Differences between Keratometry and Total Keratometry Measurements in a Large Dataset Obtained with a Modern Swept Source OCT Biometer.

Wendelstein, Jascha A; Hoffmann, Peter C; Hoffer, Kenneth J; Langenbucher, Achim; Findl, Oliver; Ruiss, Manuel; Bolz, Matthias; Riaz, Kamran M; Pantanelli, Seth M; Debellemanière, Guillaume; Gatinel, Damien; Cooke, David L; Galzignato, Alice; Yeo, Tun Kuan; Seiler, Theo G; Zinkernagel, Martin; Savini, Giacomo (2024). Differences between Keratometry and Total Keratometry Measurements in a Large Dataset Obtained with a Modern Swept Source OCT Biometer. American journal of ophthalmology, 260, pp. 102-114. Elsevier Science 10.1016/j.ajo.2023.12.003

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This study aimed to explore the concept of total keratometry (TK) by analyzing extensive international datasets representing diverse ethnic backgrounds. The primary objective was to quantify the disparities between traditional keratometry (K) and TK values in normal eyes and assess their impact on intraocular lens (IOL) power calculations using various formulas.


Retrospective multicenter inter-instrument reliability analysis METHODS: The study involved the analysis of biometry data collected from ten international centers across Europe, the United States, and Asia. Corneal power was expressed as equivalent power and astigmatic vector components for both K and TK values. The study assessed the influence of these differences on IOL power calculations using different formulas. The results were analyzed and plotted using Bland-Altman and double angle plots.


The study encompassed a total of 116,982 measurements from 57,862 right eyes and 59,120 left eyes. The analysis revealed a high level of agreement between K and TK values, with 93.98% of eyes exhibiting an absolute difference of 0.25 D or less. Astigmatism vector differences exceeding 0.25 D and 0.50 D were observed in 39.43% and 1.08% of eyes, respectively.


This large-scale study underscores the similarity between mean K and TK values in healthy eyes, with rare clinical implications for IOL power calculation. Noteworthy differences were observed in astigmatism values between K and TK. Future investigations should delve into the practicality of TK values for astigmatism correction and their implications for surgical outcomes.

Item Type:

Journal Article (Original Article)


04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Ophthalmology

UniBE Contributor:

Seiler, Günter Theodor Michael, Zinkernagel, Martin Sebastian


600 Technology > 610 Medicine & health




Elsevier Science




Pubmed Import

Date Deposited:

14 Dec 2023 11:43

Last Modified:

01 Apr 2024 00:13

Publisher DOI:


PubMed ID:


Uncontrolled Keywords:

Astigmatism Biometry Cataract Surgery Corneal Power Keratometry Swept-Source OCT Total Keratometry





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