EyeWorld Asia-Pacific June 2016 Issue

June 2016 16 EWAP FEATURE “future patients should perhaps be treated with nonsteroidal anti-inflammatory drugs prior to undergoing femtosecond laser treatment for cataract surgery.” 4 Wang et al. found that not just prostaglandins but “Inflammatory cytokines IL-1, IL-6 and PGE2 significantly increased after femtosecond laser-assisted cataract surgery, which may be the cause of intraoperative miosis seen in these patients” This was seen in spite of the fact that all patients in this study were treated with NSAIDs prior to surgery. Another group, Chen, Lin et al., found “increased aqueous humor levels of fibroblast growth factor (FGF- 2), tumor necrosis factor (TNF)-, leukemia inhibitor factor (LIF), interleukin (IL)-1ra and IL-18” in femto laser patients versus manual and concluded that “Our data indicate a disturbance of postoperative inflammation response after femtosecond laser treatment.” 5 There is also a study reporting an acidic shift in anterior chamber pH after femtosecond laser treatment due to carbonic acid created by cavitation bubbles 6 and another group showing a rise in temperature in the anterior chamber after femtosecond laser treatment. 7 The question then becomes how does it affect the surgical outcome to have the anterior chamber stew in this soup of elevated temperature, lower pH, and all these inflammatory mediators for however long it takes to vacuum this stuff out of the eye after the laser “pre treatment”? We know this causes miosis with all laser platforms 8 but what other problems might it be associated with? The large clinical comparison trials between FLACS and manual are starting to shed some light on these questions. The ESCRS FLACS study which recruited advanced FLACS users from all over Europe, many of whom were strong advocates of the technology, concluded that compared to manual surgery “Femto patients have worse post operative visual acuity, more post operative complications and more patients with a post operative visual acuity worse than pre op.” In this study there was significantly greater cornea edema, early PCO and uveitis in the FLACS group and overall complications were 82% higher with FLACS. While astigmatism was slightly less in the FLACS group the spherical outcomes were slightly closer to target in the manual group. 9 This is a trend that was also seen in the comparison trial recently published by Ewe, Abell et al. in Ophthalmology. In this study there were “more letters gained in the PCS [manual] group … mean refractive error was higher in the LCS [FLACS] compared with PCS [manual]” and complications were higher across the board with FLACS vs. manual. The laser group had higher anterior capsule tears (15 FLACS vs 3 MCS), posterior capsule tears (11 to 2), cornea haze (6 to 0), epithelial defects (7 to 0), as well as greater incidents of ocular hypertension (30 to 7), CME (8 to 1), and cornea edema (8 to 2). 10 Another recent study showed 4 times higher CME with FLACS vs. manual and noted that the CME rate associate with the laser markedly increased when a software upgrade was made to the Catalys laser in the study to increase its treatment speed using greater energy (presumably to smooth out the rhexis and make it look less serrated compared to manual). 11 While proponents of FLACS have focused on the reduction of ultrasound time as potential benefit of the technology it appears that the laser energy used to achieve that goal has its own risks associated with it that need to be reckoned with and are just beginning to be understood. FLACS advocates have also cited the “softening” of dense cataracts as a potential advantage of the technology but unfortunately the laser can only cut what it can see through and thus it is useless for segmenting the densest black and white cataracts we see in practice. I presented this 95 year old with a coal-black HM cataract to a large group of FLACS users for discussion (figure 1) and it was agreed that FLACS would not be able to segment this lens and that ECCE would be the safest option. Fortunately, the case was routinely performed with standard manual phacoemulsification without incident and the patient had an excellent outcome (figure 2). Not only does the femtosecond laser have little utility segmenting or “softening” dense lenses such as this one but a recent study also suggests that the capsulotomy created by the laser may be more prone to problems in mature cataracts. Asena and Kaskaloglu concluded that “the grade of cataract significantly increased the number of suboptimal capsulotomy outcomes in FS laser capsulotomy. In mature cataract cases the surgeon should be aware of the limitations of FS laser in order to prevent capsule related complications.” 12 In the United States, insured patients cannot be charged extra to cover the cost of using the femtosecond laser to perform covered steps in the surgery. Surgeons may however bill for non-covered refractive services and often laser-created cornea relaxing incisions are often performed in conjunction with cataract surgery with significant charges to the patient. After 6 years however we still have no good peer-reviewed studies showing that laser-created relaxing incisions are effective and able to treat more than 0.5 diopters when done at the time of cataract surgery. We have no study showing that the incisions created with a laser are as good or better than those done with a blade and certainly nothing that compares these favorably to what we can achieve with toric IOLs or laser vision correction. It seems paradoxical that we as a profession have moved away from incisional cornea refractive surgery for the last few decades because of its inherent unpredictability and instability only to embrace these incisions created by the laser without any good scientific evidence to support them. I have not adopted FLACS have no plans to use it. I see this technology as inherently flawed. It is too expensive, too limited, and too limiting. It takes too long, and introduces risks and problems to the cataract procedure that can simply be avoided by not using it. It offers no assistance on our most difficult cases and it is not needed and offers no advantages on our easier cases. I believe that as a profession we should be focusing our energy on making real strides forward to benefit our patients and that FLACS is a distraction from that task. EWAP References 1. Auffarth GU, Reddy KP, Ritter R, Holzer MP, Rabsilber TM. Comparison of the maximum applicable stretch force after femtosecond laser-assisted and manual an- terior capsulotomy. J Cataract Refract Surg . 2013 Jan;39(1):105-9. 2. Abell RG, Davies PE, Phelan D, Goemann K, McPherson ZE, Vote BJ. Anterior Femtosecond - from page 15