Histopathology in a dissecting conjunctival filtering bleb.

CASE REPORT: Four years after trabeculectomy, a patient developed unilateral tearing and presented with an ipsilateral conjunctival filtering bleb that had dissected into the cornea. The corneal portion of the bleb was excised for symptomatic relief. Histopathological examination disclosed dissection of the conjunctival filtering bleb into the cornea between Bowman's layer and the corneal epithelium. The internal portion of the bleb consisted of loose stromal tissue lacking any internal epithelial lining. COMMENTS: A conjunctival bleb dissecting into the cornea is a well-described late complication of trabeculectomy; however, its pathophysiology remains controversial. The subepithelial dissection plane in this specimen supports the concept that the conjunctival filtering bleb may dissect into, as well as "overhang", the limbal cornea.