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Previous Volume 357:1264-1265 September 20, 2007 Number 12 Next

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To the Editor: Our observations suggest that high concentrations of iodate in certain povidone–iodine formulations can cause postoperative visual loss, a severe complication, when used in an off-label but widely applied manner during povidone–iodine pleurodesis. We report three cases of bilateral severe loss of vision (ranging from 20/800 vision to the perception of hand motions only) after thoracoscopic surgery involving resection of parts of one lung and instillation of 200 to 500 ml of Jodobac, a 10% povidone–iodine solution, into the thoracic cavity for disinfection and to cause scarring of the pleura for prophylaxis against pneumothorax. (For clinical details of each case, see the Supplementary Appendix, available with the full text of this letter at www.nejm.org.) Ophthalmologic examination and fluorescein angiography revealed, in the first days after surgery, a breakdown of the diffusion barrier of the retinal pigment epithelium (Figure 1A). During the next 2 months of follow-up, a granular pattern and atrophy developed in the retinal pigment epithelium (Figure 1B).

View larger version (88K): [in this window] [in a new window]   Figure 1. Stages of Iodate-Induced Retinopathy Visible on Fluorescein Angiography. On the first day of symptoms, there was marked hyperfluorescence (Panel A). Two months later, there were sharply configured changes in the retinal pigment epithelium (Panel B).

 
Povidone–iodine pleurodesis with the use of 20 ml of 10% povidone–iodine is thought to be safe.¹ Our cases were associated with the use of Jodobac, but all available povidone–iodine formulations contain sodium or potassium iodate as a stabilizer. The toxic effects of iodate on the retinal pigment epithelium are well established, and iodate is used frequently in animal models of retinal pigment epithelium damage.² The toxic effects of iodate on the retinal pigment epithelium have also been described in humans.³ It has been proposed that toxic plasma levels are reached after ingestion of 10 mg of iodate per kilogram of body weight.⁴ One analysis showed that 100 ml of Jodobac contains approximately 1.5 g of potassium iodate, which is enough to easily exceed the toxicity threshold. Other solutions, such as Braunol and Betaisadona, contain only approximately 150 mg of potassium or sodium iodate per 100 ml, but the association of their use with clinical manifestations is not known. At these concentrations, it is unlikely that the toxicity threshold can be reached with the applied amounts of povidone–iodine solutions.

Lars Wagenfeld, M.D.
Oliver Zeitz, M.D.
Gisbert Richard, M.D.
University Medical Center Eppendorf
20246 Hamburg, Germany
l.wagenfeld{at}uke.uni-hamburg.de

References

1. Olivares-Torres CA, Laniado-Laborín R, Chávez-García C, León-Gastelum C, Reyes-Escamilla A, Light RW. Iodopovidone pleurodesis for recurrent pleural effusions. Chest 2002;122:581-583. [CrossRef][Web of Science][Medline]
2. Kiuchi K, Yoshizawa K, Shikata N, Moriguchi K, Tsubura A. Morphologic characteristics of retinal degeneration induced by sodium iodate in mice. Curr Eye Res 2002;25:373-379. [CrossRef][Web of Science][Medline]
3. Singalavanija A, Ruangvaravate N, Dulayajinda D. Potassium iodate toxic retinopathy: a report of five cases. Retina 2000;20:378-383. [CrossRef][Web of Science][Medline]
4. Burgi H, Schaffner TH, Seiler JP. The toxicology of iodate: a review of the literature. Thyroid 2001;11:449-456. [CrossRef][Web of Science][Medline]

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This article has been cited by other articles:

• Davies, H. E, Lee, Y C G., Davies, R. J O (2008). Pleurodesis for malignant pleural effusion: talc, toxicity and where next?. Thorax 63: 572-574 [Full Text]