Objective: To investigate the mechanism of action of corneal anterior stromal puncture (ASP) in humans.
Design: Immunocytochemical techniques were used to localize fibronectin, type IV collagen, and laminin in human corneas with bullous keratopathy, some of which had undergone ASP. Corneal specimens were obtained from transplant procedures performed in a related clinical study.
Setting: Outpatients in private practice settings.
Patients: Nine patients with recurrent erosion secondary to bullous keratopathy who were judged to be poor candidates for keratoplasty.
Interventions: Anterior stromal puncture was performed on each patient using a standardized needle, and corneal transplants were performed on patients whose erosions did not resolve after ASP.
Primary outcome measures: Subjective comfort and slit-lamp verification of resolution of rupture of bullae and erosions in patients who underwent ASP; Nomarski differential interference contrast photography, immunohistochemical staining, and light microscopy were applied to the corneal specimens.
Results: All three matrix glycoproteins were observed in the epithelial basement membrane of normal corneas. In patients with bullous keratopathy who did not undergo ASP, the epithelial basement membrane of the cornea did not stain with antibodies against human fibronectin, type IV collagen, or laminin. In patients with bullous keratopathy who underwent ASP, all three major proteins were present at the puncture sites and in the reactive subepithelial pannus adjacent to the puncture site. Epithelial basement membrane of untreated regions showed little or no staining.
Conclusions: The results suggest that the absence of these extracellular matrix proteins in the epithelial basement membrane of patients with bullous keratopathy may be an important factor in the development of poor epithelial adhesion and secondary erosions. Anterior stromal puncture may promote epithelial reattachment, at least in bullous keratopathy, by stimulating the production of extracellular matrix proteins that are important in the attachment of epithelial cells to the underlying connective tissue. Epithelial-stromal reactions and the development of subepithelial fibrosis may also play a role in reestablishing epithelial attachment.