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Comparison of measurement variation in keratometric readings (K's) in virgin eyes with that of eyes that have had previous corneal refractive surgery

Poster Details

First Author: S.Perera UK

Co Author(s):    H. Ali              

Abstract Details


Measurement variation in keratometry can contribute to IOL power calculation errors. The aim of this study is to ascertain if the measurement variation in eyes with previous corneal laser refractive surgery is different to that of the measurement variation seen in virgin eyes when using the IOL Master device for automated keratometry readings.


Clinical Practice


Patients undergoing cataract surgery routinely have three separate IOLMaster readings taken at our clinic. We analysed the pairwise difference in mean keratometric values for both K1 and K2 of the three readings in 30 consecutive virgin eyes (Group1) with that of 27 consecutive eyes that had previous laser refractive surgery (Group 2). Repeatability of the three measurements for each group was evaluated calculating the mean variation and standard deviation (SD)


For group 1 the mean variation between the 3 measurements in K1 and K2 were 0.109D (SD0.10) & 0.143D (SD0.14) respectively. For group 2 the mean variation between the three measurements in K1 and K2 were 0.143D (SD0.15) and 0.173 (SD 0.15) respectively. The difference in the variation for both K1 and K2 in the two groups were statistically significant. (P>0.05)


Eyes with previous corneal laser refractive surgery show a larger variation in the repeatability of keratometric measurements when compared to virgin eyes.The variation is more on the steeper axis than on the flatter axis. This increased variation in keratometric measurements may further contribute to the errors in IOL power calculations in patients with previous refractive surgery. FINANCIAL INTEREST: NONE

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