In the United States, the moderately rare condition endophthalmitis impacts 1 case per 1,100 cataract surgeries. The question may surface: Why should physicians care with a rate that is so low?
By Stephanie Skernivitz; Reviewed by Oliver D. Schein, MD, MPH
Baltimore-In the United States, the moderately rare condition endophthalmitis impacts 1 case per 1,100 cataract surgeries. The question may surface: Why should physicians care with a rate that is so low?
“For one, the population at risk is expanding,” explained Oliver D. Schein, MD, MPH, Grossman Professor of Ophthalmology, vice chairman for quality and safety, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore.
With several risk factors-though many are not modifiable-there are strategies to counter the risk factors that really make a difference, Dr. Schein said.
“The population at risk is expanding,” he said. “If you apply the current cataract surgical rate to the projected age distribution of our population, the number of cataract surgeries will at least double by 2020 and almost triple by 2030. You’ll be busy-you may not be paid for it, but you will be busy taking care of patients with cataracts.”
The disease itself has not changed in any way but ophthalmologists’ ability to reduce its rate and understand its risk factors has grown substantially, Dr. Schein noted.
He addressed acute endophthalmitis that occurs within the first week or so of cataract surgery. Virtually all (95% plus), according to Dr. Schein, are gram positive.
“We either let these organisms in during surgery or they get in in the first 12 to 24 hours,” he said.
The rate of the condition has varied according to results of various studies in Europe and the United States, including ones from Denmark and the Netherlands.
Dr. Schein shared data on incidence taken from the U.S. National Medicare Database and shows that rates in the late 90s were as high as about one in 700. Most recent reliable U.S. estimates put the rate at about 1 in 1100 cases per year.
“Interestingly, higher volume surgeons have lower rates,” he said. “Data can’t tell you why that’s true. I expect it’s because they have less of the known major risk factors, such as vitreous loss.”
The same results are found in Canada-one in 700. Again, risk factors are similar whether in the United States, Canada, or elsewhere-older age, vitrectomy, high-volume surgeons with less risk of disease.
“What do we know from these national studies? Vitreous access, older age, men more than women, and lower surgical volume are all chief risk factors.
Dr. Schein sifted through pre-, intra-, and post- operative opportunities for reducing the rate.
“Preoperatively, it’s essentially standard in the United States to use topical antibiotics on the day of surgery, ones that were all approved for conjunctivitis, though there is no indication for preoperative use and little evidence of any benefit in reducing endophthalmitis,” Dr. Schein said.
Evidence supports the standard use of povidone-iodine in preparing the ocular surface. What is not confirmed is whether povidone-iodine works better than other antiseptics, for example, 0.05% chlorhexidine, he said.
Dr. Schein is working on a national study which represents a huge series of endophthalmitis from around the country-about 92% gram positive. Of those, 90% were staph; 10% streptococcus, along with a few cases of gram negatives, he noted.
“If you did believe that using topical antibiotics before surgery was important and you’re wanting to kill the bugs that are most frequent you could do what Bascom Palmer did in 2005 when they asked the question, ‘If you took our cases of endophthalmitis and wanted to kill the bugs preoperatively, which were the most effective antibiotics, and what did they cost?’” Dr. Schein said.
According to Dr. Schein, gentamycin fared much better than the more current antibiotics primarily because it’s a good staph drug.
“But evidence that adding an antibiotic to a preop regimen is beneficial is very minimal,” he said. “There is no evidence whatsoever that one antibiotic is better than another.”he says.
There is evidence based on results of a randomized trial from Japan and two case control studies from the United States that all found a three-fold excessive risk of corneal versus scleral incisions.
“I interpret this in a simplistic manner that wound is important whether doing corneal or scleral incisions,” Dr. Schein said. “Blood is a good adhesive, and it has antibacterial properties.”
Sweden has a unique approach to endophthalmitis. He said that in reviewing national data in Sweden with the same methodology over a decade or so, there is evidence that its rate of endophthalmitis has progressively declined and then leveled out at about 0.02%.
Beginning in the late 1990s, Sweden started using intracameral cefuroxime, and published a series of case control studies. What was shown was that lack of use of cefuroxime intracamerally became the dominant risk factor for endophthalmitis, even greater than vitreous access or older age.
“In Sweden they don’t use preoperative topical antibiotics as a rule and they don’t use topical antibiotics postoperatively,” Dr. Schein said. “They use cefuroxime intraoperatively almost entirely.
“So, with all this evidence, why are we not doing it in United States?” he asked.
For one, he noted that the United States does not yet have ready access to safe, available, and predictable intracameral antibiotic.
“If you put the wrong antibiotic in or use the wrong concentration, you can blind a patient,” he said. “Because endophthalmitis is a known risk, as a surgeon you hate to be the person responsible for a catastrophe when trying to prevent it.”
Additionally, regulatory barriers add a layer of obstacles in this country.
The FDA has gone on record that to approve a drug’s intracameral use requires one if not two randomized clinical trials. It would take many millions of dollars to prove again what has been quite well substantiated, he noted.
“Finally, despite the enormous costs to Medicare and patients of perioperative topical antibiotics, there is not a good mechanism for facilities to be reimbursed the cost of delivering antibiotics on the day of surgery, even if those drugs were sufficiently long lasting in effect to substitute for eye drops currently used postoperatively,” Dr. Schein said.
Oliver D. Schein, MD, MPH
This article was adapted from Dr. Schein’s presentation during Wilmer Eye Institute’s 27th Annual Current Concepts in Ophthalmology meeting in 2014. He did not indicate any financial interest relevant to the subject matter.