Comparison of the accuracy of four Pentacam corneal astigmatism values in non-toric pseudophakic eyes
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Comparison of the accuracy of four Pentacam corneal astigmatism values in non-toric pseudophakic eyes Tianyu Zheng 1,2,3,4 & Jie Xu 1,2,3,4 & Yi Lu 1,2,3,4 Received: 23 July 2019 / Revised: 4 December 2019 / Accepted: 19 December 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Purpose To compare the accuracy of different corneal astigmatism values measured by Scheimpflug keratometry (Pentacam), including Simulated Keratometry (SimK) and three total corneal astigmatism values, equivalent K reading (EKR), true net power (TNP), and total corneal refractive power (TCRP). Methods We enrolled 168 eyes of 168 patients with non-toric IOL implantation. Pentacam examination and subjective refraction were performed 3 months after surgery. The agreement, arithmetic difference, and vector difference between refractive astigmatism (RA) and different corneal astigmatism values were compared. Results Differences in astigmatism magnitude were significant between SimK and RA in the against-the-rule (ATR) and withthe-rule (WTR) groups but not in total corneal measurements. The meridians of SimK and RA differed significantly in the oblique astigmatism group. The correlations between total corneal astigmatism values and RA were stronger than that between SimK and RA in the total, WTR, and oblique astigmatism groups in Pearson’s correlation test. Bland-Altman plots revealed more data points exceeding the limits of agreement (LoA) in SimK measurement in total and WTR subjects. In the ATR group, fewer data points exceeded LoA in EKR. The mean difference vector between SimK and RAwas larger than that of other measurements in each astigmatism group. The arithmetic mean of difference vector was significantly smaller in EKR in the total, WTR, and oblique groups. Conclusions Among different Pentacam readings, corneal astigmatism measurements considering anterior and posterior corneal surfaces were more representative of total ocular astigmatism than SimK, and EKR showed markedly better performance in astigmatism estimation. Keywords Pentacam . Corneal astigmatism . Simulated Keratometry . Equivalent K reading . True net power . Total corneal refractive power . Non-toric
Introduction Tianyu Zheng and Jie Xu contributed equally to this work. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00417-019-04585-8) contains supplementary material, which is available to authorized users. * Yi Lu [email protected] 1
Department of Ophthalmology, Eye and Ear, Nose, and Throat Hospital, Fudan University, 83 Fenyang Rd, Shanghai 200031, China
2
Eye Institute, Eye and Ear, Nose, and Throat Hospital, Fudan University, Shanghai, China
3
Key Laboratory of Myopia, Ministry of Health, Shanghai, China
4
Shanghai Key Laboratory of Visual Impairment and Restoration, Shanghai, China
Corneal astigmatism can be addressed at the time of cataract surgery with toric intraocular lens (IOL) to achieve better uncorrected visual acuity [1–3]. However, a mean overcorrection or undercorre
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