The number of centers reporting cases of TASS from February through May of 2006 is now over 100.  Twenty-three of these centers have completed a long protocol form developed by the Intermountain Ocular Research Center of the University of Utah to analyze cases of TASS.  An additional 16 surgeons and 16 surgical centers have returned short forms that were developed by the Ad Hoc Task Force in order to obtain data regarding these cases in a simpler manner.

Careful review of the information provided to date has not revealed a single cause or point source related to this most recent TASS outbreak.  However, there have been several potential etiologic factors which have arisen from review of the data.

Preliminary findings from Product Questionnaire

•     The preoperative use of nonsteroidal anti-inflammatories (NSAIDs) may be a potential factor in several of the cases reported to date.

•     The use of intracameral anesthetics is a potential factor, especially given the short ultrasound time in the majority of the cases with the possibility of ophthalmic visco surgical devices (OVD) potentiating the length of time that the anesthetic can remain in the anterior chamber of the eye.

•     The issue of epinephrine added to BSS solutions to maintain pupilary dilation during the phacoemulsification is also a potential problem.  The epinephrine must be truly preservative free.  Epinephrine solutions which have stabilizing agents such as bisulphites are still not considered preservative free and bisulphite is potentially toxic to the corneal endothelium and the structures of the anterior segment of the eye.

•     Intracameral antibiotics, if improperly dosed, mixed, or injected into the eye are another potential source of toxic inflammation.

•     Reusable cannulas may allow a residue of OVD, cortex, or other materials which can be toxic when injected into the anterior chamber.  It should be noted that residual viscoelastic can retain enzymatic detergents and ultrasonic cleaners.

•     The majority of IOLs reported were Alcon lenses.  However, given the large market share of Alcon, it is unclear whether or not this represents a larger than expected relationship of one particular IOL manufacturer to the TASS cases.  Furthermore, there may be an issue involved regarding the cleaning of the reusable inserter which is used with a disposable cartridge to place the lens.

Preliminary findings from Instrument Reprocessing Questionnaire

•     The number of surgeries in one day that are normally performed varies in the surgical centers reporting from 6 to 50.  The issue of short time available between cases to process and properly clean instruments may be important.

•     Reusable ultrasound and irrigation/aspiration hand pieces and tips are a potential source of TASS.  There have been several centers which have reported “occluded” I/A tips which raises the issue of proper flushing of hand pieces and tips between cases.  This may allow a buildup of OVD, cortex, and other materials on the inside of phacoemulsification or I/A hand pieces and tips that could cause toxicity.

•     Instrument cleaning between cases including the use of ultrasound baths, enzymes, and detergents are a potentially related issue if these materials are not properly flushed from instruments, cannulas, and hand pieces.  Note:  Rinsing in sterile deionized water is important

•     There is an ongoing issue regarding the cleaning of ultrasound water baths in order to prevent contamination with gram-negative bacteria and subsequent endotoxin contamination of instruments which is heat stable and can cause TASS even after proper autoclaving of instruments.  An alcohol rinse will remove endotoxin.

This analysis is ongoing and centers which have reported cases of TASS but have not filled out questionnaires are being contacted in order to provide more complete data related to the TASS cases associated with this outbreak.  Follow up of 53 of the 114 centers that have reported cases of TASS directly to a single manufacturer has shown that 41 of the centers have not had any further cases as of the first week of June, 2006.  An additional 12 centers have had more cases since their initial reports in April.  The TASS Adhoc Task Force will continue to analyze the cases involved in this particular outbreak and continue to evaluate possible sources of TASS and subsequently formulate recommendations on prevention of this problem.

TASS incidents should be reported to:

Nick Mamalis, MD

Intermountain Ocular Research Center

John A. Moran Eye Center

University of Utah

Salt Lake City, Utah  84132

nick.mamalis@hsc.utah.edu  

801) 581-6586. 

Toxic Anterior Segment Syndrome (TASS) Outbreak Update, May 22, 2006

http://209.183.229.213/press_releases/upload/UpdateBriefing.doc  

To access Product Questionnaire:

http://209.183.229.213/press_releases/upload/Productdatacollectionform.doc  

To access Instrument Re-processing Questionnaire