Eyeworld

EW MEETING REPORTER 63 niques—specifically, femtosecond lenticule extraction (FLEx) and small incision lenticule extraction (SMILE). Basically, both methods re- place excimer laser ablation with in- cisional lenticule formation and extraction; the difference is that, with SMILE, the lenticule is ex- tracted through a pocket incision. One disadvantage of the SMILE pro- cedure is the lack of a flap; without a flap, how do you approach enhance- ment if necessary post-op? Pseudo-SMILE, a third ReLEx procedure, was developed to address this problem. In pseudo-SMILE, a full flap is created, but not lifted; the lenticule is still extracted through a pocket incision. Dr. Tan and his col- leagues are currently in the middle of analyzing their outcomes, but early results seem comparable with LASIK at three months—it just takes a little longer for patients to get there. The most exciting thing about ReLEx procedures, said Dr. Tan, is the potential reversibility. He and his colleagues have already con- ducted experiments in rabbits in which the lenticules were stored for a month, and then reimplanted into the same rabbits' eyes. They have al- ready begun non-human primate studies, with the lenticules stored away, waiting for reimplantaiton. Editors' note: Dr. Stulting has financial interests with Alcon (Fort Worth, Texas/Hünenberg, Switzerland). Dr. Tan and his colleagues at SNEC have filed a patent on the method they use for storing lenticules. Drs. Bissen-Miya- jima and Netto have no financial inter- ests related to the content of their lectures. A future for anterior chamber IOLs In 1997, a French ban was placed on anterior chamber phakic IOLs. These lenses, said Joseph Colin, M.D., have a long history of good short- term results, but long-term failures: around a quarter of patients im- planted with anterior chamber lenses up to that point eventually had them explanted due to signifi- cant losses in corneal endothelial cell population. However, Dr. Colin believes there is a definite future for angle-supported phakic IOLs. The safety of these lenses, he said, lies in the positioning. Thanks to the de- sign of one currently available model of angle-supported lens in particular—the AcrySof Cachet pha- kic IOL (Alcon, Fort Worth, Texas/Hünenberg, Switzerland)—and careful patient selection (no patients with anterior chamber depths of less than 3.2 mm, for instance), Dr. Colin's patients have suffered en- dothelial cell losses at five years of only about 3%—a rate that he said is comparable with losses suffered by patients implanted with non-ante- rior chamber IOLs. Phakic IOLs, said Dr. Colin, have the advantage of providing predictable and stable re- fractive outcomes while preserving accommodation. Moreover, these lenses can be—and should be, some surgeons say—easily explanted, as when the patient develops a cataract. Managing multifocals Multifocal IOLs promise perfect, spectacle-free vision, but in his refer- ral practice, R. Doyle Stulting, M.D., sees things differently. Dr. Stulting frequently sees unhappy pa- tients with multifocal IOLs, most of them complaining of blurred vision, and many suffering from photic phenomena. Dr. Doyle recommends the follow- ing management algorithm: 1. Check for residual refractive error. Multifocal IOLs are very sensi- tive to minimal refractive errors. 2. Look for surgical complications or preexisting conditions. 3. Check for IOL decentration. Argon laser pupilloplasty or sur- gical repositioning can help in these cases. 4. Check pupil size. 5. Check for posterior chamber opacification, but do not man- age PCO unless you are ab- solutely sure this is the problem. 6. If you can't find anything wrong, check if the patient's distance vi- sion is acceptable to her; if so, Dr. Stulting recommends read- ing glasses. If not, then you have no choice but to perform a lens exchange. Basically, said Dr. Stulting, multifocal IOLs are imperfect, and any additional im- perfections in a pa- tient's visual system will make things expo- nentially worse. A me- thodical approach is indicated in cases where a patient is un- happy with multifocal IOLs, and clinicians, he said, should do everything possible to avoid further intraocu- lar surgery. Cones, rings, & the femto laser Until relatively re- cently, said Joseph Colin, M.D., the treat- ment of keratoconus has been either the use of contact lenses or penetrat- ing keratoplasty (PKP). Dr. Colin de- scribed one of the many options currently available to cornea sur- geons: corneo plastic procedures; i.e., additive surgery using intra- corneal rings (ICRs), and corneal crosslinking with riboflavin. Intra- corneal ring implantation aims to improve uncorrected and best cor- rected visual acuity (UCVA and BCVA, respectively) and make the eye tolerant of contact lenses. Since Intacs intracorneal ring segments were approved by the FDA, said Dr. Colin, about 48,000 corneal grafts were avoided, all thanks to this sim- ple procedure. Meanwhile, corneal crosslinking stops the progression of keratoconus. Dr. Colin emphasized the fact that crosslinking is not re- fractive surgery; it does not improve visual acuity, and isn't meant to; in- stead, it only stabilizes the cornea to prevent progression of keratoconus. The biomechanical effect of ICRs, said Dr. Colin, is perfectly comple- mented by the photochemical effect of corneal crosslinking. In his prac- tice, Dr. Colin has seen no signifi- cant difference in terms of outcomes and safety between performing the two procedures separately and per- forming them together in one com- bined procedure (in both cases, the ICRs are implanted before proceed- ing with corneal crosslinking; the difference is the amount of time the surgeon puts between the two proce- dures); he thus sees no point in put- ting crosslinking off for later, and so recommends combining the proce- dures. Implanting ICRs can be done manually or with the femtosecond laser. The laser provides a safe and accurate means of creating the tun- nels into which the segments are in- serted; there is, however, a learning curve, whether you choose the man- ual or femtosecond laser approach. Yaron S. Rabinowitz, M.D., of- fered the following pearls for im- planting ICRs: Mark the center of the pupil; begin with slightly wider channels, making them narrower as you become more accustomed to the procedure; close the wound with a through and through suture; with the femtosecond laser, you may have trouble advancing the ICR—in such situations, Dr. Rabinowitz rec- ommended using a Sinskey hook to lift the roof of the tunnel; if you don't see enough of an effect with the ICR, go ahead and re-cut. While ICRs are indicated for keratoconus in patients who are not tolerant of con- tact lenses, patient selection remains fundamental to the success of the procedure. EW Editors' note: None of the other doctors have any financial interests related to the content of their lectures. January 2011

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