Corneal Collagen Cross-linking With Hypotonic Riboflavin in Corneas Thinner Than 400 Microns

When cross-linking corneas of \> 400 microns, riboflavin in a solution with high molecular weight dextran T500 is used to prevent corneal swelling during the administration of the drops and the UV treatment. However if riboflavin is applied to a cornea in a hypotonic solution (saline), then transient corneal oedema is created with thickening of the corneal stroma. In this way it is thought that the temporarily thickened cornea can be treated with UV whilst still providing a sufficient thickness to absorb the UV to an extent that endothelial cell damage is avoided.