An Experimental Study On The Vitality Of Corneal Epithelieum After Exposed To 20% Alcohol For Different Time

Objective To evaluate the vitality of corneal epithelieum after exposed to 20% alcoholic solution for different time.Methods According to the time of rabbits sacrifice, 22 healthy adult New Zealand white rabbits were devided into 5 groups randomly . They were immediate group,3 day group , 7 day group and 10 day group and fresh control group . There were 2 rabbits in fresh control group, 8 rabbits were in immediate group, and 4 rabbits were in each other groups.In immediate group , the eyes were exposed to 20% alcoholic solution for different time(20S, 30S,40S and 50S), while in other experimental groups, the eyes were exposed to 20% alcohol for 30S and 50S.Trypan blue staining, light microscopes and scanning electron microscopes were used to study the structure of corneal epithelieum cells of rabbits. Enzyme histochemistry methods with VIDAS image analysis system were used to evaluate the metabolic enzyme activities, lactate dehydro-genase(LDH) and succinate dehydrogenase (SDH).Results (1)From the study of trypan blue staining, the corneal epithelial cells which were infiltrated by 20% alcohol for 20S and 30S, remained satisfactory vitality. The vitality of the corneal epithelial cells which were infiltrated for 40S and 50S had been weakened deeply. (2) From light microscopic study, in immediate group, after being infiltrated for 20S and 30S,the epithelial cells remained intact and lined up tightly .And the epithelium layers exposed to 20% alcohol for 40S and 50S were breaked and some cells were necrosis and lost. In 3 day group, the epithelium layers exposed to 20% alcohol for 30S and 50S,the epithelial cells regain intact and lined up tightly. (3) From enzyme histochemistry methods study, the activities of LDH and SDH in the corneal epithelial cells , which were exposed to 20% alcohol for 20S and 30S in immediate group , remained the same vitality as in fresh control group. There were no significant difference in the twokinds of enzymic activities between 7 day group and fresh control group (p>0. 05), and between 10 day group and fresh control group (p>0. 05). There was a statisteal difference between fresh control group and immediate group (p<0. 05), in which the epithelial cells were exposed to 20% alcohol for 40S and 50S;and there was a statistcal difference between fresh control and 3 day group (p<0. 05) , in which the epithelial cells were exposed to 20% alcohol for 50S. There was a statistcal difference between the epithelial cells which were exposed to 20% alcohol for 30S and which were exposed for 40S, and there was no significant difference between the epithelial cells which were exposed to 20% alcohol for 40S and which were exposed for 50S.(4) From scanning electron microscopic study, the epithelial cells exposed to 20% alcohol for 20S and 30S still remained high vitality. Those exposed to 20% alcohol for 40S and 50S had reduced to lower vitality or even no vitality. There would be 7 days until the new corneal epithelial cells appeared and be filled with vitality.Conclusions The density of alcoholic solution and the time to be exposed for are very important to laser epithelial keratomileusis(LASEK). 20% alcoholic solution last 30 seconds will be more successful.Ma Yibin (ophthalmology)Directed byProfessor Wang Chuanfu...