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Comanagement Challenge Case – by Dr. Brooks Alldredge

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Discussion

This patient has toxic anterior segment syndrome or TASS. It is a very rare early complication of cataract surgery that has only recently become well-understood. TASS typically presents within 12 to 48 hours after surgery. Usually, the only symptom is cloudy or blurry vision. The hallmark features of TASS are

1. Moderate or severe corneal edema that extends limbus-to-limbus across the cornea,

2. A breakdown of the blood-aqueous barrier leading to a marked anterior chamber reaction with fibrin. A hypopyon is common and a hyphema is not unusual, and

3. An irregular pupil from iris damage.

The cause seems to be the introduction of toxins from the operating instruments into the eye during surgery. A new study in the latest issue of The Journal of Cataract and Refractive Surgery shows that the likely culprits are detergents and other chemicals that are not adequately removed from the phaco handpieces when they are cleaned between cases. This introduction of an exogenous chemical results in an acute inflammation that, if left untreated, can lead to permanent damage of the cornea, iris and even the trabecular meshwork in severe cases.

Fortunately, mild to moderate cases can be effectively treated with intense topical steroid treatment. Even so, this is a condition that should be prevented by a surgery center's adherence to careful and immaculate cleaning technique of their instruments, particularly a thorough flushing of the phaco and other instruments that are cannulated. Anything less than a very rare case - or even better, no cases - of TASS should be a warning that a surgery center's instrument cleaning procedures may be inadequate.

Differential Diagnosis

Endophthalmitis is perhaps the most dreaded complication of intraocular surgery and the combination of poor vision, hypopyon and corneal edema in this case is very concerning. However, the patient is otherwise feeling well and comfortable, and pain is typical (although not universal) in acute endophthalmitis. This patient shows no sign of infection in the vitreous or posterior segment - the inflammation in this case is limited to the front of the eye.

Acute post operative corneal edema from endothelial trauma and inflammation is a common transient finding after cataract surgery, seen even in surgery from the best surgeons. Unlike in TASS, there is no excessive anterior chamber reaction, and most importantly, the stromal edema is usually limited to the central cornea only. In most cases of mild or moderate central edema, no changes in treatment is necessary, although increasing the topical steroid to every two hours can hasten recovery. Significant improvement occurs within days (sometimes hours) and resolution should be within a couple of weeks.