9 Things You May Not Know About TASS

In 2006, an outbreak of toxic anterior segment syndrome (TASS) caused shockwaves in the ophthalmology community. Task forces were formed, studies were undertaken, preventative measures and treatments were developed. If you were involved in the eye industry back then, you probably remember the hubbub. In the 13 years since, the panic over TASS has waned, but there's still much mystery shrouding the rare but potentially dangerous post-operative inflammation that results when a foreign substance is introduced into the eye during surgery — usually from contaminants in medications or on surgical instruments. Here's the latest.

1. The threat remains. Although there hasn't been a large outbreak since 2006, TASS remains a low-profile threat with cases still flaring up. Late last summer, 3 Seattle-area surgery centers reported 15 patients that had been diagnosed with TASS following cataract surgery from January to July. Health officials have yet to determine a cause, but possible culprits include preservatives or toxins in medications or products, or from medication or instrument handling procedures within the facilities.

"It's an ongoing issue," says Nick Mamalis, MD, one of the world's foremost experts on TASS. "We're still getting phone calls or emails regarding issues with TASS at a particular surgical center or hospital a couple times a month. Most people don't pay attention to TASS, or its causes, or prevention, until it actually happens to them." Dr. Mamalis estimates the TASS reports he's received in the last year to be in the hundreds, but says it's difficult to know how many cases of TASS there are, because many aren't reported or diagnosed properly.

"It's vastly under-reported," says Jimmy K. Lee, MD, director of cornea and refractive surgery at Montefiore Medical Center in Bronx, N.Y., "especially in situations where it's a single occurrence or a small number of cases spread among surgeons who do not operate on same days and do not communicate regularly. It really doesn't trigger awareness or attention until someone recognizes there's a cluster of potential TASS cases."

2. New cleaning and sterilization guidelines. Last April, after 3 years of collaborative research, the American Society of Cataract and Refractive Surgery (ASCRS), the American Academy of Ophthalmology (AAO) and the Outpatient Ophthalmic Surgery Society (OOSS) released ophthalmology-specific instrument cleaning and sterilization guidelines. These were the first updates to the original guidelines in a decade.

Dr. Mamalis, co-chair of the task force that authored the guidelines (osmag.net/XFmVe4), identifies insufficient instrument cleaning and sterilization as the most common cause of TASS. The task force found general surgery guidelines for instrument processing may be inappropriate for ophthalmic surgery. So they developed evidence-based, peer-reviewed, ophthalmology-specific cleaning and sterilization guidelines.

"The causes go much beyond sterilization methods in the OR," says Dr. Lee. "It's not just cleaning and care of instruments. It can be from medications, drapes and devices such as ophthalmic viscoelastic agents (OVDs), even intraocular lenses."

Dr. Mamalis, professor of ophthalmology, co-director of Intermountain Ocular Research Center, and director of ocular pathology at University of Utah's John Moran Eye Center, says a key aspect of the new guidelines involves enzymatic detergents. Many mistakenly believe ophthalmic instruments treated with enzymatic detergents are clean and sterile, but the researchers found that microscopic enzyme residues the detergents leave behind on the instruments can cause TASS. It would help if instrument manufacturers validated cleaning methods that don't require enzymatic detergent, says Dr. Mamalis, who adds that a more thorough cleaning regimen that adheres to the guidelines can alleviate the need for using enzymatic detergents entirely.

Likewise, more thorough cleaning can obviate the need to use ultrasound water baths for cleaning bulk material off of ophthalmic instruments. Research shows that these baths, if not cleaned properly after each use, can build up with gram-negative bacteria that leaves a heat-stable endotoxin residue that can cause TASS, says Dr. Mamalis.

Due to the exacting nature of cleaning and sterilization required to avoid TASS, single-use instruments present an attractive option. "In areas where you can't adequately ensure that an instrument's going to be properly cleaned, it's definitely recommended that you use single-use instruments — cannulas especially, and especially if you're using them to inject [viscoelastic] into the eye during the surgery, because it's very difficult to get all of the residual [viscoelastic] out of the cannulas," says Dr. Mamalis. "That could cause potential problems such as inflammation and TASS." But he adds that a single-use strategy across the board wouldn't be practical or cost-effective. Replacing a handpiece for removing the cortex after every surgery, for example, would be cost-prohibitive.

3. The potential causes keep expanding. Insufficient cleaning and sterilization of instruments might be the most common cause of TASS, but it's not the only one.

"We're finding that the causes go much beyond sterilization methods in the OR," says Dr. Lee. "It's not just cleaning and care of surgical instruments. It can be from medications, surgical drapes and medical devices such as ophthalmic viscoelastic agents (OVDs), even intraocular lenses. And there are cases whereas before it wouldn't have been reported as TASS, now we're identifying it as TASS."

4. You can confidentially report TASS incidents. The ASCRS TASS Task Force maintains an online TASS registry (ascrs.org/tass-registry) where you can voluntarily and confidentially report incidences. The task force uses this information "for identifying potential causes and risk factors of TASS; and educating the ophthalmic community regarding such risk factors."

The task force periodically releases reports describing the trends it's identified from the collected incidences. It'll also analyze your information and provide your center with an individualized report. Keep in mind, too, that your facility may be subject to local or state regulations that you report a TASS outbreak to a public agency.

5. It's not just a cataract surgery thing. TASS has long been associated primarily with cataract surgery; Dr. Lee surmises that's because cataract surgeries are by far the most common eye surgery. But it's turned up after other eye procedures, as well. "We've seen TASS in any anterior segment intraocular surgery," says Dr. Mamalis, citing examples of corneal transplants and glaucoma surgeries.

6. There's late-onset TASS, too. TASS is usually thought of as an acute condition that presents within 12 to 48 hours after surgery. But a rarer subset of this rare condition is late-onset TASS, which can show up weeks or months after the surgery. Dr. Mamalis says the causes of late-onset TASS are usually not related to instrument cleaning and sterilization, but rather to particular medications or lenses that are used, including ointments and petroleum-based medications. One late onset case he studied years ago, for example, was caused by problems with residual polishing compounds left on IOLs.

7. TASS is not infectious endophthalmitis. Even though the distinctions between the conditions have been clearly delineated for some time — most obviously, that the onset of TASS is more acute — they are still occasionally mistaken for each other. "People are aware of TASS, and what TASS is, but when they see post-operative inflammation, the first thing they suspect is an infection," says Dr. Lee. "TASS is usually not high in the differential diagnosis, and therefore warrants more education and raising awareness."

8. Surgeons and centers have been sued over TASS. Something else to keep in mind when assessing your exposure to the risks of TASS: Patients who have contracted TASS have filed lawsuits, says Dr. Mamalis, who has served as an expert witness periodically over the years in such suits (he declined to discuss specifics).

9. You need a TASS plan. If your facility hosts eye surgeries, you need a strategy and protocol in place to prevent, identify, treat and investigate incidences of TASS. Dr. Lee last October co-authored a paper, "Toxic anterior segment syndrome-an updated review," published in the BMC Ophthalmology journal that combs through dozens of studies to present the most recent findings and information about TASS. While it's a compelling read just for that, it also provides a customizable TASS protocol algorithm for OR leaders (osmag.net/zYV7Eq).

While TASS is no longer headline news, behind the scenes, a core group of researchers around the world has continued to study the condition. And it seems the more they find out about TASS, the more they realize there's so much that still isn't known about it. OSM