Purpose: To compare final spherical equivalent (SE) refractions in patients who previously underwent radial keratotomy (RK) undergoing routine cataract surgery using keratometry (K) values from the Tomey (Topographic Modeling System [TMS]; Tomey Corp., Phoenix, AZ) Placido topographer, manual keratometer, and IOLMaster (Carl Zeiss Meditec AG, Jena, Germany) keratometer using the Haigis formulas.
Design: Retrospective case series.
Subjects: A total of 26 RK eyes (20 patients) with a minimum of 3 months postoperative follow-up.
Methods: The following K values were evaluated: TMS topography (flattest K within first 9 rings, average K, minimum K), manual K, IOLMaster K. The final refractive goal was -0.50 diopters (D) for all eyes. The Haigis formula with target refraction -0.50 D was used. In addition, because of observed hyperopic overcorrections, IOLMaster K with the Haigis formula set to -1.00 D but with a final refractive goal of -0.50 D was also tested. The Haigis-L formula using IOLMaster K values was separately evaluated.
Main outcome measures: Mean final SE refraction, percent final SE within ideal (-0.12 to -1.00 D), acceptable (0.25 to -1.50 D), or unacceptable (<-1.50 or >0.25 D) range and within ±0.50 D and ±1.00 D of the intended result.
Results: Best results with minimal overcorrections were achieved with TMS flattest K (mean -0.68±0.60 D, 73% within ±0.50 D, and 88% within ±1.00 D of the surgical goal) and IOLMaster K set for target -1.00 D (mean -0.66±0.61 D, 69% within ±0.50 D, and 88% within ±1.00 D of the surgical goal). Other values produced more hyperopic (manual, IOLMaster K set for target -0.50 D, average topography) or higher myopic (minimum topography, Haigis-L) results.
Conclusions: For simplicity, using the IOLMaster K values combined with the Haigis formula set for target refraction -1.00 D produces acceptable results aiming for -0.50 D final SE refractions in former RK patients undergoing routine cataract surgery.
Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.