Comparison of Corneal Power, Corneal Astigmatism, and Axis Location Obtained From Partial Coherence Laser Interferometer and Autokeratometer
Purpose
To assess the repeatability and agreement of corneal power, corneal astigmatism, axis location, and astigmatic vector component measurements using a partial coherence laser interferometer and an autokeratometer.
Methods
Keratometric readings of preoperative 520 right eyes were obtained with an IOLMaster (Carl Zeiss Meditec) and a RC-5000 autokeratometer (Tomey). Measurements repeatability of an IOLMaster and agreement between the two devices in corneal power (flattest and steepest meridians), mean corneal power, corneal astigmatism, axis location, and astigmatic vector components (Jackson cross-cylinders J0, J45) were evaluated.
Results
Measurements repeatability of an IOLMaster was high. The 95% limits of agreement between two devices were from -0.62 to 0.38 diopters (D) for the flattest meridian, from -0.64 to 0.34 D for the steepest meridian, from -0.48 to 0.21 D for the mean corneal power, from -0.74 to 0.68 D for corneal astigmatism, from -40.0 to 41.5 degrees for axis location, from -0.69 to 0.88 D for J0, and from -0.62 to 0.64 D for J45.
Conclusion
IOLMaster provided excellent repeatability and comparability to autokeratometer of corneal powers. However, disagreement in corneal astigmatism and in axis location between the two devices was not negligible, suggesting that care should be taken when the measurements were applied for toric intraocular lens implantation.