Posters

Biomechanical evaluation of topographically and tomographically normal fellow eyes of keratoconus patients

Poster Details

First Author: S.Awwad LEBANON

Co Author(s):    L. Asroui   S. Dagher   J. Torbey   N. El Salloukh   B. Lopes   A. ELsheikh     

Abstract Details

Purpose:

To determine the effectiveness of biomechanical parameters, namely the Corvis Biomechanical Index (CBI), Tomographic Biomechanical Index (TBI), and Stiffness Parameter at Applanation 1 (SP-A1), at discriminating keratoconus suspects from normal eyes, and to determine the optimal cut-off value for each.

Setting:

Department of Ophthalmology, American University of Beirut Medical Center, Beirut, Lebanon.

Methods:

100 eyes of 100 normal controls, and 55 topographically and tomographically normal fellow eyes of keratoconus patients, that had been imaged and categorized using the Galilei dual placido-scheimpflug system, were imaged with Corvis and Pentacam. Fellow eyes were subdivided based on their Belin/Ambrósio Enhanced Ectasia Deviation index (BAD-D) as tomographically normal or borderline fellow eyes (TNF and TBF, respectively). The area under the receiver operator curve (AUROC) for each of the CBI, TBI, and SP-A1 was determined, in order to assess their discriminative ability.

Results:

For normal versus TBF eyes, CBI and TBI had AUROCs of 0.875 and 0.987. CBI cut-offs of 0.20 and 0.19 provided sensitivities of 68.0% and 72.1%, and specificities of 94.0% and 96.0%, respectively. TBI of 0.30 and 0.26 provided sensitivities of 80.0% and 96.0%, and specificities of 96.0% and 95.0%, respectively. For normal versus TNF eyes, CBI and TBI had AUROCs of 0.528 and 0.827. CBI of 0.20 and 0.17 had sensitivities of 26.7% and 30.0%, and specificities of 94.0% and 93.0%, respectively. TBI of 0.30 and 0.24 provided sensitivities of 50.0% and 63.6%, and specificities of 96% and 93%.

Conclusions:

Both CBI and TBI are valuable tools to rule in keratoconus when both topography and tomography are normal. The TBI seems to be the index with the greatest sensitivity and specificity for the detection of topographically and tomographically normal keratoconus suspects.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented