Corneal Astigmatism Measurements Comparison among Ray-Tracing Aberrometry, Partial Coherence Interferometry, and Scheimpflug Imaging System.

Yaqin Zhang,Maolong Tang,Bin Sun,Xiaoliang Wang,Jing Dong,Xiaogang Wang,Suhua Zhang

doi:10.1155/2020/3012748

Abstract

Purpose To investigate interdevice agreement among corneal topography/ray-tracing aberrometry (iTrace), partial coherence interferometry (IOLMaster), and Scheimpflug imaging (Pentacam) for the measurement of corneal astigmatism. Methods The analysis included 90 eyes of 90 subjects without ocular disease. The main outcome measures were corneal cylinder power and axis of astigmatism. All corneal astigmatism measurements were converted to two perpendicular components by using vector analysis. Interdevice agreement was assessed using Bland–Altman analysis, paired sample t-test, and one-way analysis of variance. Results No significant interdevice difference existed in the astigmatism magnitude, cardinal component, and oblique component (all P > 0.05). On comparing iTrace wavefront and simulated keratometry (SimK) astigmatism, significant differences were observed in the astigmatism magnitude and oblique component (both P < 0.01), but not in the cardinal component (P=0.687). On comparing Pentacam pupil 3 mm and corneal vertex 3 mm axial astigmatism, significant difference was observed in the astigmatism magnitude (P < 0.001), but not in the cardinal and oblique components (both P > 0.05). Conclusions The iTrace, IOLMaster, and Pentacam devices could be used interchangeably for corneal astigmatism measurement. However, the measurement difference in iTrace wavefront and SimK astigmatism and Pentacam pupil 3 mm and vertex 3 mm axial astigmatism should be considered in clinic practice.

Highlights

Preoperative corneal astigmatism greater than 0.5 diopters (D) should be considered for correction to gain clearer vision in case of cataract surgery [1]
Comparing the corneal astigmatism values obtained using different devices on the same eye can provide clues to understanding the trends of current corneal power measurement systems. erefore, the primary purpose of this study was to investigate the agreement among IOLMaster, Pentacam, and interdevice agreement among corneal topography/ray-tracing aberrometry (iTrace) with respect to corneal astigmatism measurements. e secondary aim was to evaluate (1) the interchangeability of corneal astigmatism values centered on the corneal vertex and pupil by using Pentacam and (2) the interchangeability of corneal astigmatism values between iTrace simulated values and corresponding wavefront values by using iTrace
Different keratometry and corneal topography devices are important for obtaining precise corneal astigmatism vector values. erefore, the purpose of this study was to evaluate the comparability and interchangeability of astigmatism measurements obtained using the three commonly used clinical devices

Summary

Introduction

Preoperative corneal astigmatism greater than 0.5 diopters (D) should be considered for correction to gain clearer vision in case of cataract surgery [1]. Effective correction of preexisting corneal astigmatism depends greatly on its accurate preoperative measurement. As a standard device for corneal astigmatism measurement, the keratometer is widely used in ophthalmic clinics. Different types of keratometers may offer different astigmatism values, which might provide different toricity choices for toric IOLs [2,3,4,5,6]. E potential measurement difference and different IOL toricity calculation formulas may cause under- or overcorrection of corneal astigmatism postoperatively [7]. Previous studies have demonstrated that the astigmatism data obtained using IOLMaster provide good outcomes when used for toric IOL selection [3, 10]

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Conclusion