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G. Grabner, R. Eilmsteiner, C. Steindl, J. Ruckhofer, R. Mattioli, W. Husinsky:
"Dynamic cornel imaging";
J. Cataract Refract Surg, 31 (2005), 163 - 174.

Purpose: To determine the clinical practicability of in vivo dynamic corneal imaging
(DCI) to assess the individual elastic properties of normal human eyes, eyes with
abnormal findings, and eyes after refractive surgery.
Setting: University Eye Clinic, Paracelsus Private Medical University, Salzburg,
Austria.
Methods: The DCI method uses sagittal, stepwise, central indentation of the
cornea with electronically controlled microprecision motors and sequential
registration of videotopography images. The indentation steps are preselected and
range from 50 to 800 mm. The computerized analysis of the videotopography
images captured during the process uses Zernike polynomials to establish a newly
defined flexing curve for normal eyes and eyes with abnormal findings.
Results: Dynamic corneal imaging was done in 187 eyes of 103 patients who had
clinically healthy corneas, distinct keratoconus, or previous refractive surgery. The
method rapidly evaluated artificially and reversibly induced changes in corneal
topography in a clinical setting using a modified Placido disk-based computerassisted
videokeratography system with a small cone. In early analysis, the flexing
curve showed a significant correlation with the applied indentation depth. Factors
influencing the shape of the curve were central corneal thickness, intraocular
pressure, and patient age. The DCI method also allowed easy examination of
keratoconic corneas and corneas after refractive surgery.
Conclusions: Dynamic corneal imaging induced a reproducible and reversible
change in corneal topography corresponding to the different indentation depths.
The results indicate that several clinical parameters are correlated with corneal
elastic behavior in vivo and that the technology could increase the predictability of
refractive corneal surgery and help in the early diagnosis of corneal diseases and
with newly developed therapies.

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