Task force releases report on TASS outbreak
No single factor identified as cause
A total of 113 cases of toxic anterior segment syndrome (TASS) were evaluated by the TASS task force set up by the Fairfax, VA-based American Society of Cataract and Refractive Surgery (ASCRS) since the increased incidence of TASS that began in early 2006.
TASS is a postoperative, acute inflammation in the anterior segment of the eye as a result of the introduction of a noninfectious, toxic substance during ophthalmic surgery. The toxic substance causes serious and potentially irreversible damage to intraocular tissue. The task force's final report concludes that there is no single factor responsible for the outbreak, but it identifies a number of potential factors that might contribute to TASS:
- Short amount of time between cases to reprocess and clean instruments.
- Use of reusable cannulated instruments that are not properly cleaned. Ultrasound hand pieces or other hand pieces used for irrigation and aspiration should be flushed thoroughly and immediately at the end of the case. The task force recommends the use of sterile, deionized/distilled water for flushing.
- Improper rinsing of instruments cleaned between cases with water baths, enzymes, or detergents. Enzyme or detergent residue on the instruments may cause TASS.
- Improperly cleaned ultrasound baths used to clean ophthalmic instruments. They should be emptied and cleaned after each use or at least at the end of the day to prevent the contamination of the water with gram-negative bacteria.
- Endotoxin contamination with the sterilizer. Steam sterilizer filters, water chambers, and inside of autoclave units should be cleaned thoroughly according to manufacturers' recommendation on a regular basis to prevent contamination by an endotoxin within the sterilizer.
- Additives that are not preservative-free. Medications placed into the eye must be preservative-free. The task force identified the addition of epinephrine to the balanced salt solution to maintain pupilary dilation as a potential problem. Epinephrine containing preservatives or stabilizing agents such as bisulphites or metabisulphites can be toxic to the corneal endothelium and other cells within the anterior segment.
- The use of intracameral anesthetics. Not only should the anesthetic be preservative-free, but the dose of the anesthetic should not be highly concentrated when injected into the anterior chamber of the eye. It should also be thoroughly diluted and flushed from the eye at the conclusion of the case.
Not mentioned in report
While he praises the task force's recommendations, Lawrence F. Muscarella, PhD, director of research and development for Custom Ultra-sonics in Ivyland, PA, and editor of The Q-Net Monthly, points out that the report does not mention the use of low-temperature sterilizing agents as a potential source of TASS. Sterilizers that use peracetic acid, hydrogen peroxide, or plasma gas to sterilize ophthalmic instruments can oxidize nickel or chrome-plated brass hubs to create copper and zinc compounds, which can be toxic to the cornea, he says. It is important that surgery managers be aware of the issues that led to the removal of the ABTOX Plazlyte system in the 1990s, he adds. (For more information, see www.fda.gov/cdrh/abtox.html.)
To see a full copy of the Task Force's final report, go to www.ascrs.org. Choose "press releases" on the navigation bar at the bottom of the home page, then select "Final TASS Report."
A total of 113 cases of toxic anterior segment syndrome (TASS) were evaluated by the TASS task force set up by the Fairfax, VA-based American Society of Cataract and Refractive Surgery (ASCRS) since the increased incidence of TASS that began in early 2006.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content