Eliminating TASS requires analysis of surgical protocols

Toxic anterior segment syndrome (TASS) is a rare but potentially devastating condition that can occur postoperatively. Awareness of the etiology, analysis, and treatment of the syndrome is essential, according to Nick Mamalis, MD, professor of ophthalmology, Intermountain Ocular Research Center, John A. Moran Eye Center, University of Utah, Salt Lake City.

TASS, an acute anterior segment inflammation, can be either sterile or nonsterile and can occur after any anterior segment surgery, but most commonly after cataract surgery. Common signs and symptoms are blurry vision, presence or absence of pain, and immediate onset within 12 to 48 hours after surgery. Clinical findings are diffuse corneal edema that extends limbus to limbus, widespread endothelial damage, marked anterior segment inflammation, and hypopyon. There also can be iris damage, dilated or irregular pupils, trabecular meshwork damage, and possible secondary glaucoma.

Since its inception in 1988, the Intermountain Ocular Research Center has established protocols, developed questionnaires, and identified a number of etiologies of TASS syndrome. These include intraocular irrigating solutions with abnormalities of pH or ionic composition, osmolarity, and particulate contamination; endotoxin contamination of balanced salt solution; preservatives in ophthalmic solutions; intraocular medications such as antibiotics in irrigating solutions and intracameral antibiotics; topical ointments; ophthalmic viscosurgical devices; and inadequate sterilization of instruments and tubing.

In a recent TASS outbreak beginning in February 2006, no single etiologic factor was identified and multiple potential causes are under investigation, according to Dr. Mamalis.

“Because the time between cases has become so much shorter, the outbreak may be due to inadequate flushing of the instrumentation,” he said. “We emphasize flushing the instruments adequately between cases to avoid buildup of residual ophthalmic viscosurgical devices.”

Dr. Mamalis recommended that an infectious etiology of TASS be ruled out. Infections have a later onset from 4 to 7 days postoperatively, anterior segment reaction, and corneal changes. Slit-lamp examination, gonioscopy, and IOP measurements should be performed. He also advised sampling and analysis of all medications and fluids used during surgery. Operating room protocols should be reviewed completely as well as the methods of instrument cleaning and sterilization protocols.

TASS is treated with intense topical corticosteroids (1% prednisolone acetate) given hourly. Careful evaluation of IOP is advised. Patients should be followed closely, especially for the first several hours and days after the onset of treatment. Most patients have rapid clearing of the inflammation in cases that are mild. Clearing is more prolonged (i.e., 3 to 6 weeks) in moderate cases of TASS. In severe cases, there may be permanent damage, corneal edema, chronic inflammation and cystoid macular edema, fixed dilated pupil, and refractory glaucoma, he said.