所谓眼底，指的是眼球的内表面，主要包括：

视盘：又称视神经乳头或视乳头，即视网膜上的视神经细胞的轴突集中穿出眼球进入颅内的地方，此处无视感觉细胞，不能感光，因此是生理盲点。

视网膜血管：视网膜中央动脉由视乳头穿入眼球时，棸阌?个分枝，按其分布的位置，分别称为鼻上、鼻下、颞上和颞下视网膜动脉，各枝逐渐分成许多分枝，布满整个眼底。同名静脉与同名动脉相伴而行，由视乳头表面穿出眼球进入颅内。

黄斑：是视网膜上视觉最敏锐的特殊区域，位于视网膜的中心部，黄斑的中心有个小凹称为中心凹，此处视网膜最薄，接受和分辨光线信息最为准确。我们平常体检检查视力，查的就是黄斑区的中心视力，黄斑区对稍有病变就会影响视力。

周边部视网膜：负责周边视力，即周边视野，但此处并不能看清物体的细节。如果用这部分视网膜对准某个人，则只能看见他的轮廓。此处视网膜不能用来做精细工作。周边视力丧失，相当于周边视野缩小，使人只能看到前方的物体，而周围的物体需要转头才能看到，患者的行动会非常不便。

有关荧光血管造影的信息请访问：http://www.fx120.net/disease4/200810/97317.html
 

自从5月12日大地震后，几乎每天都要经历余震的折磨。从最开始的恐慌，到后来慢慢已感觉到了习惯。每天多次的余震就像乘坐在大海上的船只。摇……摇……。在这过程中，很多人还是恐慌的，传言也没有停止。自己虽然很冷静，但一点风吹草动，周围的人就可能变得慌乱。在这关键之际，同事的一封电邮也验证了自己的地震的判断。

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Earthquake information

Hello everyone

It is obvious that there is still a lot of nervousness about the current situation. I think some of that occurs thru not being fully knowledgeable about circumstances surrounding an earthquake and also by the number of differing rumours that fly around in a time like this.
These are uncertain times; nobody can guarantee that there will not be other earthquake. Let me share with you my knowledge and experience. I lived for 6 years in Los Angeles USA this city is right on top of one of the most active fault lines in the world – the San Andreas fault. Living with minor and major quakes was a way of life - one occurred every month. To a certain extent having lots of minors was considered better because we knew it would relieve that pressure and stop it building to a point a major quake would occur. So here actually it is better if there are a lot of minor aftershakes to settle everything down. – Yes it’s uncomfortable but it is better.

Let’s also talk about Earthquakes
•   They are very destructive and despite all the scientific testing, measuring and monitoring its impossible to predict accurately the occurrence, sometimes they can say there is an increased likely hood of a quake along a fault line but where the epicentre would be and how big cannot today be determined ( despite what would might be hearing to the contrary)
•   Once their has been a major quake like we had, no aftershock has ever been as great
•   Aftershocks will probably occur for several months.
•   Earthquakes are measured on the Richter scale – this is a logarithmic scale – what does the mean? Here is an example – Our earthquake here was a 7.9 or 8.0 on the Richter scale the after shock on Friday was around 5.9 that means it was 100 times LESS strong That is why it was felt here as only a minor tremor. Each whole number equates to Ten times
•   So the like hood of aftershocks causing any real damage in this city is very remote – we are over 100KMS away and the size is much much smaller that the original one which we all survived as did our building that we work in.

We are also developing an evacuation plan which will be circulated today so that should we need to do so we know how, where to evaluate to and what is expected of us. Your BMT manager will run thru the plan with you.

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地震信息

大家好！

很明显，大家对当前的情形仍然有许多担心。我想这是因为大家对地震的情况及环境不了解，以及近期许多不同的谣言所造成的。
这是一个难以预测的时期，没有任何人能够保证不会再次发生地震。那么让我来跟大家分享我对地震的了解以及我的亲身经历。我曾经在美国洛杉矶住了6年，这个城市位于地球上最为活跃的断裂带之上——San Andreas fault断裂带。所以，大大小小的地震是我在那里生活中的一部分—每月一次。在一定程度上，频繁的小级别地震还比较好，因为能够释放断裂带的压力，令至压力不会滤积至出现大级别地震。所以，对于当地来说，有很多小的余震，反而是件更容易令这事平静下来。是的，这些有余震确实令人不安，不过真的比较好。

我们再来谈谈地震
■　地震的破坏性真的很大，即使是进行了很多的科学测试、测量及监控，我们也不可能准确地预测地震的发生。有时，科学家可能预测到地震发生在哪个断裂带上，但是震中和震级在今天来说确是无法确定的。
■　一旦发生了如我们所经历过的强烈地震，以后的余震是不会更强的
■　余震很可能会持续几个月
■　地震震级以里克特计算——这是一种对数的等级—这是什么意思呢？有一个例子，我们这次的地震震级为7.9或8.0里克特，周五的余震为5.9级，也就是说震动程度减弱了100倍，这就是为什么在这里感觉到的是只是轻微的晃动。每一个完整级别相当于10倍。
■　因此，余震对我们的城市造成真正破坏的可能性真的不大——我们距离震中有100公里，而且震级比原来我们已经过的地震小很多，而且那时候我们和这栋大楼也都没有受到损害。

我们也已经分发一个撤离的方案给大家。让我们了解假如这种情况真的发生时，我们知道怎么做、撤离到哪里以及大家所需要做的事情。你的经理会跟你一起来阅读这份计划。

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