Depth-dependent cohesive tensile strength in human donor corneas: implications for refractive surgery.
Depth-dependent cohesive tensile strength in human donor corneas: implications for refractive surgery.
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DOI：
10.3928/1081597x-20080101-15
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发表时间：
2008-01-01
期刊：
影响因子：
--
通讯作者：
Edelhauser, Henry F
中科院分区：
文献类型：
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作者：
Randleman, J Bradley;Dawson, Daniel G;Edelhauser, Henry F
目得：为了确定整个正常人供体角膜基质的内聚抗张强度，并评估这些研究结果的相关性，在当前的准分子激光手术technology.METHODS的背景下：从格鲁吉亚眼库获得20个正常的角巩膜按钮11个捐助者。将角膜切成3 mm的条，在不同的基质深度处解剖，使用电动引伸计通过解剖平面机械分离，并测量内聚拉伸强度。结果：角膜基质厚度与内聚抗张强度呈显著负相关（r = -0.93）。与Bowman层直接相邻的前角膜基质，其次是下面的前40%的角膜基质，具有最高的内聚拉伸强度。内聚抗张强度在角膜基质深度的40%至90%处趋于稳定，然后从基质的后10%至后弹力膜处迅速下降。前40%角膜基质的内聚抗张强度显著高于后60%（33.3 g/mm vs 19.6 g/mm，P <0.00001）。在中央40%至60%的深度，年龄的增加和增加的抗张强度之间呈正相关（r = 0.67），角膜抗张强度增加38%，从年龄20至78 years.CONCLUSIONS：中央角膜基质的前40%是最强的区域的角膜，而后60%的基质是至少50%弱。因此，消融至后基质时扩张的风险可能更大。年龄的增加与角膜内聚抗张强度的增加有关。
PURPOSE: To determine the cohesive tensile strength throughout the stroma of normal human donor corneas and evaluate the relevance of these findings within the context of current excimer laser surgical techniques.METHODS: Twenty normal corneoscleral buttons from 11 donors were obtained from the Georgia Eye Bank. The corneas were cut into 3-mm strips, dissected at varying stromal depths, mechanically separated through the dissection plane using a motorized extensometer, and measured for cohesive tensile strength. Central corneal thickness and dissection depth were measured by routine light microscopy and correlated with cohesive tensile strength measurements.RESULTS: A strong negative correlation was noted between stromal depth and cohesive tensile strength (r = -0.93). The anterior corneal stroma directly adjacent to Bowman's layer followed by the underlying anterior 40% of the corneal stroma had the highest cohesive tensile strength. Cohesive tensile strength plateaued from 40% to 90% corneal stromal depth and then declined rapidly from the posterior 10% of the stroma to Descemet's membrane. The anterior 40% of the corneal stroma had significantly higher cohesive tensile strength than the posterior 60% (33.3 g/mm vs 19.6 g/mm, P < .00001). Within the central 40% to 60% depth, a positive correlation was found between increased age and increased tensile strength (r = 0.67), with corneal tensile strength increasing 38% from ages 20 to 78 years.CONCLUSIONS: The anterior 40% of the central corneal stroma is the strongest region of the cornea, whereas the posterior 60% of the stroma is at least 50% weaker. The risk for ectasia may therefore be greater with ablations into the posterior stroma. Increasing age is associated with increased corneal cohesive tensile strength.