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Letter

Endophthalmitis in Cape Town, South Africa: Are the data real?

Zhang, Michael G. BSc; Chen, Tony S. MBChB; Lau, Oliver C.F. BE, MBBS; McPherson, Zachary E. BSc; Kam, Andrew K. BSc; Ruan, Claire MBBS; Francis, Katherine E. BE (Hons), MBBS; Agar, Ashish FRANZCO, PhD; Francis, Ian C. FASOPRS, PhD; Sim, Benjamin W.C. MBBS

Author Information
Journal of Cataract & Refractive Surgery: September 2013 - Volume 39 - Issue 9 - p 1452-1453
doi: 10.1016/j.jcrs.2013.07.023
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We appreciated the input from van der Merwe et al.,1 whose statistics revealed a 7-fold decrease in the incidence of endophthalmitis after introduction of the second-generation cephalosporin, cefuroxime, used intracamerally intraoperatively. However, their article lacks important details that could influence the external and internal validity of their work.

The number of years of experience of each cataract surgeon was not documented in the study. There was no documentation as to whether the surgeon was a consultant or a trainee. Variability in proficiency between surgeons and operative complications could potentially influence the introduction of microorganisms not only into the surgical sterile field, but also into the eye; neither of these was documented.

Our study2 of endophthalmitis between 1994 and 2003 in New South Wales, the most populous state in Australia, documented an even higher rate of endophthalmitis (0.834%) than that in the van der Merwe et al. study. Our findings were based on hospital admissions for management of each patient’s endophthalmitis. A surgeon who has accumulated cataract surgical experience over thousands of procedures might well be expected to have developed techniques that minimize his or her endophthalmitis rate. To address this, over the past 10 years, our group has developed and published techniques aimed at minimizing intraoperative contamination of the operative field. These include eradication of oil and debris accumulation on the ocular surface intraoperatively,3 especially in patients with deep-set eyes and tight lids, and definitive temporal lash exclusion.4

Current literature does not convincingly show that the endophthalmitis rate is statistically significantly different between experienced consultants and trainees. This is possibly because trainees are given less surgically challenging cases on which to operate.

The precise surgical technique for each case of cataract surgery was not documented by van der Merwe et al. It is of interest and concern that when most cataract surgeons worldwide changed their technique to nonsutured clear corneal incisions, around the turn of the millennium, the endophthalmitis rate dramatically increased.5 We have documented that the reason for the dramatic increase in endophthalmitis subsequent to this change in surgical technique was that the eye was not closed with sutures.2 It is also recognized that the cataract surgical wound is the only clean wound in all of surgery that is not closed by a suture, staple, adhesive tape, or glue.

Furthermore, the lack of documentation of the methodology in which the van der Merwe study was conducted makes it difficult to verify the internal validity of this study. Unless the study rigorously controlled the use of intracameral cefuroxime, the results could be demonstrating a correlation rather than a direct causative relationship between intracameral cefuroxime use and endophthalmitis.

Finally, as our study showed,2 patients with poor outcomes, possibly due to endophthalmitis, could have travelled to different hospitals within Cape Town and their endophthalmitis would not have been recorded in the authors’ study.

References

1. van der Merwe J, Mustak H, Cook C. Endophthalmitis prophylaxis with intracameral cefuroxime in South Africa. J Cataract Refract Surg. 2012;38:2054.
2. Francis IC, Roufas A, Figueira EC, Pandya VB, Bhardwaj G, Chui J. Endophthalmitis following cataract surgery: the sucking corneal wound. J Cataract Refract Surg. 2009;35:1643-1645.
3. Amjadi S, Roufas A, Figueira EC, Bhardwaj G, Francis KE, Masselos K, Francis IC. Microwash or macrowash technique to maintain a clear cornea during cataract surgery. J Cataract Refract Surg. 2010;36:1453-1454.
4. Fox OJ, Sim BW, Win S, Singh R, Amjadi S, Agar A, Bank A, Francis IC. Technique to exclude temporal lash incursion in phacoemulsification surgery. J Cataract Refract Surg. 2012;38:1885-1887.
5. Cooper BA, Holekamp NM, Bohigian G, Thompson PA. Case-control study of endophthalmitis after cataract surgery comparing scleral tunnel and clear corneal wounds. Am J Ophthalmol. 2003;136:300-305.
© 2013 by Lippincott Williams & Wilkins, Inc.