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Task force evaluates etiologic factors
As of late June, it appeared that the outbreak might have begun to abate, said Nick Mamalis, MD, professor ofophthalmology, Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah, SaltLake City. Dr. Mamalis oversees the TASS Ad Hoc Task Force, which seeks to determine the cause of the recentseries of cases.
“This is an ongoing investigation, and as we receive more information and more data on these patients, wewill certainly disseminate it to the ophthalmiccommunity in as efficient a manner as possible,” Dr. Mamalis said.
“We’ve tried to get the information back from these questionnaires and then go over them to see if there areany common elements that are involved in this particular TASS outbreak,” Dr. Mamalis said. “The crux of the announcement was to say that we havefound potential factors that may be involvedin the outbreak. There is no singlecause that has been thought to be involvedin this particular outbreak.
“As we receive more information from the centers that are experiencing TASS andwe’re able to analyze these, [we hope] we’llbe able to come up with more specific recommendationson how to address this problem and how to prevent it from happening,”he added.
Assessing the findings
The task force issued its recent update to let surgeons and surgical centers know which products and processes have come up in more than one report and that are therefore being looked at more carefully, Dr. Mamalis said. The report lists six preliminary findings from the product questionnaire and four from the instrument re-processing questionnaire. Items listed from the product questionnaire include the preoperative use of nonsteroidal anti-inflammatory drugs (NSAIDs); use of intracameral anesthetics; addition of preserved epinephrine to balanced salt solution; improper dosing, mixing, or injection of intracameral antibiotics; residue accumulation on reusable cannulas; and IOL use in cases associated with TASS.
“I want to make it very clear that we are not implicating a particular product or implant,” Dr. Mamalis said. “That certainly is not our intent as a task force. We’re just stating that these are potential sources that have arisen when we reviewed the data.” The use of preoperative NSAIDs was listed in the report because several centers said that they had begun to use them just before noticing an increased incidence of TASS.
“Whether this is animportant issue ornot, it’s just one of themany factors thatwe’re looking at,” Dr.Mamalis said.
The increasing use of intracameral anestheticscould be an issue in TASS given theshort ultrasound time in the majority ofcases and the possibility that ophthalmicviscosurgical devices (OVDs) may lengthenthe amount of time that the anesthetic canremain in the anterior chamber.Henry Edelhauser, PhD, from EmoryUniversity, Atlanta, a member of the taskforce, has done research on this topic.
“His contention is that we have becomeso efficient at removing cataracts that ourultrasound time is getting shorter andshorter, and that we’ve become so efficientthat we may not be using the ultrasoundand the irrigating solutions long enoughto rinse out the lidocaine,” Dr. Mamalissaid. “There could be anesthetic left behindin the eye, and it could be potentiallycausing inflammation.”
He added that reports of TASS casesshow that some are occurring at centerswith very high-volume, efficient surgeons.Intracameral antibiotics also could be asource of toxic inflammation if improperlydosed, mixed, or injected into the eye,the report noted.
Epinephrine was mentioned as a potentialfactor in cases of TASS because it mustbe truly preservative-free, the report stated.Epinephrine solutions that contain stabilizingagents such as bisulfites are not preservative-free, and bisulfite is potentiallytoxic to the corneal endothelium and thestructures of the anterior segment.The task force also reported preliminaryfindings from the instrument re-processingquestionnaire.
“Whenever there’san outbreak of TASS,one of the first thingsthat we look at is howinstruments are beingprocessed, how theyare being cleaned, andhow they are beingtaken care of,” Dr.Mamalissaid. “Certainlyissues of enzymes anddetergent residues arevery important, andthis is especially true with reusable cannulasand reusable tips.Concern over reusablecannulas stems from the potential that aresidue of OVD, cortex, or other materialscould be toxic if injected into the eye.Residual viscoelastic can retain enzymaticdetergents and ultrasonic cleaners.
“What’s also interesting is the issue thatwe’re finding now of the possibility of materialleft over within irrigation/aspirationhandpieces or ultrasound handpieces,” Dr.Mamalis added.
The task force report noted that severalcenters had reported occluded irrigationaspiration tips, which could mean improperflushing of handpieces and tips betweencases and the buildup of materialsthat could cause toxicity in future cases.
“We really think that instrument cleaningis important, and flushing reusablehandpieces and tips is critically important,”Dr.Mamalis said. He added that the issueof rapid turnover between cases is related,since the emphasis on efficiency and performingmore surgeries in a day may meanthat full flushing of instruments is not takingplace.
“I’m wondering if there’s enough timebetween cases for the staff to be properlyflushing and properly irrigating thesereusable handpieces and tips,” he said.
While the task force continues to combover reports from surgical centers to identifythe underlying causes of the TASS outbreak,there is at least some good news, Dr.Mamalis added.
“The incidence of TASS seems to beabating now,” he said. “We had a huge increasein reported cases in March andApril, but over the last month or so the reportedcases in this outbreak seem to bedecreasing. This decline could be due inpart to increased awareness or vigilanceon the part of surgeons.
“The second thing that’s good about thisis that of those centers that have reportedtheir patient outcomes, fortunately most ofthese cases of TASS are looking like they’remoderate, not severe,” Dr.Mamalis said.In most cases, the inflammation is respondingwell to intense corticosteroidtreatments, and there have been few instancesof severe corneal involvement oruncontrolled glaucoma.
Copies of the instrument re-processingand product questionnaires are availablefrom the ASCRS Web site at http://www.ascrs.org.Report TASS incidents to:Nick Mamalis, MDPhone: 801/581-6586