基于立体视觉的虹膜膨隆三维信息的实验方法探索

目的设计一种基于立体视觉技术的虹膜组织膨隆变形研究的实验系统,并在系统保持虹膜环状形态结构和组织活性条件下,通过测量计算出虹膜组织在模拟前后房压强差变化的情况下发生膨隆变形的三维信息。方法利用模拟瞳孔阻滞和虹膜膨隆的实验设备获得兔虹膜组织随前后房压强差增加而膨隆变彤的二维图像,再利用立体视觉技术计算虹膜组织发生膨隆变形的三维信息。结果本研究得到模拟前后房压强差分别为100Pa、200Pa时虹膜膨隆的二维曲线和三维信息。结果证实随着前后房压强差增大,虹膜发生膨隆变形。虹膜膨隆的二维曲线的切线和虹膜径向之间的夹角越大,房角越小,此时发生闭角型青光眼的可能性越大。     

基于立体视觉的虹膜膨隆三维信息的实验方法探索

目的设计一种基于立体视觉技术的虹膜组织膨隆变形研究的实验系统,并在系统保持虹膜环状形态结构和组织活性条件下,通过测量计算出虹膜组织在模拟前后房压强差变化的情况下发生膨隆变形的三维信息。方法利用模拟瞳孔阻滞和虹膜膨隆的实验设备获得兔虹膜组织随前后房压强差增加而膨隆变形的二维图像,再利用立体视觉技术计算虹膜组织发生膨隆变形的三维信息。结果本研究得到模拟前后房压强差分别为100Pa、200Pa时虹膜膨隆的二维曲线和三维信息。结果证实随着前后房压强差增大,虹膜发生膨隆变形。虹膜膨隆的二维曲线的切线和虹膜径向之间的夹角越大,房角越小,此时发生闭角型青光眼的可能性越大。     

虹膜膨隆变形及房角开放度的实验研究

目的对原有实验系统进行改进,并对兔眼虹膜在不同前后房压强差产生的膨隆变形及房角开放度进行实验研究。方法在保持虹膜环状形态结构和组织活性特征的前提下,搭建模拟完全瞳孔阻滞和虹膜膨隆的实验平台,获得兔眼虹膜随前后房压强差变化时的膨隆变形二维图像;再利用立体视觉技术得到膨隆变形的三维信息,并计算出膨隆曲线上虹膜根部所在点的切线斜率和虹膜膨隆最高点的曲率半径,由此对房角开放度进行衡量。结果当前后房压强差在50～200Pa之间时,虹膜根部斜率在0.29～0.55范围内逐渐增大,曲率半径在16.13～6.67的范围内迅速减小,房角在30°～15°的范围内变化;而当前后房压强差增大到200～600Pa之间时,虹膜根部斜率在0.55～0.76的范围内逐渐增大,曲率半径在6.67～4.25的范围内逐渐减小,房角在15°～10°的范围内缓慢减小。结论本文提出了一种可行的定量研究虹膜膨隆变形及房角开放度的理论和实验方法,研究结果与临床观察及研究相一致。     

一种虹膜膨隆形态提取与建模方法的研究

为研究虹膜膨隆形态与瞳孔阻滞的关系,提出了一种根据裂隙图像提取虹膜膨隆形态的方法。通过灰度变换、二值化处理、角度校正及曲线拟合等方法对图像进行处理。建立了不同压强差下无晶体抬升时虹膜膨隆形态二维曲线及三维曲面模型;以及相同压强差下晶体抬升高度不同时虹膜膨隆形态的二维曲线及三维曲面模型。从实验结果可以看出,随着压强差的不断增大,虹膜逐渐膨隆;在相同的压强差下,相对于没有晶体抬升,有晶体抬升的虹膜膨隆程度更大。     

一种虹膜膨隆形态提取与建模方法的研究

为研究虹膜膨隆形态与瞳孔阻滞的关系,提出了一种根据裂隙图像提取虹膜膨隆形态的方法.通过灰度变换、二值化处理、角度校正及曲线拟合等方法对图像进行处理.建立了不同压强差下无晶体抬升时虹膜膨隆形态二维曲线及三维曲面模型;以及相同压强差下晶体抬升高度不同时虹膜膨隆形态的二维曲线及三维曲面模型.从实验结果可以看出,随着压强差的不断增大,虹膜逐渐膨隆;在相同的压强差下,相对于没有晶体抬升,有晶体抬升的虹膜膨隆程度更大.     

在体兔眼虹膜材料模型的确定

【摘 要】 目的:确定适合表征在体虹膜力学行为的材料模型。 方法:基于在体动物实验,建立眼前节有限元模型。假设虹膜材料分别为线弹性模型、Neo-Hookean模型和二阶Ogden模型,参考相应文献,设定材料参数范围,计算对应的虹膜特征点位移。基于在体实验的测量结果,利用目标函数,比较不同模型间的差异。 结果:二阶Ogden模型对应的目标函数的最小值和平均值均最小,Neo-Hookean模型次之,线弹性模型的最大。 结论:3种模型相比,二阶Ogden模型最适合用于描述在体虹膜的力学行为。     

基于膨隆实验的血管非线性力学特性确定方法

目的基于实验测试和数值模拟结果,建立反方法确定血管的非线性力学特性。方法采用自行设计的实验装置,对血管进行压力加载,获取血管膨隆的实验数据;假设血管材料特性符合超弹性Ogden模型,建立血管膨隆的有限元模型,然后结合实测数据及数值模拟结果,利用优化算法建立反方法确定血管的力学特性。结果得到了描述兔腹主动脉非线性力学特性的Ogden模型一阶和二阶的材料参数,其中一阶Ogden模型参数α=10.86±1.98。经验证兔腹主动脉的力学特性可用超弹性力学模型描述。结论基于实验测试和数值模拟方法建立的反方法可用来识别血管的非线性力学特性。     

实时剪切波弹性成像技术定量评价正常成人睾丸、附睾

目的测量正常成人睾丸、附睾的影像弹性模量值,为临床研究提供理论依据。方法利用具有实时剪切波弹性成像(SWE)技术的彩色多普勒超声诊断仪对400名志愿者睾丸、附睾进行检查,获得弹性模量值进行统计学分析。结果睾丸中心部与周边部的纵切面弹性平均值分别为(4.236±0.315)k Pa和(4.176±0.149)k Pa,横切面弹性平均值分别为(4.105±0.158)k Pa和(4.121±0.182)k Pa。附睾头及附睾尾纵切面的弹性平均值分别为(5.629±0.275)k Pa和(5.371±0.111)k Pa,横切面的弹性平均值分别为(5.743±0.237)k Pa和(5.500±0.141)k Pa。结论睾丸及附睾测量的不同部位、不同切面不是影响睾丸及附睾弹性模量值的显著因素。     

血管壁弹性模量对颈动脉狭窄血流储备分数的影响

目的探索将血流储备分数(fractional flow reserve,FFR)引入颈动脉狭窄评估的可行性,并且分析血管壁弹性模量对颈动脉狭窄中血液动力学参数和FFR计算结果的影响。方法利用计算机辅助设计软件建立颈动脉分叉标准模型并获得不同狭窄率的模型。假设血管壁为线弹性材料,血液为不可压缩牛顿流体,在脉动流条件下,利用有限元分析软件进行颈动脉狭窄模型中血液流动的流固耦数值模拟,获得各种血液动力学参数,并计算相应的FFR值。结果当弹性模量固定时,随着狭窄率增加,模型中狭窄部位的FFR逐渐减小,且此时其弹性壁与刚性壁的FFR相对差异随着狭窄率的增加而增加;当狭窄率固定为70%时,随着弹性模量增加,FFR会逐渐减小。结论采用FFR对颈动脉狭窄程度进行功能性评估需要考虑血管壁弹性的影响;狭窄率越大,血管壁弹性模量对FFR的影响越大。     

一种高通量测量单细胞弹性模量的微流控芯片

目的设计微流控芯片以便高效简便地捕获大量单细胞并测量其弹性模量。方法根据流体力学原理,设计微流控阵列及其单细胞捕获单元的通道结构和几何尺寸。培养海拉细胞,制作微流控芯片实物,并采用该芯片进行单细胞捕获实验。采用COMSOL软件对作用在被捕获细胞上的剪切力和压差进行有限元仿真。根据作用在被捕获细胞两侧的压差值和细胞在捕获通道中的伸长长度,计算出细胞的弹性模量。结果所设计的微流控芯片能有效地捕获大量单细胞;计算的单细胞弹性模量为780.7Pa±100.5Pa,与文献中报道的763Pa±93Pa接近。结论本文所提出的微流控芯片可高效捕获单细胞并测量单细胞力学特性。     

虹膜组织力学特性的实验研究

目的 模拟眼内前后房压强差，对人眼和兔眼虹膜整体加压，研究其力学特性。方法将瞳孔水密缝合，不破坏其几何形态，对虹膜整体加压。结果 首次实现了对虹膜整体力学特性的认识，人眼和兔眼虹膜力学特性相似，虹膜是典型的粘弹性物质，面积模量与前后房压强差之间基本呈线性关系，并且在相同的前后房压强差下人眼虹膜的面积模量比兔眼虹模的略小。结论 实验结果可为青光眼致盲机理解释和瞳孔阻滞力的估算提供参考；同时，经适当修正后，兔虹膜可作为人虹膜力学特性的研究样本，大大降低研究成本。     

正常兔眼后房压强及前后房压强差值的在体监测

目的 寻求一种眼后房穿刺方法,并在体测量兔眼的前、后房压强差.方法 利用高精度压力传感器与空气差压传感器,采用＂从角巩膜缘外周1～1.5mm处进针穿透巩膜,使针水平滑行于虹膜下而进入后房＂的扎针方法,实现在体连续监测正常兔眼麻醉状态下的后房压强与前后房压强差值.结果 麻醉状态下兔眼后房压强的范围在839.93～2662.48Pa;前、后房压强差范围是46.15～85.52Pa,均值为59.73Pa,变化周期为11.17min.结论 扎针方法测量兔眼后房压强及前后房压强差值对眼球损伤较小,监测到的正常兔眼后房压强及前后房压强差值均在合理可信的范围内.监测方法的可行性为青光眼前后房压强差值的在体监测提供了新的思路.     

Aqueous humor dynamics and the iris

Solutes concentration in the aqueous humor of the eye is highest near the ciliary processes in the posterior chamber (p.c.) and lowest near the trabecular meshwork in the anterior chamber (a.c.). The high osmotic gradient across the semipermeable iris causes it to easily move forward at this location and occasionally occlude the iridocorneal angle. Vector analysis of the forces generated by miosis helps explain on osmotic grounds why it reduces the intraocular pressure, while at the same time the analysis elucidates the reason for the higher frequency of angle closure glaucoma when the anterior chamber is shallow.     

Phenotypic and immunoregulatory characteristics of monocytic iris cells

The introduction of antigen into the anterior chamber of an eye induces the antigen-specific suppression of cell-mediated immunity and the antigen-induced production of immunoglobulin G2 antibodies. To define further the role of iris monocytic cells in the systemic suppression of cell-mediated immunity that follows the entry of foreign antigen into the anterior chamber, murine iris wholemounts or cell suspensions of iris cells were stained with fluorescent anti-F4/80 and/or anti-CD11c, anti-CD11b antibodies and examined by confocal microscopy or flow cytometry, respectively. Monocytic cells in iris cell suspensions were recovered from mice receiving an injection of trinitrophenylated bovine serum albumin (TNP-BSA) into an anterior chamber and Percoll-enriched iris cells separated into cells expressing F4/80 or CD11c were injected intravenously into TNP-BSA-immunized or naive recipients. The recipients were challenged to induce delayed-type hypersensitivity (DTH) or were provided with splenocytes or thymocytes that transfer the suppression of DTH. The homing of monocytic bone marrow cells to the iris was determined by the intravenous injection of bone marrow cells from green fluorescent protein (GFP)-transgenic donors into C57 mice, and the staining of recipient iris wholemounts with anti-F4/80 antibodies. Iris cells with a dendritic morphology expressing both F4/80 and/or CD11c and CD11b, some cells expressing only F4/80 or CD11c, were detected. The irides of irradiated GFP- mice that received intravenous GFP+ bone marrow cells contained GFP+ F4/80+ cells. F4/80+ and CD11c+ cells from the irides of donors that received intracameral TNP-BSA transferred the suppression of DTH when injected intravenously into TNP-BSA-immunized recipients, activated immunoregulatory thymocytes and activated antigen-specific splenic regulatory effector cells. These results support the hypothesis that iris monocytic cells may participate in the systemic induction of regulatory T cells.     

Immature and mature neurofilament-immunoreactive trigeminal fibers can innervate the iris as studied by intraocular grafting of iris and trigeminal ganglia

Using immunohistochemistry on stretch-prepared whole mounts of adult rat irides, a dense, well-organized plexus of neurofilament-positive nerves originating in the trigeminal ganglion can be visualized. Such a two-dimensional tissue preparation is well-suited for studies on sensory and autonomic nerve fiber growth. In the present study the growth capacity of such neurofilament-positive nerves has been studied immunohistochemically. In irides homologously transplanted to the anterior eye chamber of adult albino rats, the intrinsic neurofilament-positive network had almost completely disappeared 4 days postoperatively. In whole mounts of iris grafts after 15 days and 4 weeks in oculo a gradually increasing plexus of nerves was observed. After 3.5 months in oculo a dense, regular network of fluorescent fibers had formed in the iris grafts to the same magnitude as in situ. However, whereas large axon bundles constituted a prominent feature of the distribution of neurofilament-positive nerves in situ, only a few and relatively thin axon bundles were seen in the grafts. The growth capacity of the neurofilament-positive trigeminal nerves was also studied by grafting fetal trigeminal ganglia to the anterior eye chamber. As visualized in cryostat sections, trigeminal grafts contained a large number of strongly fluorescent perikarya and a high density of positive fibers after intraocular maturation. Such grafts readily innervated the host iris. In the area immediately adjacent to the grafts, thin, parallel, rather weakly fluorescent fibers radiated out from the ganglia. When mature trigeminal grafts with attached host iris were regrafted to the anterior eye chamber of adult animals for a few days, in order to remove the intrinsic host iris innervation, such irides showed outgrowing fibers, often organized in small axon bundles, at long distances from the ganglion graft. The present report shows that both mature and immature neurofilament-immunoreactive neurons are capable of innervating the iris. Furthermore, this ingrowth can occur both in the presence and absence of normal intrinsic neurofilament-positive nerve fibers.     

基于主动脉流-固双向耦合数值模拟的微循环负载影响研究

目的研究微循环负载和其他生理结构的耦合关系,以构建合理的血流动力学模型。方法在双向流-固耦合管道模型的基础上,进一步考虑微循环负载的影响,构建具有弹性管壁的长直管和多孔介质渗流负载的模型。根据负载条件和血管壁弹性的不同计算4个算例,入口条件为瞬态单脉冲速度入口,出口条件为自由出口。结果管道内部压力处处保持在80~120 mm Hg(1 mm Hg=0.133 k Pa)。从静止状态开始,流场通过增加储存血液总量的方式提高舒张压,最终稳定在生理指标。血管壁弹性模量增加时,血压为65~140 mm Hg;而微循环阻力增加时,血压为128~166 mm Hg,微循环负载在循环系统中起到了阻碍流动并重新分配血管内压力的作用。结论在构建血流动力学模型时,必须考虑微循环负载及其耦合效应,特别对分析高血压等循环系统疾病的致病机制有重要的临床意义。