Biomechanics of the crossed-link cornea

The next steps in the evolution of corneal cross linking (CXL) therapy must seek to improve the penetration of riboflavin to the deepest corneal layers, Dr. Jesper Hjortdal told delegates Tuesday.

“We also need to improve the penetration of riboflavin throughout the epithelium and we need to shorten treatment time,”he said.

In his talk The biomenchanics of the cross linked cornea, Dr. Hjortdal touched on a wide range of studies examinging the elasticity, shear and other biomechancial features of the cross linked corneal.

They show that, for example, at high loads, the keratoconic cornea is more extensible than the normal cornea, “Within physiological limits,the short term extensibility, or stiffness, of keratoconic and normal corneas seems to be similar,” he said. “While the resistance to shear forces seems to be smaller in keartoconic corneas,”he said.

He summed up his survey by saying that CXL enhances the stiffness of the cornea in vitro and can reduce or stop the progression of kearatoconus. “It remains to be shown that CXL changes the mechanical corneal stiffness in vivio,” he said.

In relation to swelling, Dr. Hjortdal noted that crosslinking did reduce swelling in vitro, and may do so in vivo. He added that with regard to ulceration, “CXL reduces enzymatic degradation of the cornea in vitro and may help the management of ulcerative corneal disorders.”