Comparison of Corneal Curvature and Astigmatism Measurements Among Three Optical Biometers in Age-Related Cataract Patients

Summary

This study compares corneal curvature and astigmatism measurements from three biometers in age-related cataract patients and assesses inter-device agreement and differences. With a large cohort of 800 eyes, this study provides novel evidence that inter-device agreement varies substantially by parameter: excellent for simulated keratometry but poor for total and posterior keratometry, highlighting the importance of parameter-specific device selection.

Abstract

Precise preoperative corneal measurements are crucial for optimizing intraocular lens power calculation in cataract surgery. Nevertheless, the agreement among different biometers remains ambiguous. This study was designed to compare the agreement of corneal curvature and astigmatism measurements obtained with CASIA2 (device 1), IOLMaster 700 (device 2), and Pentacam HR (device 3) in patients with age-related cataract. In this cross-sectional study, 800 eyes of 593 patients with age-related cataract were examined prior to phacoemulsification. The steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism (J0, J45) of the anterior, posterior, and total cornea were documented. Repeated-measures analysis of variance (rANOVA) or Friedman tests were employed to assess inter-device differences. Agreement was evaluated using Intraclass correlation coefficients (ICCs) and Bland-Altman analysis with 95% limits of agreement (LoA). Statistically significant differences were detected in most parameters across devices. Simulated keratometry (SimK) exhibited excellent inter-device reliability, with over 95% of differences within ± 1.0 D. Total keratometry (TK) showed good agreement, whereas posterior keratometry (PK) demonstrated poor agreement. Regarding astigmatism, the J0 components displayed higher consistency than the J45 components. Bland-Altman analysis revealed clinically acceptable LoA for SimK but greater variability for TK and PK parameters. SimK measurements showed high agreement across the three devices in this cataract cohort, supporting their clinical utility. However, due to significant discrepancies in TK and PK parameters, device-specific protocols are recommended for posterior and total corneal assessments. These findings may provide guidance for device selection in preoperative cataract evaluation.

Introduction

Modern cataract surgery has transitioned from a vision-restoration procedure to a sophisticated refractive intervention, where postoperative visual quality has emerged as a primary determinant of surgical success. Considering that the cornea constitutes roughly two-thirds of the total refractive power of the eye, the precise characterization of its curvature is of paramount significance. Corneal astigmatism exceeding 0.5 diopters (D) can lead to clinically significant visual impairments, such as blurred vision, glare, and monocular diplopia¹. This refractive sensitivity necessitates careful selection of corneal topography devices, as measuremen....

Protocol

This study was approved by the ethics committee of Aier Eye Hospital of Wuhan University (approval number: 2022IRBKY032001, date: 2022-03-20) and adhered to the tenets of the Declaration of Helsinki. The study included 593 patients (800 eyes). All participants provided written informed consent prior to enrollment.

Study design
A cross-sectional comparative measurement workflow was performed in patients with age-related cataract at a tertiary eye hospital. A total of 593 patients (800 eyes) with age-related cataract who were scheduled for phacoemulsification at Wuhan Aier Eye Hospital between April 2022 and May 2023 were....

Results

Agreement of keratometry
Statistically significant disparities were detected for SimKf, SimKs, SimKm, PKf, PKs, PKm, and TKf, TKs, TKm obtained via these three biometers (all P < 0.001). The device 1 exhibited the highest mean SimK (SimKm; 44.33 ± 1.47 D), followed by the device 2 (44.22 ± 1.49 D) and the device 3 (44.05 ± 1.46 D). The device 2 had the highest TKm (TKm; 44.26 ± 1.48 D), followed by the device 3 (43.31 ± 1.5 D) and the device 1 (43.28 ± 1.44 D). The device 3 presented the .......

Discussion

This study assessed the concordance of ocular biometric measurements in cataract patients among three devices. Statistically significant disparities were identified in corneal curvature and astigmatism measurements across the devices. Specifically, device 1 presented the highest SimK values. For total keratometry, device 2 exhibited the highest TK values, while device 1 and device 3 showed comparable lower values, with device 3 measuring slightly lower TKf than device 1. Regarding posterior keratometry, device 3 recorded.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Anterior segment optical coherence tomography (AS-OCT) device	Tomey Corporation, Nagoya, Japan	CASIA2 (Device 1)	Optical coherence tomographer
MedCalc software	MedCalc Software Ltd, Ostend, Belgium	22.009	RRID: SCR_015044
Scheimpflug tomography system	Oculus Optikgeräte GmbH, Wetzlar, Germany	Pentacam HR (Device 3)	Three-dimensional anterior segment analysis system
SPSS software	IBM, Armonk, NY, USA	27.0.1.0	RRID: SCR_016479
Swept-source optical coherence tomography (SS-OCT) biometer	Carl Zeiss Meditec AG, Jena, Germany	IOLMaster 700 (Device 2)	Optical biometer