Importance of 3-D image reconstruction of spectraldomain OCT on outcome of grid laser photocoagulation for diffuse diabetic macular edema

AIM:To present the outcome of modified grid laser photocoagulation(GLP)in diffuse diabetic macular edema(DDME)in eyes without extrafoveal and/or vitreofoveal traction.METHODS:Inclusion criteria for the retrospective study were DDME eyes of patients with typeⅡdiabetes mellitus that had≥4 months of follow-up following GLP.Only one eye per patient was analyzed.Using 3-D spectral-domain optical coherence tomography(3-D SDOCT),eyes that had either extrafoveal or vitreofoveal traction,or had been previously treated by an intravitreal medication(s)were excluded.Treated DDME eyes were divided into 4 groups:A)"Classic"DDME that involved the central macula;B)edema did not involve the macular center;C)eyes associated with central epiretinal membrane(ERM);D)DDME that was associated with macular capillary dropout≥2 disc-diameter(DD).RESULTS:GLP outcome in 35 DDME eyes after 4-24(mean,13.1±6.9)months was as follows:Group A)18eyes with"classic"DDME.Following one or 2(mean,1.2)GLP treatments,best-corrected visual acuity(BCVA)improved by 1-2 Snellen lines in 44.4%(8/18)of eyes,and worsened by 1 line in 11.1%(2/18).Central macular thickness(CMT)improved by 7%-49%(mean,26.6%)in77.8%(14/18)of eyes.Causes of CMT worsening(n=4)were commonly explainable,predominantly(n=3)associated with emergence of extrafoveal traction,5-9months post-GLP.Group B)GLP(s)in DDME that did not involve the macular center(n=6)resulted in improved BCVA by 1-2 lines in 2 eyes.However,the central macula became involved in the edema process after the GLP in 3(50%)eyes,associated with an emergence of extrafoveal traction in one of these eyes 4months following the GLP.Group C)GLP failed in all 5eyes associated with central ERM.Group D)GLP was of partial benefit in 2 of 6 treated eyes with macular capillary dropout≥2DD.CONCLUSION:Eyes with DDME that involved the macular center were found to achieve favourable outcomes after GLP(s)during mid-term follow-up,unless complicated pre-GLP or post-GLP by vltreoretinal interface abnormalities,often extrafoveal traction or ERM,or by capillary dropout≥2DD.Prospective studies with larger cohorts are required.

Comparison of anti-vascular endothelial growth factors, laser treatments and a combination of the both for treatment of central retinal vein occlusion

AIM：To compare changes in visual acuity and macular edema in patients with central retinal vein occlusion（CRVO）treated with intravitreal injections of bevacizumab,macular grid photocoagulation combined with pan retinal photocoagulation（PRP）,or both（bevacizumab＋grid＋PRP）.· METHODS：Our study is a retrospective cohort clinical study that examined patients that suffered from ischemic CRVO with macular edema.Study inclusion criteria were ischemic CRVO with macula edema and the availability of complete medical records for at least 12 mo after treatment.Excluded were patients with diabetes or any other retinal disease.We reviewed the medical records of patients treated in one ophthalmology departmentcomparing changes in visual acuity and macular edema in patients treated with intravitreal injections of bevacizumab vs those that were treated with macular grid photocoagulation and PRP or both.The main outcome measures were the differences in best corrected visual acuity（BCVA） and in macular thickness,as assessed by optical coherence tomography,between the enrollment and the final follow up visits.· RESULTS：Sixty-five patients met inclusion criteria.There were no statistically significant differences among the three groups in the mean changes in macular thickness as measured by ocular coherence tomography（131.5±41.2,108.6±29.2,and 121.1±121.1,P=0.110）,or in visual acuity（0.128±0.077,0.088±0.057,and 0.095±0.065）,for intravitreal injections,macular grid photocoagulation＋PRP and a combination of the treatments,respectively,P =0.111.The proportions of patients with macular edema after treatment were：26.1%,28.6%,and 14.3%,respectively,P=0.499.· CONCLUSION：Similar benefit was observed for intravitreal injections,laser photocoagulation,or a combined regimen in the treatment of CRVO.A nonstatistically significant trend for reduction in macular edema was observed following combined treatment.

Is laser photocoagulation still effective in diabetic macular edema? Assessment with optical coherence tomography in Nepal

AIM: To find out the outcome of laser photocoagulation in clinically significant macular edema (CSME) by optical coherence tomography (OCT). · METHODS: It was a prospective, non-controlled, case series study enrolling 81 eyes of 64 patients with CSME between August 2008 and January 2010. All patients received modified grid photocoagulation with frequency doubled Nd: YAG laser. Each patient was evaluated in terms of best-corrected visual acuity (BCVA) and regression or progression of maculopathy after laser therapy at 1, 3 and 6 months. Spearman’s correlation test was used to show the correlation between BCVA and total macular volume (TMV). Analysis of variance (ANOVA) was used to compare among groups and independent t-test was used to compare in each group. · RESULTS: There is high correlation between BCVA and TMV (P ≤0.001). BCVA improved in 50.6%, remained static in 39.5 % and deteriorated in 9.9% patients after 6 month of treatment. The Baseline TMV (mean and SD) were 9.26±1.83, 10.4±2.38, 11.5±3.05, 8.89±0.75 and 9.47±1.98 mm3 for different OCT patterns, ST (sponge like thickening), CMO (cystoid macular edema), SFD (subfoveal detachment), VMIA (Vitreo macular interface abnormality) and average TMV respectively (P =0.04). After 6 months of laser treatment, the mean TMV decreased from 9.47±1.98mm3 to 8.77±1.31mm3(P =0.01). In ST there was significant decrease in TMV, P =0.01, Further within these groups at 6 months, they were significantly different, P =0.01. · CONCLUSION: OCT showed the different morphological variant of CSME while the response of treatment is different. TMV decreased the most and hence showed the improvement in vision after 6 months of laser treatment. In the era of Anti vascular endothelial growth factors (VEGFs), efficacy of laser seems to be in shadow but it is still first line of treatment in developing nation like Nepal where antiVEGFs may not be easily available and affordable.

基于移动多线激光雷达扫描的树冠叶面积估计方法

移动单线激光雷达(Laser detection and ranging,LiDAR)扫描(Mobile single-layer LiDAR scanning,MSLS)树冠叶面积估计方法使用单一视角的单线激光雷达采集树冠点云数据,获取的冠层信息不够全面,限制了树冠叶面积估计精度。本文提出一种基于移动多线LiDAR扫描(Mobile multi-layer LiDAR scanning,MMLS)的树冠叶面积估计方法,使用多线LiDAR从多个视角采集树冠点云数据,提升树冠叶面积估计精度。首先,将多线LiDAR采集的点云数据变换到世界坐标系下,通过感兴趣区域(Region of interest,ROI)提取出树冠点云。然后,提出一种MMLS树冠点云融合方法,逐个融合单个激光器采集的树冠点云,设置距离阈值删除重复点,添加新点。最后,构建MMLS空间分辨率网格,建立基于树冠网格面积的树冠叶面积估计模型。实验使用VLP-16型多线LiDAR传感器搭建MMLS系统,设置1、1.5 m 2个测量距离和间隔45°的8个测量角度对6个具有不同冠层密度的树冠进行数据采集,共得到96个树冠样本。采用本文方法,树冠叶面积线性估计模型的均方根误差(Root mean squared error,RMSE)为0.1041 m^(2),比MSLS模型降低0.0578 m^(2),决定系数R^(2)为0.9526,比MSLS模型提高0.0675。实验结果表明,本文方法通过多线LiDAR多视角树冠点云数据采集、MMLS树冠点云融合和空间分辨率网格构建,有效提升了树冠叶面积估计精度。

一种基于激光点云数据的微距栅格体积算法

针对规则格网算法难以满足激光点云模型高精度体积计算的问题,提出了一种基于激光雷达点云数据的微距栅格体积算法。该方法首先运用葛立恒凸包算法提取凸包点集,然后运用微距格网划分、高程插值和网格体积累加的方法计算体积。与规则格网法不同,这种算法充分利用激光雷达数据高密度点云特征,采用格网微分和增大插值半径的方法改善模型表面的连续性,进而提高计算精度。实验结果表明,微距栅格体积算法具有较好的时间复杂度和较高的计算精度,适宜于激光点云模型高精度体积计算。

无人机载智能塔基定位放样方法研究

电网工程架空线路塔杆放样多在复杂山区进行,传统基于经纬仪、全站仪和手持差分卫星定位等设备的放样方式劳动强度大、耗时长且数据易出错。提出了一种无人机载智能塔基定位的放样方法,该方法以无人机、激光投点器为硬件基础,研究开发智能放样软件。将电网工程架空线路上各塔杆中心桩坐标输入智能放样软件平台,可实时计算各塔杆20个放样点的平面坐标,并根据DEM模型、地表树木、交通线路及其他障碍物分布状况自动规划无人机放样航线、调整航高,在各放样点上方悬停后进行激光投点,高效引导地表人员快速确定放样点位。经过多轮测试,结果表明:采用无人机载智能塔基定位放样系统可快速、高精度完成输电线路塔杆放样,大幅降低了传统放样方式中放样点布设的次数与时长,为电网施工放样提供了有效支撑。

TK50/AP复合物三维纳米网格结构的构筑及其性能研究

为了改善1,1’-二羟基-5,5’-联四唑二羟胺盐(TK50)的释能特性,采用冰模板法构筑了TK50/高氯酸铵(AP)(TK50/AP)复合物三维纳米网格结构。通过场发射扫描电子显微镜、X射线粉末衍射、差示扫描量热仪、比表面积和孔径分析仪、热-红联用仪及激光点火装置对其形貌、微结构、热分解和燃烧性能进行了研究。结果表明,TK50/AP复合物的三维纳米网格结构包含大量的中孔(2~6 nm),比表面积和孔体积分别为7.059m^(2)·g^(-1)和0.09 cm^(3)·g^(-1)。XRD衍射峰强度大大降低,由Scherrer公式计算的平均晶粒度为83.80 nm。DSC曲线有2个放热峰,位于228.1℃处尖锐的强放热峰,其峰温较原料TK50提前12℃,活化能增加144.86 kJ·mol^(-1);位于325.6℃处弱的宽峰,其峰温较原料AP提前105.6℃,活化能增加24.21 kJ·mol^(-1)。热-红联用测试结果表明复合物的热分解速率更快、能量释放更完全。TK50/AP复合物表现出高效稳定的激光点火燃烧(LIC)性能,点火延迟时间从原料TK50的50 ms、混合物的60 ms降低到20 ms,激光点火阈值从原料TK50的25.12 mJ、混合物的12.56 mJ降低到6.28 mJ。复合物的纳米尺寸效应和多孔网格结构优异的传热传质特性是其热分解和LIC性能显著改善的主要原因。

黄斑格栅样激光光凝联合玻璃体注射雷珠单抗、曲安奈德治疗视网膜静脉阻塞性黄斑水肿的效果及对视网膜血流参数的影响

目的探究黄斑格栅样激光光凝联合玻璃体注射雷珠单抗、曲安奈德治疗视网膜静脉阻塞性黄斑水肿的效果。方法选择2019年1月至2022年10月我院收治的300例视网膜静脉阻塞性黄斑水肿患者为研究对象,以随机数字表法将其分为对照组和观察组,各150例。对照组接受黄斑格栅样激光光凝+曲安奈德治疗,观察组在对照组基础上加施玻璃体注射雷珠单抗治疗。比较两组的治疗效果。结果观察组的治疗总有效率高于对照组(P<0.05)。治疗3个月后,观察组的视网膜中央收缩期峰值流速(PSV)、舒张期峰值流速(EDV)高于对照组(P<0.05)。出院时,观察组的结缔组织生长因子(CTGF)、血小板源性生长因子-C(PDGF-C)及血管内皮生长因子(VEGF)水平低于对照组(P<0.05)。治疗3个月后,观察组的三叶草像差、总高阶像差、球差及彗差优于对照组(P<0.05)。结论黄斑格栅样激光光凝联合玻璃体注射雷珠单抗、曲安奈德治疗视网膜静脉阻塞性黄斑水肿效果满意,可调节生长因子表达,改善视网膜血流参数及视觉质量,值得推广。

基于车载激光扫描点云数据的杆状地物提取方法研究

杆状物作为道路场景中重要的公共设施,研究如何对其进行自动化精确分类十分重要。本文基于车载激光扫描点云数据,提出一种基于聚类的杆状物自动提取方法。主要实现步骤为:首先,对原始道路车载激光点云数据进行水平面投影并构建格网,以格网为单位进行地物点提取;其次,基于格网对地物点进行聚类;最后,以聚类结果的单个点云块为处理单元,根据地物的空间表达特征实现杆状物的精细提取与分类。为了对本文提出杆状物方法的有效性进行检验,使用实测道路点云数据进行实验,并将杆状物提取结果与人工提取结果进行对比,结果表明,灯杆与行道树均取得较高的探测率,证明了算法的正确性与优越性。

轮廓几何特征融合下的电网设备激光除锈控制参数自适应确定方法

基于激光除锈轮廓特征,在进行电网设备除锈控制参数确定时,主要依托于单一的轮廓几何特征,导致除锈后表面粗糙度偏差较大。设计一种以轮廓几何特征融合为核心的参数自适应确定方法,根据激光除锈工作原理,建立激光除锈有限元模型。采用边界矩分析算法,提取电网设备除锈的多个轮廓几何特征;融合多个轮廓几何特征,设计基于融合特征的参数确定方法,有效选择各项控制参数;通过响应面分析,自适应确定电网设备激光除锈控制参数。实验结果表明:该方法可使除锈后表面粗糙度与目标表面粗糙度值之间偏差减小2.7μm,与其他激光除锈控制参数设置结果相比,除锈后表面粗糙度偏差降低了54.24%、63.51%。

Intravitreal Bevacizumab with Grid Photocoagulation for Recurrent Macular Edema Secondary to Retinal Vein Occlusion

Purpose: To assess the efficacy of intravitreal bevacizumab (IVB) combined with grid photocoagulation in the management of recurrent macular edema secondary to retinal vein occlusion (RVO). Methods: This is a prospective, non-randomized, interventional study. Thirty five eyes with branch retinal vein occlusion (BRVO) and 15 eyes with central retinal vein occlusion (CRVO) were treated with grid photocoagulation combined with IVB for recurrent macular edema. The visual acuity, central macular thickness and intraocular pressure were outcome measures. The mean duration of follow-up was 18.1 ± 3.6 months. Results: One month after treatment, 45 of the 50 eyes showed complete resolution of the cystoid space. Compared with initial values, final central macular thickness was reduced significantly in both BRVO and CRVO groups (P < 0.001), but improvement in VA was significant only for eyes with BRVO (P = 0.012). The total number of IVB was 1.8 ± 0.3 for eyes with either BRVO or CRVO. Conclusion: IVB combined with grid photocoagulation is an effective treatment for reducing recurrent macular edema associated with RVO.

The Effect of Microstructural and Geometric Inhomogeneities Induced by Laser for Forming Strain Analysis on Sheet Metal Formability

A commercially available laser marking system based on diode-pumped Nd:YVO4 laser was used for creating grid patterns for forming strain analysis of a dual-phase steel. The aim was to determine and analyze the influence of laser working parameters on the formability of sheet material by means of an in-depth characterization of this induced microstructural and geometric inhomogeneity. The electrochemical etching served as the reference method without the negative effect of generating inhomogeneity. The formability was evaluated using the cupping test according to Erichsen. While the quantification of geometric inhomogeneity was based on the determination of the notch factor, light microscopy and microhardness measurement were used for the evaluation of microstructural inhomogeneity. Furthermore, on the basis of the results an empirical regression model was established which described in terms of quantity the relationship between the examined factors such as laser power, pulse frequency and scanning speed as well as the command variable and the mark depth. The results showed that microstructural inhomogeneity in the used marking parameters due to their locally very limited formation did not have an appreciable influence on the mechanical properties. In contrast to this, the induced geometric inhomogeneity had a marked influence on the material formability.

基于激光雷达与深度相机融合的SLAM算法

针对单一传感器地图构建时存在环境表征不充分,无法为移动机器人自主导航提供完整环境地图等问题,本文通过将激光雷达与深度相机获取的环境信息进行互补融合,构建出更完整精确的栅格地图。首先,对传统ORB-SLAM2算法进行增强,使其具备稠密点云地图构建、八叉树地图构建以及栅格地图构建等功能。其次,为验证增强后ORB-SLAM2算法的性能,在fr1_desk1数据集和真实场景下进行测试,数据显示增强后ORB-SLAM2算法绝对位姿误差降低52.2%,相机跟踪轨迹增长14.7%,定位更加精准。然后,D435i型深度相机采用增强型ORB-SLAM2算法,激光雷达采用的Gmapping-Slam算法,按照贝叶斯估计的规则进行互补融合构建全局栅格地图。最后,搭建实验平台进行验证,并分别与深度相机和激光雷达2个传感器建图效果进行对比。实验结果表明,本文融合算法对周围障碍物的识别能力更强,可获取更完整的环境信息,地图构建更加清晰精确,满足移动机器人导航与路径规划的需要。

雷珠单抗联合黄斑区格栅光凝治疗视网膜静脉阻塞继发黄斑水肿的效果观察

目的观察雷珠单抗联合黄斑区格栅光凝治疗视网膜静脉阻塞(RVO)继发黄斑水肿(ME的疗效。方法59例(59眼)视网膜静脉阻塞继发黄斑水肿患者,随机分为治疗组(30例,30眼)和对照组(29例,29眼)。对照组给予雷珠单抗治疗,治疗组给予雷珠单抗联合黄斑区格栅光凝治疗。比较两组患者治疗前后标准对数视力表(LogMAR)最佳矫正视力(BCVA)、黄斑中心凹厚度(CMT)及治疗6个月内雷珠单抗注射次数。结果治疗前及治疗1周、1个月、2个月,两组LogMAR BCVA比较,差异无统计学意义(P>0.05);治疗1周及1、2、6个月,两组LogMAR BCVA均低于治疗前,差异有统计学意义(P<0.05);治疗6个月,治疗组LogMAR BCVA(0.44±0.31)低于对照组的(0.80±0.10),差异有统计学意义(P<0.05)。治疗前及治疗1周、1个月、2个月,两组MCT比较,差异无统计学意义(P>0.05);治疗1周及1、2、6个月,两组MCT均低于治疗前,差异有统计学意义(P<0.05);治疗6个月,治疗组MCT(227.17±114.26)μm低于对照组的(358.00±171.00)μm,差异有统计学意义(P<0.05)。治疗组治疗6个月内雷珠单抗注射次数为(2.60±0.73)次,少于对照组的(3.07±0.80)次,差异有统计学意义(P<0.05)。结论雷珠单抗联合黄斑区格栅光凝治疗视网膜静脉阻塞继发黄斑水肿可逐步提高视力,减轻黄斑水肿,两者联合治疗更能减少就诊次数,减轻患者经济负担。

New Technology for Grids and Scales Manufacturing in Optical Devices

Using the laser controlled thermocracking method, research results for the new technology of optical grids and scales manufacturing are given in this paper. The opportunity of grids and scales manufacturing is shown for a wide range of the sizes, scale’s pitches and its width: from 10 nanometers up to 10 microns with a backlight in various optical ranges.

基于激光扫描和三维栅格地图的掘进巷道空间建模方法研究

采用常规煤矿巷道三维点云信息地图建模方法得到的点云数据庞大而繁杂,运算量很大,因此提出了基于激光扫描和三维栅格地图的掘进机截割成形三维扫描系统和掘进巷道空间建模方法。将点云数据与三维栅格进行映射,将巷道空间划分为有限个栅格,构成巷道空间三维栅格地图,并将三维栅格地图划分为多个功能区域。通过三维扫描激光雷达坐标系与巷道坐标系的转换,实现了将激光雷达获取的点云数据转换为巷道外轮廓数据,来分析掘进机截割的超挖和欠挖误差。实验表明,当三维栅格边长设定为10 cm时,采用由截割成形巷道三维栅格地图建模方法得到的栅格地图指导掘进机自主截割作业,相比采用常规点云地图可减少84.7%的数据处理量,极大减轻了截割控制系统处理器的负担。研究结果为基于激光雷达三维扫描的掘进机自主截割作业系统的设计及应用提供了依据。

基于三维激光扫描的高拱坝仓面钢筋网智能识别方法

为实现高拱坝仓面混凝土智能化振捣施工,针对仓面边角区域钢筋网密布、不利于振捣棒插入的问题,提出了基于三维激光扫描的高拱坝仓面钢筋网智能识别方法。首先,通过激光雷达感知获取点云数据;然后,基于水平Azimuth和反射强度筛选点云并映射以计算其分布情况;最后,分析点云分布并建立钢筋网格点坐标,实现钢筋网智能识别。该方法在某混凝土坝工程中进行了试验验证,经检验方法可行,为钢筋网区域的精细化振捣提供了技术支撑。

架空线路综合在线监测系统设计与安装研究

为解决自然或人为因素造成的架空线路事故问题,本研究以激光探测技术为基础,设计了一种将监测模块与信息模块进行串联的在线监测系统,该系统可以达到实时动态网络监测的效果。采用模拟实验的形式验证系统有效性,研究结果显示系统的线路设备和附属设备监测准确率均达到0.9以上。由此可见,研究设计的在线监测系统具有有效性,能够保障架空线路的整体安全。

三维扫描技术在网架提升中的应用

三维激光扫描技术是近年来发展起来的一项新型技术,在多个领域都有成功应用,将三维激光扫描技术应用到大型大跨度机库网架提升全过程中也是一次传统技术的升华和革新,用整体数据模型实时分析的方式替代了传统人工单点测量控制方式,用可视化自动三维模式取代了人工量测、分析、二维线划图的方式。为确保钢结构网架提升拼接质量,全面分析网架提升过程的安全、稳定,获取钢结构网架施工过程中的各项数据信息,利用三维激光扫描技术对网架提升全过程形态进行扫描,获取过程实时数据,为网架提升以及变形监测提供数据模型信息。

振镜扫描激光清除电网异物数值仿真研究

针对振镜激光清除高压输电线异物二维扫描技术扫描不均匀的问题,结合振镜的扫描原理,通过简单的扫描理论推导和Matlab仿真分析,利用COMSOL有限元对激光扫描轨迹进行仿真模拟。设计X-Y检流计振镜扫描进行区域全覆盖扫描,得出X-Y检流计振镜扫描存在矩形失真特性,故通过三角函数变换的思路进行补偿修正,修正后的扫描轨迹效果较好,由上到下逐行扫描,且扫描较为完整,不存在漏扫。为实现振镜式激光光斑区域全覆盖扫描,进行扫描路径设计理论推导和仿真。结果表明:随着扫描线距的增加,漏扫率逐渐增大,重叠率逐渐减小;当扫描线距与光斑半径相等时,光斑恰好没有重叠区域,重叠率为0,漏扫率为27.37%。通过COMSOL有限元对光斑轨迹扫描进行仿真,进一步说明了所提扫描方法的可行性和正确性,在振镜激光扫描系统中有着重要的参考价值。