作者：唐显庆，曾效恒，龙双莲
【关键词】 胎儿；晶状体囊；血液供应；先天性白内障
Relationship of Fetus Lens Capsule Blood Supplies and Developmental Regularity and Congenital Cataract
Abstract: Objective To observe the relationship between fetus lens capsule blood supplies and developmental regularity and congenital cataract. Methods 30 fetus specimens were obtained from the water bag abortion and embryo age distribution from 12 weeks~38 weeks. Twosided eyeball were took to enter in 10% neutral formalin fixed and dissected and observed by 16 times surgery microscope. The slices of eyeball were stained with hematoxylin eosin to determine the relation of the blood vessel and lens capsule. Results First, some branch vessels come from the central retinal artery. There are 8~10 branch vessels on the central retinal artery near the posterior polus of lens capsule, and each branch branches out 2~3 tiny branches and assumes the fasciculate or the lattice. Second, some come from ciliary body artery. The branchs circle along in the edge of lens capsule equator department to the posterior lens capsule, quantity very many, about 40. The branch vessels assume the equalspace arrangement like the annular wheel and each sends out 2 fine branches, and anastomose with the tiny branch of the transparent artery. Conclusion Two groups of blood vessels only distribute in the lens capsule, has not entered in the capsule. The artery in the edge of lens capsule equator department started atresia and vanishing at the 30th week, and vanishing complete at the end of the 32nd week in some specimens. Up to the 33rd week, two group artery of different origin were complete atresia and vanishing, were remaining the transparent vitreous body frenum.
Key words: Fetus; Lens capsule; Blood supplies; Congenital cataract
先天性白内障是一种较常见的儿童眼病，但以往在我国还没有其患病率的统计。近年来通过致盲性眼病和遗传性眼病的普查，总结出我国先天性白内障的群体患病率是5%，低于国外(Francois，0.4％)的患病率。由于本病是造成儿童失明和弱视的重要原因，从优生优育及防盲出发，要减少先天性白内障的患病率。在天津、上海和北京盲童致盲原因的调查中，发现22％～30％的盲童是因先天性白内障而致盲，占失明原因的第二位。此外，还有许多儿童因本病而导致不可逆的弱视。Francois回顾以往的资料，先天性白内障占儿童失明原因的10.0％～38.0%。先天性白内障可有完全性和不完全性白内障，又可分为核性、皮质性及膜性白内障。由于混浊的部位、形态和程度不同，视力障碍不同。因此，本文取部分标本组织切片以确定血管与晶状体囊的位置关系，晶状体囊的血液供应及其发育规律。
1 材料与方法
本文收集水囊引产完整新鲜胎儿30例，胎龄分布自12周~38周，取双侧眼球入10％中性甲醛中。固定后在16倍手术显微镜下解剖和观察。并取部分标本做成组织切片以确定血管与晶状体囊的位置关系，晶状体囊的血液供应及其发育规律。
2 结果
胎儿玻璃体动脉近晶状体囊后极处与睫状体动脉至晶状体囊后部，见表1。表1 胎儿玻璃体动脉近晶状体囊后极处与睫状体动脉至晶状体囊后部例(略)
胎龄晶状体囊血管发育规律，见表2。表2 胎龄晶状体囊血管发育规律（略）
胎儿晶状体囊的血供有二：其一，来自视网膜中央动脉。视网膜中央动脉在视神经乳头处分出鼻侧上、下动脉和颞侧上、下动脉，本干继续前行穿入玻璃体管即为玻璃体动脉。该动脉近晶状体囊后极处，发出8条～10条分支，每条分支又分2条～3条细小分支，呈丛状或网状。其二，来自睫状体动脉的分支沿晶状体囊的赤道部边缘绕至晶状体囊后部，数量甚多，约有40条左右，等距离地呈车轮状排列，每支再发出2支细支，并与透明动脉的细小分支相吻合。两组血管仅分布于囊，始终未进入囊内。胎儿自第30周始，部分标本在晶体囊赤道部边缘的动脉已开始闭锁消失，第32周以后完全消失。至第33周两组不同来源的动脉已全部闭锁消失，残留着透明的玻璃体系带。
3 晶状体解剖生理
晶状体lens位于虹膜的后方、玻璃体的前方，呈双凸透镜状；前面曲度较小，后面曲度较大，无色透明、富有弹性、不含血管和神经。晶状体由平行排列的晶状体纤维所组成，周围部称晶状体皮质，较软；中央部称晶状体核。晶状体外面包以具有高度弹性的被膜，称为晶状体囊。晶状体若因疾病或创伤而变混浊，称为白内障。
晶状体是屈光系统的主要装置。晶状体的曲度随所视物体的远近不同而改变。视近物时，睫状体内纵行排列的肌纤维收缩牵引脉络膜向前，使睫状突向内伸，睫状小带也向内而变得松弛，因而放松了对晶状体的牵拉，晶状体借助于晶状体囊及其本身的弹性而变凸，特别是前部凸度增大，晶状体的曲度增加，屈光力度加强，使进入眼球的光线恰能聚焦于视网膜上，以适应看近物。反之，睫状肌舒张时，使睫状突向外伸，睫状小带张力增大，加强了对晶状体的牵拉，使晶状体的曲度见小，以适应看远物。
随着年龄增长，晶状体核逐渐变大、变硬、弹性减退及睫状肌逐渐萎缩［1］，晶状体改变曲度的调节能力减弱，出现老视。若眼轴较长或屈光装置的屈光率过强，则物象落在视网膜前，称之为近视。反之，若眼轴较短或屈光装置屈光率过弱，则物象落在视网膜后，称之为远视。
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