方法：选择新鲜猪角膜，以13mm直径环钻制取角膜标本，依次放入4种冷冻保护液中冷平衡，“简化四步法”程序降温后放入液氮中保存，使用前40℃水浴复温。地塞米松作用组以同法制备植片，前三步冷平衡同前，最后分别放入含0.01，0.03，0.05mg/mL地塞米松保护液中4℃孵育18h，再程序降温液氮冻存。复温后用于锥兰-茜素红染色，观察内皮细胞存活情况。

结果：内皮细胞染色结果示：程序冻存组和地塞米松作用组的内皮细胞存活率均超过90%，差异比较无统计学意义(P>0.05)。

结论：在0.01～0.05mg/mL浓度范围内，未见地塞米松毒性作用，内皮细胞维持正常六角形形态，内皮细胞存活率超过90%。

METHODS: Fresh pig corneas were drilled down by 13mm-diameter trephine. Then the grafts were put into four kinds of cool cryoprotective media by turns and equilibriumed with ‘simplified four-step' method. All grafts were thawed in 40℃. All dexamethasone pretreatment corneas were additionally incubated in the last cool cryoprotective medium which had 0.01mg/mL, 0.03mg/mL or 0.05mg/mL dexamethasone for 18 hours in 4℃ before cryopreservation. Corneas thawed were stained by typan blue and alizarin Bordeaux. Survival rates of endothelia cells were observed.

RESULTS: There were no significant differences in endothelia survival rate among rate-freezing group and every dexamethasone pretreatment group.

CONCLUSION: In 0.01-0.05mg/mL of concentrations, dexamethasone shows no toxic effects. Survival rate of endothelial cells was more than 90%.