Toxic anterior segment syndrome (TASS) is a relatively rare, though extremely serious, complication that can follow intraocular surgery.
Why is toxic anterior segment syndrome worth preventing? Why should ophthalmologists be concerned?
Understanding TASS: Complications and Symptoms
The reason that TASS is so serious is because TASS can cause atrophy of the iris, optic nerve damage, posterior capsular opacification, cystoid macular edema, and other serious conditions.
TASS itself is brought about by a noninfectious agent penetrating the anterior segment and creating toxic damage vis-à-vis intraocular tissues.
TASS, by far, occurs most often following cataract surgery. That said, some ophthalmologists have recently reported post-operative complications following intraocular lens implantation.
The thing to constantly bear in mind, though, is that TASS is a post-operative condition that involves inflammation to the anterior segment, yet TASS itself is caused by a non-infection substance penetrating the anterior segment.
Complications from TASS
Any time you have toxic damage to the intraocular tissue, you worry about patients developing severe inflammation, blurred vision and possible optic nerve damage resulting in more serious complications. In fact, the inflammation associated with toxic anterior segment syndrome can be so pronounced that a layering of white blood cells around the anterior chamber itself could develop (hypopyon formation).
Hypopyon formation can present as a yellow exudate in the lower half of the anterior chamber. In patients suffering from TASS post-surgery, you might also see redness in the conjunctiva, as well as redness in the furthest-out layer of the sclera (i.e., redness in the episcleral layer).
Patients suffering from TASS will often present symptoms – namely inflammation, redness and blurred vision – within 48 hours of surgery. Patients may or may not be in pain at the time they come into your office, yet they’ll almost certainly be suffering from blurred, reduced vision and possibly a diffuse corneal edema that spans limbus to limbus.
A severe sensitivity to light and brightness (photophobia) as well as intense anterior chamber reactions are to be expected from patients. Whereas the main symptoms of TASS present themselves in patients potentially within as short a timeframe as 12 hours post-surgery, the full extent of the infectious endophthalmitis may not develop until up to a week following cataract surgery.
An Advanced Look into TASS’ Causes
Preventing TASS, unfortunately, can’t be done with a one-shot silver bullet since the potential causes are so numerous and multifaceted.
TASS may be caused at the sterilization stage, anesthetics and ointments employed by ophthalmologists and their staff before and during surgery, or TASS may even come from detergents and enzymes.
TASS’ Shocking Root Cause
The true cause of TASS could even surprise you – as cataract surgery centers have performed literally millions more cataract surgeries over the years, the time that ophthalmologists spend sterilizing their instruments may have actually decreased. How could this possibly be? It’s simple: more patients scheduled for cataract surgery means less time between surgeries. Less preparation time can lead to careless mistakes.
Making sure that all members of your staff clean your instruments according to protocol is an essential first step to preventing TASS. It’s also critical to ensure the leftover detergents and enzymes aren’t still on your instruments after you clean your instruments – residual detergents and enzymes can also result in patients developing anterior segment infections.
Advanced Troubleshooting TASS
If you’re looking for more advanced prevention tips, then make sure your autoclave reservoirs and ultrasound baths are regularly cleaned since this can cut down on the spread of endotoxin contamination and the rampant spread of gram-negative bacteria. Gram-negative bacteria destroyed during heating and autoclaving may nonetheless find their way onto your instruments in the form of heat-resistant gram-negative bacteria.
Even some intraocular medications that patients might be exposed to – e.g., irrigation solution antibiotics or intracameral antibiotics – may predispose patients to develop TASS after cataract surgery.
Ointments and poor sterilization (mentioned above) are always issues to look out for, yet some ophthalmologists downplay the dangers that metallic precipitate, certain preservatives and intraocular irrigation solutions with unusual pH levels can play in predisposing their patients to toxic anterior segment syndrome.
Conclusion: An Ounce of Prevention is Worth a Pound of Cure
This is all to say that TASS can develop as a result of exposure to medications, certain preservatives in anesthetics and medications, bacterial endotoxins, ointments and solutions with unusual pH levels.
Using properly sterilized instruments, low-preservative intraocular solutions, and eliminating endotoxins all reduce the odds of patients developing TASS.