Incidence of postoperative endophthalmitis with the use of povidone–iodine

Abstract

We read with interest the article by Nentwich et al.1 describing decreases in the rates of postoperative endophthalmitis after the introduction of different regimens of povidone–iodine preoperatively. We fully agree with the authors that povidone–iodine has an important role to play in the preoperative preventive measures used to reduce infection rates, and the authors’ results provide additional evidence to support the efficacy of povidone–iodine administered before ocular surgery. We are concerned, however, about the authors’ statement that their results “could suggest that intracameral antibiotics might not be necessary but that the preoperative use of povidone–iodine and state-of-the-art small-incision cataract surgery are.” To support this, the authors compared the rates of endophthalmitis from period 3 of their series (0.041%) with those in the group in the ESCRS Endophthalmitis Study2 that received intracameral cefuroxime (0.062%). However, although the reduction in the rates of endophthalmitis reported by the authors are impressive, one wonders whether their rates might have been lowered further if intracameral antibiotics had been administered at the end of surgery. As the authors correctly pointed out, the rates of endophthalmitis between different institutions might not be directly comparable because of variations in patient profile, surgical techniques, and many other confounding factors. The key question is whether the use of intracameral antibiotics might have further reduced the rate of postoperative endophthalmitis beyond the reduction achieved by the use of povidone–iodine. At our center, the rate of endophthalmitis during the period without the use of intracameral antibiotics was 0.064%.3 The rate decreased to 0.01% when intracameral cefazolin was administered routinely at the end of surgery. Similar reductions in infection rates are reflected in other studies evaluating the efficacy of intracameral antibiotics.4,5 Nentwich et al. also mentioned that “[o]nly povidone–iodine and intracameral cefuroxime have been successful in reducing the risk for endophthalmitis after intraocular surgery.” We would like to add that several studies also reported significant reductions in endophthalmitis rates after the addition of intracameral cefazolin (a first-generation cephalosporin).3–5 Although these studies, similar to the current paper, compared rates of infection from different time periods, we believe that these studies provide valuable information and insights for ophthalmologists to use in making informed decisions. Although it would be ideal to have randomized controlled trials to evaluate the efficacy of various preventive measures, and even the concentrations of the drugs used, in view of the low rates of endophthalmitis, the number of patients required to participate in such a study would be extremely large and it may not be practical to do so. Until such data become available, it is still prudent to rely on results in large retrospective series, such as the one currently being discussed. In summary, we strongly support the use of povidone–iodine before ocular surgery and believe that additional proven methods, such as the use of intracameral antibiotics, should be considered to achieve the lowest rate of infection possible.