Comparison of IOL Master Keratometry with Pentacam Keratometry for Intraocular Lens Power Calculation in Normal Corneas

Proper method and machine for corneal evaluation is an important factor in many anterior segment interventions. This study was performed to compare the mean keratometry (K) readings obtained with an IOL Master and Pentacam for intraocular lens power calculation in normal subjects with no history of refractive surgery. Mean K values were obtained with the automated (IOL Master) and Scheimpflug keratometer. Scheimpflug readings obtained from simulated K (SIMK) and Holladay equivalent K (EKR) were analysed. Specific formula for a defined intraocular lens was considered according to the IOL Master, Pentacam SIMK and EKR data. 100 eyes undergoing PRK were evaluated. The mean age of patients was 27 ± 4.3 year old. The mean corneal power by IOL Master, SIMK and the EKR was 44.52 D ± 1.54, 44.08 D ± 1.46 and 44.25 D ± 1.48, respectively. The mean intraocular lens power by these three machines was 17.15 D ± 2.14 and 17.6D ± 2.2 and 17.53 D ± 2.14, respectively. There was a statistically significant correlation between IOL Master and SIMK and EKR corneal power and intraocular lens power calculated by the three aforementioned techniques (P < 0.001). There was a statistically significant difference between mean corneal power by IOL Master, SIMK and EKR and intraocular lens power calculated by IOL Master, SIMK and EKR. (P < 0.001) Despite the high correlation between the mean corneal power of automated keratometry, SIMK and EKR, also indicated a high correlation between intraocular lens power calculated by automated keratometry, SIMK and EKR. There was a statistically significant difference between them and the values were not interchangeable. References 1- Elie Saad, Maya C, Shammas H, John Shammas. Scheimpflug corneal power measurements for intraocular lens power calculation in cataract surgery. Am J Ophthalmol. 2013; 156: 460-67. 2- J Santodomingo-Rubido, EAH Mallen, B Gilmartin, JS Wolffsohn. A new non-contact optical device for ocular biometry. Br J Ophthalmol. 2002; 86: 458-62. 3- Olsen T. Improved accuracy of intraocular lens power calculation with Zeiss IOLMaster. Acta Ophthalmol Scand. 2007; 85: 84-87. 4- Richard J Symes, MRCOphth, Paul G. Ursell, FRC Ophth. Automated keratometry in routine cataract surgery: comparison of scheimpflugand conventional values. J Cataract Refract Surg. 2011; 37: 295-301. 5- Borasio E, Stevens J, Smith GT. Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula. J Cataract Refract Surg. 2006; 32: 2004-14. 6- Kawamorita T, Uozato H, Kamiya K, et al. Repeatability, reproducibility, and agreement characteristics of rotating scheimpflug photography and scanning-slit corneal topography for corneal power measurement. J Cataract Refract Surg. 2009; 35: 127-33. 7- Visser N, Berendschot T, Verbakel F, Brabander P, Nuijts R. Comparability and repeatability of corneal astigmatism measurements using different measurement technologies. J Cataract Refract Surg. 2012; 38: 1764-70. 8- Richard J, Symes MR, Miranda J, Say MS, Paul G, Ursell FR. Scheimpflugkeratometry versus conventional automated keratometry in routine cataract surgery. J Cataract Refract Surg. 2010; 36: 1107-14. 9- Neuhann T. Pentacam system’s overview: understanding its benefits. Highlights of Ophthalmology. 2007; 35: 1-3. 10- Woodmass J, Rocha G. A comparison of scheimpflug imaging simulated and holladay equivalent keratometry values with partial coherence interferometry keratometry measurements in phakic eyes. Can J Ophthalmol. 2009; 44: 700-4. 11- Giacomo Savini, Piero Barboni, Michele Carbonelli, Kenneth J. Accuracy of scheimpflug corneal power measurements for intraocular lens power calculation. J Cataract Refract Surg. 2009; 35: 1193-97. 12- Barkana Y, Gerber Y, Avni I, Zadoc D. Comparison of different techniques of anterior chamber depth and keratometric measurements. Am J Ophthalmol. 2007; 143: 48-53. 13- Shirayama M, Wang L, Weikert MP, Koch DD. Comparison of corneal powers obtained from 4 different devices. Am J Ophthalmol. 2009; 148: 528-35. 14- Fledelius HC, Stubgaard M. Changes in refraction and corneal curvature during growth and adult life. A cross-sectional study. Acta Ophthalmol. 1986; 64: 487-91. 15- Lam AK, Douthwaite WA. The ageing effect on the central posterior corneal radius. Ophthalmic Physiol Opt. 2000; 20: 63-69.