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 (IM),a Bausch &Lomb manual keratometer (Man) and TOPCON KR-8800autokeratometer (Top) 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:1) IOL Master and Manual keratometer:the mean corneal power was 44.62± 1.52 D with the IOL Master and 44.60 ± 1.52 D with the Manual keratometer.The paired t-test demonstrated a statistically significant difference in the mean corneal power between the IOL Master and Manual keratometer (P=0.001).The 95％ LOAs of the two devices were-0.22 to 0.22 as shown in the Bland-Altman plot;2) IOL Master and autokeratometer:the mean corneal power was 44.62±1.52 D with the IOL Master 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 autokeratometer (P＜ 0.0001).The 95％ LOAs of the two devices were-0.24 to 0.55 as shown in the Bland-Altman plot;3) Autokeratometer and Manual keratometer:the mean corneal power was 44.60±1.52 D with Manual keratometer and 44.46±1.53 D with the autokeratometer.The paired ttest demonstrated a statistically significant difference in the mean corneal power between the autokeratometer and Manual keratometer (P＜ 0.0001).The 95％ LOAs of the two devices 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.