Structural modifications and tissue response after standard epi-off and iontophoretic corneal crosslinking with different irradiation procedures.
PURPOSE
The aim of this study is to investigate modifications in human cadaver corneas after different crosslinking procedures, including standard epi-off treatment, iontophoresis imbibition, and different exposure to ultraviolet A (UVA) sources (30 minutes at 3 mW and 9 minutes at 10 mW).


METHODS
A total of 12 human cadaver corneas was examined and divided as follows: 3 served as control (group 1), 3 were treated with a standard epi-off procedure (group 2), 6 underwent iontophoresis imbibition for 5 minutes, and then 3 were irradiated for 30 minutes with 3 mW UVA (group 3), and 3 for 9 minutes at 10 mW UVA (group 4). Deformation amplitude index was measured before and after the corneas underwent treatment. After treatment, corneas were prepared for hematoxylin-eosin and immunohistochemistry evaluation. The expression of TUNEL, matrix metalloproteinase-1 (MMP-1), collagen type I, and CD34 was investigate in all samples.


RESULTS
The deformation amplitude index decreased in all groups, in particular in group 4, indicating an improvement of corneal biomechanical properties. Immunohistochemical staining showed a significant stromal alteration in group 2, mild damage in group 3, and no modifications in corneal morphology in group 4. The TUNEL (P < 0.001) and MMP-1 (P = 0.002) positivity was more evident in group 4. Collagen type I positivity significantly increased in groups 3 (P = 0.002) and 4 (P = 0.002). The CD34 expression was more evident in groups 2 (P = 0.003) and 3 (P = 0.003).


CONCLUSIONS
Iontophoresis imbibition followed by UVA irradiation for 9 minutes at 10 mW determined less tissue damage and better stromal remodeling.
['Mastropasqua|Leonardo|L|', 'Lanzini|Manuela|M|', 'Curcio|Claudia|C|', 'Calienno|Roberta|R|', 'Mastropasqua|Rodolfo|R|', 'Colasante|Martina|M|', 'Mastropasqua|Alessandra|A|', 'Nubile|Mario|M|']
D002102:Cadaver D003094:Collagen D003315:Cornea D003432:Cross-Linking Reagents D006801:Humans D007150:Immunohistochemistry D007478:Iontophoresis D007640:Keratoconus D014466:Ultraviolet Rays
crosslinking iontophoresis keratoconus