December 2010

 

COVER FEATURE

 

What's ahead

Using antibiotics in irrigation solutions


by Faith Hayden EyeWorld Staff Writer

   

With no clear answer, the debate continues

Medications

Some aspects of irrigation solution selection during cataract surgery are simple; the product hasn't changed much in the last few years and neither have the brand-name options. Balanced salt solutions (b.s.s.) are used instead of saline in order to better emulate the aqueous and provide additional protection during surgery. The decision to add antibioticssuch as vancomycinto prevent endophthalmitis is the contentious aspect. Do the possible benefits outweigh the potential risks? Cataract surgeons are split. Using antibiotics in irrigation solution is a "contentious issue," said Audrey R. Talley-Rostov, M.D., Northwest Eye Surgeons, Seattle. "There are many different protocols that people use to prevent endophthalmitis, but there's really no conclusive definitive evidence for any one particular thing, although a combination of things is probably helpful." Sterile operating rooms and strict pre- and post-operative regimens all factor into lowering the risk of endophthalmitis, but even those methods aren't foolproof. For example, when Dr. Talley-Rostov first started practicing in the 1990s, she did not use antibiotics in irrigating solutions. "Then I had a couple of cases of endophthalmitis and was searching for why," she explained. "I couldn't find anything definitive." After calling around to a few fellow surgeons, Dr. Talley-Rostov found that a handful did in fact practice the controversial method. "So I started using antibiotics in the irrigation solution, and I haven't had a case of endophlamtis since," she said, noting it's been 13 or so years without any hiccups. Currently, Dr. Talley-Rostov mixes 10 mg of vancomycin with 500 cc of balanced salt solution.

On the flip side, Thomas A. Oetting, M.D., professor of clinical ophthalmology, University of Iowa, Iowa City, Iowa; and chief, Eye Service, and deputy director, Surgery Service, VA Medical Center, Iowa City, Iowa, previously used antibiotics in irrigating solutions but has since stopped. "We used to use vancomycin in the irrigating solution but decided to stop for two reasons," he said. "One was a paper [that] proposed the idea that this was a risk factor for cystoid macular edema. The other was a concern that we might mix the antibiotic improperly and damage cornea or retina. Due to these potential problems and as it was not clear that there was any benefit we stopped several years ago." Improper dosing, as well as a possible allergic reaction, are some of the reasons many cataract surgeons choose not to mix antibiotics into irrigating solution, says Richard M. Awdeh, M.D., assistant professor of ophthalmology, Bascom Palmer Eye Institute, Miller School of Medicine, University of Miami, Miami, who does not use antibiotics in the irrigation solution. "There is no good trial that examines if this practice has an impact on endophthalmitis or not," he said. "Additionally, it adds another layer of uncertainty to the operative process. You could use the wrong antibiotic, the wrong concentration, or the patient could be allergic to the antibiotic."

Another risk factor is Toxic Anterior Segment Syndrome (TASS), an inflammation of the eye that can cause vision loss. TASS is one of the reasons Nick Mamalis, M.D., professor of ophthalmology, John A. Moran Eye Center, Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, chooses not to inject antibiotics into irrigation solutions and instead favors topical antibiotics used pre- and post-op. "I'm always a little leery of mixing antibiotics by a nurse, by a facility, even by a pharmacist," he said. "There's a potential for an improper dosing or an improper mixing that could lead to toxicity.

"There was actually an outbreak of TASS in England where the nurse made an error in the dilution and ended up with a dose five times greater than what they should have. All the patients ended up with TASS," he continued. "There was also an episode reported where a compounding pharmacy mixing vancomycin made an error. The dose was too high and the P.H. was too low and a series of patients came away with TASS."

As Uday Devgan, M.D., chief of ophthalmology, Olive View-UCLA Medical Center, Sylmar, Calif., points out, there's also an added risk of contamination. Using antibiotics article summary

"A bottle of b.s.s. from the factory is guaranteed to be totally sterile," said Dr. Devgan. "When you add additional things into the bottle there's certainly a risk that you've caused some contamination, even if the risk is low. I hope it's still sterile, and I hope I put in the right dose, but I have no way of knowing. It can get complicated." Dr. Devgan does not use antibiotics in irrigation solution in his private practice, but he does in the county hospital where he trains residents. "There was a bad infection 15 years ago, so the ophthalmology department started a protocol to add antibiotics to the irrigation solution," he explained. "Resident cases are also more complicated because their cases are prolonged with a higher risk of complications. A resident can take an hour to do cataract surgery and if there is a capsule rupture, the eye has a ten-fold higher risk of endophthalmitis."

Another issue is how long the medication is expected to stay in the anterior chamber, said Dr. Devgan, stating that the chamber washes itself out approximately every 90 minutes. Antibiotics are frequently added to irrigation solutions in other surgeries such as brain and abdominal, so the theoretical benefit is certainly there, but in these larger parts of the body the medicine has more of an opportunity to affect the target tissue and there is less turnover of fluid so the antibiotics can be expected to remain longer. There are a couple of ways around this. One is to inject antibiotics intra-camerally, a procedure Dr. Talley-Rostov practices. Howard Gimbel, M.D., chair, Department of Ophthalmology, Loma Linda University, Lorma Linda, Calif., however, injects a b.s.s./vancomycin mixture directly into the capsular bag under the IOL. By doing this, the antibiotic has more of a chance to work instead of being naturally flushed out of the anterior chamber. Dr. Gimbel began using this method in 1990 because of a case of endophthalmitis that was in the capsular bag. "It seemed logical to me that the most likely entrance of bacteria was putting the lens into the eye," he said. "The capsular bag is where organisms can get sequestered."

Since then, Dr. Gimbel has seen one case of endophthalmitis and it was very low grade. "Endoph-thalmitis should be considered a preventable problem," he said. "We haven't lost vision in the last 10 years, from 1990 to September 2010, we have 40,174 cases with only one eye losing vision to 20/25."

Even so, Dr. Gimbel doesn't want to give vancomycin all the credit. He also attributes his success to using Millipore filters, proper wound closure, and advising patients to stay away from sweets before and after surgery. "I think we have to focus more than on just antibiotic," he said. "Enough attention isn't being given to wound closure and filtering solutions." "A lot of surgeons will swear by [antibiotics in irrigation solutions]," Dr. Devgan said. "If you can assure me there will be no contamination, no TASS syndrome from an overdose, and it's all done correctly, I think there's almost no downside. But you can't guarantee that." There are few guarantees in medicine, but there are precautions you can take to increase the likelihood of a positive outcome, should you choose to explore this method. For example, Dr. Gimbel makes sure the same staff mixes the solution each time. "We only have a couple of people that are authorized to do the mixing," he said. "It reduces the risk of human error when mixing is limited to experienced people or to the surgeon."

Dr. Talley-Rostov cites reliance on reliable, knowledgeable staff with little overturn. "Make sure everyone has checklists for the exact protocol for how to put the antibiotics for the irrigation solution or for an injection at the end of the case," she said. "It's not dissimilar in some ways to mixing antibiotics for subconjunctival injection. There are a lot of different medications that can be supplied one way by a pharmacy but need to be mixed by your operating room staff. It's not a new idea and doesn't require a different skill set; it's something they do every day." According to Dr. Mamalis though, the ultimate solution would be a commercially available antibiotic. The problem is none currently exist, and getting approval for such a product would require an incredible amount of funding and a massive study of hundreds of thousands of patients. Even so, the demand from cataract surgeons is there. "If we had a commercial available, sterile, non-preserved single-use dosage than we'd all use intra-cameral injections because it would eliminate the compliance issues with patients, and ensure we'd get the correct dose into the eye at the conclusion of the case," said Dr. Mamalis. "That would certainly take care of the problems."

Editors' note: The physicians interviewed did not indicate financial interests related to their comments.

Contact information

Awdeh: richard.awdeh@gmail.com
Devgan: devgan@ucla.edu
Gimbel: hvgimbel@gimbel.com
Mamalis: nick.mamalis@hsc.utah.edu
Oetting: thomas-oetting@uiowa.edu
Talley-Rostov: atalleytostov@nweyes.com

Related articles:

Comparing aqueous humor penetration antibiotic eyedrops

New antibiotic option for the treatment of blepharitis by Marguerite B. McDonald, M.D.

Antibiotic regimen, phaco technology the keys to avoid infection

20-year study supports use of antibiotics, dangers of vitreous loss by Rich Daly EyeWorld Contributing Editor

New topical broad spectrum antibiotic on the horizon by Tony Realini, M.D.

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