METHODS: LSCD was induced through corneal alkali burn, C57 mice and New Zealand rabbits were used to establish the animal models. Corneal alkali burn manipulation was accomplished in experimental animals under general anesthesia combined with surface anesthesia in the operated eye. Specifically, mice(n=30)were used to induce complete LSCD model. In brief, the filter paper(diameter of 3mm)that immersed in 1mol/L potassium hydroxide solution was placed on the central corneal surface of the left eye for 30s, followed by washing with saline. In addition, rabbits(n=19)were utilized to establish the partial LSCD model. Briefly, the nictitating membrane(third eyelid)was resected, and the filter paper(diameter of 5mm)that immersed in 1mol/L potassium hydroxide solution was placed on the superior temporal peripheral corneal surface of the left for 30s, followed by washing with saline. After surgery, the model eyes were treated with 0.5% Levofloxacin Hydrochloride Eye Drops four times a day. In addition, the slit-lamp microscope was adopted for observation and photo-taking before burn, as well as at 1, 2, 4wk and 2mo after burn; meanwhile, complications such as corneal ulcer and perforation were recorded. 2mo after surgery, the corneal goblet cell distribution was detected with impression cytology, and the severity of LSCD was classified according to slit-lamp microscopic findings and corneal impression cytology. The animals were sacrificed 2mo after surgery, cornea and conjunctiva sections were made to observe angiogenesis and goblet cell distribution in cornea. Animals died accidentally were not counted into the total number, and the successful induction rates of complete LSCD and partial LSCD models were compared.

RESULTS: Six out of the 30 mice died accidentally, while 2 developed corneal perforation after burn, and the remaining 22 had developed complete LSCD only, yielding the successful induction rate of 92%. 2mo after burn, extensive angiogenesis distribution in the superficial and deep corneal stromal layers could be observed, and pathological sections revealed corneal angiogenesis. Seven out of the 19 rabbits died accidentally, while the remaining 12 had various degrees of LSCD only(partial LSCD, average involving 1.17±0.39 quadrants). Additionally, no corneal perforation was observed, and the successful induction rate was 100%. The result of Fisher's exact test P value is 0.543, without statistical difference. No goblet cells were observed in the normal corneal region, while goblet cells were observed in the LSCD region, with the average density of 58.60±12.58 cell/HP.

CONCLUSION: Central corneal alkali burn can induce complete LSCD; however, some animals will experience failure in model induction due to corneal ulcer and perforation, LSCD is generally serious and may be combined with angiogenesis in deep cornea. Alkali burn in superior temporal cornea can induce partial LSCD, which may be combined with relatively minor corneal lesion, and the corneal angiogenesis is located in the superficial layer.