Results of cross-linking for corneal melting disorders
Corneal cross-linking (CXL) can help treat corneal melting, Dr. Theo Seiler told delegates at the ESCRS Congress.
Riboflavin and UVA creates additional chemical bonds within the collagen molecule and, most probably, between adjacent collagen molecules, he remarked.
Such cross-links reduce the docking sites on the collagen molecule available to collagenases, Dr. Seiler noted. Early clinical results of CXL and corneal melting were published in 2000 by Schnitzler et al, and in three out of four cases the melting was stopped.
Dr. Seiler related an elegant experiment by Wollensak, where pieces of pig cornea, one cross-linked and one not, were put in a solution of collegenases. The cross linked cornea dissolved unevenly. The surface, where the cross-linking had an effect, resisted dissolution.
The normal cornea, on the other hand, dissolved evenly, demonstrating that collegenases had a much smaller effect on the cross-linked cornea.
Dr. Seiler revealed that his clinic had six cases of therapy-refractory corneal melting. Three cases related to infection, there was 1 case each of Mb Terrien and Mb. Sjogren, and 1 case after LASIK.
In all cases melting stopped after cross-linking. Additional therapies were applied for the cases relating to infection, LASIK and Mb Sjogren, he stated, though no additional therapy was pursued for the Mb Terrien.
In the cases of infection, additional therapies included PKP, ALKP and PRK. The LASIK case was additionally treated with DLKP while the Sjogren received ALKP.
Dr. Seiler concluded that CXL is an interesting option in cases of corneal melting. It appears to be effective, but its safety is not clear. We observed corneal thickening after CXL in Mb Terrien, but this is just one observation and needs to be confirmed.”