Wavefront aberrometry in Cataract Surgery and Laser vision Correction

66 CataraCt & refraCtive Surgery today euroPe SePtember 2012 The Munnerlyn ablation profiles first used in laser vision correction did not respect the normal prolate shape of the cornea. As a result, these profiles induced aberrations that reduced patients’ quality of vision. In recent years, enhanced understanding and technological adaptation to address spherocylindrical refractive error and higher-order aberrations (HOAs) have resulted in vast improvements in patients’ quality of vision after laser vision correction. Today, the goal of refractive surgeons is to enable their patients to see better than 20/20 and to improve their quality of vision beyond what they might expect with glasses or contact lenses. The term wavefront-guided approach refers to an ablation profile that considers preoperative HOAs. The final goal is to avoid inducing aberrations and to eliminate some that exist. The laser ablation profile is computed preoperatively according to the results of aberrometry and is transferred to the excimer laser system for use during surgery. Despite the many advantages that wavefront technology offers refractive surgeons, customized ablation surgery based on an ocular wavefront has been subject to controversy over the effectiveness of the procedures. Shortcomings of ocular wavefront technology include a relatively limited number of points of analysis over the pupil area, and the false assumptions by some models of local corneal flatness of the analyzed area. Additionally, generic variables such as accommodation, tear film distribution, and the pupil’s motility can induce changes in HOAs that will influence the accuracy and efficacy of the customized ablation. Cataract surgeons have developed and refined methods for calculating IOL power to achieve accurate and satisfactory postoperative refractive results. The same technology that helps provide optimal visual acuity with laser vision correction is now being used for cataract patients. Modern aspheric IOLs address the tendency of the cornea to induce less negative spherical aberration with advancing age, and some surgeons advocate customizing the choice of IOL depending on a patient’s individual optical aberrations.1 Perhaps the culmination of this attitude has been the development of intraoperative wavefront aberrometry, with which a wavefront refraction measurement can be taken of the eye in the aphakic state at the time of surgery to guide the choice of IOL. This month’s Peer Review column highlights important findings of several recent studies evaluating wavefront aberrometry for both laser vision correction and cataract surgery. Having been treated last year by Eric D. Donnenfeld, MD, I (AB) have personally benefited from the fantastic results of customized LASIK. It is, therefore, a particular pleasure to put together this column. Wavefront aberrometry in Cataract Surgery and Laser vision Correction