A Comparative Study on the Inter-Session and InterExaminer Reliability of Corneal Power Measurement Using Various Keratometry Instruments
- Author:
Md Muziman Syah MM
;
Mutalib HA
;
Sharanjeet Kaur MS
;
Khairidzan
- Publication Type:Original Article
- Keywords:
Inter-session repeatability, inter-examiner reproducibility, inter-device agreement, corneal
- From:
The International Medical Journal Malaysia
2016;15(1):69-74
- CountryMalaysia
- Language:English
-
Abstract:
The purpose of this study was to evaluate inter-session repeatability, inter-examiner
reproducibility and inter-device agreement of corneal power measurements from manual keratometer,
autokeratometer, topographer, Pentacam high resolution and IOLMaster. Methods: Two sets of mean
corneal power measurements (n=40) were compared for inter-session repeatability and inter-examiner
reproducibility in each instrument. Repeatability and reproducibility were evaluated by within-subject
standard deviation (Sw), coefficient of variation (COV) and intraclass correlation coefficient (ICC). A oneway
repeated measures analysis of variance was conducted to compare differences in the corneal power
between each instrument pair. The Bland and Altman analysis and Pearson’s correlation were employed to
assess agreement and determine strength of relationship between measurements. Results: There were no
significant differences in mean corneal power measurements between 2 different visits (p > 0.05). The Sw
and COV values between 2 visits were lower than 0.09 D and 0.20 % respectively. The ICCs were stronger
than 0.99 in all instruments. For reproducibility of each instrument, differences of the measurements
between 2 different examiners were also insignificant (p > 0.05). The Sw and COV values between 2
examiners were lower than 0.11 D and 0.23 % respectively. The ICCs were 0.99 and above in all instruments.
The 95% limit of agreement between instruments ranged from -0.29 to 1.13 D and the r-values were stronger
than 0.84. Conclusion: The corneal power measurements using these 5 instruments were repeatable and
reproducible. These instruments can also be used interchangeably, however the topographer should be used
with caution.
