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EW RESIDENTS 62 November 2015 by Grace L. Paley, MD, PhD, Angela Jiang, MD, Wesley C. Green, MD, Thomas Shute, MD, Kisha Piggott, MD, PhD, and Susan M. Culican, MD, PhD in small incision cataract surgery, enabling the automation of certain key steps including corneal incision, anterior capsulotomy, and lens frag- mentation. The femtosecond laser may decrease phacoemulsification time and energy, 1,2 thus providing a theoretical safety benefit to patients. However, it remains unclear whether femtosecond laser- assisted cataract surgery (LCS) leads to improved visual outcomes and lower compli- cation rates over standard manual phacoemulsification cataract surgery (PCS). In the November 2015 issue of the Journal of Cataract & Refrac- tive Surgery, Ewe and colleagues report their experience comparing the incidence of postoperative cystoid macular edema (CME) with LCS versus standard PCS. 3 In this non-randomized, prospective cohort study of 1,341 eyes, a single surgeon performed cataract surgery with (LCS) or without (PCS) femtosec- ond laser-assisted capsulotomy and fragmentation followed by standard phacoemulsification lens removal and intraocular lens insertion. Data were collected over 28 months. The primary outcome measure was the rate of clinical CME in either group. The clinical diagnosis of postop- erative CME was defined as visual acuity below expectations after 3–4 weeks and confirmed on spectral domain optical coherence tomogra- phy (SD-OCT). Adult patients were offered the choice of laser-assisted or stan- dard cataract surgery, with certain exceptions that were only offered standard surgery (age 18–22 years, corneal scarring, corneal ring in- lays, prior glaucoma, or refractive surgery). Patients who chose the laser option paid an extra out-of- pocket cost. Baseline demographics of age, gender, and cataract grading did not differ significantly between groups. All patients in both groups were prescribed a course of topical non-steroidal and antibiotic eye drops from 2 days preoperatively un- til 4 weeks postoperatively, and also topical steroid eye drops from the day of surgery until 4 weeks postop- eratively. Laser settings were consis- tent throughout the study with the exception of treatment speed, which changed across software upgrades in the LCS group. A s technological advances for ophthalmic surgery continue to evolve, so too will the myriad of potential ophthalmic applications. It is at this interface of innovative devices and their un- known long-term ocular effects that ophthalmologists emerging from training will need to make informed decisions about incorporating these tools into their surgical practice. Providing residents with ongoing opportunities to review and ana- lyze the ophthalmic literature will facilitate their ability to evaluate the data published about these new technologies. The femtosecond laser is one such novel adjunct to an al- ready well established and very safe surgical procedure. The femto laser has emerged as a potentially revolutionary tool Review of "Cystoid macular edema after phacoemulsification cataract surgery – a Is there a difference in the rate of clinical CME between manual phaco and femtosecond laser-assisted cataract surgery? The Washington University residents reviewed this study published in the November issue of JCRS. –David F. Chang, MD, EyeWorld journal club editor Susan Culican, MD, PhD, residency program director, Washington University School of Medicine, St. Louis EyeWorld journal club The investigators found that rates of postoperative CME did not differ significantly between groups: 0.8% (7/883 cases) in the laser group and 0.2% (1/458 cases) in the stan- dard group (p=NS; no quantitative value reported). The rates of CME in both groups agree with published rates of CME following standard phacoemulsification surgery (0.1– 2.35%). 4,5 The authors should be applaud- ed for undertaking a prospective, long-term, consecutive-patient, and relatively large study looking into a particularly relevant topic in ophthalmology. There are many strong points of this study, but also several limitations and discrepan- cies. Scrutiny for both strengths and limitations of published research is critically important to understand the validity of the conclusions, as well as if and how these conclusions will have meaningful clinical impli- cations. When evaluating a given condi- tion, it is important to understand the baseline incidence. Less com- mon conditions will require a great- er number of study subjects in order to reveal statistically significant differences between groups. This article included 1,341 eyes, but was evaluating a condition that is quite uncommon. There was no mention of a power analysis to determine the probable study size required to iden- tify a given difference between study groups. Furthermore, there was no specified reason that the study was performed between the given dates or up to the specified study size. Without a power analysis and appro- priate study size, there may actually be a true statistical difference, which was not realized due to the lack of study power. During the course of this study, there were changing parameters within the LCS group. A speed and software upgrade was performed in December 2012 and a second software upgrade in May 2013. These upgrades potentially intro- duce confounders within the LCS study group. Similarly, this promotes a desire to perform post-hoc anal- yses as in this study. There were discrepancies between the post-hoc analysis descriptions within the text when compared to the provid- ed table (see below; Table 3 in the original paper). The investigators Cystoid macular edema after femtosecond laser-assisted versus phacoemulsification cataract surgery – a prospective comparative cohort case series Shaun Y.P. Ewe, MBBS, Carmen Oakley, MBBS, Robin G. Abell, MBBS, Penelope L. Allen, PhD, Brendan J. Vote, FRANZCO J Cataract Refract Surg (Nov.) 2015;41. Article in press Objective: To evaluate the incidence of postoperative clinical cystoid macular edema (CME) associated with femtosecond laser-assisted cataract surgery (LCS) versus phacoemulsification cataract surgery (PCS) Design: A non-randomized, single surgeon, prospective, comparative cohort case series Participants: One-thousand three hundred and forty-one eyes underwent cataract surgery with LCS (n=883) or PCS (n=458) at a single center. Methods: Patients undergoing LCS and PCS between March 2012 and July 2014 were included in the study. The LCS group underwent anterior capsulotomy, lens fragmentation ± corneal incisions via femtosecond laser pretreatment. Standard phacoemulsification surgery and foldable acrylic intraocular lens insertion proceeded in all cases. All patients received topical non-steroidal drops commencing 2 days preoperatively and continuing for 4 weeks postoperatively. The incidence of postoperative clinical CME (OCT confirmed) and comparison between groups were measured. Main outcome measure: Clinical CME rates Results: Both groups had similar baseline parameters. There were 7 cases of postoperative CME (0.8%) in the LCS group compared to 1 case (0.2%) in the PCS group, highlighting a trend toward greater cystoid macular edema in the LCS group. This correlated with a change in laser treatment speed (software upgrade) suggesting retinal safety thresholds need further careful analysis. Conclusion: Increased cystoid macular edema may be a subthreshold retinal injury safety signal following femtosecond laser pretreatment and warrants further investigation.

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