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Letter

Femtosecond versus (gold) standard phacoemulsification

Davidorf, Jonathan M. MD

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Journal of Cataract & Refractive Surgery: May 2015 - Volume 41 - Issue 5 - p 1124
doi: 10.1016/j.jcrs.2015.03.014
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Abell et al.’s1 article was notable because the complication rate with the femtosecond technique seemed unaffected by any learning curve (reportedly similar incidence of complications during the first half of the cases compared with the second half). However, it appears that the authors’ conclusion might not accurately reflect the data.

First, the authors concluded, “Significant intraoperative complications likely to affect refractive outcomes and patient satisfaction were low overall.” The authors cite an article by Chan et al.2 that does not study the effect of anterior or posterior capsule tears on refractive outcomes. I agree that deviations from a perfectly centered and perfectly round anterior capsulotomy would not be expected to affect refractive outcomes.A,B However, a frank anterior capsule tear undoubtedly has the potential to affect refractive outcomes; it may preclude the safe implantation of a multifocal or toric intraocular lens (IOL), and it may lead to IOL malpositioning. The nearly 2% incidence of anterior capsule tears (Table 2 in Abell et al.) in the femtosecond group is not only a statistically significant difference compared with the phacoemulsification group (8 times higher incidence in the femtosecond group), it is clinically relevant and would not be considered “low overall” by an experienced surgeon.3

In addition, the article concludes, “The 2 cataract surgery techniques appear to be equally safe.” Besides anterior capsule tears, the incidence of every complication described was markedly higher in the femtosecond group despite the femtosecond group having 20% fewer eyes and despite the non-femtosecond group being more likely to have complicated cases—“Eyes with previous trauma or deemed likely to be challenging (eg, small pupil, floppy-iris syndrome, intumescent cataract) were more likely to have manual phacoemulsification cataract surgery…” Regarding posterior capsule tears, the authors conclude that the safety was the same in the 2 groups, despite the data showing an over 2-fold higher incidence in the femtosecond group. The conclusion is based on a P value of “NS” (Table 2 in Abell at al.; I calculated it to be 0.06). Normally, articles in JCRS show all P values, large and small, and do not use the “NS” notation.

The omission of the P values and the strong conclusion of “sameness” given results suggesting a contrary conclusion are noteworthy. As it turns out, this article was prominently featured on the ASCRS web site (until the February JCRS issue was published) and an e-mail blast from Cataract & Refractive Surgery Today (January 26, 2015) and Cataract & Refractive Surgery Today Europe (February 2014C) advertised this article, boldly highlighting and propagating its unsupported conclusion.

I do applaud the authors for collecting and publishing their data with the purpose “to compare the intraoperative complications and safety of femtosecond laser–assisted cataract surgery and conventional phacoemulsification cataract surgery.” After reading the article, I concluded that the results suggest that the incidence of intraoperative complications is higher and the safety lower in femtosecond laser–assisted cataract surgery than in conventional phacoemulsification cataract surgery.

References

1. Abell RG, Darian-Smith E, Kan JB, Allen PL, Ewe SYP, Vote BJ. Femtosecond laser–assisted cataract surgery versus standard phacoemulsification cataract surgery: outcomes and safety in more than 4000 cases at a single center. J Cataract Refract Surg. 2015;41:47-52.
2. Chan E, Mahroo OAR, Spalton DJ. Complications of cataract surgery. Clin Exp Optom. 93, 2010, p. 379-389, Available at: http://onlinelibrary.wiley.com/doi/10.1111/j.1444-0938.2010.00516.x/pdf. Accessed March 21, 2015.
3. Marques FF, Marques DMV, Osher RH, Osher JM. Fate of anterior capsule tears during cataract surgery. J Cataract Refract Surg. 2006;32:1638-1642.

Other Cited Material

A. Findl O, Hirnschall N, Weber M, Maedel S, Draschl P, Wiesinger J, “Influence of Rhexis Size and Shape on Postoperative IOL Tilt, Decentration and Anterior Chamber Depth,” presented at the XXXI Congress of the European Society of Cataract and Refractive Surgeons, Amsterdam, Netherlands, October 2013. Abstract available at: http://escrs.org/amsterdam2013/programme/free-papers-details.asp?id=16160&day=0. Accessed March 21, 2015
B. Davidorf JM, “Impact of Capsulorrhexis Morphology on the Predictability of IOL Power Calculations,” presented at the annual meeting of the American Academy of Ophthalmology, Chicago, Illinois, USA, November 2012
C. Large study reports LACS as safe as conventional phacoemulsification. Cataract & Refractive Surgery Today Europe 2015, February, page 12. Available at: http://crstodayeurope.com/pdfs/0215CRSTE_news.pdf. Accessed March 21, 2015
© 2015 by Lippincott Williams & Wilkins, Inc.