Intraocular Lens Power Selection After RK: Topography, Manual, and Partial Coherence Interferometry Keratometry Results Using Haigis Formula
Narrative Responses:
Purpose
To compare final spherical equivalent (SE) refractions in former radial keratotomy (RK) patients undergoing routine cataract surgery using keratometry (K) values from the Tomey (TMS) topographer, office-based and IOLMaster keratometers utilizing the Haigis formula
Methods
Retrospective analysis of 19 RK eyes (12 patients) with minimum 5 months postoperative follow-up. The following K values were evaluated: TMS (flattest K within first 9 rings, average K, minimum K), manual K, IOLMaster K. The Haigis formula with final target refraction –0.5 D was used. In addition, IOLMaster K with Haigis target of –1.0 D was also tested. The Haigis-L formula using IOLMaster K values was separately evaluated.
Results
Best results with minimal overcorrections were achieved with TMS flattest K (mean -0.79 ± 0.66 D, 63% within ± 0.5 D and 84% within ± 1.0 D of the surgical goal) and IOLMaster K set for target –1.0 D (mean -0.74 ± 0.69 D, 53% within ± 0.5 D and 84% within ± 1.0 D of the surgical goal). Other values produced more hyperopic (manual, IOLMaster –0.5D, average topo) or higher myopic (min topo, Haigis-L) results.
Conclusion
For simplicity, using the IOLMaster K values combined with the Haigis formula set for target refraction –1.0 D produces quite acceptable results in former RK patients undergoing routine cataract surgery.