Official ESCRS | European Society of Cataract & Refractive Surgeons


Repeatability and validity of total corneal power measurements (TrueK) with a new optical biometer (IOLMaster 700)

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Session Details

Session Title: Anterior Segment Imaging

Session Date/Time: Monday 16/09/2019 | 14:00-16:00

Paper Time: 14:00

Venue: Free Paper Forum: Podium 4

First Author: : M.Shajari GERMANY

Co Author(s): :    R. Sonntag   W. Mayer   G. Steinwender   S. Priglinger                    

Abstract Details


A recently introduced optical biometer (IOL Master 700) can measure the total corneal power (TrueK). The purpose of this prospective randomized controlled trial was to evaluate the repeatability and validity (compared to total corneal refractive power of Pentacam) of the corneal power measurements.


Ludwig Maximilians University hospital Munich


94 eyes of 94 patients were measured three times with the optical biometer (IOL Master 700) and the Scheimpflug device (Pentacam). The order of measurement was chosen randomely. Patients with an irregular cornea, previous corneal surgery, dry eyes or corneal astigmatism abover 3 diopters were excluded. TrueK of the optical biometer was compared to standard K (IOL master), SimK (Scheimpflug), TCRP (Scheimpflug) and TNP (Scheimpflug). Repeatability was analyzed by calculating the within subject standard deviation. Validity was analyzed by Bland Altman Analysis.


Repeatability was 0.42 for standard K, 0.4 for TrueK, 0.45 for TCRP, 0.43 for TNP and 0.56 for SimK. Bland Altman analysis revealed no significant difference between standard K and TrueK (P=0.193) with a mean difference of -0.047 D and coefficient of repeatability of 0.326. A significant difference was found when comparing TrueK to TCRP with P=0.001, a mean difference of 0.018D and coefficient of repeatablity of 0.612. A difference >0.5D between astigmatism measurements between Truek and TCRP was found in 11 cases.


Total corneal refractive power measurements between the recently introduced TrueK and TCRP cannot be used interchangeably. Future studies are necessary to evaluate which measurement will result in a better outcome when the respective measurements are used for toric IOL calculation

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