AIM: To Study the anti-fungal effect of corneal collagen cross-linking combined with natamycin in vivo and in vitro, so as to provide the treatment and experimental basis for the treatment of clinical fungal keratitis.

METHODS: Three common pathogenic fungi(Aspergillus flavus, Fusarium Solani and Candida albicans)were used. The experimental group was divided into cross-linking combined natamycin group, natamycin combined riboflavin group, natamycin combined UVA irradiation group, cross-linking group and natamycin group as the control group. The drug was added to the center of the Sabouraud dextrose agar(SDA)plate coated with liquid with each fungal spores with the same maid turbidity of 1.5. Ten minutes later, it was irradiated with collagen cross-linking instrument for 10min and cultured at 28℃ for 36h, and then the inhibition zone size was measured and analyzed statistically. The rabbit model of Fusarium Solani corneal infection was prepared. The model rabbits were randomly divided into model control group, cross-linking treatment group, natamycin treatment group, cross-linking combined natamycin group, 5 rabbits in each group. And another 5 normal rabbits were taken as control, and five rabbits were irradiated in accordance with corneal collagen cross-linking therapy. The results were observed by anterior segment photography, corneal scraping and confocal microscopy, and the ultra micro structural changes of the corneas were observed by electron microscope after the treatment.

RESULTS: Corneal collagen cross-linking alone had shown no effect on each fungus in vitro. Corneal collagen cross-linking combined with natamycin produced significant anti-fungal effect(P<0.05). However, the anti-fungal effect of natamycin combined riboflavin group and natamycin combined ultraviolet light group showed no statistical difference(P>0.05)comparing with the control group. For the model of rabbit fungal infection, the course of disease was about 14d in the natamycin group and CXL combined with natamycin group, and it was about 21d in CXL group. After the treatment, all the groups healed. There were no defects in the corneal epithelium, no mycelium in the corneas, except for more corneal neovascularization. The results of the anterior segment photography showed that the treatment effect of the cross-linking combined natamycin group was better than other groups, with fewer scar tissue, better corneal healing and relatively short course of disease.

CONCLUSION: Corneal collagen cross-linking combined with natamycin treatment is able to enhance anti-fungal effect, promote corneal healing, and shorten the course of disease. So it is a promising therapeutic technique for the clinical treatment of fungal keratitis.