Influence of corneal shape parameters on corneal deformation responses measured with a Scheimpflug camera.

ABSTRACT

PURPOSE: To investigate the effect of corneal shape parameters on corneal deformation responses measured with a Scheimpflug camera. METHODS: A total of 241 eyes of 241 participants were enrolled in this study. The anterior and posterior corneal curvature radii (CCR), anterior and posterior corneal Q-values, and corneal diameters of the participants were measured using the Pentacam HR. A total of 17 corneal deformation parameters including time, velocity, deflection amplitude, length, and area during ingoing applanation, highest concavity, and outgoing applanation were recorded by corneal visualization using Scheimpflug technology (Corvis ST). The effect of corneal shape parameters on corneal deformation responses was evaluated using multivariate regression models. RESULTS: Multivariate regression analyses showed that six, five, four, and three corneal deformation parameters were significantly correlated with anterior CCR, posterior CCR, anterior Q-value, and posterior Q-value, respectively. Steeper anterior corneal curvature was associated with faster velocity during ingoing applanation and greater deformation during outgoing applanation. Steeper posterior corneal curvature was correlated with faster velocity during outgoing applanation and greater deformation during ingoing applanation. Eyes that had steeper corneal curvatures were associated with less stiff corneas. More negative anterior Q-value corresponded with faster velocity and greater deformation during ingoing applanation. Eyes that had more prolate posterior corneal surfaces showed more resistance to corneal deformation at the highest concavity. However, corneal diameter was not selected in any corneal deformation parameters models. CONCLUSION: Corneal deformation response is significantly influenced by anterior and posterior corneal curvature and corneal asphericity, but not corneal diameter.