Ophthalmology Volume 121, Number 11, November 2014
Figure 3. Comparison of segmentation of retinal layer analysis determined by the new segmentation application of the Spectralis optical coherence tomograph (OCT; Segmentation Technology, Heidelberg Engineering, Heidelberg, Germany) in a patient with multiple sclerosis (MS) disease and a healthy subject. The MS patient showed a decrease in the thickness of the ganglion cell and inner plexiform layers.
Re: Rudnisky et al.: Antibiotic choice for the prophylaxis of post-cataract extraction endophthalmitis (Ophthalmology 2014;121:835-41) Dear Editor: We read the article by Rudnisky et al1 with interest; however, we believe that further discussion of the methodology used in the study is needed. In their retrospective study, the authors show an 0.03% rate of endophthalmitis and that it was not influenced by intracameral antibiotic use (vancomycin or moxifloxacin; 0.898), subconjunctival antibiotic use (cefazolin, gentamicin, or cefuroxim; 0.331), preoperative fluorochinolone (P ¼ 0.132), or other than moxifloxacin postoperative topical antibiotic (including polymyxin B, tobramycin, ofloxacin, ciprofloxacin, and gatifloxacin). The odds of endophthalmitis occurring was raised if timolol was used at the end of the procedure (P ¼ 0.0002). However, these results should be discussed in the light of other, similar studies. The effectiveness of intracameral cefuroxime was shown in 2 studies, 1 retrospective (22-fold lower rate of infection)2 and the other a large, prospective trial.3 It was also shown that intracameral moxifloxacin use led to a 70% decrease in the risk of endophthalmitis.4 The unusual results observed within the study by Rudnisky et al1 could be related to some methodologic problems. The study sample size was small in terms of the total number of cases of endophthalmitis, and this underpins the statistically analyses presented. With only 23 cases, the study was powered to detect relatively large differences. There are issues with postoperative antibiotic use comparing one antibiotic with “all other antibiotics,” because this does not capture the effect of a single antibiotic. It may have been more informative to use the most commonly used antibiotic (tobramycin) as the control comparison. The finding that timolol increased the risk of endophthalmitis is misleading, because timolol use is completely confounded by surgeon (only one surgeon used it and that surgeon happened to have the highest event rate). Could the authors please clarify the reason for differences event rate between Tables 2 and 4 for the
e64
comparison of public versus private hospitals? Table 2 implies a similar event rate between public and private facilities, whereas in Table 4 the private surgical facility had markedly higher odds of endophthalmitis.
ANDRZEJ GRZYBOWSKI, MD, PHD1 ALICJA R. RUDNICKA, PHD2 1 Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland; 2Population Health Research Institute, St George’s, University of London, London, UK
References 1. Rudnisky CJ, Wan D, Weis E. Antibiotic choice for the prophylaxis of post-cataract extraction endophthalmitis. Ophthalmology 2014;121:835–41. 2. Shorstein NH, Winthrop KL, Herrinton LJ. Decreased postoperative endophthalmitis rate after institution of intracameral antibiotics in a North California eye department. J Cataract Refract Surg 2013;39:8–14. 3. Friling E, Lundstrom M, Stenevi U, et al. Six-year incidence of endophthalmitis after cataract surgery: Swedish National Study. J Cataract Refract Surg 2013;39:15–21. 4. Matsuura K, Miyoshi T, Suto C, et al. Efficacy and safety of prophylactic intracameral moxifloxacin injection in Japan. J Cataract Refract Surg 2013;39:1702–6.
Author reply Dear Editor: Thank you for the opportunity to address the Shorstein paper1 that reports on a service area where the rate of endophthalmitis falls from 0.3% to 0.01%. The authors attribute the reduction to the increased use of intracameral antibiotics, despite the fact that there was also increased utilization of postoperative gatifloxacin, which is clearly visible in Figure 1.1 The authors present only univariate analyses, and thus have not controlled for postoperative antibiotics or other important variables; a controlled analysis is necessary before one can make a final conclusion about their study.
Figure 3. Comparison of segmentation of retinal layer analysis determined by the new segmentation application of the Spectralis optical coherence tomograph (OCT; Segmentation Technology, Heidelberg Engineering, Heidelberg, Germany) in a patient with multiple sclerosis (MS) disease and a healthy subject. The MS patient showed a decrease in the thickness of the ganglion cell and inner plexiform layers.
Re: Rudnisky et al.: Antibiotic choice for the prophylaxis of post-cataract extraction endophthalmitis (Ophthalmology 2014;121:835-41) Dear Editor: We read the article by Rudnisky et al1 with interest; however, we believe that further discussion of the methodology used in the study is needed. In their retrospective study, the authors show an 0.03% rate of endophthalmitis and that it was not influenced by intracameral antibiotic use (vancomycin or moxifloxacin; 0.898), subconjunctival antibiotic use (cefazolin, gentamicin, or cefuroxim; 0.331), preoperative fluorochinolone (P ¼ 0.132), or other than moxifloxacin postoperative topical antibiotic (including polymyxin B, tobramycin, ofloxacin, ciprofloxacin, and gatifloxacin). The odds of endophthalmitis occurring was raised if timolol was used at the end of the procedure (P ¼ 0.0002). However, these results should be discussed in the light of other, similar studies. The effectiveness of intracameral cefuroxime was shown in 2 studies, 1 retrospective (22-fold lower rate of infection)2 and the other a large, prospective trial.3 It was also shown that intracameral moxifloxacin use led to a 70% decrease in the risk of endophthalmitis.4 The unusual results observed within the study by Rudnisky et al1 could be related to some methodologic problems. The study sample size was small in terms of the total number of cases of endophthalmitis, and this underpins the statistically analyses presented. With only 23 cases, the study was powered to detect relatively large differences. There are issues with postoperative antibiotic use comparing one antibiotic with “all other antibiotics,” because this does not capture the effect of a single antibiotic. It may have been more informative to use the most commonly used antibiotic (tobramycin) as the control comparison. The finding that timolol increased the risk of endophthalmitis is misleading, because timolol use is completely confounded by surgeon (only one surgeon used it and that surgeon happened to have the highest event rate). Could the authors please clarify the reason for differences event rate between Tables 2 and 4 for the
e64
comparison of public versus private hospitals? Table 2 implies a similar event rate between public and private facilities, whereas in Table 4 the private surgical facility had markedly higher odds of endophthalmitis.
ANDRZEJ GRZYBOWSKI, MD, PHD1 ALICJA R. RUDNICKA, PHD2 1 Department of Ophthalmology, University of Warmia and Mazury, Olsztyn, Poland; 2Population Health Research Institute, St George’s, University of London, London, UK
References 1. Rudnisky CJ, Wan D, Weis E. Antibiotic choice for the prophylaxis of post-cataract extraction endophthalmitis. Ophthalmology 2014;121:835–41. 2. Shorstein NH, Winthrop KL, Herrinton LJ. Decreased postoperative endophthalmitis rate after institution of intracameral antibiotics in a North California eye department. J Cataract Refract Surg 2013;39:8–14. 3. Friling E, Lundstrom M, Stenevi U, et al. Six-year incidence of endophthalmitis after cataract surgery: Swedish National Study. J Cataract Refract Surg 2013;39:15–21. 4. Matsuura K, Miyoshi T, Suto C, et al. Efficacy and safety of prophylactic intracameral moxifloxacin injection in Japan. J Cataract Refract Surg 2013;39:1702–6.
Author reply Dear Editor: Thank you for the opportunity to address the Shorstein paper1 that reports on a service area where the rate of endophthalmitis falls from 0.3% to 0.01%. The authors attribute the reduction to the increased use of intracameral antibiotics, despite the fact that there was also increased utilization of postoperative gatifloxacin, which is clearly visible in Figure 1.1 The authors present only univariate analyses, and thus have not controlled for postoperative antibiotics or other important variables; a controlled analysis is necessary before one can make a final conclusion about their study.
