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First Author: C.Mazzotta ITALY
Co Author(s): A. Paradiso S. Baiocchi T. Caporossi A. Caporossi
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Qualitative investigation of corneal micro-structural modifications in keratoconic patients undergoing Epi-Off standard and Epi-On experimental trans-epithelial cross-linking.
Departement of Ophthalmology Siena University
Prospective, observational open study on 20 patients with progressive keratoconus aged between 16 and 27 years (mean age 21 y). 10 patients at stage III KC, selected for Epi-On CXL had a corneal thickness in the range of 350-390 ?m at the thinnest point and 10 patients with corneal thickness over 400 ?m (range 401 - 490 ?m) measured by AC OCT system underwent Epi-Off cross-linking treatment. Epi-On CXL was performed by 0.1% riboflavin - 15% dextran solution supplemented with TRIS plus sodium EDTA and Epi-Off CXL with Riboflavin 0.1%-Dextran 20% solution according to Siena protocols. In vivo HRT II laser scanning confocal analysis.
After Epi-On CXL epithelial cells showed apoptosis with mosaic alterations gradually disappearing. Epithelium re-growth after Epi-Off was achieved after 3 days improving progressively. Keratocytes apoptosis in Epi-Off CXL was detected until 300 ?m of stroma while keratocytes apoptosis after Epi-On CXL was variable, superficial and uneven with a maximum depth of penetration at about 100 ?m in corneal stroma. Epi-On Treatment respected sub-epithelial and stromal nerves that did not disappear while the anatomy of the sub-epithelial plexus was restored one year after the operation. No variation in endothelial cell was observed in both procedures.
In vivo confocal analysis showed a limited apoptotic affect of in Epi-On CXL, about one third of the Epi-Off CXL. The limited penetration correlated with limited biomechanical and clinical efficacy.