Evaluation of the sensitivity and specificity of corneal visualization scheimpflug technology biomechanical index in the diagnosis of keratoconus

Objective

To study the sensitivity and specificity of parameter Corvis biomechanical index (CBI)— a new biomechanical index of Corvis ST in the diagnosis of keratoconus and evaluate the role of CBI in the diagnosis of keratoconus and the change of biomechanic.

Methods

A diagnostic trial study was adopted, and 66 eyes from 49 keratoconic patients (keratoconus group) and 91 right eyes from 91 myopic patients (control group) from April in 2018 to August in 2018 in Henan Eye Hospital were enrolled.Pentacam and Corvis ST examinations were performed by the same operator after the basic eye examinations.Using the evaluation of diagnostic test, consistency test, and receiver operating characteristic (ROC) curve analysis, gain the outcome of the sensitivity, specificity, consistency, Youden index, and area under the ROC curve of the parameter CBI.This study protocol was approved by Ethic Committee of Henan Eye Hospital and followed the Declaration of Helsinki.Written informed consent was obtained from each patient prior to any medical examination.

Results

Sixty eyes were diagnosed as keratoconus by the parameter CBI of Corvis ST.Evaluation of diagnosis test: the sensitivity was 97.0%, and the specificity was 97.8%; consistency check: Kappa=0.948, P<0.05.ROC curve analysis: the sensitivity was 98.5%, the specificity was 96.8%, Youden index was 96.3%, P<0.000 1 and AUC was 0.996.

Conclusions

CBI can separate healthy eyes from keratoconic eyes with highly sensitivity and specificity, which was highly consistency with results of Rabinowitz keratoconus diagnostic criteria.CBI could be used as a new biomechanical indicator for the diagnosis of keratoconus.

Corneal visualization scheimpflug technology; Corneal biomechanics; Keratoconic diagnosis; Corvis biomechanical index; Sensitivity; Specificity