Data is gathered using a non-contact tonometer air-jet and a high-speed Scheimpflug camera which captures 4,330 frames per second of the corneal distortion during the applanation process. The Scheimpflug geometry (angle between film plane and objective plane) allows for a focused slit image through the cornea.
It is well known that IOP measurements by Goldmann applanation tonometry (GAT) and non-contact tonometry (NCT) are influenced by the corneal thickness of the cornea. Not so well known is that the IOP measurements are even more affected by the biomechanical properties of the cornea. The results of a theoretical study suggest that the potential error of IOP readings can be huge: the theoretically predicted values between a stiff and a weak cornea can differ up to 10mmHg.1 Based on the measured IOP, the biomechanical properties and the corneal thickness, the Corvis ST has the potential to determine a highly accurate value close to the 'true IOP'. The Corvis ST can also be used to monitor changes of the deformation response of the cornea caused by, for example, corneal ectasia and corneal cross-linking.
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