Toxic anterior segment syndrome (TASS) following cataract surgery is distinguished from infectious endophthalmitis by which clinical characteristic?

• A Onset at day 4–7 with hypopyon; vitritis is marked and vitreous tap/culture is positive
• B TASS causes corneal edema while endophthalmitis spares the cornea
• C TASS is caused by Propionibacterium acnes and responds only to complete IOL removal
• D Onset within 12–24 hours with fibrin in anterior chamber; vitritis is minimal or absent ✓

Explanation

TASS is a sterile postoperative inflammatory reaction caused by non-infectious substances entering the anterior segment (contaminated irrigation solutions, BSS with wrong osmolality, OVDs, endotoxins). It presents within 12–24 hours (rarely up to 72 hours) with severe anterior segment inflammation including fibrin, hypopyon, and corneal edema — but vitritis is minimal because the inflammation is confined to the anterior segment. Infectious endophthalmitis typically presents later (day 4–7), has marked vitritis, and cultures are positive. P. acnes causes delayed chronic endophthalmitis, not TASS.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.