Table 1 Parameters that can be obtained from a device using an air puff and the Scheimpflug’s fast camera (using the example of the Corvis ST tonometer)
From: Novel dynamic corneal response parameters in a practice use: a critical review
Parameter | Deformation phase | Description |
|---|---|---|
A1 length (mm) | A1 | Length of the flattened cornea at the first applanation |
A1 velocity (mm/ms) | Velocity of the corneal apex during the first applanation | |
A1 time (ms) | Time from the measurement beginning to the first applanation moment | |
A1 DeflAmp (mm) | Corneal deflection amplitude during the first applanation, determined as the displacement of the corneal apex in relation to the initial state without the whole eye movement | |
DA ratio (2Â mm) | Near A1 | Deformation amplitude ratio at 2Â mm |
DefA ratio (2Â mm) | Deflection amplitude ratio at 2Â mm | |
SP-A1 | Stiffness parameter A1 | |
SP-HC | Stiffness parameter HC | |
DA (mm) | HC | Maximum deformation amplitude (measured at the moment of the highest corneal concavity). It is the actual sum of corneal deflection amplitude and whole eye movement |
HC time (ms) | Time from the measurement beginning to the moment of reaching the highest concavity | |
HCDeflAmp (mm) | Corneal deflection amplitude at the moment of the highest corneal concavity | |
HCDeflArea (mm2) | Highest concavity deflection area | |
HCdArclength (mm) | Highest concavity delta arc length | |
Peak distance (mm) | Distance between the corneal peaks at the moment of the highest corneal concavity | |
HC radius (mm) | Radius of corneal curvature during the moment of its highest concavity | |
InvRadMax (1/mm) | Maximum inverse radius | |
WEMmax (mm) | A2 | Maximum whole eye movement |
A2 length (mm) | Length of the flattened cornea at the second applanation | |
A2 velocity (mm/ms) | Velocity of the corneal apex during the second applanation | |
A2 time (ms) | Time from the measurement beginning to the second applanation moment |