Dynamic corneal imaging could increase refractive corneal surgery predictability

A diagnostic tool called dynamic corneal imaging may allow earlier diagnosis of corneal disease and may increase the predictability of refractive corneal surgery, investigators suggest.

Günther Grabner, MD, and colleagues at the University Eye Clinic in Austria used in vivo dynamic corneal imaging to assess the elastic properties of normal human eyes, eyes with abnormal findings and eyes after refractive surgery.

In dynamic corneal imaging, videokeratography is used to record the response of the cornea to sequential indentation with electronically controlled “microprecision motors,” Dr. Grabner and colleagues said. The measurement technique was performed in 187 eyes of 103 patients who had clinically healthy corneas, distinct keratoconus or previous refractive surgery. The technique quickly evaluated artificially and reversibly induced changes in corneal topography in a clinical setting, the investigators said. An early analysis showed that factors influencing the shape of the corneas flexing curve included central corneal thickness, IOP and patient age. The method also allowed the researchers to easily examine keratoconic corneas and corneas after refractive surgery.

The investigators have yet to determine which method produces data on the mechanical properties of the cornea in vivo “that is the most easy to interpret (and is significant) clinically,” the authors said. “Possibilities include wavefront analysis of topographical corneal height data, Fourier decomposition … and flexing-curve analysis.”

Tensile strengths of the cornea varies considerably, so “a method to measure elasticity in vivo would help establish narrower clinical safety guidelines for LASIK and other ablative surgical techniques based on individual measurements rather than on trial and error, with a follow-up of several years required,” the study authors said in the January issue of the Journal of Cataract & Refractive Surgery.