous Retinal Detachment: A Systematic Review and Meta-Analysis Comparing Vitrectomy vs. Vitrectomy Combined with Scleral Buckling, Lens-Sparing vs. Phako Procedures

Aim: This study aimed to assess and compare the functional and anatomical results of pars plana vitrectomy (PPV) alone versus PPV combined with scleral buckling (SB), and lens-sparing versus phaco-procedures for treating rhegmatogenous retinal detachment. Methods: A comprehensive literature search was performed using the Web of Science, MEDLINE, EMBASE, and Cochrane Library databases to retrieve comparative studies. The main objective was to assess the BCVA, while reattachment rates and ocular adverse events were considered secondary measures. Rev Manager software was used for statistical analysis. Results: The literature search identified 10 articles comprising 1518 eyes, with 682 eyes in the PPV group, 193 eyes in the lens-sparing versus phaco-procedure group, and 643 eyes in the combined PPV and SB surgery group. Quality assessment revealed a low risk of bias in most domains. The meta-analysis results revealed a significant difference in postoperative BCVA between the PPV and PPV combined with SB groups (WMD = −0.17, 95% CI [0.27, 0.07], p = 0.001). The primary reattachment rates were 82.80% for PPV alone and 87.52% for PPV combined with SB (p = 0.34). The final reattachment rates did not differ significantly between PPV and PPV combined with SB (99% vs. 99.8%;RR = 1.00, 95% CI [1.01, 0.99], p = 0.96). PPV alone demonstrated a significantly reduced risk of macular edema compared to PPV combined with scleral buckling (9.9% vs. 23%;p = 0.006). The incidences of macular hole development (p = 0.46), recurrent retinal detachment (p = 0.27), proliferative vitreoretinopathy development (p = 0.48), epiretinal membrane proliferation (p = 0.77), and limited choroidal hemorrhage (p = 0.69) were not significantly different between the two groups. Conclusions: These findings suggest that PPV alone may be a more effective treatment option in terms of visual acuity (VA) improvement, lower risk of macular edema and cataract development. However, there was no significant difference in VA improvement or complication rates between the lens-sparing and phaco-procedure groups. .

Ratio of Primary Episcleral Buckling Surgery versus Primary Vitrectomy for Rhegmatogenous Retinal Detachment

Purpose: To assess the ratio of the frequency of primary scleral buckling procedures versus the frequency of vitrectomies performed as treatment for rhegmatogenous retinal detachments in a primary retinal surgical department.Methods: The study included all patients with rhegmatogenous retinal detachments who underwent retinal or vitreoretinal surgery in the study period from 2002 to 2006. The size of the retinal defect and the amount of proliferative vitreoretinopathy were not exclusion criteria. Patients with tractional retinal detachment due to proliferative ischemic retinopathies were excluded.Results: In the study period, 875 primary retinal and vitreoretinal surgeries were performed on 875 eyes. Among the surgeries, episcleral sponges(42.9%) formed the largest part,followed by pars plana vitrectomies(35.0%) and encircling bands(22.2%). Combining episcleral sponges and encircling bands into an episcleral surgery group revealed that two thirds(65%).of the surgeries were episcleral interventions. In the episcleral sponge group, the retinal re-detachment rate after the first surgery was 13%.Conclusion: In a university department as a primary referral unit for retinal detachments, episcleral retinal surgery can still outnumber vitreoretinal interventions, with retinal re-detachment rates which do not differ markedly from the re-detachment rates reported in randomized trials comparing vitreoretinal surgery with episcleral surgery.

Lateral buckling of non-trenched high temperature pipelines with pipelay imperfections

An analysis method for the buckling process of a pipe section with a random pipelay imperfection is proposed. Four basic lateral modes, acquired by finite-element （FE） eigenvalue buckling analysis, are combined to provide the needed grid configurations for describing a real pipelay imperfection and an arc-length algorithm is used to analyze the snap-through process of the shell-element-grid model under nonlinear frictional boundary conditions. This paper also presents evaluation methods for the lateral buckling of two types of pipe-in-pipe systems that are used in the offshore oil and gas industry. For evaluating the buckling and postbuckling of compliant pipe-in-pipe systems FE analyses were carried out to judge the occurrence of the system buckling and furthermore to check postbuckling stresses induced in the buckles. The calculated results of the modified Riks algorithm indicate that only when high temperature would not trigger an abrupt short-wavelength buckle and when no yielding has been induced in the unavoidable long-wavelength buckles, the thermal stability and safety of compliant pipe-in-pipe systems can be proved. In the non-compliant pipe-in-pipe systems, firstly small-amplitude buckles of the carrier pipe may occur in the annulus between carrier pipe and casing pipe and the contact forces between the spacers and the casing pipe may drive the buckle of the pipe-in-pipe systems on the seabed. Based on the classical analytical solution of pipe buckling, four potential buckling modes corresponding to finite- element models are developed to evaluate the stability and the postbuckling strength of such pipe-in-pipe systems.

Thermal buckling of axisymmetrically laminated cylindrically orthotropic shallow spherical shells including transverse shear

The nonlinear thermal buckling of symmetrically laminated cylindrically orthotropic shallow spherical shell under temperature field and uniform pressure including transverse shear is studied. Also the analytic formulas for determining the critical buckling loads under different temperature fields are obtained by using the modified iteration method. The effect of transverse shear deformation and different temperature fields on critical buckling load is discussed.

Effects of local thickness defects on the buckling of micro-beam

A buckling model of Timoshenko micro-beam with local thickness defects is established based on a modified gradient elasticity.By introducing the local thickness defects function of the micro-beam,the variable coefficient differential equations of the buckling problem are obtained with the variational principle.Combining the eigensolution series of the complete micro-beam with the Galerkin method,we obtain the critical load and buckling modes of the micro-beam with defects.The results show that the depth and location of the defect are the main factors affecting the critical load,and the combined effect of boundary conditions and defects can significantly change the buckling mode of the micro-beam.The effect of defect location on buckling is related to the axial gradient of the rotation angle,and defects should be avoided at the maximum axial gradient of the rotation angle.The model and method are also applicable to the static deformation and vibration of the micro-beam.

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

SNAP-BUCKLING OF DISHED SHALLOW SHELLS UNDERUNIFORM LOADS

A theoretical analysis is presented for the snap-buckling behaviour of dished shallow shells under uniform loads. By means of the modified iteration method the second approximate formula of elastic behaviour. and a set of numerical solutions are given. And effects of parameters beta and k on the snap-buckling behaviour are discussed.

SNAP-BUCKLING OF DISHED SHALLOW SHELLS UNDER LINE LOADS

A theoretical analysis is presented for the snap-buckling behavior of dished shallow shells under axisymmetric distributed line loads. The second approximate formula of elastic behavior of dished shallow shells with various boundary conditions are given, and effects of geometrical parameters gamma, beta and k on non-linear behavior are discussed.

应用异体硬脑膜行改良后巩膜加固术治疗病理性近视的临床效果观察

目的:探讨应用异体硬脑膜行改良后巩膜加固术(PSR)治疗病理性近视(PM)的临床效果。方法:选择2022年1—10月南昌爱尔眼科医院收治30例(33只眼)PM患者,均应用异体硬脑膜行改良PSR治疗。比较治疗前后屈光度(SE)、眼轴长度、视盘与黄斑血流密度、最佳矫正视力(BCVA)、眼压(IOP),并记录术后并发症发生情况。结果:治疗后3个月,SE及黄斑区浅层毛细血管丛(SCP)、深层毛细血管丛(DCP)血流密度均高于治疗前,眼轴长度短于治疗前,差异均有统计学意义(P<0.05)。治疗前、治疗后3个月,BCVA、IOP、视盘内及周围血流密度比较,差异均无统计学意义(P>0.05)。术后短期内30例患者未发生严重并发症,但均出现轻度结膜充血水肿,症状2周后明显缓解,有3例(3只眼)出现轻度视物变形,4例(4只眼)出现一过性眼压升高,使用7 d降眼压滴眼液后均改善。结论:应用异体硬脑膜行改良PSR治疗PM安全可行,改善黄斑区视网膜血流循环,延缓SE、眼轴长度增长。

改良巩膜扣带手术与玻璃体切割术在孔源性视网膜脱离治疗中的效果比较

目的比较改良巩膜扣带手术(RSB)与玻璃体切割术(PPV)在孔源性视网膜脱离治疗中的效果。方法回顾性分析,收集信阳职业技术学院附属医院在2020年6月至2022年6月收治的93例孔源性视网膜脱离患者的临床资料,根据手术方式将入选患者分为观察组(RSB治疗,47例)和对照组(PPV治疗,46例)。两组患者均完成6个月的随访,比较两组患者术后视网膜复位情况,术前、术后1周、术后3个月、术后6个月最佳矫正视力(BCVA)以及术后并发症发生情况。结果观察组初次手术视网膜复位成功率低于对照组,但差异无统计学意义(χ^(2)=0.156,P=0.693)。两组术前、术后6个月BCVA比较,差异无统计学意义(P>0.05);两组术后1周、术后3个月、术后6个月BCVA均较术前逐渐降低,且观察组术后1周、术后3个月BCVA比对照组低,组间、时点、组间时点交互作用有统计学意义(P<0.05)。观察组并发症总发生率较对照组低,差异有统计学意义(P<0.05)。结论RSB与PPV均可有效复位孔源性视网膜脱离患者的视网膜,促进患者视力改善。但与PPV相比,孔源性视网膜脱离患者RSB术后早期视力恢复较快,术后并发症发生率较低。

设置多级屈服耗能BRB的桥梁排架墩等能量设计方法

传统防屈曲支撑(BRB)被广泛用于桥梁排架墩的减震控制,但其屈服后刚度较低和变形能力较小,难以有效控制强震下的峰值位移和残余位移。为此,将传统单一材料组成的BRB核心变形段替换为两种具有不同屈服点的材料,使其整体力学特性呈分级屈服的多线性,形成多级屈服耗能的防屈曲支撑(MSBRB)。将MSBRB作为保险丝构件应用于排架墩以提升其抗震性能,采用等能量的设计方法,以设置MSBRB排架墩体系的能力曲线为设计目标,考虑体系在逐渐增强的地震动荷载作用下的塑性发展机制和能力曲线特征,在中国公路抗震设计规范基础上发展了三阶段的抗震设计流程。最后,结合一排架墩设计案例并通过非线性时程分析证明了所提出设计方法的可行性和准确性。结果表明:设计方法可以较好地预测不同地震水平下MSBRB排架墩体系的性能状态,设计值与模拟值最大误差不超过6%,能达到不同地震水平的设计目标;设置MSBRB能显著降低排架墩的墩顶位移,E2地震作用水平下可使排架墩保持弹性状态,在更强的地震水平下也可有效降低排架墩的损伤,说明MSBRB可更为高效地提升排架墩抗震性能,实现排架墩的损伤控制。