Light and electron microscopic study on the effect of topically applied hyaluronic acid on experimentally induced corneal alkali burn in albino rats

Introduction and aim of work:The corneal epithelium acts as a transparent barrier, being the first line of defense against physical, chemical, and biological insults. Corneal wounds as a result of alkali exposure cause reduced transparency of the cornea and disability in the form of permanent visual impairment or even blindness. Moreover, they do not heal properly spontaneously and there is a lack of satisfactory therapy. Thus, the therapeutic efficacy of topical application of hyaluronic acid was investigated on a corneal alkali burn model in albino rats. Materials and methods:Thirty adult albino rats of both sexes were used and were divided equally into six groups. Group I was the control group. Groups II, III, and V comprised rats with bilateral sodium hydroxide alkali-burnt corneas; these rats were sacrificed at 1 day, 1 week, and 2 weeks, respectively. Groups IV and VI comprised rats with bilateral hyaluronic acid-treated alkali-burnt corneas; these rats were sacrificed at 1 and 2 weeks, respectively. The corneas were subjected to light microscopic, transmission electron microscopic, and histomorphometric studies. Results:Corneal alkali burn resulted in various degrees of corneal epithelial defects in group II. It did not heal spontaneously and caused residual ulcerations and degenerative changes in the corneal stroma and endothelium in groups III and V. However, the cornea healed properly in the hyaluronic acid-treated groups, particularly 2 weeks after alkali burn. Conclusion and recommendation:Hyaluronic acid is recommended for the treatment of corneal injury as it effectively promoted the healing of corneal wounds caused by alkali burn when topically applied for a proper duration.