Comparison of keratometric data by optical biometers and Scheimpflug camera in patients before lens surgery

Purpose. To compare keratometry values determined by three different devices in patients before lens surgery. Material and methods. 55 patients which mean values of keratometry were compared using two optical biometers (IOL-Master 500, Carl Zeiss Meditec AG, Germany, and Tomey OA-2000, Japan) and Scheimpflug camera (Pentacam-HR, Oculus, Germany), according to which the values of standard keratometry (Axial), equivalent keratometric indicators (EKR) and total corneal refractive power (TCRP) were used. Results. Mean keratometry values according to IOL-Master 500 were 43.47±1.36, Tomey OA-2000 — 43.46±1.24, Axial — 43.34±1.4, EKR — 43.19±1.4, TCRP — 42.7±1.4. Pentacam-HR keratometric data (for all maps and zones) are significantly lower than the corneal optical power determined by IOL-Master 500. Comparison of Tomey OA-2000 and Pentacam-HR revealed statistically significant low values of keratometry according to TCRP and EKR maps. Conclusion. The standard keratometry results used in most IOL calculation formulas may vary depending on the method of their determination. The values of the optical corneal power according to keratometry data, taking into account the posterior surface of the cornea, are significantly lower than the values of standard keratometry, which is due to the leveling of the index 1.3375. Key words: keratometry, corneal power, biometrics, keratotopography