Several studies have reported the repeatability and reproducibility of aberrometry obtained by the 2 devices. In addition to ocular aberrometry, this device has an incorporated Placido-based topographic system that provides corneal topographic maps. The iTrace system (Tracey Technologies Corp., Houston, TX) uses the principle of ray tracing for obtaining the wavefront aberrations of the eye. The Topcon KR-1W system includes 3 different technologies for analysis of the human eye: wavefront aberrometry based on the Hartmann-Shack principle, Placido-disk corneal topography, and standard auto-refraction. For all the devices, the corneal power can be calculated by the anterior corneal curvature in certain central corneal surface, the standard corneal refractive index (1.3375) and the refractive index of air (1.000). There are several types of devices that can be used for corneal power measurement, such as manual or automated keratometry (e.g., IOLMaster), computerized videokeratography based on Placido-disk (e.g., Allegro Topolyzer), Slit-scan system (e.g., Orbscan), Scheimpflug rotating camera system (e.g., Pentacam) and optical coherence tomography (e.g., RTVue100 Fourier-domain OCT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Ĭompeting interests: The authors have declared that no competing interests exist.Īccurate corneal power measurement is essential for managing keratorefractive surgery, calculating intraocular lens (IOL) power, and fitting orthokeratology or customized contact lenses. ![]() This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All relevant data are within the paper and its Supporting Information files.įunding: Financial support provided by the Health Bureau of Shanghai City (201440029) to Q. Received: ApAccepted: DecemPublished: January 11, 2016Ĭopyright: © 2016 Hua et al. PLoS ONE 11(1):Įditor: Sanjoy Bhattacharya, Bascom Palmer Eye Institute, University of Miami School of Medicine, UNITED STATES When poor vision occurs after a premium lens implantation, an undilated scan with the iTrace will bring the root cause to light.Citation: Hua Y, Xu Z, Qiu W, Wu Q (2016) Precision (Repeatability and Reproducibility) and Agreement of Corneal Power Measurements Obtained by Topcon KR-1W and iTrace. Since the iTrace is the only device that can accurately scan the complex architecture of a premium IOL, these post-surgical benefits are not exclusive to toric lenses. A surgeon can easily review the estimated benefits of rotating a toric lens with a patient after understanding how much cylinder is likely to change. The iTrace’s wavefront map displays both the axis of the cylinder internally and the corneal steep axis, which is confirmed by topography.īecause ray tracing is the only way to accurately measure through a toric lens, the iTrace is the only device that calculates the predicted post-surgical refraction and automatically suggests any rotation that will optimize the location of a toric lens. The iTrace calculates cross cylinder and verifies whether a toric IOL is off-axis or off-power.Īfter a toric implantation, the lens cylinder power should match the corneal steep axis. Determining the post-operative axis location does not need to be a time-consuming or uncomfortable process. ![]() A 30-second iTrace exam evaluates the post-operative alignment of a toric lens without dilating a patient.
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