EyeWorld India December 2014 Issue

34 EWAP CATARACT/IOL December 2014 (OCT) imaging of the anterior and posterior capsule. Based on these surface fits, the center of the capsule is identified and then projected onto the anterior capsular surface, and a capsulotomy of the specified diameter is automatically positioned around that centration point. Given that an IOL’s springlike haptics naturally center the implant within the anatomical dimensions of the capsule (without regard to the optical center), it makes sense to me to also create the capsulotomy in the center of the capsule, so that the optic anchored in the capsule will be similarly centered and symmetrically aligned behind that opening. We decided to compare how two of these methods (pupil- centered and scanned capsule) perform for routine use. To test the two approaches, we randomly used one method or the other in 50 consecutive eyes. Preoperatively, the surgeon can flip back and forth to view the outlines of both the pupil-centered and scanned capsule-centered capsulotomy. Regardless of which method was used, we programmed the laser to create a 5.1-mm capsulotomy in all cases. Complete capsulotomies with no tags were achieved in all eyes. IOLs were implanted and centered to the best of our abilities in all cases. Postoperatively, we analyzed the position of each IOL relative to the capsular opening and assessed the degree of capsular overlap. Using the raw video footage from the laser and operating room video, we determined whether the alternate method (e.g., scanned capsule in an eye with a pupil- centered capsulotomy) would have improved or worsened centration of the capsulotomy over the implanted optic. In some eyes, the two methods resulted in quite different locations for the capsulotomy. Looking at the capsulotomy options with respect to the implanted IOL in the case in Figure 1, 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. Additionally, the pupil-centered opening would not have provided 100% overlap of the optic edge. Overall, the scanned capsule method offered the better position in 82% of eyes; 9% were in a better position with a pupil-centered capsulotomy; and there was no difference in the other 9%. 100% of the scanned capsule eyes had 360-degree optic overlap by the capsule, compared to only 78% of the eyes with pupil-centered capsulotomies. We found that scanned capsule centration usually results in a slightly more superior and nasal capsulotomy than if it were pupil centered. As a refractive surgeon, I find it interesting that this is similar to the slightly superonasal position of the undilated pupil relative to the limbus. Based on these results, my current practice is to make a 5.0- mm capsulotomy and to always choose the scanned-capsule method if the pupil is well dilated. In an eye with poor dilation, this will sometimes result in a capsulotomy plan that is too close to the iris edge to fit within the safety parameters. In such cases, I will center on the pupil instead. Further research is needed to understand the implications of this small study. I believe we are only just beginning to refine our understanding of the factors that influence ELP, determine where and how to best center the capsulotomy, and imagine what other elements of cataract surgery we might be able to improve with the aid of the high- resolution imaging built into these femtosecond lasers. References 1. Hill WE. Effective lens position following laser anterior capsulotomy. Paper PA005, presented at the 2011 American Academy of Ophthalmology meeting, Orlando, Fla. 2. Friedman NJ et al. Femtosecond laser capsulotomy. J Cataract Refract Surg. 2011;37(7):1189–98. Erratum in: J Cataract Refract Surg. 2011;37(9):1742. 3. Nagy ZZ, Kranitz K, Takacs AI, et al. Comparison of intraocular lens decentration parameters after femto- second and manual capsulotomies. J Refract Surg. 2011;27(8):564–9. 4. Kranitz K, Takacs A, Mihaltz K, et al. Femtosecond laser capsulotomy and manual continuous curvilinear capsulorrhexis parameters and their effects on intraocular lens centration. J Refract Surg. 2011;27(8):558–63. Editors’ note: Dr. Bafna is in practice at the Cleveland Eye Clinic in Brecksville, Ohio. He has financial interests with AMO. Contact information Bafna : drbafna@clevelandeyeclinic.com Index to Advertisers Moria Page: 15 www.moria-surgical.com OCULUS Optikgeräte Page: 30 www.oculus.de Topcon Corporation Page: 19 www.topcon.co.jp Ziemer Page: 68 www.ziemergroup.com ASCRS Page : 7, 17 , 28 , 36 , 37 , 47 , 67 www.ascrs.org APACRS Page : 2, 5, 45 , 53 www.apacrs.org Capsulotomy - from page 33