Objective: To investigate immunological mechanism of corneal melting

perforation and ophthalmitis after alkali burn. Methods: A model of severe corneal alkali burn was established in rats. Immunohistochemical method (ABC method) was carried out on wholemounts of the cornea

iris

choroid and retina at different time after corneal burns to detect MHC class Ⅱ positive cells. Results: In the early stage of the burn

slight increase of the number of MHC class Ⅱpositive cells in the cornea and iris was found. At the time of corneal melting and perforation

a massive influx of the positive cells was not only seen at the limbus but also in the corneal melting area

iris and choroid. Morphological changes of the cells were also noted. In restoration stage

a number of positive cells was also found in iris. In the normal control group and in the early stage of the burn

the MHC class Ⅱantigen was not expressed in the retina tissue

but at the the time of corneal melting and the restoration stage MHC class Ⅱ positive cells were discovered. Conclusion: The immunological reaction is involved in the pathogenesis of the eye tissue damage induced by severe alkali burn of cornea and the mechanism may be related to autoimmune reaction.