Inter-Device Agreement in Keratometric Readings Measured With Scheimpflug-Based Topography and Ray-Tracing Technology
Purpose
To determine the agreement in keratometric readings measured with Pentacam (Oculus, Optikgerate GmbH) and iTrace (Tracey Technology) in a 60 to 80 year old population.
Methods
Prospective comparative study performed at Bascom Palmer Eye Institute, Miami, FL, including 32 eyes. Sixty to eighty year old patients undergoing cataract surgery preoperative evaluation were enrolled. Pentacam and iTrace were performed by a trained operator. Refractive keratometry readings (Ref Ks) and Simulated keratometry readings (Sim Ks) from iTrace were compared to Pentacam keratometric measurements. Agreement in keratometric readings was assessed using Bland Altman Method. The inter-device 95% limits of agreement (95% LoA) and 95% confidence interval for upper and lower limits of agreement were calculated.
Results
Based on Pentacam measurements, averages of max-K, min-K and mean-K were 43.59 ± 1.87 D, 42.57 ± 1.17 D, and 43.07 ± 1.38 D, respectively. Limits of agreement between Pentacam and iTrace Ref Ks were: -3.78 D to 3.22 D for max K; -2.50 D to 2.20 D for min-K and -3.50 D to 2.88 D for average K. Limits of agreement between Pentacam and iTrace SimKs were -4.23 D to 3.97 D for max-Ks, -3.94 D to 3.48 D for min-Ks and -4.01 D to 3.62 D for average K.
Conclusion
Preliminary results showed a higher agreement between Pentacam and iTrace Ref Ks than with Pentacam and iTrace SimKs, with narrower limits of agreements.