Cataract Surgery Bonus Feature

OCTOBER 2011 CATARACT & REFRACTIVE SURGERY TODAY EUROPE 31 A classic problem in cataract surgery is the a priori determination of the ideal power of the IOL to be implanted. After a long history of efforts by many practitioners and enthusiasts, current IOL power calculation methods provide reasonably good average accuracy. However, the price for this progress is an increasing number of formulas that must be considered and the steps necessary to choose the proper calculation procedure for each patient. For these reasons, the need for more deterministic models has been suggested.1 Most IOL power calculation procedures are based upon regression analysis. Therefore, it is common sense that these calculations are accurate on average but not as accurate as desired in a given individual. It was recently reported that biometry errors leading to wrong IOL powers were the second most frequent cause of malpractice claims.2 This resulted in payment of damages in 62% of closed cases, according to an analysis of the causes of malpractice claims related specifically to cataract surgery in the National Health Service in England from 1995 to 2008. It is well understood that, although current IOL power calculation procedures provide good outcomes on average, results on an individual scale still need improvement. This is especially evident in cases in which patients present some peculiarity, such as an abnormal cornea or extreme eye geometry. New generations of IOLs designed to correct corneal aberrations will not achieve their maximum potential visual benefit if the IOL power is not accurately determined.3-6 Blur associated with any significant residual refractive error would mask the visual advantage related to the correction of the aberrations. Another important and limiting point is the paraxial nature of most current IOL power calculations. Paraxial approaches might not be sufficient for higher levels of aberrations, such as those in post-LASIK eyes.7 The use in clinical practice of different instruments to accurately describe the eye, such as corneal topographers, may also be incorporated to improve the predictability of IOL power calculations.