Dynamic Corneal Imaging – First Clinical Application in Corneal Cross Linking

Abstract

Purpose: : To assess individual elastic properties of human corneas using a newly developed clinical system for in–vivo measurement of elasticity (Dynamic Corneal Imaging, DCI).

Methods: : The DCI system is based on controlled indentation of the central cornea with the help of electronically controlled micro–motors and sequential registration of video–topography images. Indentation is performed in a step–wise manner and controlled by a force sensor system. The system was tested in 30 normal patients, 20 patients with keratoconus and 5 patients before and 3 months after corneal cross–linking (CCL). A newly defined "flexing curve" was calculated for each video–topography image using Zernike polynomials.

Results: : The flexing curve showed a significant correlation to the applied force. Eyes with keratoconus showed a markedly increased flexibility of the central zone when compared to healthy eyes. A marked "stiffening" of the cornea could be measured 3 months after CCL. First data on stability and clinical results of this new method will also be presented.

Conclusions: : CCL using riboflavin/ultraviolet–A treatment was recently described for stabilizing the corneal structure in early keratoconus. The DCI–system might serve as a valuable tool for evaluating not only the immediate effect of the method on the biomechanical properties but also the stability of its effect in the medium and long–term follow–up, possibly adding information as to when additional treatment might be advisable.

Keywords: topography • imaging/image analysis: clinical • keratoconus