实验性近视鸡模型眼形态学改变的研究

The morphological study of form deprivation myopia in chicks

本实验选用出生当天的彼得逊肉食鸡雏，将实验组右眼睑缝合作为实验眼，左眼为对照眼。于小鸡出生当天检测其屈光状态，用Ａ超测量其前房深度、晶体厚度和眼轴长度，计算玻璃体腔长度。分别于小鸡出生后１５、３０、４５天对小鸡作上述检查后处死实验组、空白对照组各１０只，作病理切片观测鼻、颞侧及后极部巩膜软骨层、纤维层厚度，做相应部位巩膜软骨细胞、双核细胞计数。取４５天小鸡实验、对照眼后极部巩膜做透射电镜切片。结果发现：小鸡被形觉剥夺后，实验眼出现明显轴性近视，眼轴延长主要以玻璃体腔延长为主；后极部巩膜软骨层变厚，纤维层变薄，巩膜软骨基质呈嗜酸性红染，提示有退行性变化。

Similar neurochemical events appear to be involved in the development of myopia in chicks and mammals.The rapid post hatching development of the chick is ideal for studying experimental myopia of form deprivation.In this investigation,right eye of 1 day old chicks was deprived of form vision for 2、4、6 weeks and then compared to the fellow,non deprived eye by histology and light and electron microscopy.All deprived eyes showed a high refractive error and ocular enlargement.In deprived eyes,the posterior cartilaginous sclera was thicker and the fibrous sclera of the same section was thinner than the control.Scleral morphological changes were rectricted to the posterior pole.We found that the cartilaginous sclera exhibited several differences from that in the corresponding nonmyopic region:its cell density was lower,and the number of chondrocytes and binucleate cells was higher.Results of this morphological study suggest an increased proliferation of chondrocytes and active synthesis of extracellular matrix in visually deprived eyes.The elongation of the ocular axis that accompanies myopia is caused primarily by an active remodeling and differentiation in a restricted section of the posterior scleral cartilage.These facts indicate the posterior scleral cartilage may be more immature than cartilage in anterior and lateral segments.