Rabbit model of aspergillus keratitis induced by modified corneal surface lens method

Background Animal model of fungal keratitis is an available tool to the experimental study of the pathogenesis mechanism of fungal keratitis. Current modeling methods of fungal keratitis include corneal scratching, corneal stroma injection and corneal surface lens methods. But these methods still have their own shortages. Objective This experiment was to create a fungal keratitis animal model by modifying corneal surface lens method. Methods Modified animal models of fungal keratitis were created by modified corneal surface lens method in 12 general adult New Zealand white rabbits. The filter papers soaked 108 spores / ml or A106spores / ml of spergillus fumigatus suspension were attached on the de-epithelial cornea surface and fixed with contact lens and tarsorrhaphy for 2 days, and the filter paper with physiological saline was used as control group. The symptoms of anterior segment were examined under the slit lamp in 3 ,7 and 14 days after surgery and scored based on the criteria of Dong. Corneal scraping was stained with 10% potassium hydroxide and calcofluor white stain to observed mycelium under the fluorescence microscope. Corneal tissue sections were examined by hematoxylin-eosin staining and periodic acid Schiff staining under the light microscope. The use of animal followed the Standard of Association for Research in Vision and Ophthalmology. Results Fungal keratitis models were successfully established in 6 eyes and 4 eyes in 108 spores/ml group (6/6) and 106 spores/ml group respectively. The symptom was more severer and score was higher in the eyes of 108 spores/ml group than that in 106 spores/ml group. At 3 and 7 days after surgery,the symptom scores of fungal keratitis models were higher than those of control group from 3 through 7 days with the statistically significant difference (P<0. 01) and the symptom scores of 108 spores/ml group were significantly higher than those of 106 spores/ml group (P<0. 01). At 14 days after surgery, the symptom scores of 108 spores/ml group were still higher than those of control group (P<0. 05). Fungal hyphae was seen in the corneal scrapes in 108 spores/ml group and 106 spores/ml group respectively from 3 through 7 days after surgery. Inflammatory cell infiltration, stroma cells necrosis and fungal hyphae were presented in 108 spores/ml group, and the corneal neovascularization could be observed in 108 spores / ml group 14 days later. Fungal culture revealed the positive outcome in both 3 and 7 days after surgery in 108 spores/ml group,but in 106 spores/ml group,the positive result was only in the 3rd day. Conclusion Modified corneal surface lens method is more feasible and sample in the model of Aspergillus keratitis. This animal model of Aspergillus keratitis is practical for the further study of fungal keratitis. Key words: Aspergillus;  Fungal keratitis;  Animal model;  Corneal surface lens