Refractive error after triple and non-simultaneous procedures: Is the application of a standard constant keratometry value in IOL power calculation advisable?

Abstract

Purpose: The purpose of this investigation was to determine whether or not the use of a standard constant keratometry value in cases of preoperative abnormal keratometry values in biometry for triple procedures is advisable. Methods: Cataract surgery and penetrating keratoplasty were performed in 82 eyes; 53 eyes underwent triple procedures and 29 eyes underwent non-simultaneous procedures. A standard constant keratometry value of 42.50D was applied in 18 triple-procedure eyes because the preoperative measured keratometry values were outwith the normal range (41-47D). The spherical equivalent and expected values were compared after a mean follow-up of 20.5months. Results: Cases in the triple-procedure group that achieved spherical equivalent within ±2.0D of expected values included nine of 18 eyes (50%) in which a standard constant keratometry value of 42.50D was applied, three of 17 eyes (18%) in which keratometry values outwith the normal range were applied (p=0.044), and eight of 18 eyes (45%) in which keratometry values within the normal range were applied (p=0.862). Cases in the non-simultaneous procedure group that achieved spherical equivalent within ±2.0D of expected values included 22 of 24 eyes (92%) in which keratometry values within the normal range were applied (p=0.0025), and five of five eyes (100%) in which a standard constant keratometry value was applied. Conclusions: The application of a standard constant keratometry value of 42.50D for intraocular lens power calculation in triple procedures can be recommended if abnormal keratometry values were measured previously. If possible, non-simultaneous procedures should take priority. © 2006 Acta Ophthalmol Scand.