EyeWorld India June 2013 Issue

18 June 2013 EWAP FEAturE Update - from page 16 perfect capsulotomy, and the lens fragmentation reduce the risk of an errant capsulorhexis, the amount of phaco energy required to emulsify the lens, the amount of irrigation fluid running through the eye, intraocular manipulations, and the risk of a leaky wound,” said Neil J. Friedman, MD , adjunct clinical associate professor, Stanford University School of Medicine, and director of cataract and lens implant surgery, Pacific Vision Institute, San Francisco, Calif., USA. (See the list of additional suggested references for more details.) No matter how good a surgeon someone is, “it’s very difficult to make a perfect circle. It’s very difficult to make the exact same size incision every single time,” said Michael J. Endl, MD , partner, Fichte Endl & Elmer Eyecare, Niagara Falls, NY, USA. Creating a corneal incision, capsulotomy, and fragmenting the crystalline lens can all be performed manually, “but with the aid of a femtolaser, we can have more central incisions, have exact size and diameters every time, and we can guarantee that the edge of the IOL will be covered by a 0.25- to 0.5-mm anterior capsule to provide better centration compared to manual surgery,” Prof. Nagy said. For these experts, the ability of the femto to “improve the safety of surgery in challenging situations that have an increased risk of complications (i.e., mature cataract, dislocated lens, weak zonules, etc.)” is perhaps the most exciting, Dr. Friedman said. “Some data show that the refractive outcomes are slightly better due to a capsulotomy that perfectly overlaps the IOL optic keeping it closer to the predicted effective lens placement.” Prof. Nagy’s group 2,3 “achieved better centration, less posterior capsule opacification (our results will be published shortly), predictable geometry of corneal wounds, less endothelial stress and damage, and possibly less cystoid macular edema,” he said. The potential to improve safety “is incremental because any of the potential complications are still very rare,” Dr. Friedman said. Tens of thousands of cases—maybe hundreds of thousands—will need to be performed with these technologies before a true claim of complication reduction can be made, he said. Dr. Culbertson believes the femtolaser will inevitably lead to fewer cases of endophthalmitis “because the wounds don’t leak,” but also said more than 100,000 cases will need to be performed to show any true advantage. When the lens is broken up via laser instead of manually, “it’s a little less likely to rip in the bag,” Dr. Endl said, adding that, too, is a rare occurrence. Cases that used to be difficult with phaco—such as shallow anterior chambers—are not as problematic “because the in-built optical coherence tomography controls the anatomy of the eye, and surgeons can avoid hitting the endothelial cell layer,” Prof. Nagy explained. “In zonular dehiscence, femtolaser is a great advantage because we eliminate the zonular stress, and the SoftFit patient interface [Alcon, Fort Worth, Texas, USA/Hünenberg, Switzerland] can compensate for lens tilt.” Key attributes and drawbacks A typical healthy LASIK patient can expect postop uncorrected vision of 20/20 upward of 95% of the time. Until recently, however, Dr. Endl said even the best cataract surgeons may achieve this outcome only 70% of the time. “The femto laser will look to make cataract surgery outcomes more precise and predictable,” he said. With acknowledged downsides of the technology being both the cost and the additional surgical time, the reproducibility “allows more surgeons and patients to ultimately benefit,” Dr. Friedman said. “If cost/reimbursement issues and time were not an issue, femto would immediately become the preferred method of cataract surgery.” Prof. Nagy said there is a “promise for colleagues and patients that the benefits of the advanced technology IOLs can be better used if a femtolaser is incorporated into the ophthalmic practice.” Dr. Endl said one difficulty with integrating the new technology is patient flow and trying to minimize the number of stops a patient has to make, but his patients have readily accepted the slight inconvenience. Patient particulars Not every patient is a candidate for the femtolaser, these experts warned. For instance, patients with small pupils (<6.5 mm) or significant corneal opacities are not ideal. Dr. Endl agreed, saying the technology has helped ease some of his fear in more difficult cases (the laser “doesn’t care if it’s a white cataract—it’ll put the circle anywhere you want it to go”), but none of the surgeons said the technology is without any potential complications. Dr. Friedman said complications associated with the femtolaser are incomplete capsulotomy, a substantial increase in intraocular pressure during the procedure, or subconjunctival hemorrhage, “but that differs among the various devices.” A partial capsulotomy “may account for anterior capsular tears,” but surgeons should follow the contour of the capsulotomy during their learning curves to minimize the issue, Prof. Nagy said. “Capsular blockage syndrome can also be avoided if the surgeon is using the so called ‘rock-and-roll’ technique: gentle hydrodissection and push down a bit and move the lens (rock and roll), then the gas bubble is allowed to leave toward the anterior chamber, not causing blockage syndrome,” Prof. Nagy said. Avoiding the conjunctival vessels during wound creation will avoid the potential for an incomplete corneal cut, he said. Ideally, Prof. Nagy said, he’d like to see a femtolaser “with multifunctional use: cataract, corneal surgery, possibly glaucoma control, and maybe vitreoretinal use. I do not know whether it can come true, we will see it. But without a vision, no development is possible.” Perhaps Juan Battle, MD , said it best during last year’s ESCRS conference: “The femtosecond laser in cataract surgery makes normal cases easier, tough or difficult cases like normal cases, and impossible