Single sick swallow does not make a summer: Femtosecond laser–assisted cataract surgery versus standard phacoemulsification

LETTERS

vancomycin, all of which can increase our understanding of drugs in the eye. Grzybowski and Bardeci mentioned the cases of hypersensitivity, including the first case of anaphylaxis caused by topical moxifloxacin drops reported in the same issue of the journal as our paper.3 It is not surprising to find rare allergic cases, even severe ones, given the millions of topical moxifloxacin 0.5% (Vigamox) drops administered globally to date. Moxifloxacin has never been reported to cause severe ophthalmic sequelae such as hemorrhagic occlusive retinal vasculitis or toxic anterior segment syndrome resulting from dilution errors. However, a recent report4 of a significant reduction in the rate of infective postoperative endophthalmitis with intracameral moxifloxacin in a series of over 600 000 cases has added another layer of evidence to the mountain of data supporting intracameral moxifloxacin use. There are no perfect drugs, and when one superior to moxifloxacin becomes available, we will certainly consider transitioning.dSteve A. Arshinoff, MD, FRCSC, Milad Modabber, MD, MSc REFERENCES

1. Ophthalmic moxifloxacin (Vigamox) and gatifloxacin (Zymar). Med Lett Drugs Ther 2004; 46:25–27 2. Asbell PA, Ma FS, Sanfilippo CM, DeCory HH. Antibiotic susceptibility of bacterial pathogens isolated from the aqueous and vitreous humor in the Antibiotic Resistance Monitoring in Ocular Microorganisms (ARMOR) surveillance study. J Cataract Refract Surg 2016; 42:1841–1843. Available at: http://www. jcrsjournal.org/article/S0886-3350(16)30473-4/pdf. Accessed March 7, 2017 3. Ullman MA, Midgley KJ, Kim J, Ullman S. Anaphylactic reaction secondary to topical preoperative moxifloxacin. J Cataract Refract Surg 2016; 42:1836–1837 4. Haripriya A, Chang DF, Ravindran RD. Endophthalmitis reduction with intracameral moxifloxacin prophylaxis: analysis of 600,000 surgeries. Ophthalmology 2017 Feb 14 [Epub ahead of print] €m C. Prophylac5. Montan PG, Wejde G, Setterquist H, Rylander M, Zetterstro tic intracameral cefuroxime; evaluation of safety and kinetics in cataract surgery. J Cataract Refract Surg 2002; 28:982–987

Single sick swallow does not make a summer: Femtosecond laser–assisted cataract surgery versus standard phacoemulsification

The new case-control study by Manning et al.,1 based on a prime and well-designed multinational database on cataract and refractive surgery, the European Registry of Quality Outcomes for Cataract and Refractive Surgery, is a splendid work for which we congratulate the authors. It adds further data to our ongoing quest of comparing a relatively new method, laser-assisted cataract surgery, which was introduced by Nagy et al. in 20092 and taken up by an increasing number of surgical centers and hospitals in Europe and elsewhere ever since, with a well-established and very successful techniquedstandard (or conventional) phacoemulsification. Reading the study is not possible without a deep sense of loss and sadness: It is dedicated to Peter Barry, an outstanding researcher, colleague, and

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friend who was taken away from our community way before his time. The authors point to a couple of structural weaknesses in the study: Only 83% of the original 3379 laser cataract surgery cases were successfully matched to conventional phacoemulsification cataract surgery controls for age and preoperative corrected distance visual acuity (CDVA). In addition, the laser-assisted cataract surgery cases included in the study were not consecutive. The intended 1:2 case-to-control ratio was not achieved because there were not enough conventional phacoemulsification controls in the database with matching preoperative CDVA and matching (young) age, which is somewhat surprising given the large number of almost 300 000 conventional cases. It is difficult to compare 1 group receiving a monofocal intraocular lens (IOL) (99% in standard phacoemulsification group) with 43% far more challenging cases of multifocal, toric, multifocal toric, and accommodating IOLs in the laser-assisted cataract surgery group. Also, both groups were “not matched exactly” regarding ocular comorbidities and surgical difficulty. These are essential parameters when comparing intraoperative and postoperative complications. A higher percentage of patients in the laser-assisted cataract surgery group had previous refractive surgery. These highly demanding patients have an altered cornea, which might be responsible for a higher rate of postoperative issues and a less perfect visual outcome. In addition, there was a larger percentage of patients with pseudoexfoliation in the laser-assisted cataract surgery group, and these patients are more prone to complications. This is, unfortunately, not the only instance in which the study designers have compared things that defy comparison. The laser platforms currently on the market come with different profiles, from the type of interface to the ability to perform arcuate incisions. None of these different technological circumstances under which the femtosecond laser is used has obviously played a role in the study’s results. Finally, the important factor of surgical experience has not been mentioned. A number of 50 laser cataract surgery operations is given as the marker at which the learning phase is supposed to be behind a surgeon. It takes much more to become an experienced femtosecond laser cataract surgeon. The study paints an important but incomplete picture and does not mention the benefits of laser-assisted cataract surgery that have been described in the literature. We encourage the authors to continue with their meritorious research and broaden its perspective and provide us not with a snapshot but with a panorama. H. Burkhard Dick, MD, PhD Tim Schultz, MD, FEBO Bochum, Germany Ronald D. Gerste, MD Washington, DC, USA

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REFERENCES

€m M. 1. Manning S, Barry P, Henry Y, Rosen P, Stenevi U, Young D, Lundstro Femtosecond laser–assisted cataract surgery versus standard phacoemulsification cataract surgery: study from the European Registry of Quality Outcomes for Cataract and Refractive Surgery. J Cataract Refract Surg 2016; 42:1779– 1790. Available at: http://www.jcrsjournal.org/article/S0886-3350(16)304886/pdf. Accessed April 7, 2017 2. Nagy Z, Takacs A, Filkorn T, Sarayba M. Initial clinical evaluation of intraocular femtosecond laser in cataract surgery. J Refract Surg 2009; 25:1053–1060

Reply: We thank Drs. Dick, Schultz, and Gerste for their interest in our study. Although “1 swallow does not a summer make,” the results from 18 centers in 10 countries, collected in a registry that is completely free from the influence of industry, can be hard to swallow. Drs. Dick, Schultz, and Gerste describe weaknesses of this study already highlighted in the published manuscript. Although correct in stating that there is a high frequency of multifocal IOL use in the laser-assisted cataract surgery group, this was overcome by comparing and drawing conclusions only from patients who had implantation of a monofocal IOL after cataract extraction assisted by the

Volume 43 Issue 5 May 2017

femtosecond laser or performed in the conventional manner. The argument that different laser platforms perform differently does not apply to our study, and such details were intentionally excluded from our analysis. The study approach was to show results from the patient’s perspective and not to compare the different technologies and laser platforms with the potential to add bias. If laser-assisted cataract surgery is to gain credence throughout the scientific community, the technique must show visual and refractive benefits that are independent of the equipment platform. Drs. Dick, Schultz, and Gerste do not agree that technical proficiency in laser-assisted cataract surgery can be achieved after 50 procedures. This was the number suggested by the experienced laser cataract surgery surgeons who contributed to this study. Finally, we are preparing a report in which all laser-assisted cataract surgery cases submitted to the European Registry of Quality Outcomes for Cataract and Refractive Surgery will be analyzed as a cohort. One swallow can be hard to swallow.d Sonia Manning, MD, FRCSI (Ophth), Ype Henry, MD, FEBO, Paul Rosen, FRCS, FRCOphth, Ulf Stenevi, MD, PhD, Mats Lundstr€om, MD, PhD