Repeatability of new Corvis ST parameters and influencing factors in myopia patients

Authors: Ren Shengwei,  Yang Kaili,  Xu Liyan,  Fan Qi,  Zhai Yaohua,  Pang Chenjiu

DOI: 10.3760/cma.j.issn.2095-0160.2019.12.011
Published 2019-12-10
Cite as Chin J Exp Ophthalmol, 2019,37(12): 990-994.

Abstract

Objective

To evaluate the repeatability of corneal biomechanics parameters measured by Corneal Visualization Scheimpflug Technology (Corvis ST) and explore the factors that influence the repeatability.

Methods

A diagnostic test study was performed.A total of 190 eyes in 95 myopia patients (34 males and 61 females) were enrolled from September to October 2017 in Henan Eye Hospital.All the subjects underwent 5 repeated examinations with the Corvis ST.The intraclass correlation coefficient (ICC), Cronbach α coefficients and repeatability coefficient (RC) were computed to evaluate repeatability of Corvis ST parameters.The multiple linear regression analysis was used to study the factors that affect the magnitude of the test-retest variability (within subject SD) of new Corvis ST parameters.This study was approved by the Ethics Committee of Henan Eye Hospital (HNEECKY-2019[5]), and written informed consent was obtained from each subject.

Results

Among the 39 biomechanics parameters, The ICC and Cronbach α were greater than 0.75 for 26 parameters, within 0.60-0.75 for 4 parameters, and lower than 0.60 for deflection amplitude max time (DLAMT). The ICC and Cronbach α of DA ratio max[1 mm], DA ratio max [2 mm], max inverse radius, Ambrósio’s relational thickness horizontal (ARTh), biomechanical intraocular pressure (bIOP), integrated radius, stiffness parameter applanation 1 (SPA1) and Corvis biomechanical index (CBI)were all above 0.920.The multivariate regression results indicated that the within subject SD of bIOP increased with the increase of IOP (β=0.210, P=0.010). The within subjects SD of DA Ratio Max [1 mm]decreased with the increase of central corneal thickness (CCT) (β=-0.218, P=0.008). The within subjects SD of DA Ratio Max [2 mm]decreased with the increase of CCT(β=-0.295, P<0.001). The within subject SD of CBI decreased with the increase of astigmatism, axial lengths and CCT (β=-0.190、-0.148、-0.428, all P<0.05).

Conclusion

The Corvis ST parameters showed favorable measurement repeatability in myopia patients, especially for the new parameters.Astigmatism, axial lengths and CCT significantly affected the repeatability of CBI.

Key words:

Cornea; Biomechanics; Myopia; Repeatability; Test-retest variability; Influence factors

Contributor Information

Ren Shengwei
Henan Provincial People’s Hospital, Henan Eye Hospital, Henan Eye Institute, People’s Hospital of Zhengzhou University, Zhengzhou 450003, China
Yang Kaili
Xu Liyan
Fan Qi
Zhai Yaohua
Pang Chenjiu
(Read 57 times, 1 visits today)
Updated: January 20, 2020 — 1:30 am