ABSTRACT
Background To maintain corneal transparency is important for good visual function.A new treatment concept and the selection of surgical techniques and timing of surgery are critical for stopping the infringement of cornea tissue after alkali burning and other chemical warfare agents.Objective This study was to investigative the ultrastructure and histopathological status following the femtosecond laser-assisted deep lamellar keratoplasty (DLK) for acute alkali burn of cornea.Methods Acute corneal alkali burn models were established in 12 New Zealand rabbits by putting the 6 mm filter paper with 1 mol/L NaOH at the central cornea for 30 seconds.The rabbits were randomly allocated to femtosecond laser-assisted DLK group and model control group according to the randomized number table method.Femtosecond laser-assisted DLK was performed to transplant the corneal grafts of domestic rabbits to the model rabbits 24 hours after burning.The rabbits were sacrificed 1 week,2 weeks and 4 weeks after modeling,and the corneas were extracted for the preparation of corneal section.The cornea were performed with hematoxylin and eosin staining to assess the histopathological status under the optical microscope,and the ultrastructure of grafts and corneas was examined under the transmission electron microscope (TEM).Results Acute corneal alkali bourn models were successfully eatablished.In the fourth week after surgery,corneal graft was clear in the femtosecond laser-assisted DLK group.However,corneal swelling,conjunctival congestion and neovascularization were found in the model control group.Histopathological examination revealed the defect of corneal epithelium,edema of stroma,loose arrangement of collagen fibers,much vacuoles,few neovascularization and infiltration of a large number of inflammatory cells in the model control group,but in the femtosecond laser-assisted DLK group,the inflammatory response was slight.More desmosomes among the endothelial cells were seen,and the nuclei were intact in the grafts.In the fourth week after surgery,the transplanted corneas were transparent with the regular arrangement of collagen fibers and entire fibroblasts in the femtosecond laser-assisted DLK group under the TEM.However,flat surface corneal epithelial cells and shedding of some epithelial cells were exhibited in the modelcontrol group.Conclusions Femtosecond laser-assisted DLK can effectively alleviate the inflammatory response,promote epithelial healing and enhance intercellular tight junction in the cornea with acute alkali burn.