JAN 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

Issue link: https://digital.eyeworld.org/i/233841

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Page 56 of 66

54 EW RESIDENTS January 2014 EyeWorld journal club New technology and good outcomes, but … by Saba T. Alniemi, MD, Elizabeth A. Atchison, MD, Saranya C. Balasubramaniam, MD, Jasmina Bajric, MD, Victoria I. Lossen, MD, Maya H. Maloney, MD, Rachel C. Mercer, MD, Harish Raja, MD, Aarika L. Menees, MD, Sejal R. Amin, MD, Francisco Castillo, MD, and Heidi E. Gollogly, MD, Mayo Clinic residents Cheryl L. Khanna, MD, ophthalmology residency program director, Mayo Clinic The January JCRS has two interesting articles on femtosecond laser outcomes with cataract surgery. I invited the Mayo Clinic residents to review both papers for EyeWorld readers and this month's "EyeWorld journal club." –David F. Chang, MD, chief medical editor F emtosecond laser-assisted cataract surgery (FLACS) is a recent advancement in cataract surgery that offers an attractive new option for performing accurate and reproducible anterior capsulotomies, lens fragmentation, refractive keratotomies, and clear corneal incisions. Although prior studies have reported the potential advantage of this technique over traditional phacoemulsification cataract surgery (PCS), few have reported on the safety of this new technology. FLACS has been shown in prior studies to improve the reproducibility of the capsulorhexis, lens centration and potentially refractive outcomes. The safety of this new technique has been evaluated in several case series including the largest published series to date conducted by Bali and co-authors.1 They compared their early complication rate in the first 200 cases against their rates once they became familiar with the use of this technology in the subsequent 1,300. Their reported anterior capsular tags rate was 10.5%, anterior capsular radial tears was 4%, posterior capsular rupture was 3.5%, and dropped nuclear fragments was 2% of the initial 200 cases with significant reductions in these numbers in the latter series.2 In the January issue of the Journal of Cataract & Refractive Surgery (JCRS), Chang et al and Nagy et al report their experience using FLACS as they introduce this technology to their own practices. Both studies had small patient populations (100 cases by Nagy et al and 170 cases by Chang et al) and report low complication rates, such as anterior capsular tags and tears, posterior capsular rupture, and dropped nuclear fragments. While it is tempting to compare this information with the current reported rates of complications in PCS, the study population for these studies, including inclusion and exclusion criteria, was not clearly defined. This effectively precludes the authors' ability to draw conclusions regarding the safety of this novel technique. FLACS allows the surgeon to design the corneal incision, rhexis and nuclear fragmentation in a variety of configurations. The benefits of this go beyond central positioning of the intraocular lens. As novel techniques are developed, it has been postulated that FLACS will allow for safer removal of nuclear fragments with less manipulation in the eye and less phacoemulsification energy. It is conceivable the technology has the potential to increase the safety of cataract surgery in patients with weakened zonular fibers, trauma, or abnormal anterior chamber anatomy due to less manipulation of nuclear fragments. Conversely, the laser may perform poorly in patients with poor dilation, hazy media, or dense cataracts. While the authors in both studies conclude that FLACS is a safe technique, the population in which their conclusions hold true was not described. Chang et al report no statistically significant difference in the cumulative dispersed energy (CDE) between FLACS and PCS for grade 1, 3 or 4 cataracts, while a significantly higher CDE was required for grade 2 cataracts removed with FLACS. No explanation was offered for this finding, and the significance of CDE on surgically induced endothelial injury is not established in FLACS. While FLACS was reported to have no significant effect on the total phacoemulsification energy necessary to remove a cataract, it markedly increases the cost to perform the surgery. The justification for increased cost per case is not addressed in either study. Prior studies have suggested that increased instrumentation is correlated with elevated risk of endophthalmitis, with increasingly complex surgeries and repeated insertion and removal of instruments exposing the anterior chamber to cumulative bacterial loads.3 While both reports discuss laser time, there is no mention of the total surgical time comparing FLACS with PCS. In addition, the need for additional instruments that contact the eye raises the possibility for exposure to non-sterile equipment. While no cases of endophthalmitis were reported in either series, the studies would be underpowered to find a significant difference if there is one, given the rarity of this complication. The use of the femtosecond laser poses a few additional variables to be considered as potential sources for surgical complications. During Initial evaluation of a femtosecond laser system in cataract surgery John S.M. Chang, MD, Ivan N. Chen, FRCS(Edin), FCOphth(HK), FHKAM (Ophthalmology), Wai-Man Chan, FRCS(Edin), FRCOphth, FHKAM (Ophthalmology), Jack C.M. Ng, BSc(Hons), MPH, Vincent K.C. Chan, BSc(Hons), Antony K.P. Law, BSc(Hons), MSc J Cataract Refract Surg (Jan.) 2014; 40:29–36 Purpose: To report the early experience and complications during cataract surgery with a noncontact femtosecond laser system. Setting: Hong Kong Sanatorium and Hospital, Hong Kong Special Administrative Region, China. Design: Retrospective case series. Methods: All patients had anterior capsulotomy or combined anterior capsulotomy and lens fragmentation using a noncontact femtosecond laser system (LENSAR) before phacoemulsification. Chart and video reviews were performed retrospectively to determine the intraoperative complication rate. Risk factors associated with the complications were also analyzed. Results: One hundred seventy-eyes were included. Free-floating capsule buttons were found in 151 eyes (88.8%). No suction break occurred in any case. Radial anterior capsule tears occurred in nine eyes (5.3%); they did not extend to the equator or posterior capsule. One eye (0.6%) had a posterior capsule tear. No capsular block syndrome developed, and no nuclei were dropped during irrigation/aspiration (I/A). Anterior capsule tags and miosis occurred in four eyes (2.4%) and 17 eyes (10.0%), respectively. Different severities of subconjunctival hemorrhages developed in 71 (43.8%) of 162 eyes after the laser procedure. The mean surgical time from the beginning to the end of suction was 6.72 minutes ± 4.57 (SD) (range 2 to 28 minutes). Conclusions: Cataract surgery with the noncontact femtosecond laser system was safe. No eye lost vision because of complications. Caution should be taken during phacoemulsification and I/A to avoid radial anterior capsule tears and posterior capsule tears. Financial disclosure: Dr. Chang received travel expenses from Abbott Medical Optics and Technolas Perfect Vision and lecture honoraria from Abbott Medical Optics, Technolas Perfect Vision, and Alcon Laboratories. Dr. Chang was a consultant to Abbott Medical Optics from 2010 to 2011. No author has a financial or proprietary interest in any material or method mentioned.

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