Observation on ultrastructure and histopathology of cornea following femtosecond laser-assisted deep lamellar keratoplasty for acute corneal alkaline burns

AIM： To demonstrate the changes in ultrastructure and histopathology of the cornea in acute corneal alkaline burns after femtosecond laser-assisted deep lamellar keratoplasty.·METHODS： The New Zealand white rabbits treated with alkaline corneal burn were randomized into two groups,Group A（16 eyes） with femtosecond laser-assisted deep lamellar keratoplasty 24 h after burn and Group B（16 eyes）without keratoplasty as controls. All eyes were evaluated with transmission electron microscopy（TEM） at 1, 2, 3,and 4wk follow-up, then all corneas were tested by hematoxylin and eosin staining histology.· RESULTS： The corneal grafts in Group A were transparent, while those in Group B showed corneal stromal edema and loosely arranged collagen fibers. One week after treatment, TEM revealed the intercellular desmosomes in the epithelial layers and intact non-dissolving nuclei in Group A. At week 4, the center of the corneas in Group A was transparent with regularly arranged collagen fibers and fibroblasts in the stroma. In Group B, squamous cells were observed on the corneal surface and some epithelial cells were detached.· CONCLUSION： Femtosecond laser-assisted deep lamellar keratoplasty can suppress inflammatory responses, prevent toxic substance-induced injury to the corneal endothelium and inner tissues with quicker recovery and better visual outcomes.

Research on mouse model of grade Ⅱ corneal alkali burn

AIM： To choose appropriate concentration of sodium hydroxide（Na OH） solution to establish a stable and consistent corneal alkali burn mouse model in grade II.·METHODS： The mice（n =60） were randomly divided into four groups and 15 mice each group. Corneal alkali burns were induced by placing circle filter paper soaked with Na OH solutions on the right central cornea for 30 s.The concentrations of Na OH solutions of groups A, B, C,and D were 0.1 mol/L, 0.15 mol/L, 0.2 mol/L, and 1.0 mol/L respectively. Then these corneas were irrigated with 20 m L physiological saline（0.9% Na Cl）. On day 7 postburn, slit lamp microscope was used to observe corneal opacity,corneal epithelial sodium fluorescein staining positive rate, incidence of corneal ulcer and corneal neovascularization, meanwhile pictures of the anterior eyes were taken. Cirrus spectral domain optical coherence tomography was used to scan cornea to observe corneal epithelial defect and corneal ulcer.·RESULTS： Corneal opacity scores（ x ±s） were not significantly different between the group A and group B（P =0.097）. Incidence of corneal ulcer in group B was significantly higher than that in group A（P =0.035）.Incidence of corneal ulcer and perforation rate in group B was lower than that in group C. Groups C and D had corneal neovascularization, and incidence of corneal neovascularization in group D was significantly higher than that in group C（P =0.000）.·CONCLUSION： Using 0.15 mol/L Na OH can establish grade II mouse model of corneal alkali burns.