Awareness of TASS features enables appropriate surgeon response

February 15, 2006

Chicago—Awareness of the etiology and treatment of toxic anterior segment syndrome (TASS) is essential because while rare, TASS is a potentially devastating complication of cataract surgery, said Liliana Werner, MD, PhD, during the annual meeting of the American Academy of Ophthalmology.

Chicago-Awareness of the etiology and treatment of toxic anterior segment syndrome (TASS) is essential because while rare, TASS is a potentially devastating complication of cataract surgery, said Liliana Werner, MD, PhD, during the annual meeting of the American Academy of Ophthalmology.

Dr. Werner is an assistant professor of ophthalmology at the John A. Moran Eye Center, University of Utah, Salt Lake City. The TASS studies there are performed under the direction of Nick Mamalis, MD.

"The corneal endothelium is very sensitive to preservatives, such as benzalkonium chloride, bisulfite, and EDTA, and so it is important to use products that are preservative-free," Dr. Werner said.

Cases of TASS have also occurred secondary to postoperative exposure to topical antimetabolites after glaucoma surgery, use of subconjunctival antibiotic injections, and topically applied ointments.

"We have recently analyzed some very interesting cases of patients who had uneventful phaco with a clear corneal incision and had their eye patched after application of a topical ointment that appeared to gain access into the eye," Dr. Werner said.

Potential etiologies

Other potential etiologies include remnants of ophthalmic viscosurgical device in the anterior chamber or denatured material introduced through the use of reusable cannulas or handpieces, and endotoxins or ethylene oxide, detergent, or enzyme residues contaminating sterilized instruments and tubing. Particulate contaminants, including talc, fibers, rubber bottle stopper pieces, and metallic or titanic flecks, as well as residual polishing compound used in IOL manufacture, have also been associated with TASS.

Recognition of the numerous possible causes is important because sampling and analysis of all medications and fluids used during surgery, along with a complete review of the operating room and instrument cleaning protocols, should be performed in investigating a TASS outbreak, Dr. Werner noted.

Patient evaluation mandates ruling out an infectious etiology, and in that regard, several features help to differentiate TASS from infectious endophthalmitis. While both conditions are characterized by an anterior segment reaction with hypopyon and fibrin, endophthalmitis generally has a later onset (usually after 4 to 7 days), does not typically manifest with limbus-to-limbus corneal edema, and is more likely to have vitreous involvement. In addition, anterior chamber and vitreous cultures are negative in TASS, although they may also be negative in some patients with endophthalmitis.

Treatment of TASS involves intensive topical steroids, careful evaluation of IOP, and close follow-up, Dr. Werner said.

"IOP may be low initially in these patients, but as aqueous humor production recovers, it may increase suddenly. These patients should be watched closely in the first several hours and days after diagnosis to make sure the inflammatory process is not worsening and to rule out endophthalmitis," Dr. Werner said.