The TASS Task Force, sponsored by the ASCRS and under the leadership of Dr. Nick Mamalis, has been meeting on an ongoing basis and has compiled data regarding the increased incidence of TASS that began in early 2006.  This final report addresses the findings and recommendations of the Task Force as a result of those efforts.

The number of centers reporting cases of TASS from January 17 to July 11, 2006 is 113.  Twenty-six of these centers completed a long protocol form developed by the Intermountain Ocular Research Center at the University of Utah to analyze cases of TASS.  An additional 40 centers or surgeons returned a shorter version in the form of two questionnaires that were developed by the adhoc TASS Task Force in order to obtain data regarding the cases involved in this outbreak in a more simplified manner. The number of reported cases and completed surveys peaked in April, 2006.  Subsequent to that time, the reported cases of TASS have decreased to what is considered a baseline level.  While the Task Force will continue to evaluate potential etiologic factors involved in TASS, it appears as though the early 2006 outbreak has subsided significantly.

There were no conclusive epidemiologic data to suggest that any one product was responsible for the increase in TASS cases that were reported.  Careful analysis of the information provided did not reveal a single cause or point source related to this TASS outbreak.  Our investigation failed to identify evidence supporting an association between a shared product and the cases of TASS reported.  Failure to make that association does not mean that the association does not exist, nor does it mean that the increase in cases was due to a change in reporting.  Either or both of these explanations might be correct, along with other hypotheses including those of a multifactorial nature.  Thorough analysis of the data provided has revealed multiple potential etiologic factors that could be involved in the outbreak of TASS.  The cleaning and sterilization of instruments for cataract surgery appears to be the most important factor involved in many of the cases of TASS reviewed.  In addition, all of the products involved in preoperative preparation of the patient through postoperative care, were reviewed and several potential factors identified as possible causes of TASS.  The results of this investigation were shared with representatives of the FDA and the CDC.

Instrument Reprocessing Questionnaire (including instrument cleaning and sterilization)

•   The number of cataract surgeries performed on an average day varied in reporting centers from 5 to 50 (median 15).  When questioned about any pattern observed in TASS cases regarding the surgical case of the day or day of the week, three-fourths of respondents noted no particular pattern  A concern raised by the Task Force when reviewing data was the short time available between cases to reprocess and properly clean instruments. This may be an important factor in the etiology of TASS. (median number of instruments trays was 3.)
• The use of reusable cannulated instruments of any kind is a potential source of TASS.  Ultrasound hand pieces as well as similar hand pieces used for irrigation and aspiration may be a potential source of material that may incite inflammation.  There were several centers evaluated which reported “occluded I/A tips” which raises the issue of proper flushing of hand pieces and tips between cases.  It is imperative that all reusable hand pieces and cannulas are flushed thoroughly (and immediately at the conclusion of the case).  Seven centers reported reuse of Phaco tubing.  The use of single use devices where no instructions are provided by the manufacturer should be prohibited unless validated.  Devices designed for single use should not be reused.  If they are to be salvaged for construction of another single use device, they should be reprocessed in accordance with FDA directives (www.fda.gov/cdrh/comp/guidance/1168.pdf).  The Task Force has recommended the use of sterile, deionized/distilled water for flushing.  The majority of manufacturers of phacoemulsification hand pieces similarly recommend flushing of both the irrigation and aspiration ports of phacoemulsification and I/A hand pieces with specified volumes of sterile, deionized/distilled water at the conclusion of the case.  Inadequate flushing may allow a build up of residual cortex, Ophthalmic Viscoelastic Device (OVD), and other materials on the inside of the phacoemulsification or I/A hand pieces that could conceivably cause TASS.  Similarly, all reusable cannulas should be thoroughly flushed immediately following the conclusion of the previous case to avoid any residual material left within the cannulas.  Disposable cannulas are recommended wherever possible in these surgical cases and should not be reused. 
• Another important issue is the cleaning of instruments between cases with the use of water baths, enzymes, or detergents.  If any of the materials in these solutions are not properly rinsed from the instruments, the residual material may cause TASS.  This issue has become especially important at some centers where ophthalmologic instruments are cleaned with enzymatic detergents and ultrasound alongside instruments used in non-ophthalmologic surgery.  If these steps are to be undertaken with ophthalmic surgical instruments, it is critical that instruments are thoroughly rinsed.  Once again, this should be done with sterile, deionized/distilled water at the conclusion of any treatments with these solutions to remove any residual detergent or enzyme. Autoclaving will not deactivate any enzyme or detergent.
• A further issue involving the use of ultrasound water baths to clean instruments between cases is the potential contamination of the water bath with gram-negative bacteria.  Growth of these bacteria with subsequent endotoxin production could cause contamination of the instruments.  The endotoxin is very heat stable and will survive autoclaving and may cause TASS, even after the bacteria is incapacitated by the heat from the autoclave. (Nine centers reported cleaning their ultrasound baths only once weekly.) Ultrasound baths should be emptied and thoroughly cleaned after each use or at least at the end of each day.
• The last potential issue that was identified, in terms of instrument cleaning and sterilization, is the possibility of contamination within the steam sterilizer itself.  The filters, water chambers, and inside of autoclave units should be thoroughly cleaned according to manufacturers recommendations on a regular basis to prevent the possibility of contamination by endotoxin within the sterilizer itself, as well as any material coming from the water supply for the steam sterilizer.Finally, the number of reporting centers acknowledged the absence of a written protocol for cleaning their cataract surgical equipment.  Opportunities to reduce errors in reprocessing lie in the development of written protocols, in the certification of competency with their execution and in monitoring of compliance with them.

Product Questionnaire

• Additives to any of the solutions or medications going into the eye at any point of the surgery should be preservative free.  One potential problem that has arisen is epinephrine which is added to the balanced salt solution (BSS) to maintain pupilary dilation during phacoemulsification.  Not only must the epinephrine be preservative free but it should also be free of stabilizing agents such as bisulphites or metabisulphites.  Although these are not considered to be traditional preservatives, they are toxic to the corneal endothelium as well as other cells within the anterior segment of the eye and can lead to TASS.  It is important that any medications that are placed into the eye are indeed preservative free.  The “directions for use” on these products state that no additives should be added to the irrigating solution.
• The issue of intracameral anesthetics was also evaluated carefully and has been found to be a potential factor related to TASS.  This is especially important in the era of very efficient phacoemulsification with a very short ultrasound time in the majority of cases leaving the possibility that anesthetic may remain in the anterior chamber of the eye and not be adequately diluted and flushed out at the conclusion of the case.  As with other additives, it is important that the anesthetic be preservative free.  Also, the dose of the anesthetic is important and the anesthetic should not be highly concentrated when it is injected into the anterior chamber of the eye.  A final factor is the possibility that OVDs may also potentiate the length of time the anesthetic can remain in the anterior chamber of the eye. 
• The issue of the use of intracameral antibiotics was also addressed and no specific problems where found.  However, it remains extremely important that the antibiotic be properly mixed or reconstituted, as well as properly dosed for injection into the anterior chamber of the eye.  A high dose of antibiotic has the potential to cause toxicity within the anterior segment. 
• As mentioned in the instrument cleaning and sterilization questionnaire, reusable cannulas are a potential source of residual cortex, OVD, or other materials that can be toxic if injected into the anterior chamber of the eye.  It is critically important that any of the reusable instruments or cannulas be thoroughly flushed at the conclusion of the previous case.  In addition, any enzymes, detergents or ultrasound cleaners used on these instruments should be thoroughly rinsed from these cannulas using sterile, deionized water prior to sterilization.  It should be noted that the OVDs can dry on the instruments and cannulas when exposed to air, which make cleaning difficult.
• There was no single type of intraocular lens that was found to be exclusive to the TASS syndrome.  Intraocular lenses from three major IOL manufacturers in the United States were found in these cases and seem to represent market share of the lenses in the centers involved. 
• The issue of injectors was evaluated and no single factor was found.  However, there was a potential issue involving the cleaning of reusable inserters used in conjunction with a disposable cartridge for the injection of the IOL.  There is a possibility that residual material (OVD, tissue, blood, etc.) in the reusable injector could be involved in TASS.

Conclusions

• While no single factor was found to be responsible for this outbreak of TASS, there were multiple potential etiologic factors that were evaluated by the Task Force.
• In addition, evaluation of outcomes in the majority of cases involved in this outbreak has shown that the degree of inflammation in these patients was rated as moderate in most cases.  Fortunately, the majority of patients have recovered good visual acuity without significant ocular sequelae from the TASS.  Unfortunately, there were a small group of patients who had more severe inflammation and have been reported to have ongoing ocular problems from the toxic insult.

The Task Force will continue to evaluate data that is submitted and will also continue meeting by conference call on a regular basis.  During visits by nurse consultants to over 17 sites experiencing TASS, issues with cleaning ophthalmic surgical instruments were a common observation.  Therefore, a symposium was held at Emory University and gathered many members of the Task Force as well as nurses and other personnel involved in the cleaning and sterilization of ophthalmic surgical instruments.  The purpose of the meeting was to discuss the establishment of guidelines for the cleaning, sterilization, and processing of ophthalmic instruments with the goal of preventing future TASS outbreaks.  It is the intent of the Task Force to help in the establishment of these guidelines.

Adhoc TASS Task Force

Nick Mamalis, MD

Henry Edelhauser, PhD

Walter Hellinger, MD

Kandon Kamae, MD

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