Experimental Study On Inhibitory Of Corneal Neovascularization By Carteolol In Rats

Objective:to observe the structural characteristics of the cornea in normal SD rats with IVCM,and to obtain the basic corneal confocal datas of normal SD rats.The corneal neovascularization（CNV）model of alkali burn in rats was established to observe the hyperplasia process of CNV after alkali burn.To observe the inhibitory effect of different concentrations drugs（1%and 2%carteolol eye drops）on CNV in rats,so as to provide a new drug for the treatment of corneal neovascular diseases.Methods:Forty-nine healthy adult（6-8 weeks old）male SD rats with weight（200±20）g were selected.Before the experiment,they were examined by slit lamp to exclude corneal lesions.Then,10 rats were selected as the blank control group（group A）by completely randomized method.The remaining 39 rats were established corneal alkali burn models,and a perforator was used to make a circular filter paper with a diameter of 3mm during the modeling.All the eyes of the established corneal alkali burn models were the right eye.After the model was established,levofloxacin eye drops were administered to the eye 4 times/day for 3 consecutive days.On the 4th day,selected 30 rats with successful modeling were randomly divided into three groups:negative control group（group B）,1%Carteolol group（group C）and 2%Carteolol group（group D）.From day 4 to day 17,group B（saline,2 times/day）,group C（1%Carteolol,2 times/day）,and group D（2%Carteolol,2 times/day）were given,respectively.On the day(the 1^stt and the 4^thh day after the model was established,the4^th、the 6^th、the 12^th、the 14^thday after the medication),the rats in each group were examined by anterior gangliography and corneal confocal microscopy,record the inspection results,calculated the corneal neovascularization score、corneal edema score、corneal neovascularization area、corneal epithelial cell count、keratocyte count、corneal inflammatory cell count and corneal endothelial cell count,and obtained the corneal thickness.Completed statistical analysis of experimental results at last.Results:normal SD rats with dilated posterior anterior segment showed regular round dilated pupil,cornea was clear,peripheral iris was clear,no obvious opacity of lens,and no dilation and filling of blood vessels at the corneosclera limbus.In vivo confocal microscopy（IVCM）examination showed that the corneal epithelial cell boundaries were highly reflective and the cytoplasm showed low reflection signals.The corneal epithelial cells were counted as 5267±125/mm².The corneal stromal layer had two types,One is fiber bundles and the other is star-shaped shapes,sometimes the two structures could coexist.The superficial stroma nerves of corneal in rats were slender and tortuous,while the deep nerves were thick and straight.The nucleus of corneal stromal cells showed a circular high reflection signal,and the normal rats’corneal stromal cells count was:74±10/mm².The cytoplasm of corneal endothelial cells showed highly reflective and the boundaries showed low reflection signals,most of them were regular polygons.The count of corneal endothelial cells was 3377±279/mm².The corneal thickness was:145.5±9.2 um.Photographic result of the anterior segment results:On the 4^thh day after the model was established,brushy neovascularization was observed at the corneosclera limbus.Corneal neovascularization score、corneal edema score and corneal neovascularization area were higher in the negative control group than in the carteolol group,and there were differences（P<0.05 for each group）.The corneal neovascularization area of all three groups reached their peak on the 14^thday after the model was established,the normal saline group was 20.91±1.68mm²,1%carteolol group was 11.15±1.45mm²,the 2%carteolol group was 10.83±1.28mm².Corneal in vivo confocal microscopy（IVCM）examination results:On the 4^thday after the model was established,the corneosclera limbus neovascularization grew into the corneal stroma;On the 14^thh day,the neovascularization grew the densest,the diameter of the blood vessels were thick,and the blood flow signals were abundant.The cell count of corneal epithelial cells and endothelial cells in the blank control group was the highest,with 5267±125/mm²and 3377±279/mm²,respectively.In the modeling group,the counts of these two terms decreased,and the difference was significant（both P values were 0.000）.Compared with the normal saline group,2%carteolol intervention reduced the decrease of corneal epithelial cell count and endothelial cell count,with P value of0.039、0.000 in the two groups,and 1%carteolol intervention reduced the decrease of corneal endothelial cell count（P value=0.03）.The number of corneal stromal cells and inflammatory cells increased on the day of modeling and reached the peak on day7th and 4th,respectively.The carteolol intervention significantly reduced the number of stromal cells（P value of 0.000 in both groups）and inflammatory cells（P value of0.003 and 0.001 in both groups）.The corneal thickness of normal SD rats was 145.5±9.2um,and there was a markedly difference in corneal thickness after alkali burned（P=0.000）.Corneal thickness increase in normal saline group was not statistically significant（P=0.062）,while there was significant difference between the normal saline group and the carteolol group（both P values were 0.002）,and no difference between the carteolol group and the blank control group（both P=1.000）.Analysis of corneal thickness after the medication 12^thh and 14^thh days showed that carteolol thinned corneal thickness with significant difference（P values of 0.000 and 0.003,respectively）.All the above statistical indicators showed that there was no statistical difference between 1%carteolol group and 2%carteolol group（P values of each group were greater than 0.05）.Conclusion:Carteolol eye drops can effectively inhibit corneal neovascularization.In vivo confocal microscopy（IVCM）examination can clearly display the corneal structural characteristics of normal SD rats,and the corneal epithelial cells、stromal cells and endothelial cells could be counted.In vivo confocal microscopy（IVCM）examination can clearly show the pathological changes of alkali-burned corneal in SD rats.Carteolol eye drops may play an antiangiogenic role by inhibiting corneal inflammatory cell infiltration,reducing corneal edema,improving corneal nerve injury,reducing corneal epithelial and endothelial cell destruction and inhibiting stromal cell proliferation.In this experiment,both 1%and2%carteolol eye drops could inhibit the growth of CNV,and there was no difference in the efficacy between the two.