【摘要】 目的:应用准分子激光对兔眼角膜进行切削,改变角膜的厚度。研究在离体状态下兔眼角膜与兔眼角膜中央厚度、眼压三者间的关系。方法:健康新西兰大白兔15只30眼。分3组,1组:正常组,未切削眼;2组:切削原角膜厚度的1/3,3组:切削原角膜厚度的1/2。把角膜试样固定于自制夹具,暴露全部角膜,通过连通器对角膜内表面加压。每个压力状态下三维激光扫描仪扫描。分析在不同压力状态下不同角膜厚度时角膜前凸的变化情况。实验数据用SPSS13.0统计软件进行方差分析和趋势检验。结果:不同眼压下相对基线平面的角膜凸出度dx(x=10～80)转化成logd1后3组间比较,差异无统计学意义(P>0.05)。各眼压与初始眼压状态下角膜凸出度的差值d-x10(x=20～80)转化成logd2后3组间比较:3组与1组和2组差异均有统计学意义(P<0.05)。1组和2组差异无统计学意义(P>0.05)。相邻眼压的角膜凸出度的差值d(x+10)-x(x=10～70)转化成logd3后3组间比较差异无统计学意义(P>0.05)。各压力状态下角膜凸出度dx(x=10～80)转化成logd1随压力的增大而增大呈线性趋势,3组间的趋势差异无统计学意义(P>0.05)。结论:LASIK术后角膜的前凸与生物力学存在一定关系。为了确保屈光手术的安全性和稳定性,剩余角膜基质床厚度不应小于原始角膜厚度的1/2。同时眼压应维持在正常范围的较低水平。更多还原

【Abstract】 AIM:To study biomechanical changes in the cornea of rabbits in ex vivo after laser in situ keratomileusis(LASIK) surgery.To explore the relations between corneal biomechanical properties of rabbits and the central corneal thickness(CCT) and the intraocular pressure(IOP). METHODS:1) A total of thirty eyes of fifteen New Zealand rabbits were included in the study.The thirty eyes were divided into three groups.Each group had ten eyes of five rabbits;ten eyes were incised 1/3 primary corneal thickness with excimer laser and ten eyes were incised 1/2;the other ten eyes were regarded as control.2) The isolated cornea was cut into a round sample whose diameter is 15mm.The sample was put on the clamping apparatus,pressurized by cross-connection device and scanned with three dimensional laser scanner.At last changes of corneal anterior process of the corneal sample were analyzed under different pressures and different corneal thickness.3) All the parameters were converted into logarithm and the measurement data were evaluated through variance analysis and tendency test. RESULTS:1) The differences of corneal protrusion dx(x=10-80)(logd1) under different pressures are statistically meaningless in the three groups.2) The differences of corneal protrusion dx-10(x=20-80)(logd2)between every experimental pressure and primary pressure among three groups are as below:1) The differences between ablation1/2 group and normal group,ablation 1/3 group are statistically meaningful(P <0.05).2) The difference between normal group and ablation 1/3 group is statistically meaningless(P <0.05).3) The differences of corneal protrusion d(x+10)-x(x=10-70)(logd3)under adjacent pressures are statistically meaningless in the three groups.4) Corneal protrusion under different pressures grows with the increase of pressure dx(x=10-80)(logd1),which has a linear trend.But the trend differences among the three groups are statistically meaningless. CONCLUSION:1) The change of corneal biomechanics has some relationship with CCT after LASIK surgery.The corneal biomechanics of ablation 1/3 group is close to that of normal group and in safety margin.The corneal biomechanics of ablation 1/2 group is obviously degraded.2) There is certain relationship between IOP and the corneal biomechanics.When the IOP is high enough,the corneal anterior process is irreversible.3) To insure the stability and security of LASIK,the residual corneal stroma-bed thickness must not be less than half of the primary thickness and IOP must be maintained at the low level of normal range.更多还原