Changes in Central Corneal Thickness With Air-Puff-Induced Corneal Deformation Using a Method to Correct Scheimpflug and Refractive Distortion.

PURPOSE

To establish a method to determine central corneal thickness (CCT) and anterior chamber depth (ACD) of an air-puff-deformed cornea at the highest concavity (HC) state.

METHODS

The Fink method for refractive correction of Scheimpflug images of a convex pre-deformed (PRE) cornea was implemented for 155 eyes of 155 participants imaged with the Corvis ST (Oculus Optikgeräte GmbH). This method was subsequently modified for the HC state of deformation. The tracked edges of each participant's cornea were exported at the PRE and HC states. Ten participants who had a visible crystalline lens in the image were selected to determine ACD in both states. The center points on the corneal tracked edges and lens were used to determine uncorrected CCT and ACD, respectively.

RESULTS

Average undeformed CCTPRE was significantly lower than deformed CCT (584 ± 31 and 626 ± 34 µm, respectively) ( < .0001). No significant difference was found for the corrected ACD between the two states. Corrected CCT and ACD were significantly greater than the corresponding uncorrected values for both deformation states ( < .0001). Percent change in CCT was found to be correlated to change in arc length at HC ( < .0001).

CONCLUSIONS

Distortion in Corvis ST images at the HC state can be corrected using a modified Fink method. CCT was found to increase in the HC state, compared to the PRE state. The CCT change during deformation may be important in the study of the compressive response of the cornea. .