Comparison of Corneal Dynamic and Tomographic Analysis in Normal, Forme Fruste Keratoconic, and Keratoconic Eyes.

PURPOSE: To investigate and compare the diagnostic ability of corneal tomography and dynamic corneal response to differentiate between normal eyes and those with forme fruste keratoconus and keratoconus.

METHODS: Corneal tomography was performed using Pentacam (Pentacam HR; Oculus Optikgeräte, Wetzlar, Germany). Corneal deformation response was captured via Corvis ST (Optikgeräte) using a beta version of Corvis software. Classification analysis between normal eyes and eyes with forme fruste keratoconus and between normal and keratoconic eyes was evaluated using receiver operating characteristic curves. The area under the ROC curve (AUC) and partial AUC (pAUC) for each classifying parameter were compared.

RESULTS: Twenty-one patients with forme fruste keratoconus in one eye and clinically evident keratoconus in the fellow eye and 38 normal individuals were recruited. Overall, 21 eyes with forme fruste keratoconus and 18 eyes with keratoconus were compared with 73 normal eyes. The mean age of the participants was comparable between groups. Comparative analysis between Pentacam and Corvis ST parameters showed significantly lower AUC and pAUC for Corvis ST parameters in differentiating keratoconic from normal eyes (P ≥ .049). However, comparable AUC and pAUC was observed between the Corvis Biomechanical Index (AUC = 0.785; pAUC = 0.079) and D value of the Belin/Ambrósio Enhanced Ectasia Display (AUC = 0.757; pAUC = 0.068) (P ≥ .477) for detection of forme fruste keratoconus with sensitivities of 63.2% and 52.6%, given a common specificity of 80.3%.

CONCLUSIONS: The current study showed the feasibility of use of non-tomographical parameters obtained from the Corvis ST for differentiating normal eyes and those with forme fruste keratoconus and keratoconus. The diagnostic ability of the Corvis ST was comparable to that of the Pentacam for differentiating normal eyes and eyes with forme fruste keratoconus. [J Refract Surg. 2017;33(9):632-638.].