Fundus photography,fundus fluorescein angiography,and optical coherence tomography of healthy cynomolgus monkey,New Zealand rabbit,Sprague Dawley rat,and BALB/c mouse retinas

Background:A variety of experimental animal models are used in basic ophthalmological research to elucidate physiological mechanisms of vision and disease pathogenesis.The choice of animal model is based on the measurability of specific parameters or structures,the applicability of clinical measurement technologies,and the similarity to human eye function.Studies of eye pathology usually compare optical parameters between a healthy and altered state,so accurate baseline assessments are critical,but few reports have comprehensively examined the normal anatomical structures and physiological functions in these models.Methods:Three cynomolgus monkeys,six New Zealand rabbits,ten Sprague Dawley(SD)rats,and BALB/c mice were examined by fundus photography(FP),fundus fluorescein angiography(FFA),and optical coherence tomography(OCT).Results:Most retinal structures of cynomolgus monkey were anatomically similar to the corresponding human structures as revealed by FP,FFA,and OCT.New Zealand rabbits have large eyeballs,but they have large optic disc and myelinated retinal nerve fibers in their retinas,and the growth pattern of retinal vessels were also different to the human retinas.Unlike monkeys and rabbits,the retinal vessels of SD rats and BALB/c mice were widely distributed and clear.The OCT performance of them were similar with human beings except the macular.Conclusions:Monkey is a good model to study changes in retinal structure associated with fundus disease,rabbits are not suitable for studies on retinal vessel diseases and optic nerve diseases,and rats and mice are good models for retinal vascular diseases.These measures will help guide the choice of model and measurement technology and reduce the number of experimental animals required.

Fundus photography,fluorescein angiography,optical coherence tomography and electroretinography of preclinical animal models of ocular diseases

The eye is an immune-privileged and sensory organ in humans and animals.Anatomical,physiological,and pathobiological features share significant similarities across divergent species(1).Each compartment of the eye has a unique structure and function.The anterior and posterior compartments of the eye contain endothelium(cornea),epithelium(cornea,ciliary body,iris),muscle(ciliary body),vitreous and neuronal(retina)tissues,which make the eye suitable to evaluate efficacy and safety of tissue specific drugs(2).

Evaluating visual outcomes using optical coherence tomography(OCT)in pediatric multiple sclerosis and other neuroinflammatory conditions

Optical coherence tomography(OCT)is a technology that is widely used to assess structural abnormalities in the retina for a variety of pediatric conditions.The introduction of this instrument has allowed for widespread access to minimally invasive standardized,reproducible quantified structural assessments of the optic nerve and retina.This has had important implications in pediatric optic neuropathies,populations in whom monitoring of disease activity is essential to make treatment decisions.OCT has had particular relevance for inflammatory optic neuropathies,as onset of an inflammatory optic neuropathy may herald the onset of a chronic inflammatory disorder of the central nervous system(CNS)such as multiple sclerosis,neuromyelitis optica spectrum disorder(aquaporin 4 antibody positive),and myelin oligodendrocyte glycoprotein(MOG)associated disorders.This paper will focus on the application of OCT technology to this group of disorders in pediatrics.After reviewing pediatric-specific anatomic and practical issues pertinent to OCT,we will review knowledge related to the use of OCT in inflammatory pediatric optic neuropathies,with a focus on structural outcomes and their correlation with functional outcome metrics.

基于端到端深度神经网络和图搜索的OCT图像视网膜层边界分割方法

视网膜层边界的形态变化是眼部视网膜疾病出现的重要标志,光学相干断层扫描(optical coherence tomography,OCT)图像可以捕捉其细微变化,基于OCT图像的视网膜层边界分割能够辅助相关疾病的临床判断.在OCT图像中,由于视网膜层边界的形态变化多样,其中与边界相关的关键信息如上下文信息和显著性边界信息等对层边界的判断和分割至关重要.然而已有分割方法缺乏对以上信息的考虑,导致边界不完整和不连续.针对以上问题,提出一种“由粗到细”的基于端到端深度神经网络和图搜索(graph search,GS)的OCT图像视网膜层边界分割方法,避免了非端到端方法中普遍存在的“断层”现象.在粗分割阶段,提出一种端到端的深度神经网络—注意力全局残差网络(attention global residual network,AGR-Net),以更充分和有效的方式提取上述关键信息.具体地,首先设计一个全局特征模块(global feature module,GFM),通过从图像的4个方向扫描以捕获OCT图像的全局上下文信息;其次,进一步将通道注意力模块(channel attention module,CAM)与全局特征模块串行组合并嵌入到主干网络中,以实现视网膜层及其边界的上下文信息的显著性建模,有效解决OCT图像中由于视网膜层形变和信息提取不充分所导致的误分割问题.在细分割阶段,采用图搜索算法去除AGR-Net粗分割结果中的孤立区域或和孔洞等,保持边界的固定拓扑结构和连续平滑,以实现整体分割结果的进一步优化,为医学临床的诊断提供更完整的参考.最后,在两个公开数据集上从不同的角度对所提出的方法进行性能评估,并与最新方法进行比较.对比实验结果也表明所提方法在分割精度和稳定性方面均优于现有方法.

SS-OCT在角膜成像中的应用进展

成像技术的进步彻底改变了眼科领域,改变了我们对眼科疾病的理解、诊断和治疗。扫频源光学相干断层扫描(SS-OCT)是一种最新的非接触式高分辨率成像技术。它进一步提高了成像深度和扫描速度,增加了新的算法和功能。SS-OCT允许对角膜结构进行三维评估,提供角膜前、后表面的曲率和高度图以及角膜厚度图。这可以帮助眼科医生筛查和诊断角膜病变,如圆锥角膜、角膜营养不良和变性。SS-OCT更快、更精准和更灵敏的角膜测量有助于对即将进行角膜和屈光手术的患者做好术前计划和术后监测。文章总结SS-OCT技术的发展及其在角膜疾病中潜在的临床效用与在手术中的应用进展,以支持更多未来可能的研究和临床治疗。

OCT光学放大效应对儿童青少年轻中度近视黄斑区视网膜厚度测量的影响

目的:利用光学相干断层扫描(OCT)评估光学放大效应对儿童青少年近视眼黄斑区视网膜厚度测量的影响。方法:选取2023-04/2024-01就诊于我院眼科中心的68例126眼6-18岁儿童青少年。按照等效球镜度数(SE)分为轻度近视组(-0.50 D0.05)。在中度近视组中,校正前后黄斑区各象限视网膜厚度以及平均视网膜厚度比较有差异(均P<0.001)。校正前,两组间黄斑区外环颞侧和外环上方的视网膜厚度存在显著性差异(P=0.019、0.035)。其他象限的视网膜厚度在两组间比较无差异(均P>0.05)。校正后,两组间的黄斑区中心凹、内环鼻侧、内环颞侧、内环上方、内环下方、外环鼻侧视网膜厚度及平均视网膜厚度存在显著性差异(均P<0.05)。光学放大效应校正前,黄斑区外环的视网膜厚度与SE呈正相关(均P<0.05),与AL呈负相关(均P<0.05)。通过校正,发现黄斑区中心凹、内环视网膜厚度和平均视网膜厚度与SE存在显著负相关(均P<0.05)。此外,黄斑区各象限的视网膜厚度及平均视网膜厚度与AL均呈正相关(均P<0.001)。结论:光学放大效应对儿童青少年近视眼黄斑区视网膜厚度测量的准确性产生影响,并且随着AL的增加,这种影响变得更为显著。

Central retinal artery resistive index and optical coherence tomography in assessment of glaucoma progression

AIM: To assess the relation between central retinal artery(CRA) resistive index(RI) and retinal nerve fiber thickness measured by optical coherence tomography(OCT) in assessment of disease progress in cases of open angle glaucoma.METHODS: Twenty-three patients with diagnosed open angle glaucoma were included in this study. They were examined by colored duplex ultrasonography of CRA with estimation of RI of CRA and ophthalmic artery(OA)with estimation of CRA/OA RI ratio as well as OCT measurement of the average retinal nerve fiber layer(RNFL) thickness in order to assess the disease progress.RESULTS: There was strong inverse relation between the increased RI in CRA as well as the increased CRA/OA RI ratio and the decrease in average RNFL thickness in cases of open angle glaucoma.CONCLUSION: Assessment of CRA RI can indirectly assess the vascular changes associated with glaucoma and can assess the degree of retinal atrophy helping in evaluating prognosis thus guiding the choice of treatment.

急性冠脉综合征患者血清尿酸水平与罪犯血管斑块OCT特征的关联性研究

目的探讨急性冠脉综合征(ACS)患者血清尿酸(sUA)水平与罪犯血管斑块特征的关联性。方法回顾性分析2018年1月至2022年10月青岛大学附属烟台毓璜顶医院心血管内科收治的268例ACS患者的临床资料,根据sUA水平将其分为高sUA组(≥6 mg/dL,117例)和低sUA组(<6 mg/dL,151例)。比较两组一般临床资料以及冠脉造影和光学相干断层扫描(OCT)检查资料,通过多因素回归分析sUA水平与罪犯血管斑块特征的关联性。结果高sUA组体质量指数水平高于低sUA组,男性、合并高脂血症的人数比例大于低sUA组,年龄小于低sUA组,差异均有统计学意义(P<0.05)。高sUA组血红蛋白、肌酐、甘油三酯、脂质蛋白a和同型半胱氨酸水平高于低sUA组,差异均有统计学意义(P<0.05)。低sUA组侧支循环形成率高于高sUA组,差异有统计学意义(P<0.05)。两组其余冠脉造影指标比较差异无统计学意义(P>0.05)。高sUA组管腔狭窄率、近端管腔参考面积、远端管腔参考面积、红色血栓形成率、巨噬细胞浸润率均高于低sUA组,差异有统计学意义(P<0.05)。多因素分析结果显示,sUA水平升高是促进红色血栓[OR(95%CI)=1.490(1.071~2.075),P=0.018]和巨噬细胞浸润[OR(95%CI)=1.278(1.045~1.563),P=0.017]发生的危险因素,与近端管腔参考面积呈正关联[β(95%CI)=0.492(0.155~0.828),P=0.004]。结论sUA水平升高是促进红色血栓形成和巨噬细胞浸润发生的危险因素,值得临床医师关注。

OCT和OCTA生物学标志物在糖尿病性黄斑水肿预后和监测中的应用

糖尿病性黄斑水肿(DME)是糖尿病视网膜病变(DR)的并发症,也是DR患者视力下降和失明的主要原因。光学相干断层扫描(OCT)和光学相干断层扫描血管造影(OCTA)作为无创、非侵入性评估视网膜各层微结构和微血管病理改变的主要检查手段,是检测和评估DME的常用方法。随着OCT和OCTA技术的不断发展,各种参数被赋予生物标志物的作用,例如中央凹厚度(CST)、黄斑部平均厚度(CAT)和黄斑部容积(CV)、视网膜内层结构紊乱(DRIL)、高反射灶(HRF)和中央凹下神经视网膜脱落(SND)等,广泛运用于临床。OCT可以直观显示黄斑区视网膜及脉络膜的层次变化和细微结构,而OCTA更常运用于微血管改变。本文就OCT及OCTA相关生物学标志物在DME中预后和监测的作用进行阐述,同时检测结果中可见的生物学标志物可以为DME的监测和治疗策略提供新思路,并为DR和DME的发病机制提供新的见解。

OCT和OCTA在特发性黄斑前膜术后视力预测中的研究进展

特发性黄斑前膜(IERM)是指一类没有任何已知其他眼病的黄斑前膜,多发于50岁以上的中老年人。随着IERM的进展,会引起黄斑区视网膜结构和功能的改变,引起视力下降、视物变形等症状。目前关于IERM的发病机制尚不明确,手术是主要的治疗方式,但对于手术时机尚未标准化,术后的视力恢复结局也存在差异。光学相干断层扫描(OCT)和OCT血管成像(OCTA)作为一种无创、快速的检测手段,可观察黄斑区视网膜微结构和血流变化,已经在临床中广泛应用。利用OCT和OCTA各参数去预测术后视力已经成为IERM的研究热点。本文就OCT与OCTA各参数和IERM术后视力预测的相关研究现状进行综述,以期为临床工作者确定手术时机,权衡手术收益和风险时提供依据。

一种快速的OCT内外指纹提取方法

针对现有光学层析成像(optical coherence tomography,OCT)技术中内外部指纹提取算法速度较慢的问题,尤其是许多算法在提取指纹之前需要耗时的原始体数据去噪操作,为了解决这一问题,提出了一种简单快速的OCT内外部指纹提取算法。对于OCT指纹体数据,首先根据每张轴向切片(B-scan)图像的一阶微分最大值,拟合一条基本覆盖角质层轮廓的曲线,然后再根据一阶微分的次最大值,拟合出一条基本穿过活性表皮交界处轮廓脊谷处的曲线,最后在这两个曲线上下各N个像素点的位置,利用两条曲线附近的灰度值均值信息,按B-scan图片顺序进行拼接,生成提取到的内外部指纹图像。通过实验确定了N的最佳取值,然后与现有的内外部指纹提取算法对比,证明所提出的算法能够在不降低指纹质量的情况下,快速地提取出内外部指纹图像,提取内外部指纹的时间比层次聚类算法和梯度法都快很多倍。

视网膜静脉阻塞继发黄斑水肿中OCT生物标志物的研究进展

视网膜静脉阻塞(RVO)是第二常见的致盲性视网膜血管性疾病,其继发的黄斑水肿(ME)是导致中心视力损害的重要原因。光学相干断层扫描(OCT)可生成高分辨率的组织横截面图像,清楚地显示视网膜和脉络膜的各层结构,OCT生物标志物对RVO-ME的早期精准诊断、疾病发展的预示及视力预后的判断具有重要意义。文章对OCT下RVO-ME的视网膜厚度、视网膜内层结构紊乱、视网膜内层超反射率、外界膜及椭圆体带的完整性、中央凹第三高反射带、高反射点、急性黄斑旁中心中层视网膜病变、中界膜征、浆液性视网膜脱离高度、黄斑体积以及脉络膜厚度等生物标志物进行综述,以期为RVO-ME病情评估、治疗方案的制定以及视功能的预后判断提供客观依据。

Photodynamic therapy of brain tumors and novel optical coherence tomography strategies for in vivo monitoring of cerebral°uid dynamics

Photodynamic therapy(PDT)is a promising tool for least-invasive alternative methods for the treatment of brain tumors.The newly discovered PDT-induced opening of the blood–brain barrier(BBB)permeability open novel strategies for drug-brain delivery during post-surgical treatment of glioblastoma GBM.Here we discuss mechanisms of PDT-mediated opening of the BBB and age differences in PDT-related increase in BBB permeability,including with formation of brain edema.The meningeal lymphatic system plays a crucial role in the mechanism of brain drainage and clearance from metabolites and toxic molecules.We discuss that noninvasive photonic stimulation of°uid clearance via meningeal lymphatic vessels,and application of optical coherence tomography(OCT)for bed-side monitoring of meningeal lymphatic drainage has the promising perspective to be widely applied in both experimental and clinical studies of PDT and improving guidelines of PDT of brain tumors.

Anti-Spoof Reliable Biometry of Fingerprints Using <i>En-Face</i>Optical Coherence Tomography

Optical coherence tomography (OCT) is a relatively new imaging technology which can produce high resolution images of three-dimensional structures. OCT has been mainly used for medical applications such as for ophthalmology and dermatology. In this study we demonstrate its capability in providing much more reliable biometry identification of fingerprints than conventional methods. We prove that OCT can serve secure control of genuine fingerprints as it can detect if extra layers are placed above the finger. This can prevent with a high probability, intruders to a secure area trying to foul standard systems based on imaging the finger surface. En-Face OCT method is employed and recommended for its capability of providing not only the axial succession of layers in depth, but the en-face image that allows the traditional pattern identification. Another reason for using such OCT technology is that it is compatible with dynamic focus and therefore can provide enhanced transversal resolution and sensitivity. Two En-Face OCT systems are used to evaluate the need for high resolution and conclusions are drawn in terms of the most potential commercial route to ex- ploitation.

APPLICATION OF DOPPLER OPTICAL COHERENCE TOMOGRAPHY IN RHEOLOGICAL STUDIES:BLOOD FLOW AND VESSELS MECHANICAL PROPERTIES EVALUATION

Doppler Optical Coherence Tomography(DOCT)is a noninvasive optical diagnostic technique,which is well suited for the quantitative mapping of microflow velocity profiles and the analysis of flow-vessel interactions.The noninvasive imaging and quantitative analysis of blood flow in the complex-structured vascular bed is required in many biomedical applications,including those where the determination of mechanical properties of vessels or the knowledge of the mechanic interactions between the flow and the housing medium plays a key role.The change of microvessel wall elasticity could be a potential indicator of cardiovascular disease at the very early stage,whilst monitoring the blood flow dynamics and associated temporal and spatial variations in vessel’s wall shear stress could help predicting the possible rupture of atherosclerotic plaques.The results of feasibility studies of application of DOCT for the evaluation of mechanical properties of elastic vessel model are presented.The technique has also been applied for imaging of sub-cranial rat blood flow in vivo.

Integrated System for Combined Optical Coherence Tomography-Raman Spectroscopy of Neocaridina denticulate sinensis

Optical coherence tomography(OCT)and Raman spectroscopy(RS)can be complementary biological tissue optical analysis methods.To study the internal structure and tissue compositions of biological samples,an OCT-RS system was built to carry out OCT section imaging and RS analysis in common.Neocaridina denticulate sinensis were collected regularly for morphological observation by OCT imaging and biochemical investigation based on the Raman spectra.The internal structure of the N.denticulate sinensis was imaged by OCT,and the morphology of the tissues and the position in the body were distinguished according to the gray scale changes.The imaging depth along the vertical direction of Z-axis in N.denticulate sinensis is about 1.60 mm.RS detection was selectively performed based on the OCT images.The main Raman peaks of the rostrum,the cephalothorax,the abdominal segment,and the telson section are at 1006,1156,1447,1491 and 1515 cm-1,which are identified as proteins and amino acids.The presence of 1497 cm-1 at the cephalothorax is different from other parts,probably due to the presence of organs such as ovary,whose compositions are different from those of other tissues.The combination of optical coherence tomography and Raman spectroscopy can provide information about morphological and biochemical features of tissues,and has potential applications in biomedical detection and imaging.

3D automatic segmentation method for retinal optical coherence tomography volume data using boundary surface enhancement

With the introduction of spectral-domain optical coherence tomography(SD-OCT),much larger image datasets are routinely acquired compared to what was possible using the previous generation of time-domain OCT.Thus,there is a critical need for the development of three-dimensional(3D)segmentation methods for processing these data.We present here a novel 3D automatic segmentation method for retinal OCT volume data.Brie°y,to segment a boundary surface,two OCT volume datasets are obtained by using a 3D smoothingfilter and a 3D differentialfilter.Their linear combination is then calculated to generate new volume data with an enhanced boundary surface,where pixel intensity,boundary position information,and intensity changes on both sides of the boundary surface are used simultaneously.Next,preliminary discrete boundary points are detected from the A-Scans of the volume data.Finally,surface smoothness constraints and a dynamic threshold are applied to obtain a smoothed boundary surface by correcting a small number of error points.Our method can extract retinal layer boundary surfaces sequentially with a decreasing search region of volume data.We performed automatic segmentation on eight human OCT volume datasets acquired from a commercial Spectralis OCT system,where each volume of datasets contains 97 OCT B-Scan images with a resolution of 496
512(each B-Scan comprising 512 A-Scans containing 496 pixels);experimental results show that this method can accurately segment seven layer boundary surfaces in normal as well as some abnormal eyes.

基于改进MobileNetV2神经网络的视网膜OCT图像多分类

光学相干断层成像(optical coherence tomography,OCT)是一种具有无接触、高分辨率等特点的新型眼科医学诊断方法,现在已经作为医生临床诊断眼科疾病的重要参考物,但人工分类疾病费时费力,视网膜病变的早期发现和临床诊断至关重要.为了解决该类问题,本文提出了一种基于改进MobileNetV2神经网络对视网膜OCT图像多分类识别方法.此方法利用特征融合技术处理图像并设计增加注意力机制改进网络模型,二者在极大程度上提高OCT图像的分类准确率.与原有算法相比,分类效果具有明显提升,本文模型的分类准确率、召回值、精确度、F1值分别达到98.3%、98.44%、98.94%、98.69%,已经超越人工分类的准确率.此类方法不仅在实际诊断中加快诊断流程、降低医生负担、提高诊断质量,同时也为眼科医疗研究提供新的方向.

Corrective Change of Retinal Thickness Measured by Optical Coherence Tomography and Histologic Studies

Purpose:To evaluate the correlation of retinal thickness between optical coherence tomography(OCT)images and histologic slides.Methods:Retinal thickness was measured in 16 rabbit retinal histologic slides.The same eyes has been previously measured by OCT fr the comparison of results between two methods.Retinal thickness of each OCT image section was measured using both the manually assisted(requiring localization of reflectivity peaks by observer)and automated modes of the computer software.Results:Retinal thickness measured by OCT demonstrated a high degree of correlation with retinal histologic study.The automated method(Cc=0.66,P<0.01) was less reliable than the manually assisted one (Cc=0.84,P<0.001).The former had an error in 95% confidence interval,ranged between-0.71 and 11.09μm.The latter had a less error,ranged from -2.99 to 5.13μm.Conclusion:OCT can quantitatively measure the retinal thickness.However,automatical identification of the reflective boundaries by computer may result in errors in some cases.To masure the retinal thickess by manually assisted mode can increase the accuracy.

High-Speed Time-Domain En Face Optical Coherence Tomography System Using KTN Optical Beam Deflector

We developed high-speed time-domain (TD) en face optical coherence tomography (OCT) system using KTN optical beam deflector. The KTN optical beam deflector operates at a high repetition rate of 200 kHz with a fairly large beam deflection angle. We proposed a high-speed en face OCT system that used a KTN optical deflector as the sample beam scanning. In the experiment, we obtained en face OCT images of human fingerprint with a frame rate of 800 fps, which is the fastest speed obtained by a TD-OCT imaging. Furthermore, a 3D-OCT image was also obtained at 0.2 s (=5 volumes/s) by our imaging system.