Be aware of the signs, treatment of toxic anterior segment syndrome

TASS is similar to infectious endophthalmitis but can be differentiated by time of onset, pain and lack of vitritis.

Issue: November 1, 2006

BySimon P. Holland, MB, FRCSC

Introduction

Amar Agarwal

Toxic anterior segment syndrome has been more widely reported since it was first recognized as a specific entity in 1992. The classic features of toxic anterior segment syndrome, or TASS, are early and intense postoperative inflammation after anterior segment surgery without vitreal involvement. Previously, postoperative inflammation that appeared to be noninfectious was sometimes described as sterile endophthalmitis or postoperative uveitis of unknown origin. My special guest in this column is Simon P. Holland, MB, FRCSC, of Vancouver to explain this new development.

Amar Agarwal, MS, FRCS, FRCOphth

TASS is described as a group of signs and symptoms, but it lacks a precise definition due to overlap with early infectious endophthalmitis, uveitis from retained cortex and history of iritis. The expected characteristics are early onset after surgery (24 to 72 hours), intense anterior segment inflammation including fibrin deposition and corneal edema, minimal or no pain, and the absence of vitritis. Infectious endophthalmitis can be differentiated by later presentation (peaks between day 3 and day 7), pain and vitritis. However, early cases of endophthalmitis may present as TASS, and whenever there is doubt regarding the diagnosis, the case should be treated as infectious endophthalmitis.

The case illustrated (Figure 1) shows the appearance 8 hours after cataract surgery and was initially thought to be TASS. The patient was subsequently diagnosed as having endophthalmitis, culture-positive for Staphylococcus aureus. The second case shows a more classical presentation on day 1 (Figure 2). Table 1 summarizes the differentiating features between infectious endophthalmitis and TASS.

Early endophthalmitis presenting on the day of surgery.

TASS on the first postoperative day.

Images: Holland SP

Vitritis

Vitritis is almost never associated with TASS and indicates infectious endophthalmitis. However, it is possible that some cases of culture-negative endophthalmitis may also be caused by toxins and contaminating agents that cause TASS and be a “spill over” of the anterior segment inflammation. Better differentiation between infectious, culture-negative or sterile endophthalmitis and TASS may occur with newer techniques such as PCR analysis of aqueous and vitreal aspirates.

Response to steroids

TASS cases usually respond rapidly to frequent topical steroids without need for surgical intervention; thus, this feature has been used as a confirmation of the diagnosis of TASS.

TASS etiology

TASS is multifactorial, and determining the cause can be difficult. Surgeons in centers experiencing a TASS outbreak are likely to make multiple, simultaneous changes; thus, retrospectively determining the causative agent is frequently impossible. Multiple possible factors have been demonstrated to be associated with TASS (Table 2).

Treatment

Frequent topical steroids every 30 to 60 minutes are usually effective, with improvement seen within the first 24 to 48 hours. In cases where corneal and endothelial toxicity occurs, a corneal transplantation may be necessary.

Outcomes

Early diagnosis and treatment invariably lead to excellent outcomes, with the majority of patients achieving best corrected visual acuity of 20/40 or better. Patients can develop glaucoma from initial trabeculitis and long-term as a result of fibrin membranes.

For More Information:

Amar Agarwal, MS, FRCS, FRCOphth is director of Dr. Agarwal’s Group of Eye Hospitals. Dr. Agarwal is author of several books published by SLACK, Incorporated, publisher of Ocular Surgery News, including Phaco Nightmares: Conquering Cataract Catastrophes, Bimanual Phaco: Mastering the Phakonit/MICS Technique, Dry Eye: A Practical Guide to Ocular Surface Disorders and Stem Cell Surgery, and Presbyopia: A Surgical Textbook. He can be reached at 19 Cathedral Road, Chennai 600 086, India; fax: 91-44-28115871; e-mail: dragarwal@vsnl.com; Web site: www.dragarwal.com.

Simon P. Holland, MB, FRCSC, can be reached at Eye Care Center UBC/VGH, 2550 Willow St. Sec. G, Vancouver, British Columbia V5Z 3N9, Canada; 604-875-5850; fax: 604-875-5860; e-mail: simon_holland@telus.net.

References:

Agarwal S, Agarwal A, Agarwal A. Four volume textbook of ophthalmology. India: Jaypee; 2000.

Agarwal A. Handbook of Ophthalmology. Thorofare, NJ: SLACK Incorporated; 2005.

Agarwal A. Refractive Surgery Nightmares. Thorofare, NJ: SLACK Incorporated; 2007 (in press).