Abstract
Purpose :
We compare accuracy of spherical equivalent prediction in patients undergoing cataract surgery using keratometric values from the manual keratometer, IOL Master 500 and 700, and Pentacam. Our null hypothesis is that there is no difference in predicted spherical equivalent accuracy when comparing different keratometry platforms.
Methods :
This study was an ongoing retrospective case series of all eyes undergoing cataract surgery by a single surgeon from 2019 to 2020 at Wake Forest University. Preoperative, biometric, intraoperative, and post-operative data were collected including keratometry measurements from each platform, predicted spherical equivalent based on the Barrett Universal II formula, and post-operative manifest refraction. All manual keratometry measurements were performed by the surgeon.
Results :
133 eyes met inclusion criteria for the study. Average best-corrected visual acuity improved from 20/50 (0.40 logMAR) pre-operatively to 20/22 (0.04 logMAR) post-operatively. Average spherical equivalent was -0.83 D pre-operatively and -0.31 post-operatively. There was no significant difference in prediction error: -0.05 D for the IOL Master 700, -0.05 D for the IOL Master 500, -0.10 D for the manual keratometer, and -0.19 D for the Pentacam (p = 0.17). There was also no significant difference in percentage of cases within 0.5 D of predicted spherical equivalent: 72% IOL Master 700, 87% IOL Master 500, 73% manual keratometer, and 73% Pentacam (p = 0.65).
Conclusions :
There was no significant difference in keratometry measurements and accurate prediction of spherical equivalent after cataract surgery across the four platforms. This can reduce time and expense in obtaining multiple keratometry measurements unless there is suspicion for unreliability. Refractive accuracy of this study is similar to what is reported in the literature. IOL Master prediction tends toward more myopia and accuracy which is likely due to the smaller keratometric ring diameter measuring the steeper central cornea. Reaching 100% refractive accuracy will involve improved prediction of effective lens position, incorporating direct measurements of posterior corneal power, and post-operative refraction modification.
This is a 2021 ARVO Annual Meeting abstract.