Abstract
Purpose: :
To evaluate the effects of transepithelial corneal crosslinking on epithelium and stroma in human corneas.
Methods: :
Fifteen corneal buttons were examined. Ten were from patients with keratoconus submitted to penetrating keratoplasty (PKP). Five of them were treated with transepithelial crosslinking 2 hours before PKP, five of them were treated with transepithelial crosslinking 3 months before PKP. Five normal corneal buttons from healthy donors were used as controls. Transepithelial crosslinking was performed with two different time of imbibition: 30 minutes and 2 hours. All samples were prepared for the detection of keratocyte apoptosis by TUNEL assay and for the morphological evaluation of epithelium and stroma by immunohistochemical analysis (β Catenin, Connexin 43, CD34, collagen I).
Results: :
Normal corneas exhibited no TUNEL positive keratocytes while keratoconus and transepithelial crosslinked samples showed moderate apoptotic cells in the anterior part of the stroma. In cross-linked corneas CD34-positive keratocytes were regularly distributed throughout the whole corneal stroma as in the control, and keratoconus was associated with patchy loss of immunoreactivity. Moreover, the samples treated with transepithelial crosslinking 2 hours before PKP showed also an almost completely deteriorated epithelium with TUNEL positive cells. The epithelial positivity for connexin 43 and β catenin was similar in the control and in the corneas with crosslinking 3 months before PKP, while seemed more scattered in the keratoconus. In the samples treated with transepithelial crosslinking 2 hours before PKP the positivity was patchy in the few remained epithelial cells.
Conclusions: :
The treatment with transepithelial crosslinking leads to epithelial damage and a reduction of keratocytes in the sub-epithelial region in the corneas treated 2 hours before PKP. In the samples treated with transepithelial crosslinking 3 months before PKP the positivity of both CD34 keratocytes and βCatenin and connexin-43 epithelial cells is similar to control.
Keywords: keratoconus • cornea: basic science • cornea: stroma and keratocytes