Table 4 A brief description of Corvis ST parameters.

bIOP

Biomechanically corrected IOP

CCT(c)

Central corneal thickness by Corvis ST

CCT(o)

Central corneal thickness by OCT

CCT(p)

Central corneal thickness by Pentacam HR

DA ratio

Maximum deformation amplitude ratio between the apex and at 2 mm from the apex

IR

Integrated radius

ARTh

Ambrósio’s Relational Thickness to the horizontal profile based on the thickness profile in the temporal-nasal direction. ARTh = corneal thickness thinnest/pachymetric progression

SP-A1

Stiffness parameter A1 uses the displacement between the apex in the undeformed state and the deflection at A1

Arc length

Highest concavity delta arc length

Defle A

Highest deflection amplitude

DefleA ratio

Deflection amplitude ratio between the apex and at 2 mm from the apex

EMo

Whole eyeball movement

ICR

Maximum inverse concave radius during the concave phase of the deformation response

A1L

First applanation length

A1V

First applanation velocity

A1T

Time to first applanation

A2L

Second applanation length

A2V

Second applanation velocity

A2T

Time to second applanation

HCT

Time to highest concavity

PD

Peak distance of highest concavity

HCR

Highest concavity radius

Def A

Highest deformation amplitude

CBI

Corneal biomechanical index (CBI) based on logistic regression analysis which combined deformation response parameters with corneal thickness profile. CBI = EXP (Beta)/(1 + EXP(Beta))

Where Beta = B1 × A1Velocity + B2 × ARTh + B3 × Stiffness parameter-A1 + B4 × DARatio1mm + B5 × DARatio2mm + B6 × SD–Deflection Amplitude + B7

and B1 =  − 59.487, B2 =  − 0.027; B3 =  − 0.092, B4 =  − 27.169, B5 = 5.472, B6 =  − 0.599, B7 = 46.576

TBI

tomographic and biomechanical index (TBI), combined Scheimpflug-based corneal tomography and biomechanics for enhancing ectasia detection

SSI

stress strain index, based on the numerical modeling input and output parameters CCT, bIOP, and SP-HC(stiffness parameter at highest concavity)