Clinical features and possible pathogenesis of multiple evanescent white dot syndrome with different retinal diseases and events:a narrative review

●Multiple evanescent white dot syndrome(MEWDS)is a rare fundus disease,characterized by acute vision loss and visual field defects.Many previous studies have explained the possible pathogenesis and clinical features of primary MEWDS.However,as the number of reported cases increases,secondary MEWDS occurs in other related retinal diseases and injuries,exhibiting some special characteristics.The associated retinal diseases include multifocal choroiditis/punctate inner choroidopathy(MFC/PIC),acute zonal occult outer retinopathy,best vitelliform macular dystrophy,pseudoxanthoma elasticum,and ocular toxoplasmosis.The related retinal injury is laser photocoagulation,surgery,and trauma.Although primary MEWDS often have a self-limiting course,secondary MEWDS may require treatment in some cases,according to the severity of concomitant diseases and complications.Notably,MEWDS secondary to MFC/PIC that is prone to forming choroidal neovascularization and focal choroidal excavation,needs positive treatment with corticosteroids.The possible underlying pathogenesis of secondary MEWDS is the exposure of choroidal antigen after the disruption of Bruch’s membrane.The MEWDS-related features in secondary MEWDS are still evanescent under most circumstances.Its prognosis and treatment depend on the severity of complications.Current studies propose that the etiology is associated with immune factors,including viral infection,inflammation in choroid and Bruch’s membrane,and antigen exposure caused by retinal and/or choroidal insults.More pathogenic studies should be conducted in the future.Accurate diagnosis for secondary MEWDS could benefit patients in aspects of management and prognosis.

基于Evanescent Wave吸收的光纤传感器灵敏度计算分析

基于Evanescent Wave吸收的U形光纤传感器是比较便于实用推广,可被用于化学传感的新型传感器。对于U形光纤传感器的渐逝波穿透深度和灵敏度进行了计算与分析,并与普通直线传感器做了比较,具体讨论了影响U形传感器灵敏度的几何参数因素和灵敏度优化公式。

Linearly polarised three-colour lasing emission from an evanescent wave pumped and gain coupled fibre laser

A novel Whispering-Gallery-Mode （WGM） fibre laser, emitting linearly polarised three-colour light, is demonstrated by pumping and gain coupling with evanescent waves. The pump light is longitudinally coupled into a bare optical fibre immersed in a dye solution of lower refractive index. The dye molecules around the bare fibre are excited by the evanescent waves of pump light when they propagate along the fibre in a total internal reflection. When the pump beam within the fibre is a meridian beam, the WGM lasing emission from the fibre laser is a linearly polarised transverse electric wave, while it is a mixed wave of the linearly polarised transverse electric and magnetic waves if the pump beam is a skew beam within the fibre. Because the excited molecules are located within the evanescent field of WGM, a good spatial overlap between the dye gain and the evanescent field leads to a high pumping efficiency and a longer gain distance along the fibre. Once the bare fibre is inserted into three glass capillaries filled with Rhodamine 6G, 610 and 640 dye solutions, respectively, WGM laser oscillations at the wavelengths of 567-575, 605-614 and 656-666 nm occur simultaneously, and a linearly polarised three-colour lasing emission is achieved in a single optical fibre.

Design and fabrication of a high-performance evanescently coupled waveguide photodetector

In this paper, we present the design, fabrication, and measurement of an evanescently coupled waveguide photode- tector operating at 1.55 gm, which mainly comprises a diluted waveguide, a single-mode rib waveguide and a p-i-n photodiode with an extended optical matching layer. The optical characteristics of this structure are studied by using a three-dimensional finite-difference time-domain （3D FDTD） method. The photodetector exhibits a high 3-dB bandwidth of more than 35 GHz and a responsivity of 0.291 A/W at 1550 nm directly coupled with a cleaved fiber. Moreover, a linear response of more than 72-mW optical power is achieved, where a photocurrent of more than 21 mA is obtained at a reverse bias voltage of 3 V.

Spectral-domain optical coherence tomography dynamic changes and steroid response in multiple evanescent white dot syndrome

Dear Editor,Multiple evanescent white dot syndrome （MEWDS） was first described in 1984 as a rare, acute, unilateral,multifocal retinochoroidal disorder, typically affecting young myopic women. Previous studies with fluorescein angiography （FA） and electrophysiology suggested that MEWDS to be a disease in the retinal pigment epithelium （RPE） or outer retina, while recent studies with spectral- domain optical coherence tomography （SD-OCT） suggested it may be an outer retinal disease due to observation of hyperreflective material in outer retina and subtle disruptionsof the ellipsoid zone without RPE disruption.

Optical matching layer structures in evanescent coupling photodiodes at a wavelength of 1.55 μm:physics,design and simulation

We have studied the optical matching layers （OMLs） and external quantum efficiency in the evanescent coupling photodiodes （ECPDs） integrating a diluted waveguide as a fibre-to-waveguide coupler, by using the semi-vectorial beam propagation method （BPM）. The physical basis of OML has been identified, thereby a general designing rule of OML is developed in such a kind of photodiode. In addition, the external quantum efficiency and the polarization sensitivity versus the absorption and coupling length are analysed. With an optical matching layer, the absorption medium with a length of 30μm could absorb 90% of the incident light at 1.55μm wavelength, thus the total absorption increases more than 7 times over that of the photodiode without any optical matching layer.

InP-based evanescently coupled high-responsivity photodiodes with extremely low dark current density integrated diluted waveguide at 1550 nm

In this paper, we have demonstrated a high performance waveguide photodiode integrated diluted waveguide serving as a fibre-to-waveguide coupler to achieve high coupling efficiency. High responsivity （〉 1 A/W）, high saturation power （〉 45 mA） in the static state and extremely low dark current density （0.04 pA/μm2） with 3 dB bandwidth at 13.4 GHz have been achieved.

Generation of sub-half-wavelength micro-optical traps by dichroic evanescent standing waves

The bi-dimensional optical lattices formed by several sets of laser evanescent standing waves propagating at the surface of a dielectric prism are investigated. The characteristics of the optical traps including their depths and the sizes are analysed. It is shown that the micro-optical lattice with a sub-half-wavelength size can be achieved by the interference of the selected evanescent waves. The scheme together with the recently developed atomic chip may be used for atomic quantum manipulation.

A Discrete Model of the Evanescent Light Emission from Ultra-Thin Layers

A discrete model of the Differential Evanescent Light Intensity (DELI) technique was developed to calculate and map 3D nanolayers thicknesses from the evanescent light intensity captured from optical waveguides. The model was used for ultra-thin Pd nanometric layers sputtered on glass substrates. The layers thickness profiles were displayed in 3D and 1D profiles plots. The total thickness profiles of the ultra-thin Pd films obtained in the range of 1-10 nm were validated using AFM measurements. Based on the model developed the evanescent photon extraction parameter of the material was estimated.

Changes of Indocyanine Green and Fluorescein Angiography in Multiple Evanescent White-dot Syndrome: A Case Report

Purpose: To study the clinicopathological change on "Multiple Evanescent White-dot Syndrome (MEWDS)"through fundus angiogrphy analyses.Methods:Examing the case with fluorescein angiography (FFA) and indocyanine green angiography(ICGA), visual field and following up for 15 months.Results :There exist multiple white dots in the fundus photo and angiography. The changes on ICGA maintain longer than fundus photo and FFA. Papille may be edematous and macula could present with special hypofluorescent flecks.Conclusions:MEWDS has specific angiographic features. Its pathological changes involve deep retinal pigment epithelium(RPE) as well as choroidal capillaries. The prognosis of the visual acuity for MEWDS is very good.

A Portable Evanescent Wave Optic Fiber Immunosensor for Sensitive and Rapid Detection of 2,4-D in Water Samples

A portable evanescent wave optic ?ber immunosensor was developed for detection of 2,4-dichlorophenoxyacetic acid(2,4-D) using a indirect competitive immunoassay. In this paper, hapten conjugates 2,4-D-OVA were immobilized with covalent binding methods. After pre-reacting, 2,4-D-antibody-Cy5.5 in sample specifically recognized the 2,4-D antigens binding sites on surface of the optical fiber probe. Under optimum conditions, 2,4-D could be detected in less than 18 min for each assay cycle. The regeneration of the optic ?ber surface allowed more than 200 times without losing performance. The limits of detection of 0.039 ug/L and the quantitative detection range of 0.47 - 81.02 ug/L were obtained when the concentration of 2,4-D was 1 mg/L. This immunosensor shows great potential in rapid simultaneous detection of 2,4-D in waters samples.

Choroidal neovascularization as the initial manifestation of multiple evanescent white dot syndrome

To report the case of a patient who presented with idiopathic choroidal neovascularization(CNV)as the first sign of multiple evanescent white dot syndrome(MEWDS).A 25-year-old woman presented with recent onset of decreased vision and metamorphopsia in the right eye.The results of fundoscopic examination,fluorescein angiography,and optical coherence tomography(OCT) were compatible with a diagnosis of idiopathic CNV,which was treated with one intravitreal injection of bevacizumab.Five years later,the patient returned complaining of photopsia and decreased vision in the same eye.The fundoscopic examination showed typical signs of MEWDS.After 3 months,recurrence of CNV was observed in the same eye.In conclusion,idiopathic CNV might be the only manifestation of a subclinical occurrence of MEWDS.In this case,it was followed by a recurrence of MEWDS and subsequent reactivation of CNV.

Palladium Ultra Thin Layer Profiles Evaluation by Evanescent Light

Nanometric profiles of sputtered ultra-thin Pd layers with thicknesses in the range 1 - 10 nm were investigated by capturing the leaking evanescent light from optical waveguides. The Pd films were deposited by sputtering on glass substratesalso servingas light waveguides. Calibrating the thickness values for the ultra-thin Pd films obtained from the sputtering rate combined with the DELI estimation technique, gave detailed 1Dand 3D morphological nanometric profiles of the deposited layers.

An Evanescent Light Wave Cannot Possess a Transverse Spin

It is pointed out that the evanescent light wave occurring at total reflection does not possess a transverse spin angular momentum as Bliokh, Bekshaev, and Nori claimed recently in (2014) Nature Communications, 5,3300. This is not only because of the nonlocality of the photon spin but also because the evanescent wave is such a state whose angular momentum cannot be separated into spin and orbital parts.

Evanescent Fields inside a Cut-off Waveguide as Near Fields

Usually, electromagnetic evanescent waves are some kinds of near fields. However, it looks as if the evanescent waves inside a cut-off waveguide had nothing to do with any near field. In this paper, we will show that the evanescent waves inside a cut-off waveguide can also be regarded as the near fields of an aerial array.

Improving the sensitivity of protein microarray by evanescent-field-induced fluorescence

To improve the sensitivity of protein microarray, a prism surface replaces the surface of the common microscope slide.The protein targets arrayed on the surface are hybridized and labelled by fluorescent probes. Evanescent excitation occurs when the convergent laser reaches the surface, and a photomultiplier tube detects the emitted fluorescent signal. A two-dimensional actuator scans the whole surface to achieve planar laser excitation and fluorescence collection. The penetration depth of the evanescent field into the protein targets is only some hundred nanometers and can be controlled by different incident angle of the laser beam, so the undesired background signals are reduced dramatically and the detection sensitivity is improved by a factor of 50 to 100 comparing to confocal excitation. This approach can detect low abundance analytes without signal amplification.

An Array Consisting of 10 High-Speed Side-Illuminated Evanescently Coupled Waveguide Photodetectors Each with a Bandwidth of 20 GHz

We design and fabricate a parallel system with 10 high speed side-illuminated evanescently coupled waveguide photodetectors （ECPDs）. The 10 ECPDs exhibit a uniform 3dB bandwidth of 20 GHz and low dark current of about i nA at 2 V reverse bias. The 10 ECPDs also exhibit uniform photo-responsivity of about 0.23A/W with an active region of 5 × 25μmS. The photodetector array has a total bandwidth of more than 200 GHz and can be integrated with other optoelectronic devices.

High-performance evanescently-coupled uni-traveling-carrier photodiodes

A new evanescently-coupled uni-traveling-carrier photodiode （EC-UTC PD） based on a multimode diluted waveguide （MDW） structure is fabricated, analysed and characterized. Optical and electrical characteristics of the device are investigated. The excellent characteristics are demonstrated such as a responsivity of 0.36 A/W, a bandwidth of 11.5 GHz and a small-signal 1-dB compression current greater than 18 mA at 10 GHz. The saturation current is significantly improved compared with those of similar evanescently-coupled pin photodiodes. The radio frequency （RF） bandwidth can be further improved by eliminating RF losses induced by the cables, the probe and the bias tee between the photodiode and the spectrum analyzer.

新型冠状病毒感染相关视网膜病变的小型病例研究

目的:观察新冠肺炎(COVID-19)相关视网膜病变患眼的多模式影像特征,探讨相关发病危险因素,并分析治疗和预后结果。方法:选取2022-12-13/2023-01-13在天津医科大学总医院确诊的COVID-19相关视网膜病变患者7例7眼。纳入患者均行眼底彩照、红外眼底照相(IR)、频域光相干断层扫描(SD-OCT)、眼底自发荧光(FAF)等眼科检查和血清学检查。结果:纳入患者中,视网膜中央静脉阻塞(CRVO)2例2眼表现与既往CRVO不同,患者均为青年,视网膜出血呈中心白点状的类圆形、梭形出血斑,其中1例1眼半侧视网膜静脉阻塞(HRVO)患者血管性血友病因子抗原(vWF:Ag)水平升高(161.8%),另1例1眼CRVO患者狼疮抗凝物试验(+);多发性一过性白点综合征(MEWDS)2例2眼,FAF示后极部散在圆点样高自发荧光,给予激素治疗后预后良好;急性黄斑神经视网膜病变(AMN)3例3眼,IR示黄斑旁边界清楚的低反射病灶,SD-OCT示外核层(ONL)、外界膜(ELM)高信号,EZ/IZ信号断裂,预后良好。结论:COVID-19可能引发炎症风暴,累及视网膜各层组织及血管,导致视网膜多种病变的发生,激素治疗可能有效,多预后良好,其中CRVO眼底出血可见Roth斑,狼疮抗凝物和vWF:Ag增高可能是COVID-19后易发CRVO的危险因素。

全声波方程波场深度延拓倏逝波压制研究

与经典的单程波深度偏移方法相比,全声波方程波场深度偏移方法在成像质量和计算效率方面会面临新的难题,还有诸多理论问题值得深入研究,其中倏逝波的压制问题是全声波方程波场深度延拓及深度偏移方法面对的一项特殊挑战.为了解决该问题,本文提出了两种新的倏逝波压制策略.策略I是以经典频率-波数域方法为基础,提出广义低通滤波器方法;策略II是以能量守恒原理为基础,来解决波场延拓中倏逝波的振幅爆炸问题.对梯度速度模型的脉冲响应计算表明,本文提出的两种倏逝波压制策略在横向速度变化剧烈情况下的数值结果都是稳定的,并且能够实现与有限差分方法相同的波场延拓计算精度.在对盐丘模型成像时,在相同计算参数下,本文所提新策略解决了在使用传统低通滤波器压制倏逝波时无法对高角度构造进行准确成像的缺点.相较于压制倏逝波的谱投影方法,本文所提新策略不仅在成像质量上达到了与之相同的水平,而且具有更高的计算效率.通过一系列数值模拟实验表明:与传统倏逝波压制策略相比,本文所提新策略在实现全声波方程波场深度延拓及成像时,更好地平衡了计算效率和计算精度,具有更好的实用价值.