Abstract
Purpose: :
To compare 4 different corneal power measurement methods in determining accuracy for intraocular lens power calculation prior to cataract surgery.
Methods: :
We retrospectively reviewed the records of 53 eyes of 29 patients who had phacoemulsification and posterior chamber lens implantation during the past 2 years. All patients had no prior corneal surgery and no corneal pathology. Each of the patients had preoperative corneal curvature measurements taken with manual keratometry, IOL-Master, corneal topography, and Pentacam Scheimpflug camera. 2 corneal power measurements were derived from the Pentacam (simulated keratometry, BESSt formula). Following cataract surgery, using the manifest refraction obtained at 6 weeks postoperatively, the Holladay II formula was used to derive the actual corneal curvature value for each eye. These values were compared to the pre-operative corneal curvature measurements to contrast the mean absolute errors.
Results: :
The mean absolute error for manual keratometry, IOL-Master, corneal topography, and Pentacam by simulated K and BESSt formula were 0.47 diopters, 0.43 diopters, 0.57 diopters, 0.63 diopters, and 0.60 diopters, respectively. 95% limits of agreement were -0.33 to 1.19 for the IOL-Master, -0.43 to 1.36 for manual keratometry, -0.44 to 1.58 for TMS, -0.23 to 1.49 for Pentacam simulated K, and -0.25 to 1.44 using the BESSt formula. Overall the statistical analysis was significant (P<0.05).
Keywords: cornea: clinical science • intraocular lens