Comparative study of corneal tangent elastic modulus measurement using corneal indentation device

The aim of this study is to examine the corneal tangent modulus measurement repeatability and performance of the corneal indentation device (CID). Twenty enucleated porcine eyes were measured and the eyes were pressurized using saline solution-filled manometer to 15 and 30. mmHg. Corneal tangent moduli measured using the CID were compared with those measured using high precision universal testing machine (UTM). The within-subject standard deviation (Sw), repeatability (2.77. ×. Sw), coefficient of variation (CV) (Sw/overall mean), and intraclass correlation coefficient (ICC) were determined. The mean corneal tangent moduli measured using UTM and CID were 0.094. ±. 0.030 and 0.094. ±. 0.028. MPa at 15. mmHg, and 0.207. ±. 0.056 and 0.207. ±. 0.055. MPa at 30. mmHg, respectively, with a difference less than 0.13%. The 95% limit of agreement was between -0.009 and 0.009. MPa. The Sw, repeatability, CV and ICC of corneal tangent moduli measured by the CID were 0.006. MPa, 0.015. MPa, 4.3% and 0.993, respectively. The results showed that the corneal tangent moduli measured by the CID are repeatable and are in good agreement with the results measured by the high precision UTM.