Immunohistochemical Changes of Rabbit Cornea After Excimer Laser Surface Ablation: collagen type III, IV, VI, VII

ABSTRACT

We performed photorefractive keratectomy(PRK) on 10 rabbit eyes and determined the distribution of collagen type III, IV VI, VII at postoperative 2, 4 and 6 months to examine immunohistochemical changes after PRK. Type III collagen was not found in the normal cornea but strongly detected in the regenerated corneal stroma at all intervals. It was most prominent at 2 months after surgery and then decreased. Type IV collagen was detected in basement membrane in both normal and ablated corneas at all intervals and the staining was more intense in ablatd corneas than in normal cornea. There was no difference of staining intensity among the groups of different intervals. Type IV collagen was found in both normal and healed corneal stroma at all intervals and there was no difference of staining intensity between normal and ablated corneas and among the groups of different intervals. Type VII collagen was observed as a linear continuous band along the basal surface of epithelium in normal cornea. At 2 months after surgery, type VII collagen staining in basement membrane zone became denser than normal cornea, but segmented. At 4 months after surgery, continuous band of collagen type VII staining was observed, but it was less intense than in normal cornea. At 6 months after surgery, the intensity of continuous band of collagen type VII was the same as in normal cornea. This results suggest that the presence of type III collagen in the regenerated cornea may be related to the development of postoperative subepithelial opacity after PRK and the normalization of collagen type IV and VII at postoperative 6 months may mean the complete reestablished of the adhesion of regenerated epithelium and stroma.