Agreement in Keratometric Measurements Using Placido-Based Corneal Topography and Ray-Tracing Technology
Purpose
To evaluate inter-device agreement in keratometric measurements using iTrace (Tracey Technologies) and Tomey.
Methods
Twenty-eight eyes of 28 patients were included in a prospective study performed at Bascom Palmer Eye Institute, Miami, FL. Every patient presenting for preoperative cataract surgery evaluation underwent keratometric measurements using Tomey and iTrace. Refractive keratometry readings (Ref Ks: max-K, min-K and average-K) and Simulated keratometry readings (Sim Ks) from iTrace were compared to keratometric measurements performed with Tomey. The inter-device 95 per cent limits of agreement (95% LoA) and 95% confidence interval for upper and lower limits of agreement were calculated.
Results
Based on Tomey measurements, mean max-K, mean min-K and mean average-K were 43.58 ± 1.77D, 42.66 ± 1.16D and 43.12 ± 1.31 D, respectively. The same parameters with iTrace were 43.72 ± 1.90D, 42.92 ± 1.51D and 43.32 ± 1.61 D, and iTrace Sim Ks were 43.30± 1.85D, 42.41± 1.51D and 42.85± 1.59D respectively. Limits of agreement between Tomey and iTrace Ref Ks were -1.52 D to 1.40 D for average-K. Limits of agreement between Tomey and iTrace Sim Ks were -1.22 D to 1.73 D for average-Ks.
Conclusion
A good agreement in keratometric measurements was found between the 2 devices that can therefore be interchangeable in cataract surgery preoperative evaluation.