Immunohistochemical study of localization of extracellular matrix after holmium YAG laser irradiation in rat cornea

Purpose: To better understand the corneal responses to holmium YAG (Ho:YAG) laser irradiation, we used immunofluorescent microscopy to examine changes in the localization of the extracellular matrix components, which play imp ortant roles in the maintenance of corneal morphology and functions. Methods: Rats were irradiated with a Ho:YAG laser. On days 1, 3, and 7 afte r irradiation, the eyes were enucleated and frozen. Cryosections were made with a cryostat and were stained with antibodies against type I collagen, f ibronectin, type IV collagen, or laminin for immunohistochemical study. Results: One day after Ho:YAG laser irradiation, contraction of the stromal collagen fibrils was observed. Keratocytes could not be observed at the ir radiated stromal region on day 1 after irradiation. One week later, however , keratocytes returned to the irradiated area. Although the stromal collage n fibrils had contracted, they were stained by an antibody against type I c ollagen. Dense fluorescence for fibronectin was observed at the margin of t he stromal acellular zone. Both laminin and type IV collagen were observed at the basement membrane under the corneal epithelium, regardless of whethe r or not the corneas had been irradiated. Conclusion: These results suggest that Ho:YAG laser irradiation might be us eful for the collagen contraction of stroma, without causing serious damage to the corneal epithelium and the basement membrane. (C) 2000 Japanese Oph thalmological Society.