Monday, September 15, 2008

Controversy continues over intracameral antibiotic injection

To hear Ireland’s Peter Barry, MD, tell it, the evidence in favour of intracameral injections of cefuroxime to prevent endophthalmitis is incontrovertible. The 2006 ESCRS study showed a rate of 0.05 per cent in 8,000 patients receiving injections and antibiotic drops compared with a rate of 0.35 per cent in patients receiving placebo drops and no injection. Further, a 2007 study examining 225,000 patients from the Swedish registry, most of whom received cefuroxime injections, showed a similar endophthalmitis rate of 0.048 per cent, Dr Barry told a symposium on global practice choices at the XXVI Congress of the ESCRS. Similarly, those patient who were not treated with intracameral antibiotic injections showed infection rates very similar to the placebo group in the ESCRS study.

While these results have driven many European ophthalmologists to intracameral injections, they haven’t in many other parts of the world. For example, Dr Bissen-Miyajima reported that surgeons in Japan do not use intracameral antibiotic injections at all because there are no agents approved. Nonetheless, endophthalmitis rates in Japan also are in the 0.05 per cent range. Dr Bissen-Miyajima attributed much of it to the use of prophylactic antibiotic eyedrops. Her own research suggests that this cuts down on the bacterial load on the surface of the eye that is thought to be the root cause of most endophthalmitis infections. She also noted that most Japanese surgeons prefer a scleral incision because it has been shown in some studies to reduce endophthalmitis rates compared with clear corneal incisions.

Nick Mamalis, MD, of the US also emphasised the importance of both reducing infectious agents on the surface of the eye before surgery and carefully constructing incisions, particularly clear corneal incisions, to seal them against ingress of bacteria from the surface of the eye. A similar strategy was voiced by Jose Villar-Kuri, MD, who reported that many Mexican surgeons suture the incision to prevent infection. He reported a series of 12,000 cases without a single case of endophthalmitis by surgeons using this technique.

Dr Mamalis also pointed out that the fourth-generation flouroquinolones available in the US penetrate the surface of the eye, reducing the chances of infection. He also expressed concerns among US physicians about the lack of single-dose ophthalmic preparations of antibiotics leading to toxicity resulting from errors in dilution and preparation. However, he believes that should a single-use ophthalmic preparation become available, many US surgeons would use it.

Dr Barry commented that such preparations are being considered, but that maintaining stability of a solution in such minute quantities is difficult. He does believe the obstacle can be overcome. “The writing is on the wall. Let us read it and move on to the manufacture of cefuroxime in a single sterile FDA-approved unit dose for ophthalmic use.”

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