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Confirmation and refinement of the Diehl/Miller nomogram for intraocular lens power calculation after LASIK
Session Title: Biometry
Session Date/Time: Tuesday 08/10/2013 | 08:00-10:30
Paper Time: 09:39
Venue: Elicium 2 (First Floor)
First Author: : K.Miller USA
Co Author(s): :
To validate the Diehl/Miller equation for achieving emmetropia at the time of cataract surgery in post-LASIK eyes and to present a refined equation. Diehl/Miller relates the manifest refractive spherical equivalent (MRSE) change induced by LASIK to an adjusted target postoperative refractive error (RE) to be used in IOL power calculations.
Jules Stein Eye Institute, Los Angeles, California, USA.
Preoperative and postoperative refractive and cataract surgery data were collected from medical records of post-LASIK patients who underwent cataract surgery between July 2007 and June 2011. IOL power data and postoperative refractive information were used to calculate the target refractive error (REtarget) that should have been chosen to achieve emmetropia. Regression analysis of the combined data from Diehl/Miller and the current study was used to develop a refined equation.
Twenty-three eyes from 18 patients were evaluated. The target RE calculated from Diehl/Miller differed from REtarget in the current study by an absolute mean of 0.481 ± 0.376 D. Regression analysis of the combined data from Diehl/Miller and the current study yielded a 2nd-order polynomial equation: Target RE = -0.0198(MRSE change)2 + 0.170(MRSE change) 0.0079. The calculated target RE fell within ± 0.50 D of REtarget for 49% of patients and within ± 1.00 D for 93% of patients.
This study is the first validation that the Diehl/Miller equation accurately predicts the target RE for achieving emmetropia in post-LASIK eyes. The refined Diehl/Date/Miller equation and associated look up tables can be utilized to avoid postoperative refractive surprises.