Question of the Week

You are a fourth-year ophthalmology resident and have just completed your 100th cataract surgery. The surgery went well without complications. Six hours postoperatively, the patient’s uncorrected vision is 20/40 and IOP is 25 mmHg. The following evening, the patient calls the on-call physician reporting blurry vision and 4/10 eye pain that is minimally relieved with acetaminophen. She is instructed to return to the clinic the next morning.

By the time you see her, it has been 30 hours since surgery. She says she was seeing better when she first arrived home, but now her vision is blurry. VA is 20/150 and IOP is 34 mmHg. On exam, there is corneal edema, 4+ cell and flare, and a small hypopyon. Posterior segment visualization is limited. A vitreous tap is performed and sent for bacterial and fungal cultures. Intravitreal ceftazidime and vancomycin are administered.

The following day, VA is 20/200 and the hypopyon has enlarged. Gram stain shows no organisms, and cultures remain negative at 24 hours. What is your next step?

A) Start topical 1% Prednisolone acetate

B) Repeat vitreous tap and cultures

C) Perform a vitrectomy

D) Start oral antibiotics

Answer

The correct answer is A.

Explanation:

The diagnosis in this case is toxic anterior segment syndrome (TASS), a rare, sterile, noninfectious inflammatory reaction after anterior segment surgery, most commonly cataract surgery. TASS typically presents within 12–48 hours after surgery with blurry vision, corneal edema, anterior chamber inflammation, elevated IOP, and sometimes hypopyon. The exact cause is often unknown and likely multifactorial, with proposed causes including bacterial endotoxins or particulate contamination of balanced salt solution, abnormal pH or osmolarity of intraocular irrigating solutions, denatured viscoelastics, intraocular medications, topical ointments, inadequate sterilization or flushing of surgical instruments and tubing, preservatives, and metallic precipitates. Most patients do well with prompt treatment using intensive topical corticosteroids (A). Severe cases can lead to permanent corneal edema, iris damage, secondary glaucoma, cystoid macular edema, or vision loss. The differential includes infectious endophthalmitis, retained lens material, and postoperative uveitis. In this case, performing a vitreous tap and starting intravitreal antibiotics at the first sign of eye inflammation was correct because early TASS can closely mimic infectious endophthalmitis, and infection must be ruled out urgently. However, the very early onset within 30 hours, prominent anterior segment findings, elevated IOP, negative Gram stain, and lack of culture growth at 24 hours favor TASS over infectious endophthalmitis, which more typically presents 2–7 days after surgery and often has greater posterior segment involvement. Choices B, C, D are all potential options if postoperative endophthalmitis remained highest on your differential.

Verma L, Malik A, Maharana PK, Dada T, Sharma N. Toxic anterior segment syndrome (TASS): A review and update. Indian J Ophthalmol. 2024;72(1):11-18. doi:10.4103/IJO.IJO_1796_23