植入微电极的人工视网膜

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植入片的名词解释

植入片的名词解释

植入片的名词解释人类社会的科技发展日新月异,让我们的生活变得更加便利和丰富多样。

其中,植入片技术是一项备受关注的创新科技。

植入片是一种被植入到人体内部的微型装置,它可以起到监测、治疗和增强人体功能等作用。

本文将对植入片进行详细解释,探讨其技术原理、应用领域以及潜在的利与弊。

植入片的技术原理主要是将微电子技术与生物学相结合。

它通常由一个微型芯片、传感器和电池等组成。

芯片上搭载有各种微小的元件,可以通过传感器检测人体内的生理指标、环境参数或其他感知信息。

而电池则为植入片提供能量。

通过与身体自身的信号交互,植入片可以实时监测身体状况,并将相关数据传输到外部设备。

植入片的应用领域非常广泛。

在医疗领域,它可以被用于监测患者的血压、体温、心率等生理参数,为医生提供更准确的病情评估和治疗方案。

同时,它还可以用于拓宽残障人士的运动能力,比如帮助截肢者掌握和控制假肢的运动。

此外,在生活中,植入片还可以用于身份认证、支付信息存储等功能。

它的使用对个人隐私安全提出了新的挑战。

然而,植入片技术也存在一些潜在的利与弊。

在利方面,植入片可以帮助提高医疗诊断的准确性和治疗效果,为生命健康提供更加精准的保障。

此外,植入片作为一种身份认证和支付工具,可以方便快捷地完成各种交易。

然而,与此同时,植入片也带来了一些潜在的安全和伦理风险。

比如,有人担心植入片可能被滥用,导致个人隐私泄露或成为被监控的对象。

此外,与身体长期植入物相连,可能存在感染、过敏反应等风险。

为了平衡植入片技术的利与弊,应当在多个方面进行监管和控制。

首先,应加强数据保护和隐私安全措施,确保植入片使用者的个人信息不被滥用或泄露。

其次,对植入片的生产和销售进行监管,确保产品的质量和安全。

同时,应开展广泛的公众讨论,确保植入片技术的推广和应用是建立在对伦理和法律风险进行充分评估和公正决策的基础上。

总而言之,植入片是一项既有创新性又有争议性的技术。

它的出现极大地拓展了医疗和交易领域的可能性,但也给个人隐私和身体健康带来一系列的挑战。

人工视网膜技术原理及应用

人工视网膜技术原理及应用

人工视网膜技术原理及应用如果用数码相机来做类比,人眼的角膜和晶状体就相当于镜头,眼球后方的视网膜是感光器件,视神经等同于连接感光器件和存储卡之间的线路,而大脑后部的视觉皮层则是存储卡和后期处理软件。

色素性视网膜炎或老年性黄斑变性这样的疾病会让视网膜失去功能,让这部相机无法感知任何图像;而美国的第二视觉(Second Sight)公司,正在尝试用电子器件替换失去功能的视网膜,帮助这些患者重新获得基本的视觉。

这种技术,就是人工视网膜技术。

它和人工耳蜗的原理类似使用电流刺激依然完好的神经,让大脑能够接收到信号并认为感官依然在正常工作。

在过去的20多年里,已经有数十万人通过人工耳蜗获得了听力,但是人工视网膜的进展却有些停滞不前。

这是因为视觉系统复杂得多。

我们所获取的信息中,有大约80%来自于视觉。

人们至今也无法制造出性能堪比人眼的照相机,而感光细胞和视神经之间的精确对应关系也还是个谜。

再考虑到技术的限制人工视网膜芯片的大小一般只有数平方毫米,厚度只有不到100微米想获得如人眼般精确的视觉,是相当困难的事情。

虽然早在1924年,人们就已经发现使用电刺激作用于视觉皮层时会产生幻视觉,但是直到1967年,植入视觉皮层的人工视觉装置才被开发出来。

但是,这种方式产生的视觉质量很差,对这一领域的研究也开始逐渐由视觉皮层植入转向视网膜植入。

在过去的30年里,许多研究机构和厂商都投入到这一领域当中,研究思路也分成了两类:视网膜下植入和视网膜外植入技术。

视网膜下植入技术是将芯片植入到视网膜神经感觉上皮和色素上皮之间的区域,代替光感细胞感受光照,直接利用视网膜本身的编码和解码机制来将电信号转化成视觉。

它依然利用患者自身的镜头,就像是为数码相机换一块感光器件一样。

这种技术需要外接供能单元,手术难度高,使用范围较小,但是不用外挂一部摄像机。

视网膜下植入技术的主要研究者有芝加哥大学Alan Chow的研究小组和德国图宾根大学的Eberhart Zrenner小组等。

MEA的特点与作用

MEA的特点与作用

MEA的特点与作用1. 什么是MEAMEA(Microelectrode Array)中文名为微电极阵列,是一种用于记录和刺激神经信号的生物医学仪器。

MEA由多个微型电极组成的阵列,在生命科学领域中广泛应用于神经科学研究、药物筛选、疾病模型构建等方面。

2. MEA的特点2.1 高空间分辨率MEA的微电极阵列通常具有高密度排列的优势,能够在较小的区域内记录到大量的神经元活动。

相较于传统的单电极记录方法,MEA可以提供更高的空间分辨率,能够同时监测多个神经元的活动。

2.2 长时间稳定记录MEA具备较好的稳定性,可以长时间记录神经活动而不会造成损伤。

这使得MEA成为长期监测神经系统活动的理想工具,尤其在动物实验中可以持续监测动物行为和神经活动的变化。

2.3 可多通道记录与刺激MEA通常由数百个微电极组成,每个微电极都可以独立地记录和刺激神经信号。

这种多通道的设计使得MEA可以同时记录多个神经元的活动并模拟复杂的脑神经网络。

2.4 方便的数据分析与处理MEA采集的数据可以通过计算机软件进行实时分析和处理。

研究人员可以利用各种算法和工具对神经信号进行分析,实现信号的滤波、频谱分析、事件检测等操作,从而获得更多的生理信息。

3. MEA的作用3.1 神经科学研究MEA在神经科学研究中被广泛应用。

它可以记录大量神经元的活动、研究神经网络的结构和功能,为理解脑功能和疾病机制提供重要的信息。

近年来,MEA已成为研究脑机制、神经可塑性和神经退行性疾病的重要工具。

3.2 药物筛选与安全性评估MEA在药物筛选和安全性评估中发挥着重要作用。

研究人员可以在MEA上培养生物模型,通过记录神经元的活动来评估药物的疗效和毒性。

这种方法可以提供更真实、高通量的生物反应数据,有助于开发更安全有效的药物。

3.3 疾病模型构建MEA可以模拟和构建多种疾病模型,包括癫痫、帕金森病、阿尔茨海默病等。

通过记录和刺激神经信号,研究人员可以深入探索疾病的机制,寻找新的治疗方法和药物。

仿生学:浅谈仿生眼及其在现代医学中的应用

仿生学:浅谈仿生眼及其在现代医学中的应用

自然的奥秘与仿生学课程论文《浅谈仿生眼及其在现代医学中的应用》姓名:王振国学号:201300110089专业:化学类年级:2013级班级:化学1班浅谈仿生眼及其在现代医学中的应用仿生眼简介仿生眼,又称电子仿生眼(eyeclops bionic eye )设备包括一副装有摄像头和信号传送器的眼镜、一个视频处理器、一个信号接收器和一个电极。

佩戴这种眼镜前,患者首先要接受眼部手术,将一个极薄的电子信号接收器和电极板植入视网膜上。

电子仿生眼是运用仿生学原理,模拟人眼的成像原理,帮助失明患者重新获得视觉能力的仿生科技产品。

仿生学原理一、人眼成像仿生原理人眼成像原理图如下,所取的距离为250米,则人眼成像见下图:自然界各种物体在光线的照射下,不同颜色可以反射出明暗不同的光线,这些光线透过角膜、晶状体、玻璃体的折射,眼球中的角膜和晶状体的共同作用,相当于一个“凸透镜”,在视网膜上形成倒立、缩小的实像,构成光刺激。

视网膜上的感光细胞(圆锥和杆状细胞)受光的刺激后,经过一系列的物理化学变化,转换成神经冲动,由视神经传入大脑层的视觉中枢,然后我们就能看见物体了,经过大脑皮层的综合分析,产生视觉,人就看清了正立的立体像。

人的眼睛是个复杂的成像系统,而人的大脑像CPU处理这些图像,让人能在视觉上感知到图像。

人眼成像最主要的是晶状体和视网膜。

晶状体调整眼睛的焦距是光束集中到富有视锥细胞和视柱细胞的视网膜上,在进行光电(生物电)变化,由视觉神经把信号传至大脑生成图像。

人类的目标就是能制造出能过可以和眼睛相媲美的视觉系统,这是机器智能化的关键部分。

二、电子眼就是一套摄像系统要了解电子眼的工作原理,我们首先要对人的视觉机理有一个清晰的了解。

人的视觉过程可以分成三个环节:接收信息,外界的光线通过眼球的晶状体会聚在眼球后面的视网膜上成像;传递信息,视网膜把接收到的,通过与它连接的视神经把信息传递到大脑的侧膝体,再传递到大脑的视皮层;解读信息,大脑的视皮层将对接受到的各类信息加工整理、去伪存真,还要与原来储存的信息进行比较,最后得出结论。

仿生眼

仿生眼

加拿大验光师加斯韦伯发明Ocumetics仿生隐形眼镜。这种 眼镜能够让你在无需佩戴任何眼镜的情况下拥有“超人视 力”,甚至比正常标准视力还要好上2倍。
“Ocumetics仿生隐形眼镜”看起来就像一个小按钮,只 需要8分钟就可以植入眼睛中,而且这一过程没有任何痛 苦。植入过程很像白内障手术,即将眼中的晶状体摘除, 然后用人工晶状体代替。
仿生眼及仿生眼镜
研究目的:
矫正近视眼,帮助失明者重见光明,看到周围的环境; 由于电子眼可取代视网膜细胞的功能,可望为那些视网膜色素变性或 因年老而黄斑点退化的人们提供基本程度的视力。
国外研发现状
仿生眼ArgusII开始在美国市场正式发售。
ArgusII的人工视网膜装置主要针对的是因视网膜受损(色素视网 膜炎患者)而不幸失明的人群,该装置使用电子光学感应装置充 当“视网膜。
演讲结束 谢谢!
研究人员们必须解决的问题之一是释放电极的位置,同时增加电极 的数量,电极尺寸越小,激活的视网膜神经节细胞就少,这样视觉分辨 率就会高。
视网膜植入装置的目标是取代眼球上的数百万个感光细胞,要让视 障人士获得像一般人一样的视力,需要提高刺激视觉的空间分辨率;扩 大可以感知的视觉区域;电子装置所提供的影像解析度可能需要达到上 千才行,但这可能还需数十年的研究时间。
仿生眼视觉图像处理系统:
系统以TM320DM642为核心,由4个部分组成视频采集、图像处理、视频输出、串 口通信系统。 流程如图1所示,CCD摄像头采集的视频图像,经过视频解码芯片转化为便于DSP 处理的视频码流,然后在DSP中设计合适的视频图像处理算法,分割、识别出运 动目标,并计算出目标的位置参数,最后将位置参数通过串口发送给眼动控制 模块,同时利用视频编码芯片编码DSP输出的视频码流,送到显示器实时显示, 便于人机交互。

视觉假体研究进展

视觉假体研究进展

Epiretinal implant
美国Harvard University与Massachusetts Institute of Technology的Rizzo和Wyatt[14]教授研究小组 (Boston Retinal Implant Project, BRIP)
图1.1 人工视网膜系统分为眼外装置和眼内植入装置(左)。植入装置包含植入电路和植入耦合线圈两部分(中)。植入装置在视 网膜的分布示意如图(右)。

Friday, 18 December 2009 Bionic Vision Australia will receive $42 Million over four years for the development of this life-changing technology.


德国目前主要有四家研究单位开展视觉假体的研发。Bonn company IMI开发的IRIS,德国RWTH Aachen University研制的表层型视网膜 假体EPI-RET-3,方案类似。EPI-RET-3已完成6例受试者的植入手术 [16]。德国Bonn university的Rolf Eckmiller等提出混合型视网膜 假体,包含传统的刺激器和药物缓释器。 德国Tubingen university的Eberhart Zrenner教授等[17]研究芯片 (Retina Implant AG)3×3mm2,将微光电二极管阵列芯片植入视网 膜外层细胞区域,能接受光产生电刺激脉冲传递给植入电极,采用眼 外红外线能源为植入芯片提供电能。

人工视网膜是将微电极序列植入眼球后部,微电极序列能把视觉信息转换成 电子脉冲以刺激相邻的神经节细胞,神经节细胞通过视神经把信息传入大脑, 使患者能感知到图像。这种能够激活内层视网膜的装置,称为人工视网膜(视 网膜假体)。

人工视网膜在日本开始临床应用

人工视网膜在日本开始临床应用

人工视网膜在日本开始临床应用
日本大阪大学医学院教授瓶井资弘等人近日开始了一项人造视网膜的临床试验,该试验需要向接近失明的患者眼内植入电极。

据称,接受试验的第一例患者的视力恢复到了能够辨别物体形状的程度。

研究团队预定在6月实施第二例手术。

在确认安全性与治疗效果后,计划在2018年得到日本厚生劳动省的批准的
临床试验的对象为“视网膜色素变性
症”患者。

在患者眼球后侧植入电极,对仍
存活的视网膜细胞等施加电刺激。

人造视网膜的工作原理是,利用安装在
眼镜上的摄像头拍摄影像,通过可挂于腰上
的装置将影像转变为电信号。

该信号再通过
耳后的装置传至已植入的电极,并借助对视
网膜的刺激将视觉信号转达至大脑,最终形成视觉。

人造视网膜目前在美德等国已投入临床应用。

研究团队1月末将人造视网膜植入了第一例患者眼中。

手术前该患者仅能识别明暗,但在术后,患者不仅能够抓住眼前的长棒,还能识别出长棒运动的方向。

在2015~2016年度,大阪大学计划与企业以及其他大学合作,以10~15位患者为对象,开展正式的临床试验。

视网膜色素变性症会导致视觉细胞减少。

日本国内约有1万人以上的患者。

人造视网膜无法使接近失明的患者恢复到正常人的视力,但至少能改善至识别物体形状等,使患者的日常生活变得方便。

研究团队期待人造视网膜能与利用万能细胞的iPS细胞进行的再生
医疗一样,成为使失明患者恢复视力的治疗方法。

视网膜技术

视网膜技术

视网膜技术视网膜技术是一种先进且引人注目的技术,可以改善人类视力并治疗一些眼睛相关的疾病。

它是通过植入人工视网膜来实现的,是医学领域取得的巨大进步之一。

视网膜技术对于那些因为视网膜疾病而失明的人来说,无疑是一丝曙光。

视网膜位于眼球的后部,负责将光线转化成电信号,并将其传递到大脑中。

然而,一些视网膜相关的疾病如黄斑变性、糖尿病性视网膜病变和视网膜血管阻塞等会导致视网膜损伤,从而影响人们的视力。

过去,这些疾病一旦发展到一定程度,基本上是不可逆转的。

但是,随着视网膜技术的发展,人们可以看到一丝希望。

视网膜技术的原理是通过植入人工视网膜来取代受损的自然视网膜。

人工视网膜通常由微小的电子元件组成,可模拟和代替自然视网膜的功能。

当光线进入眼睛并照射到人工视网膜上时,电子元件会将光线转化成电信号,并通过传导系统将其传递到大脑中。

这种技术可以帮助病患重现视觉,改善他们的生活质量。

然而,视网膜技术仍然面临着一些挑战和限制。

首先,该技术的成本较高,对于一般人来说并不易于承受。

其次,植入人工视网膜需要进行外科手术,涉及一定的风险和并发症。

此外,当前的人工视网膜虽然可以提供一定的视觉,但仍然无法完全还原自然视网膜的功能。

因此,对于那些希望通过视网膜技术恢复完整视力的人来说,目前仍然是一个无法实现的愿望。

尽管如此,视网膜技术的发展仍然给那些视力受损的患者带来了希望。

通过植入人工视网膜,一些病患可以恢复到一定程度的视觉,从而更好地适应日常生活。

例如,他们可以看清楚家人的面容,阅读文字,甚至参与到一些简单的工作中。

这无疑为他们带来了莫大的改变和希望。

随着科学技术的不断进步,视网膜技术也在不断改进和创新。

研究人员正在致力于开发更先进、更精确的人工视网膜,以提高视觉重建的效果。

他们还在探索如何通过视网膜技术来治疗其他眼睛相关的疾病,如青光眼和白内障等。

未来,希望视网膜技术能够取得更大的突破,为更多的患者带来希望和康复。

综上所述,视网膜技术是一项重要的医学技术,为那些因视网膜疾病而失去视力的人们带来了希望和改善。

植入式柔性神经微电极的微纳制备与光电集成技术研究

植入式柔性神经微电极的微纳制备与光电集成技术研究

植入式柔性神经微电极的微纳制备与光电集成技术研究植入式柔性神经微电极的微纳制备与光电集成技术研究摘要:随着神经科学研究的进步,植入式神经微电极已经成为研究神经系统的重要工具。

然而,传统的神经微电极存在着材料刚性、对生物组织损伤大、信号稳定性等问题。

因此,研究柔性神经微电极成为了当前的热点。

本文介绍了植入式柔性神经微电极的微纳制备技术,主要包括纳米材料的合成、微细加工技术、材料表面改性等方面。

同时,我们还介绍了光电集成技术在柔性神经微电极中的应用,包括光纤耦合和光学成像等方面。

最后,本文以植入式神经微电极在Parkinson's病患者治疗中的应用为例,论述了植入式神经微电极材料和制备技术的关键问题,并对未来发展进行了展望。

关键词:神经科学,植入电极,柔性材料,微纳制备,光电集成技术一、引言神经系统体系的研究一直是科学家们的热点问题,特别是对于人类大脑的认知以及一系列神经系统疾病的治疗。

植入式神经微电极成为了这一研究领域中的重要工具,因为它可以在实验对象体内直接接触神经元,获取神经元活动的信息,从而获得神经系统体系的结构和功能的相关数据。

但是,传统神经微电极由于材料刚性、对生物组织损伤大、信号稳定性等问题,限制了其在神经科学研究领域的应用。

因此,柔性神经微电极成为了当前的研究热点。

二、植入式柔性神经微电极的微纳制备技术1、纳米材料的制备柔性材料的制备是植入式柔性神经微电极制备的关键步骤,常用的柔性材料有聚合物、碳纳米管、金属纳米线、导电高分子等。

其中,碳纳米管因其良好的导电性和柔性特性,成为了柔性神经微电极的材料之一。

针对碳纳米管的制备,可以采用化学气相沉积、物理气相析出、化学还原法、碳化等方法。

此外,还可以将碳纳米管与其他纳米材料如金属纳米粒子、有机高分子等复合,以进一步提高柔性神经微电极的导电性和柔性性能。

2、微细加工技术微细加工技术包括微纳加工技术和生物加工技术。

其中,微纳加工技术主要包括光刻、薄膜沉积、等离子体刻蚀等。

单眼植入新无级连续视程人工晶体的视近效果

单眼植入新无级连续视程人工晶体的视近效果

白内障手术联合焦深扩展人工晶体植入术后单眼临床视力结果及近视力范围1美国德克萨斯州休斯顿休斯顿卫理公会医院Blanton眼科研究所2美国纽约Weill Cornell Medicine通讯作者Rahul T. Pandit;rtpandit@2018年8月13日接受; 2018年11月15日通过; 2018年12月13日出版学术编辑:Lisa Toto版权所有©2018 Rahul T. Pandit。

本文是根据知识共享署名许可转发的开源文章,原始作品被正确引用的前提下允许在任何媒体中不受限制地使用、转发和复制。

重要性.对于Symfony连续视程人工晶状体(EDOF 人工晶体),临床上尚未评估近视力和中间距离视力的视程大小。

背景.评估植入EDOF 人工晶体的单眼近距离视力的视程。

设计.回顾性病例队列研究。

参与者. 2017年1月到2018年3月期间单个术者的连续患者。

方法. 白内障超声乳化术联合EDOF 人工晶体植入。

主要观察指标。

未矫正的远视力(UDVA),未矫正的近视力(UNVA),矫正远视力(CDVA),最佳矫正远视力下的近视力(DCNVA),DCNVA视程和最佳视近焦距。

结果. 48名患者的76只眼(34个或71%的女性,平均年龄:68岁)被纳入,平均随访68天。

平均值如下:最小分辨角对数(logMAR)UDVA 0.02±0.09,平均距离51 cm时的logMAR UNVA 0.12±0.09,logMAR CDVA -0.05±0.07,平均距离51厘米时的logMAR DCNVA 0.08±0.07,等效球镜-0.16±0.35屈光度。

达到20/30的DCNVA的眼睛的百分比在36cm处为84%,在41cm处为92%,在51cm处为99%,在61cm处为93%,在71cm处为74%。

在35cm的范围内,近100%的眼睛达到20/40或更高的DCNVA。

植入式电子设备的研发和应用

植入式电子设备的研发和应用

植入式电子设备的研发和应用第一章植入式电子设备的概述植入式电子设备,是指将微型电子元件植入人体内,实现对人体状态的监测和控制设备。

它广泛应用于医疗、安全和监控领域,可以实现对人体的实时监测、调控和控制。

目前,植入式电子设备在医疗领域特别是神经科学、心脏病学、肿瘤学等领域中得到了广泛的研究和应用。

第二章植入式电子设备的技术原理植入式电子设备中,最关键的一项技术是微电子技术。

微电子技术是指将电子元件集成在微小的芯片中,然后将这些芯片植入到患者体内,实现对患者身体状态的实时监测。

除了微电子技术之外,生物传感器技术、无线传感器网络技术、材料科学技术等都是植入式电子设备的关键技术。

第三章植入式电子设备的研发植入式电子设备是一个综合性的系统,需要依靠多个领域的专业知识进行研发。

目前,植入式电子设备的研发主要由医学专家、生物传感器研究人员、微电子工程师、材料科学专家等进行研究。

植入式电子设备的研发需要采用复杂的工艺流程,如微加工技术、射频技术、生物材料化学等。

此外,植入式电子设备的研发还需要进行充分的临床实验。

第四章植入式电子设备在医学领域的应用植入式电子设备在医学领域得到了广泛的应用,特别是在神经科学、心脏病学、肿瘤学等领域。

在神经科学领域中,植入式电子设备可以帮助研究人员了解神经系统如何工作,并可以用来帮助治疗癫痫、帕金森氏病等疾病。

在心脏病学领域中,植入式电子设备可以监测和控制心脏功能,可以帮助心脏病患者恢复正常的生活。

在肿瘤学领域中,植入式电子设备可以帮助医生实时监测癌细胞的变化,以便提高癌症治疗的效果。

第五章植入式电子设备的风险和挑战植入式电子设备虽然具有许多潜在的优势,但也存在一些风险和挑战。

首先,植入式电子设备可能会对人体产生一定的刺激和反应,造成一定的身体不适。

其次,植入式电子设备也可能会被黑客攻击,造成人体受到威胁。

此外,植入式电子设备的生命周期是有限的,需要定期取出和更换,这也会对患者造成一定的负担。

人视网膜muller细胞)

人视网膜muller细胞)

--产品简介1、产品名称:Muller细胞2、组织来源:人眼球视网膜3、产品规格:5xl05细胞/25cm2培育瓶4、细胞简介:脊椎动物视网膜的神经胶质细胞。

其上端达外界膜,下端达内界膜,是贯穿网膜全层的大型细胞。

在发生学上是来源于室管膜细胞(ependymal cell X作为网膜的支持组织, 对神经的爱护、养分、代谢等方面可能起着重要作用。

止匕外,也有人认为和网膜电位的发生有关。

本公司生产的人Muller细胞采纳酶解法制备而来,细胞总量约为5x105个/瓶,细胞纯度可达90%以上,且不含有HIV-l、HBV、HCV、支原体、细菌、酵母和真菌等。

5、培育基信息:1)培育基类型:RPMI-16402 )添加因子:FBS , EGF , Insulin , Hydrocortisone , Streptomycin , penicillin1、您收到细胞后,请根据以下方法进行操作:取出25cm2培育瓶,75%酒精擦拭培育瓶,拆下封口膜,放入37℃z5%CO2细胞培育箱中静置4-6小时或过夜,以稳定细胞状态,然后换用新奇完全培育液连续培育或进行试验。

2.培育瓶或培育皿的预处理:1)包被液的配制:用无菌0.01%醋酸溶液配制成50ug/ml鼠尾I型胶原溶液;2 )培育瓶或培育皿的包被:取出培育瓶或培育皿,每个培育瓶或培育皿中加入适量的包被液,使包被液匀称的分布在培育瓶或培育皿的底面,置培育瓶或培育皿室温放置2h 以上,吸出包被液以风干培育瓶或培育皿,最终用PBS清洗2遍后使用。

3 .细胞传代:1)细胞生长至掩盖培育瓶的80%面积时,弃25cm2培育瓶中的培育液,用PBS清洗2 )添加0.125%胰蛋白酶消化液约2ml至培育瓶中,倒置显微镜下观看,待细胞回缩变圆后加入完全培育液终止消化,再轻轻吹打细胞使之脱落,然后将悬液转移至15ml离心管中 , 1500rpm/min ,离心5min ;3 )弃上清,沉淀细胞用12ml完全培育基重悬,然后按1:2比例进行分瓶传代,最终放入37。

眼科医疗领域的新技术

眼科医疗领域的新技术

眼科医疗领域的新技术眼科医疗领域一直是一个技术更新换代特别快的领域,因为我们的视力是我们生活中最重要的感官之一。

新的技术可以改善许多视力问题,从而使人们的生活品质提高。

本文将介绍几种最近在眼科医疗领域引起人们关注的新技术。

1. 人工晶状体人工晶状体技术是一种新兴的外科技术,它可以用来替代作废或有缺陷的天然晶状体。

晶状体是人眼的一部分,位于眼睛的中央,是组成眼内沉积的透明结构。

随着人们年龄的增长,晶状体会因为老化而变得模糊或浑浊,进而导致白内障。

人工晶状体可以安装到眼睛里,来替换那个受损的晶状体,从而让病人的视力大大改善。

在现在,人工晶状体的类型包括折叠式人工晶状体和多焦人工晶状体等。

折叠式人工晶状体就像是一种平板电视,可以通过微小的切口卡进眼睛并展开;多焦人工晶状体则能够提供不同的焦点来矫正视力问题。

这些人造晶状体现在已经被广泛使用,无论是作为白内障手术的标准治疗,还是作为角膜移植手术的一部分。

2. 激光屈光手术激光屈光手术现在已经成为眼科医疗领域的一项重要技术,主要是用来矫正近视、远视和散光等视力问题。

其基本原理是利用高能量的激光在眼角膜上削减组织来改善视力,手术具有高效、安全和无痛的等优点。

最近,激光屈光手术又有了一种新的形式:小切口激光近视矫正术(SMILE)。

与传统的激光手术不同,SMILE手术是在保证角膜层结构稳定的条件下,通过微小的切口来进行激光矫正,从而减少并防止患者眼睛角膜太薄或过度削减而产生的各种并发症,这也使得此技术的安全性显著提高。

3. 视网膜生物电子皮肤装置视网膜生物电子皮肤装置(RETINA)是一种非侵入性的可穿戴设备,被用于监测和治疗眼底疾病。

这种设备基于生物成分制造,只有数毫米宽,可以贴在眼睛上部位,就好像是一条胶带,使用起来非常便捷简单。

RETINA的作用主要是通过传感器和嵌入在其设备中的微处理器来监测视网膜的活动,并通过一系列相互联系的类神经网络和用户交互界面来将信息反馈给患者。

基于MEMS的人工视网膜微电极阵列设计仿真

基于MEMS的人工视网膜微电极阵列设计仿真

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子信号 , 电子信号传送到眼内的微刺激电极 ; 微电极直接
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高考物理电磁学知识点之传感器基础测试题及答案解析(6)

高考物理电磁学知识点之传感器基础测试题及答案解析(6)

高考物理电磁学知识点之传感器基础测试题及答案解析(6)一、选择题1.某兴趣小组对火灾报警装置的部分电路进行探究,其电路图如图所示,其中是半导体热敏电阻,它的电阻随温度的变化关系如图所示.当所在处出现火情时,通过电流表的电流I和a、b间的电压U与出现火情前相比()A.I变大,U变小B.I变小,U变小C.I变小,U变大D.I变大,U变大2.如图电路中,电源电动势为E,内阻为r,R G为光敏电阻,R为定值电阻。

闭合开关后,小灯泡L正常发光,当光照增强时,A.小灯泡变暗B.小灯泡变亮C.通过光敏电阻的电流变小D.通过光敏电阻的电流不变3.某兴趣小组做一实验,用力传感器来测量小滑块在半圆形容器内来回滑动时对容器内壁的压力大小,且来回滑动发生在同一竖直平面内.实验时,他们把传感器与计算机相连,由计算机拟合出力的大小随时间变化的曲线,从曲线提供的信息,可以判断滑块约每隔t 时间经过容器底一次;若滑块质量为0.2kg,半圆形容器的直径为50cm,则由图象可以推断滑块运动过程中的最大速度为v m.若取g=lO m/s2,则t和v m的数值为()A.1.0s 1.22m/s B.1.0s 2.0m/s C.2.0s 1.22m/s D.2.0s2.0m/s4.电视机遥控器是用传感器将光信号转化为电流信号。

下列属于这类传感器的是A.走廊中的声控开关 B.红外防盗装置C.热水器中的温度传感器 D.电子秤中的压力传感器5.下列说法中正确的是( )A.电饭锅中的敏感元件是光敏电阻B.测温仪中的测温元件可以是热敏电阻C.机械式鼠标中的传感器接收到连续的红外线,输出不连续的电脉冲D.火灾报警器中的光传感器在没有烟雾时呈现低电阻状态,有烟雾时呈现高电阻状态6.与一般吉他以箱体的振动发声不同,电吉他靠拾音器发声。

如图所示,拾音器由磁体及绕在其上的线圈组成。

磁体产生的磁场使钢质琴弦磁化而产生磁性,即琴弦也产生自己的磁场。

当某根琴弦被拨动而相对线圈振动时,线圈中就会产生相应的电流,并最终还原为声音信号。

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Visual perception in a blind subject with a chronicmicroelectronic retinal prosthesisMark S.Humayun a,*,James D.Weiland a ,Gildo Y.Fujii a ,Robert Greenberg b ,Richard Williamson b ,Jim Little b ,Brian Mech b ,Valerie Cimmarusti b ,Gretchen Van Boemel a ,Gislin Dagnelie c ,Eugene de Juan Jr.aaDoheny Retina Institute at the Doheny Eye Institute,University of Southern California,1450San Pablo Street (Room 3600),Keck Schoolof Medicine,Los Angeles,CA 90033,USA bSecond Sight,LLC TM ,Valencia,CA,USAcWilmer Ophthalmological Institute at Johns Hopkins Hospital,Baltimore,MD,USAReceived 10September 2002;received in revised form 18February 2003AbstractA retinal prosthesis was permanently implanted in the eye of a completely blind test subject.This report details the results from the first 10weeks of testing with the implant subject.The implanted device included an extraocular case to hold electronics,an intraocular electrode array (platinum disks,4·4arrangement)designed to interface with the retina,and a cable to connect the electronics case to the electrode array.The subject was able to see perceptions of light (spots)on all 16electrodes of the array.In addition,the subject was able to use a camera to detect the presence or absence of ambient light,to detect motion,and to recognize simple shapes.Ó2003Elsevier Ltd.All rights reserved.1.IntroductionMillions of people worldwide lose their photorecep-tors either due to retinal degenerations (e.g.retinitis pigmentosa (RP)or age-related macular degeneration (AMD))(Heckenlively,Boughman,&Friedman,1988;Klein,Klein,Jensen,&Meuer,1997;Klein,Klein,&Linton,1992).The feasibility of an implantable retinal prosthesis that would partially restore vision by direct electrical stimulation of retinal neurons is supported by several studies.Morphometric analyses in post-mortem eyes with almost complete photoreceptor loss either due to RP or AMD have shown as many as 90%of the inner retinal neurons remain histologically intact (Humayun et al.,1999;Kim,Sadda,Humayun,et al.,2002;Kim,Sadda,Pearlman,et al.,2002;Santos et al.,1997).In tests where electrical stimulating devices were tempo-rarily positioned on the retina,blind subjects reported seeing percepts that corresponded in time and locationto the electrical stimulus (Humayun et al.,1996;Hu-mayun,de Juan,et al.,1999).Several research groups have investigated various aspects of retinal prostheses,ranging from electrical stimulation of retinal neurons to surgical implantation methods (Chow &Chow,1997;Eckmiller,1997;Humayun,2001;Rizzo &Wyatt,1997;Zrenner et al.,1997).Two distinct retinal prosthesis ef-forts have materialized depending on the position of the stimulating electrode array.In the first,the electrodes are positioned on the ganglion cell side of the retina (epiretinal approach)(Eckmiller,1997;Humayun,2001;Rizzo &Wyatt,1997),whereas in the second the elec-trodes and most of the electronics are placed between the retina and the retinal pigment epithelium (subretinal approach)(Chow &Chow,1997;Zrenner et al.,1997).Both approaches have advantages and disadvantages (Zrenner,2002).The device developed for this study has a 16electrode stimulating array positioned on the epiretinal surface,an electronic implant positioned outside the eye to generate stimulation pulses,and an external system for image acquisition,processing,and wireless communication (to the implanted unit;Fig.1).Herein,we report on the results of our first human*Corresponding author.Tel.:+1-323-442-6523;fax:+1-323-442-6519.E-mail address:humayun@ (M.S.Humayun).0042-6989/$-see front matter Ó2003Elsevier Ltd.All rights reserved.doi:10.1016/S0042-6989(03)00457-7Vision Research 43(2003)2573–2581/locate/visresepiretinal implant in a blind subject with retinitis pig-mentosa.2.Material and methods 2.1.Subject selectionAfter obtaining FDA approval and institutional re-view board approval from the University of Southern California to conduct an investigational study,subjects with bare or no light perception secondary to photore-ceptor loss were considered for enrollment in the study.Subjects with visual loss due to all other causes were rmed consent was obtained,which ex-plicitly stated the investigational nature of both the de-vice and surgery and also emphasized that the subject should not expect any short or long-term benefit.Once consented,standard electrophysiological tests and psy-chophysical tests designed to assess very low levels of vision were used to determine whether the subject Õs vi-sual function met the qualifications for a test subject (i.e.bare light perception or worse vision in at least one eye).These tests included dark-adapted flash detection/dis-crimination;static and kinetic perimetry;electroretino-gram (ERG);visually evoked potential (VEP);scanning laser ophthalmoscopy (SLO);and electrically evoked response (EER).Baseline anatomical condition was documented with fundus photography,fluorescein an-giography,and optical coherence tomography.2.2.Electronic implantThe electronic device implanted was developed by our group in conjunction with Second Sight,LLC TM (Va-lencia,CA).As shown in Fig.1,it consists of an im-planted and an external unit.The external unit consists of a small camera worn in the glasses that connects to a belt-worn visual processing unit (VPU)TM (VPU TM not shown in figure).The VPU TM encodes visual informa-tion acquired from the camera and transfers electrical stimulation commands to the implanted unit.The data transfer is accomplished via a wireless link using an external antenna that is magnetically stabilized over the electronic implant.Personal computer based custom software was also used to actively control the electrical stimulation command through the VPU.The implanted unit consists of an extraocular (electronic case)and an intraocular component (electrode array).The extraocu-lar unit is surgically attached to the temporal area of the skull.A subcutaneous cable connected to this extraoc-ular electronic case is used to conduct electrical current across the eye wall to an intraocular electrode array placed on the retinal surface.The electrode array con-sists of 16disc shaped platinum electrodes in a square 4·4layout.Each electrode was (520)l m in diameter.Edge-to-edge separation between two adjacent elec-trodes was 200l m.2.3.Surgical procedureAbout two weeks prior to the surgery botulinum toxin (BOTOX â,Allergan,Inc.,Irvine,CA)was in-jected in the superior,inferior,medial and lateral rectus muscles of the test subject,due to the concern that the subject Õs eye movement might break the cable connect-ing the intraocular electrode array to the extraocular electronic case.Under general anesthesia,the electronic implant was placed in a recessed well created in the temporal skull as is done for cochlear implants (Webb,Pyman,Franz,&Clark,1990).To secure and protect the cable,a shallow groove was created along the tem-poral skull.The cable was then placed in the groove and delivered through a lateral canthotomy into the perioc-ular space.The cable and electrode array were passed subconjunctivally under each of the four recti muscles and introduced into the eye through a 5mm circum-ferential scleral incision placed 3mm posterior to the limbus.Prior to introduction of the implant,the ma-jority of the vitreous gel was removed.The electrode array was then positioned just temporal to the fovea and a single retinal tack (second sight retinal tack)was in-serted through the electrode array and into the sclera.At the end of the implant procedure,the device was tested electrically to assure that all wires were intact.The subject was examined on post-operative day 1and then three times a week for the next 2.5months.Fig.1.Schematic showing the concept of the retinal prosthesis.(A)Camera in the glass frame;(B)wireless transmitter;(C)extraocular electronic case (receiver)and (D)intraocular implant (electrodes array).2574M.S.Humayun et al./Vision Research 43(2003)2573–25812.4.Electrical stimulation testsSubject testing was conducted in three ways:double masked,subject masked,or subject training.Double masked tests were designed as forced choice tests during which both the tester and subject were masked as to the actual stimulus and the subject was trained to describe the perception in a limited number of ways.Subject masked tests were designed to allow the subject to provide detailed descriptions of the percepts.The tester, who was aware of the stimulus conditions,would ask questions such as‘‘Do you see anything?’’followed by, for example,‘‘Where did you see the spot?’’False pos-itive testing(i.e.no stimulus presented)was included in the subject-masked tests to verify the responses.Subject training experiments were designed to teach the subject to discriminate patterns of stimulation.Subject training was usually followed by double masked testing.Double masked testing was used to evaluate the subjectÕs ability to spatially discriminate and locate two or more elec-trodes.Subject masked testing was used to determine stimulus thresholds and investigate properties of single percepts.Most testing was conducted with a computer supplying the test pattern,but in a limited number of tests a camera was used to detect high contrast images. Testing was limited to4h/day,2–3days/week.Electrode impedance was typically measured twice a day.The subjectÕs left(unoperated)eye was patched during test-ing.The implant was only activated in the clinic.An electrically evoked potential was recorded using scalp electrode positioned in a standard visual evoked po-tential configuration.3.ResultsOn the basis of the results of tests listed under subject selection section,we identified a74year old male with X-linked retinitis pigmentosa.The subject had no light perception in his right eye and bare light perception in his left eye.In fact,we had tested this subject over the last10years to confirm the level of vision in each eye. The subject reported not seeing from his right eye for more than50years.This eye was selected for implan-tation of ourfirst electronic device,as it had no vision at all.The surgical implantation was without any compli-cations(Fig.2).Threshold current to elicit a visual response was found for all16electrodes.A statistical analysis of the threshold current versus time showed that three elec-trodes showed a significant decrease in current,10 electrodes had no significant change in threshold cur-rent,and three electrode showed a statistically signifi-cant increase in current(increase or decrease determined by slope of line from regression analysis of threshold stimulus current performed with MS Excel data analysis tool,p<0:05for significance of slope).The thresholds ranged from39l A to1.3mA during thefirst days of testing,and from50to500uA at10weeks after the surgery.The timing of the pulse was typically a biphasic current pulse,1ms/phase with a1ms intraphase delay. These numbers were chosen based on prior studies that suggest a stimulus impulse longer than0.5ms can target bipolar cells(Fig.3).The threshold level of electrical stimulus charge remained below0.35mC/cm2electrodes on13electrodes of the16(81.25%)electrodes(0.35mC/ cm2is an established long-term safety limit for platinum when pulses of at least0.6ms are used)(Greenberg, 1998).The threshold stimulus for each electrode posi-tion is shown onfirst day of stimulation and then2.5 months later in Fig.4A,B.The most dramatic decrease in threshold was seen at the electrodes furthest away from the fovea(i.e.at the perimeter of the electrode array).Electrode impedances ranged from4to55 kOhms(at1KHz,average,23kOhms)over2.5months of testing(Fig.5).Visual perceptions elicited by electrical stimulation of the retina with a single electrode produced a single spot described in one of two general different forms.Most percepts were described as round spots of light.Less frequently reported was a lighted center with a black surrounding ring.This dark ring was described as a ‘‘halo’’,darker than the background.The halo was typically seen at stimulus currents near perception threshold.Four different colors were reported.The lighted spots were usually described as either yellow or white and occasionally as red-orange.Blue colored percepts were noted when high frequency stimulation was extinguished(i.e.the blue percept was an‘‘off-response’’).When asked to describe the size of visual percepts at an armÕs length,the subject reported spots ranging from a match head to a quarter.The subject drew these percepts as small as0.25cm in diameter on a drawing board positioned in his lap(approximately 30cm away from his eye).In general,the size of the phosphenes increased with higher stimulation current (Table1).The subject reported the location of the perception that in general matched the location of the active stim-ulating electrode.The subject could distinguish between two adjacent electrodes of the array with center-to-center separation of720l m.The subject was asked to describe the location of each electrode as it was acti-vated.All the electrodes were positioned temporal to the fovea of the right eye and all the elicited perceptions were described in the subjectÕs nasal visualfield(Fig.2). In general,the reported position of the electrode cor-responded with the location of the electrode on the retina.Fig.2B shows a map describing the location of the percepts reported by the subject.The subject demonstrated the ability to describe the relative location of percepts generated by selectedM.S.Humayun et al./Vision Research43(2003)2573–25812575electrodes.For these tests,a training period preceded double masked testing.In the first set of two-alternative forced choice tests,the subject was told that one of two electrodes would be activated and was instructed to identify the active ing various pairs of vertically or horizontally aligned electrodes in five sep-arate trials,the subject was asked to describe the stim-ulus as ‘‘up’’versus ‘‘down’’(vertically aligned pair)or ‘‘left’’versus ‘‘right’’(horizontally aligned pair).Subject scored 10/12,12/12,6/8,8/8,and 8/8(correct responses/total responses,chance ¼50%correct;Table 2).In the second set of tests,two electrodes were activated in succession (within 3s)and the subject was asked to describe the order in which the electrodes were activated based on the location of the percepts.Four trials of this type were run.In one trial,the subject was askedtoFig.2.(A)Fundus photo taken 2weeks after surgery showing electrode position on the retina (black arrow indicate a reference point in the pig-mentary change).(B)Schematic showing the position of the percepts in the subject Õs visual field.These are perceptions as viewed from the subject Õs viewpoint (i.e.as the subject was looking out).In general,electrodes superiorly located induce percepts inferiorly located.This map is already correct for the horizontal orientation (electrodes temporally located induce percepts nasally located).Not all electrodes are included because the threshold current to elicit a response with those electrodes were relatively high at that time.2576M.S.Humayun et al./Vision Research 43(2003)2573–2581describe the pattern as either ‘‘up–down’’or ‘‘down–up’’;subject score 7/8(chance ¼50%correct).In one trial,the subject was asked to describe the pattern as ‘‘left–right’’or ‘‘right–left’’;subject score 8/8(chance ¼50%correct).In two trials,the subject was asked to describe the pattern in one of four ways:‘‘up–down’’,‘‘down–up’’,‘‘left–right’’,or ‘‘right–left’’;sub-ject scores 6/8and 6/8(chance ¼25%correct;Table 2).Brightness tests revealed that with increasing or de-creasing current the visual perception got brighter or dimmer,respectively.For each of the 12electrodes tes-ted the current was decreased 12times and increased eight times by 6–12%each transition (20transitions per electrode).On average,the subject identified the transition correctly more than 74%of the time (chance ¼50%correct).The subject was given an arbi-trary scale of 0–10with 10being the brightest and 0representing no perception.During the course of the 2.5months,the subject identified all 10levels of brightness on all tested electrodes.However,in general the percepts produced by the electrodes nearer the fovea demon-strated a more consistent correlation between brightness and stimulus current.In contrast,the percepts generated by peripheral electrodes in general were lessresponsiveFig.3.Graph showing the threshold current to elicit a response for all 16electrodes over 2.5months of testing (range,average).Clinical units are related logarithmically to microamperes,e.g.100CU ¼14l A,150CU ¼77l A,200CU ¼400l A.M.S.Humayun et al./Vision Research 43(2003)2573–25812577to increases in stimulus current and tended to remain dim.The subject demonstrated the ability to use the VPU TM to detect ambient light and to distinguish the direction of motion of objects.With the camera initially covered (i.e.,no light),the subject was asked to deter-mine if the camera remained covered or if the camera was exposed to light.In a double masked trial,the subject scored 10/10(chance ¼50%correct;Table 2).In a darkened room,the subject could locate a flashlight carried by a person who was 200cm away in 10/10trials on three different days (Table 2).In another test,the subject could locate a dark object under normal room light conditions (a 15cm square black box at 60cm away).Also,a 15cm square book with a black cover was held 5cm away from the camera in normal lighted room conditions.The book was moved up or down out of the field of the camera.In 4/5trials,the subject cor-rectly and immediately identified the direction the book was moved (chance ¼50%correct).Cortical evoked potential were elicited by electrical stimulation of the retina with the implant.N1–P1am-plitude was 4.29l V,and the N1and P1latencies were 23.2and 52ms,respectively (Fig.6).The cortical signal was repeatable over several trials,suggesting the evoked potential was correlated to the stimulus despite the poor signal to noise ratio.VEPs could not be recorded from either eye pre or post-operatively.Even though the left eye had bare light perception,the perception of light could only be evoked with a photographic flash,which is more intense than the standard bright flash used forVEP recording.Even the perception of the photographic flash was transient,so that only the first few in a series of flashes could be detected.Serial photographs were obtained of the implant both preoperatively and on scheduled post-operative dates (Fig.7).The photographs reveal minimal if any movement of the device.A comparison of pre operative and post-operative fluorescein angiograms showed no changes in the vasculature of the retina and choroid.4.DiscussionRetinitis pigmentosa afflicts 1/4000and a large number of these patients become legally blind in their fifth decade (Heckenlively et al.,1988).An even greater number of people lose vision due to photoreceptor loss in age related macular degeneration (AMD)(Klein et al.,1997;Klein et al.,1992).Although some treat-ments to slow the progression of AMD are available,no treatment exists that can replace the function of lost photoreceptors.We have summarized our results from the first 10weeks of testing an electronic device im-planted in an RP subject who has a history of being completely blind in the implanted eye for more than 50years due to photoreceptor loss.Electrical stimulation results in the subject seeing spots of light (phosphenes)that are both reliable and reproducible with respect to the spatial location of the stimulating electrodes on the retina and the stimulating electrical current.The threshold currents to elicit the responses areconsider-Fig.5.Graph showing impedances of all 16electrodes over 21/2months of testing (range,average).Table 1Visual percepts Forms Mostly perceived as round spots of light.Less frequently reported as a lighted center with a black surrounding ringSizeSpots size ranging from a ‘‘match head’’to a ‘‘quarter’’Location The location of the perception in general matched the location of the active stimulating electrode Resolution 120arc min (2°)or 20/2400Brightness At least 10levels of brightness on all tested electrodesColor The lighted spots were mostly described as either yellow or white and occasionally as red-orange or blue DurationMost visual percepts had the duration of the electrical stimulation (about 0.1s)2578M.S.Humayun et al./Vision Research 43(2003)2573–2581ably lower than previously reported short-term tests (Humayun et al.,1996;Humayun,de Juan,et al.,1999). Over time,the thresholds also appear to stay the same or decrease for a number of the electrodes.Most of the threshold currents are within safe limits for long-term electrical stimulation of neurons using platinum elec-trodes.This has significant,positive implications for the success of a retinal implant because lower threshold currents mean less power required by the electronics and therefore less heat dissipated in the eye.The electrode size for this prototype was based on safely supplying a stimulus current of700l A for1ms.This corresponds to charge density less than0.35mC/cm2.Since the actual current needed is in many cases lower,electrodes can be made smaller yet still support the same current.Thus, lower current requirements may lead to the use of a smaller,more densely packed electrode array that would put hundreds of individual percepts in the macula, possibly increasing the resolution afforded by the im-plant(Robblee&Rose,1990).The location of the percept corresponded to the electrode that was stimulated.The size and brightness of the percept were dependant upon the stimulus parame-ters.The elicited percept size was calculated from the drawings of the subject.The closest electrode separation we could test due to the electrode array design was re-solved by the subject.We have not yet tested the subject to evaluate independent mobility and this functionality remains to be proven for the electronic implant.One suggested disadvantage of epiretinal stimulation is that it would produce percepts not spatially consistent with the electrode location because the axons of gan-glion cells from many areas of the retina pass immedi-ately under the electrode.If these axons were stimulated in addition to the bipolar and ganglion cell soma,then the reported perceptions may no longer be retinotop-ically correct(i.e.correspond to the electrode position on the retina).The fact that the subject reported per-ceptions of round spots in locations consistent with the electrode supports experimental and modeling studies suggesting that deeper retinal cells can be targeted without stimulating the superficial ganglion cell axons (Greenberg,1998;Greenberg,Velte,Humayun,Scarla-tis,&de Juan,1999).The relationship between brightness and stimulus level is also important,since this suggests that information on relative intensity of light can also beTable2Testing resultsTest type Test description Chances of randomly correct Number of trials Correct answersPair of vertically aligned electrodes ‘‘Up’’versus‘‘down’’50%210/12(83.3%)and12/12/(100%)Pair of horizontally aligned electrodes ‘‘Left’’versus‘‘right’’50%36/8(75%),8/8(100%),and8/8(100%)Sequential activation of a pair of electrodes ‘‘Up–down’’versus‘‘down–up’’50%17/8(87.5%)‘‘Left–right’’versus‘‘right–left’’50%18/8(100%)‘‘Up–down’’or‘‘down–up’’or‘‘left–right’’or‘‘right–left’’25%26/8(75%)and6/8(75%)Camera testing On–offlight in front ofcamera50%110/10(100%)Locating aflash light in movement in a darkened room N/A310/10(100%);10/10(100%)and10/10(100%)Detecting motion of ablack box moved in frontof the camera50%14/5(80%)Fig.6.Electrically evoked response(EER)was recorded using eightstimulation electrodes in parallel:M1,M5,L3,L7,M2,M6,L4,andL8at threshold.Figure shows shorter latency and distinct N1and P1responses compared to visual evoked responses(VEPs).N1–P1am-plitude was4.29l V,and the N1and P1latencies were23.2and52ms,respectively.VEPs could not be recorded from either eye.(Scale:Yaxis¼4.88l V/division;X axis¼40ms/division.)Although only half ofthe array was used during stimulation,which corresponds to a1.2·2.6mm area of retina directly under the array,N1–P1peak is at least twicethe peak to peak noise.M.S.Humayun et al./Vision Research43(2003)2573–25812579partially restored.This ability would allow a continuum of contrast to be presented to the subject rather than a binary (‘‘on/off’’)representation of an image.Colorful perceptions had also been described by our subjects who had undergone short-term tests (Humayun et al.,1996;Humayun,de Juan,et al.,1999;Humayun &de,1998).Yellow is the predominant color of most of the percepts reported.Given that we have far more red and green sensitive cones,one explanation for the yellow color could be that a mix of the neural circuits that normally subserve these two color pathways is being stimulated.At this time,it is not clear how to reliably elicit the other reported red-orange and blue colors.Using pattern electrical stimulation of the retina,the subject was able to repeatedly report the order in which different electrodes were activated based on the location of the electrodes.Individual percepts were used in combination and the subject was able to distinguish a ‘‘direction’’that corresponded to the order of electrode activation.This is a first step towards providing infor-mation about direction as well as edges and shapes so the subject can possibly attain unaided mobility or read large print.We can successfully get the subject to see 2spots in sequence and thus convey the sensation of di-rection.Probably the most important information from this testing is that in this short period of testing we also observed that his ability to locate the phosphene in a retinotopically correct visual field increased with use.A similar learning effect was seen with increased use of the camera.These tests are more realistic than the computer controlled tests and more closely approximate vision in a daily environment.The first day the subjectused a video camera to control the electrical stimulation pattern,he was able to locate a spot of light on a wall located 120cm away.The subject could also locate a flash light carried by a person located 200cm away in a darkened room.With increased use of the camera,the subject was able to do more complex tasks.Under normal room lighting,the subject could locate and de-tect the direction of motion of a dark object.This could parallel the training period that many cochlear implant subjects need (Tyler,Parkinson,Woodworth,Lowder,&Gantz,1997).Longer-term investigation would be required to clarify and characterize this potentially beneficial effect.In summary,the subject can reliably and reproducibly report spots of light elicited by activation of individual electrodes positioned on the retina.Currently,the sub-ject can determine some directional movement.Further training and testing will be necessary to determine the maximum effectiveness of this type of treatment for re-storing vision that would allow mobility and recognition of simple forms.The next generation electronic retinal prosthesis is expected to provide higher number of elec-trodes and more complex stimulation control capability.AcknowledgementsThe authors would like to acknowledge the following individuals and institutions for their assistance.Agen-cies that have supported the preclinical development of the retinal implant include the National Science Foun-dation,The Whitaker Foundation,Research toPreventFig.7.Fundus photograph taken 2months after surgery showing the relative stable positioning of the electrode array over 6weeks.Electrode array does not move relative to the pigmentary changes of the retina (black arrow indicates same pigmentary changes shown in Fig.2A as reference).2580M.S.Humayun et al./Vision Research 43(2003)2573–2581。

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