| Objective:Through establishing alkali burn models, evaluate the effects of removing and reserving corneal epithelium by using Dexamethasone only and Dexamethasone combined with amniotic membrane homogenate supernatant on early stage of corneal alkali burn in rabbits.Methods:Twenty-four adult rabbits were randomly divided into four experimental groups: groupA,groupB, groupC and groupD.Every group had six rabbits.They were choosen to establish alkali burn models with their right eyes. The rabbits ingroup A were received to remove corneal epithelium and combined with subconjunctival Dexamethasone.Group B, were removed corneal epithelium, subconjunctival Dexamethasone and combined with amniotic membrane homogenate supernatant eye-drops; Group C were reserved corneal epithelium and combined with subconjunctival Dexamethasone;And group D were reserved corneal epithelium, subconjunctival Dexamethasone and combined with amniotic membrane homogenate supernatant eye-drops.Corneals were stained by Fluorescein Natrici at different stages after alkali burn and were taken pictures.Repair rates of corneal epithelium were determined by the computer image analyzing system.Pathological specimens were observed by light and electron microscopes at different stages.Results:1.The repair rates of corneal epithelium:After corneal alkali burn,the corneal epithelium was gradually repairing as time went by.The repair rates of corneal epithelium on the 1st day in group B (0.4632±0.01222) was better than group A(0.3925±0.03352), group A was higher than group D (0.3541±0.01457), and group D was superior to group C (0.3009±0.02575). All groups had statistical differences (P<0.05). On the 3rd day, the corneal epithelium repair rate of group B (0.8143±0.02444) was the best of all, while group C (0.7025±0.01258) was the worst. Group A(0.7694±0.02181) or group D (0.7625±0.03187) laid between the above two groups,and they had no statistical differences(P>0.05).On the 7th day, except group A (0.9620±0.02681) and D (0.9594±0.02607) statistical differences existed between two of other groups. The corneal epithelium repair rate of group B (0.9905±0.01075) was higher than group A and D.But group A and group D were superior to group C (0.9057±0.00853).2.Observation by light microscope:On the 7th day after corneal alkali burn,the corneal epithelial cells of group B were well repaired with 3-4 layers,and cell morphology was regular. While in group C corneal epithelium cells were about 2-3 layers.And cell morphology was abnormal, with cells arrangement disorder.Corneal epithelium cells were about 2-4 layers in group A or D,and part of the cells arrangement was irregular.On the 14th day, compared with group A, C and D,the stromal collagen fiber of group B was regular.However,it was disorder in group C.Group B had the least inflammatory cells, while group C had the most of all. The morphological changes of group A or group D were between the above two groups.3.Observation by transmissing electron micoscope:On the 14th day after alkali burn,group B had normal cells in morphology by large.And with more desmosomes between cells, and was rich in mitochondria,rough endoplasmic reticulum,Golgi complexes and chromatin. The stromal collagen fiber in group B was regular.However in group C, corneal epithelial cell morphology was irregular, cell gap was bigger than normol.and without desmosome.These cells had more condensation or vacuolization of mitochondria and fat droplet.Stroma collagen fibers in group C were irregularly arranged.The changes of group A or group D were between the above two groups.They had less desmosomes and fat droplet.Conclusions:1.Effect of receiving medical treatment after removing corneal epithelium in corneal alkali burns of rabbits is superior to no epithelial curettage groups.2.Effect of using Dexamethasone combined with amniotic membrane homogenate supernatant for corneal alkali burn was better than Dexamethasone only. |
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