Detection of keratoconus with the new Corvis ST biomechanical index

Session Details

Session Title: Corneal Biomechanics

Session Date/Time: Tuesday 13/09/2016 | 16:30-18:00

Paper Time: 17:00

Venue: Auditorium C6

First Author: : R.Vinciguerra ITALY

Co Author(s): :    R. Ambrosio   A. Elsheikh   C. Roberts   B. Lopes   C. Azzolini   P. Vinciguerra     

Abstract Details

Purpose:

To evaluate the ability of the new Corvis Biomechanical Index (CBI), based on thickness profile and corneal deformation parameters, to separate normal from keratoconus patients.

Setting:

Patients were enrolled in two clinics (Vincieye Clinic in Milan, Italy (1) and from the Rio de Janeiro Corneal Tomography and Biomechanics Study Group – Rio de Janeiro, Brazil-2) to test the capability of the CBI to separate healthy and keratoconic eyes in more than one ethnic group.

Methods:

Six hundred and sixty-two patients were included in this multicenter retrospective study. Database 1 comprised 255 healthy and 79 keratoconus eyes, while database 2 included 227 healthy and 101 keratoconus eyes. The biomechanical response data were analyzed using the Corvis ST (OCULUS Optikgeräte GmbH; Wetzlar, Germany) and logistic regression was employed to determine the optimal combination of individual parameters based on database 2 as the development dataset. Optimal cutoff points of the CBI were obtained, and the formula was subsequently independently validated on Database 1.

Results:

The final formula included Deformation Amplitude ratio at 1 and 2 mm, Applanation 1 velocity, Highest Concavity Radius and ARThARTh (Ambrósio's Relational Thickness to the horizontal profile). The ROC curve analysis of database 2 showed an Area Under the Curve (AUC) of 0.978 with a cut-off value of 0.5. This threshold correctly classified 97.3% of the cases with 99.6% specificity and 92.1% sensitivity. In the validation dataset (database 1) the same cut-off point classified correctly 99.8% of the cases with 99.6% specificity and 100% sensitivity.

Conclusions:

In conclusion, CBI was shown to be highly sensitive and specific alone to separate healthy from keratoconic eyes. The presence of an external validation dataset confirms this finding and suggests the possible use of CBI in everyday clinical practice to aid in the diagnosis of keratoconis.

Financial Disclosure:

... receives consulting fees, retainer, or contract payments from a competing company