In vivo confocal microscopy of subepithelial infiltrates in human corneal transplant rejection

Purpose: Corneal allograft rejection is the leading cause of penetrating keratoplasty failure in the first year after surgery. We report 2 cases of subepithelial infiltrates in corneal transplant rejection imaged by in vivo confocal microscopy. Methods: Case report and review of relevant literature. Results: Two subjects with subepithelial infiltrates in previously clear penetrating corneal transplants were assessed. In vivo confocal microscopy revealed focal accumulations of hyperreflective dendritic-like particles, postulated to represent Langerhans cells, at the level of the basal epithelium and Bowman membrane. Altered keratocytes with visible cytoplasmic processes were observed posterior to these foci. Conclusions: To our knowledge, these are the first reported cases of in vivo confocal microscopy appearance of corneal allograft rejection in humans. In vivo confocal microscopy may provide a valuable clinical tool to aid in the diagnosis of early corneal transplant rejection and in the differential diagnosis of other inflammatory conditions of the cornea.