AIM: To evaluate the agreement and interchangeability of a Scheimpflug camera(Pentacam)and a partial coherence interferometry keratometer(IOL Master)in eyes having preoperative assessment for routine cataract surgery.

METHODS: In this prospective clinical study, 41 patients(64 eyes)with normal cornea from January 2017 to June 2017 in our hospital were enrolled. Simulated K, true net power and Holladay equivalent K(EKR)measured at 1.0 to 7.0 mm corneal diameters were measured by the Pentacam system and mean keratometer(Km)was measured by the IOL Master. Paired samples t test, Pearson correlation analysis and Bland-Altman method were used for statistical analysis.

RESULTS: Among patients with cataract of normal cornea, the mean Scheimpflug K for true net power and EKR at 1.0mm, 2.0mm, 3.0mm corneal diameters were statistically significantly less than the mean Km(IOL Master). The EKR at 4.5mm, 5.0mm, 6.0mm, 7.0mm of corneal diameters were significantly greater than the mean Km(IOL Master)(P<0.01 for all). The difference between Sim K and EKR at 4.0mm measured by Pentacam and Km measured by IOL Master was the smallest(-0.03D±0.252D and 0.04D±0.244D, respectively; t=-1.018, P=0.313; t=1.461, P=0.149), and it had the best uniformity with 95% credible interval of -0.53D to 0.46D(sim K)and -0.43D to 0.52D(equivalent K at 4.0mm). A Pearson correlation revealed a high correlation for corneal power measurements between the two devices(r>0.9 for all, P<0.01 for all).

CONCLUSION: The sim K and EKR at 4.0mm had the closest match with the Km(IOL Master)for Chinese patients with cataract of normal cornea. However, the application of these devices should be combined with clinical features.