Comparing the corneal curvatures obtained from three different keratometers-IOL Master, Bausch & Lomb Manual keratometer and TOPCON KR 8800 autokeratometer

AIM: To compare the corneal curvature and to investigate the agreement between three different keratometers. METHODS: In this prospective study, keratometry was performed using an IOL Master, a Bausch & Lomb manual keratometer and TOPCON KR-8800 autokeratometer on 252 eyes of patients recruited from camps for cataract surgery. The average keratometry values were recorded and compared. The agreements between the instruments were analyzed using the Bland Altman statistical method. The main outcome measure was average keratometry values.RESULTS: The mean corneal power was 44.62±1.52 D with the IOL Master, 44.60±1.52 D with the manual keratometer, and 44.46±1.53 D with the autokeratometer. The paired t test demonstrated a statistically significant difference in the mean corneal power between the IOL Master and manual keratometer (P=0.001), IOL Master and autokeratometer (P<0.0001), autokeratometer and manual keratometer (P<0.0001). The 95% limits of agreement (LoA) of the IOL Master and manual keratometer were -0.22 to 0.26; IOL Master and autokeratometer were -0.24 to 0.55; autokeratometer and manual keratometer were -0.30 to 0.57 as shown in the Bland-Altman plot. CONCLUSION: Keratometry data obtained with different instruments may not be interchangeable, a fact that has important implications for cataract surgeons with respect to both surgical planning and outcomes auditing.