EyeWorld India December 2014 Issue

33 EWAP CATARACT/IOL December 2014 Figure 1. Looking at the capsulotomy options with respect to the IOL implanted here, one can see that the scanned capsule-centered capsulotomy (purple) is better centered over the optic than the pupil-centered capsulotomy (green) would have been. Source: Shamik Bafna, MD it to be slightly tilted, potentially inducing aberrations or reducing the quality of vision, especially with a multifocal IOL. Warren Hill, MD , has shown that the greatest surgical influence on ELP is the capsule opening, advocating that the capsulotomy be round and slightly smaller than the optic, with 360-degree overlap of the optic edge by the capsule, in order to meet the demands of modern refractive cataract surgery. 1 Femtosecond lasers offer a high degree of precision and may make it easier to create a “perfect” capsular opening. The first step has been to ensure that these lasers can make a complete and free-floating capsulotomy with no capsule tags. Surgeons still report difficulty with this on certain laser by Shamik Bafna, MD Capsulotomy centration in laser cataract surgery Study shows that scanned-capsule centration offers the best chance of 100% capsule-optic overlap T he capsulorhexis is a critical element of cataract surgery. Not only does it set the stage for everything that follows, but it plays a key role in IOL positioning. A too-small or too-large capsular opening can potentially, over time, lead to anterior or posterior displacement of the lens optic and a change in the effective lens position (ELP). Even when there is no frank displacement of the lens, uneven capsular contraction around the lens optic can cause platforms. Published analyses have shown greater consistency in size and circularity with femtosecond laser capsulotomies. 2–4 Nagy and colleagues reported fewer cases of incomplete capsule overlap in a group of femto patients (11%) compared to manual capsulorhexis patients (28%)3 and a lower rate of IOL decentration in the laser group. 4 Indeed, the use of these lasers completely changes what is possible for us to do, raising a lot of questions about the “ideal” capsulotomy along the way. Capsulotomy centration study The femtosecond laser system that my colleagues and I use, the Catalys system (Abbott Medical Optics, AMO, Santa Ana, Calif., U.S.), allows the surgeon to choose among several methods for positioning the capsulotomy, including centering based on the pupil, the limbus, or the scanned capsule; decentering the opening using a custom setting; and maximizing it for the largest possible capsulotomy. If the pupil center represents the center of the visual axis (an assumption that may not always be correct), then it would be ideal to center the capsulotomy—and the IOL—on the pupil. Pupil centration also matches how most surgeons create a capsulorhexis manually. Scanned-capsule centration is a unique capability of the Catalys system. The laser maps the capsular surfaces based on full volume, three-dimensional optical coherence tomography continued on page 34