Overhanging-Dissecting Blebs: Immunohistochemical Characterization

The purpose of this study was to determine if glaucoma filtering blebs migrate over or under the cornea epithelium using histopathologic and immunohistochemical techniques to evaluate the likely origin of the surface epithelium and bleb matrix.

Histologic and immunohistochemical evaluations were performed of normal conjunctiva (n=4), corneal overhanging-dissecting blebs (n=4), and leaking blebs over the scleral surface (n=6). Antibodies were used against epithelial [cytokeratin 3 (CK3)+12, CK13] and extracellular matrix [decorin and keratan sulfate (KS)] antigens. Labeling was graded in a semiquantitative manner.

The epithelium of dissecting (over cornea) blebs was labeled primarily with CK3+12 antibody. KS staining was faint and comparable in normal conjunctiva, and the stroma of dissecting and leaking blebs (P=0.12). Decorin staining in the normal conjunctival stroma was of moderate intensity and comparable with the dissecting bleb staining and; significantly greater than that in the leaking blebs (P=0.02).

Histology and ICH indicate that the epithelium of the dissecting blebs has a corneal epithelial phenotype. The extracellular matrix immunophenotype was similar to the normal conjunctival stroma suggesting that dissecting blebs migrate under the corneal epithelium.