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. 2021 Aug 2;10(9):36.
doi: 10.1167/tvst.10.9.36.

A Novel Indentation Assessment to Measure Corneal Biomechanical Properties in Glaucoma and Ocular Hypertension

Yunzhi Xu  1 , Yiming Ye  1 , Iok Tong Chong  2 , Zidong Chen  1 , Jiangang Xu  1 , Yangfan Yang  1 , Keming Yu  1 , David C C Lam  2 , Minbin Yu  1
Affiliations

A Novel Indentation Assessment to Measure Corneal Biomechanical Properties in Glaucoma and Ocular Hypertension

Yunzhi Xu et al. Transl Vis Sci Technol. .

Abstract

Purpose: To evaluate the ability of the new in vivo corneal indentation device (CID) to measure corneal biomechanical properties.

Methods and results: In total, 186 eyes from 46 healthy subjects, 107 patients with primary open-angle glaucoma, and 33 patients with ocular hypertension were enrolled in a cross-sectional study. Measurements were performed using corneal visualization Scheimpflug technology (Corvis ST) and the CID. The deformation amplitude (DA), inward applanation time, inward applanation velocity (A1V), outward applanation time (A2T), outward applanation velocity (A2V), highest concavity time, DA ratio, max inverse radius (MIR), integrated radius, and stiffness parameter A1 were included as Corvis ST parameters, and stiffness and modulus were included as CID parameters. Associations between the Corvis ST and CID parameters and correlations between central corneal thickness and corneal biomechanical parameters were analyzed. The stiffness was significantly correlated with all the Corvis ST parameters (P < 0.05). The modulus was significantly correlated with the DA, A1V, A2T, A2V, highest concavity time, and MIR (P < 0.05). The DA, inward applanation time, A1V, A2T, A2V, DA ratio, MIR, integrated radius, and stiffness parameter A1 values and both CID-derived values were significantly correlated with central corneal thickness (P < 0.05).

Conclusions: Parameters derived from the CID and Corvis ST demonstrated agreement in the measurement of corneal biomechanical properties. The stiffness and modulus can characterize in vivo corneal biomechanical properties.

Translational relevance: Agreeing with the Corvis ST regarding the assessment of corneal biomechanical properties, the CID can be a novel clinical tool for biomechanical evaluation of the cornea.

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Conflict of interest statement

Disclosure: Y. Xu, None; Y. Ye, None; I.T. Chong, None; Z. Chen, None; J. Xu, None; Y. Yang, None; K. Yu, None; D.C.C. Lam, None; M. Yu, None

Figures

Figure 1.
Figure 1.
Images of a CID and measurement. (A) CID measurement after disinfection, reset procedures. (B) CID comprises a 2-mm circular flat surface indenter, a main unit, and a computer. Prototype from Hong Kong University of Science and Technology (Patent No. WO2012163080 A1).
Figure 2.
Figure 2.
Measurement difference between Corvis ST and CID. (A) Initial state of Corvis ST measurement. (B) Corvis ST deforms cornea by air-puff. (C) Corneal deformation result by Corvis ST. (D) Initial state of CID measurement with indenter fully contact cornea. (E) CID's indenter moves 1 mm inward. (F) A real force–displacement curve from corneal indentation.)
Figure 3.
Figure 3.
Correlation between CID parameters (Stiffness, Modulus) and Corvis ST parameters (DA, A1T, A1V, A2T, A2V, HCT, DA Ratio, MIR, IR, SPA1).
See this image and copyright information in PMC

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