Intraocular Lens Calculation After Refractive Surgery

Abstract

More and more patients who have had corneo-refractive surgery present for intraocular lens (IOL) implantation. IOL calculation in these patients is still a challenge. After refractive surgery, if eyes are treated as normal eyes, high hyperopic errors can occur in previously myopic eyes and moderate myopic errors in formerly hyperopic eyes. Three main sources for these errors can be identified: the radius measurement error, the keratometer index error and the IOL formula error. The literature presents a confusing variety of procedures and formulas to cope with this situation. An analysis of the available literature reveals the different methods used to address the individual error contributions, the magnitude of which is assessed by model calculations. The most relevant formulas for clinical practice are the no-history procedures, which require no previous patient data. Using these methods to calculate IOL power after refractive surgery makes it possible to obtain clinical outcomes of a similar quality to that for normal eyes.