Abstract
Abstract: :
Purpose:To analyze the structural and histopathological features of human corneal tissue after totally conduced excimer laser versus surgical Deep Lamellar Keratoplasty (elDLK versus sDLK). Methods: Two young men with keratoconus stage 3 submitted DLK, the first one by excimer laser, the second one by manual dissection. In both cases, nevertheless a satisfactory anatomic result, after some months the sight deteriorated and the patients underwent penetrating keratoplasty. The corneal tissues were histologically investigated by standard techniques, as hematoxylin–eosin and periodic acid–Schiff staining after formalin fixed, paraffin embedded, and by immunohistochemical analysis including anti–α–actin, anti CD34 and anti–cytokeratins monoclonal antibodies. Results: Light microscopy evidenced in both grafts an epithelium homogenously tickened with normal immunophenotype (CK3+/CK19–) and focal marginal breaks of Bowman layer in correspondence with surgical or photoablative edges. At this level epithelial ingrowth was observed in elDLK and, in both corneas, foci of "activated" keratocytes in the superficial stroma, resembling myofibroblasts were observed too. In the lower third of the stroma the presence of a laminar, discontinuous PAS–positive membrane layer of Descemet type gave evidence of a full thickness button placing on the DLK bed of recipient corneas. In the sLDK, the presence of blood vessels in the lateral and deep interface between donor and recipient tissue was observed. Staining with antibodies against α–actin showed a positivity of myofibroblasts and around new vessels in the stroma. Keratocytes were positive to antibody against CD34 except in the areas where they showed myiofibroblatic features. Conclusions:This is the first case of human graft analysis by light microscopy after totally conduced excimer laser DLK compared to surgical DLK. Donor anterior and deep recipient morphological and immunophenotypical abnormalities in both cases are reported and discussed.
Keywords: keratoconus • cornea: stroma and keratocytes • cornea: endothelium