Detection of postlaser vision correction ectasia with a new combined biomechanical index

Purpose: To validate and evaluate the use of a new biomechan-ical index known as the Corvis biomechanical index-laser vision correction (CBI-LVC) as a method for separating stable post-LVC eyes from post-LVC eyes with ectasia. Setting: 10 clinics from 9 countries. Design: Retrospective, multicenter, clinical study. Methods: The study was designed with 2 purposes: to develop the CBI-LVC, which combines dynamic corneal response (DCR) pa-rameters provided by a high-speed dynamic Scheimpflug camera (CorVis ST; OCULUS Optikgerate GmbH) and then to evaluate its ability to detect post-LVC ectasia. The CBI-LVC includes integrated inverse radius, applanation 1 (A1) velocity, A1 deflection amplitude, highest concavity and arclength, deformation amplitude ratio of 2 mm, and A1 arclength in millimeters. Logistic regression with Wald forward stepwise approach was used to identify the optimal com-bination of DCRs to create the CBI-LVC and then separate stable from LVC-induced ectasia. Eighty percentage of the database was used for training the software and 20% for validation. Results: 736 eyes of 736 patients were included (685 stable LVC and 51 post-LVC ectasia). The receiver operating char-acteristic curve analysis showed an area under the curve of 0.991 when applying CBI-LVC in the validation dataset and 0.998 in the training dataset. A cutoff of 0.2 was able to separate stable LVC from ectasia with a sensitivity of 93.3% and a specificity of 97.8%. Conclusions: The CBI-LVC was highly sensitive and specific in distinguishing stable from ectatic post-LVC eyes. Using CBI-LVC in routine practice, along with topography and tomography, can aid the early diagnosis of post-LVC ectasia and allow intervention prior to visually compromising progression.

Language

English

Source (journal)

Journal of cataract and refractive surgery. - Fairfax, Va

Publication

Fairfax, Va : 2021

ISSN

0886-3350

DOI

10.1097/J.JCRS.0000000000000629

Volume/pages

47 :10 (2021) , p. 1314-1318