An Experiment Study On Treatment Of Fungal Corneal Ulcer Using Q-Switched Nd: YAG Laser

Objective:To evaluate the possibility of treatment of fungal corneal ulcer using Q-switched Nd:YAG laser. To investgate the best treatment parameters and observe the therapeutic effects of Q-switched Nd:YAG laser for fungal corneal ulcer.Methods1 inoculaedThe Fusarium specie was inoculated on Sabouraud,s agar, and grown six days at 28℃. Then the fungal specie was crushed, reconstituted in sterile water, counted on a hemocytometer, and the released Fusarium adjusted to 5×107/ml .AnimalsThe first step:24 healthy New Zealand white rabbits weighing 2.0~2.5Kg were divided randomly into 5 groups, one was normal group(2rabbits, 4eyes). one was experimental group(4rabbits, 8eyes). the other three were control groups(6 rabbits 12eyes each). Energy was 5mJ,10mJ,20mJ repectively. The second step:20 rabbits were divided randomly into 2 groups, (10 rabbits, 20eyes each). One group was treated by laser combining medicine, the other group was treated by debridement combining medicine. Making of animal modelDouble eyes were inoculaed in every rabbit. 0.25% chloromycetin was applied topically 3days before inoculated. The rabbits were anesthesized. The central corneal epithelium was removed within a 3mm diameter and 0.2ml Fusarium was instilled on the corneal surface. A soft contact lens was used to cover the cornea. Then sutured the third eyelids with the opposite bulbar conjunctiva and tarsorrhaphy was performed, took out stitches 24 hours post-inoculation, examined the cornea. If the infection was not severe, Tarsorrhaphy was performed again, took out stitches 12 or 24 hours later again.4 Experiment method4.1 The first step4.1.1 Laser treatment:The pathological changes has reached the middle of lamellae 5 days post-inoculation. The necrosis on the surface of cornea ulcer was debrided by pinpoint bombing uaing Q-switched Nd:YAG laser with an output energy of 5mJ,10mJ,20mJ respectively, spot 500um in diameter from outer to center, and from the surface to the deep until the surface of ulcer become a clean one, noting the number of treating at the same time.Observe targetClinical examination:Rabbits were examined by slit-lamp biomicroscopy everyday.Stained corneal endothelial cell:The corneal endothelial cell were stained using alizarin red S-trypan blue in normal group,control group,1hour and 1 day post-laser respectively. Observed the corneal endothelial cell.Light microscopy:Histological changes were examined in normal group,control group,1hour and 1 day post-laser respectively.Electron transmicroscopy:The corneal endothelial cell ultrastructure changes were examined in normal group,control group,1hour and 1 day post-laser respectively. The second step4.2.1 The treated group animals were treated using the laser that was selected at the first step. 0.5ml 0.2% Fluconazole was injected subconjunctival everyday after laser treatment. The control group animal were treated using corneal lesion resection and 0.5ml 0.2% Fluconazole was injected subconjunctival everyday.4.2.2 Clinical examination:Animals were examined by slit-lamp biomicroscopy everyday, compared the cure rates of the two groups.ResultsMaking of animal modelNicking the surface layer, using the soft contact lens combined with performing the tarsorrhaphy at the same time was a very good method of making the fungal corneal ulcer animal model. All the animal models were succeeded. Most of the infection eyes were in light or middle degree.Stained corneal endothelial cell The control group and 1hour post-5mJ laser:There was a little of irregular in the shape of the endothelial cells. Cubage of the cells was enlarged; 1hour post-10mJ laser:The shape of the corneal endothelial cells was irregular obviously. The cubage of the corneal endothelial cells was enlarged. The boundary of the cells was not obvious; 1hour post-20mJ laser:The shape of some corneal endothelial cell was irregular obviously. Some corneal endothelial cells were lost; 1 day post-laser:the shape of endothelial cell of...