# Comparison of the reliability of corneal curvature and eccentricity measurements in myopic eyes using four different devices

## TL;DR

This study compares how well four devices measure corneal curvature and eccentricity in myopic eyes, finding that some devices agree more closely than others.

## Contribution

The study provides new insights into the reliability and interchangeability of corneal measurements using four different devices in myopic eyes.

## Key findings

- Low agreement was found in corneal curvature measurements across the four devices.
- Eccentricity measurements showed high agreement among TMS-4, Medmont E300, and Pentacam HR for Em and Eccentricity flat.
- Eccentricity steep (Es) measurements showed low agreement between TMS-4 and Pentacam HR.

## Abstract

Myopia is a global public issue which is increasing worldwidely. Instruments are essential for measurement in the diagnosis and evaluation of myopia. Comparing the agreement of corneal curvature and eccentricity measurements obtained using four different devices is meaningful for clinical research. We present enrolled 175 patients in this prospective study. The corneal curvature were measured by The Canon RK-F1, Tomey TMS-4, Medmont E300, Pentacam HR, eccentricity measured by last three devices. The agreement and differences were compared among the four instruments. There was a weak correlation between the TMS-4 and Pentacam HR in eccentricity steep (Es) compared to other devices. The Bland–Altman plots with 95% level of agreement showed low agreement of corneal curvature measured by the four instruments. The 95% LoA of K steep (Ks) and K flat (Kf) were > 0.5D for all instruments. For eccentricity, eccentricity mink (Em), also eccentricity flat, showed high agreement among the TMS-4, Pentacam HR, and Medmont E300 topographers, but Es showed low agreement. The agreement of corneal curvature measured by the four instruments was low, which cannot be used interchangeably in clinical practice. The Es obtained from TMS-4, Medmont E300, and Pentacam HR can be used interchangeably.