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Anne Poulsen, Amy Lu, David Cui, Catherine Seeger, Erik Lehman, Ingrid U Scott, Seth Pantanelli; Repeatability of Keratometry Measurements with Swept-Source Optical Coherence Tomography in Normal Eyes. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4732.
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© ARVO (1962-2015); The Authors (2016-present)
Keratometry measurements are an important component in planning for cataract surgery, especially when surgical correction of astigmatism is anticipated. Increasing emphasis is being placed on posterior keratometric indices. Recently, the IOLMaster 700 gained the capability to measure posterior corneal curvature using swept-source optical coherence tomography (SS-OCT), but there are no studies on the repeatability of these measurements. The purpose of this study was to investigate the repeatability of posterior keratometric measurements relative to traditionally measured anterior keratometry.
Prospective consecutive case series of patients evaluated for cataract surgery between January and November 2019 at Penn State Eye Center. After obtaining informed consent, measurements were obtained three times on each eye with a swept-source enabled optical biometer (IOLMaster 700, Carl Zeiss Meditec) and once with a dual-Scheimpflug placido disc corneal tomographer/topographer (Galilei G4, Zeimer). Exclusion criteria included prior surgical intervention, significant ocular trauma, clinically significant dry eye, other corneal pathology known to affect the shape or regularity of the cornea (e.g., anterior basement membrane dystrophy, keratoconus), and inability to obtain good quality topography measurements (as defined by the devices’ four image quality metrics).
Seventy eyes from 37 patients met criteria for study inclusion. The mean within-subject standard deviation (Sw) for the anterior spherical equivalent (SEa), posterior spherical equivalent (SEp), anterior steep axis, and posterior steep axis were 0.12 D, 0.03 D, 15.9 degrees, and 11.5 degrees, respectively. The intraclass correlation coefficients were excellent (> 0.87) for all keratometry indices except posterior corneal axis (0.75). Bland-Altman analysis revealed that most indices from the IOLMaster and Galilei G4 cannot be used interchangeably. The IOLMaster consistently reported flatter posterior corneal curvatures than the Galilei G4.
The IOLMaster 700’s posterior corneal power measurements are more repeatable than its anterior and total corneal power measurements. Measurements taken using the SS-OCT and dual-Scheimpflug placido disc topographer should not be considered interchangeable.
This is a 2020 ARVO Annual Meeting abstract.
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