OcuLearning › Adnexa

Blebitis

URGENT — Adnexa

Symptoms

  • Red eye and mucous discharge localized to the bleb area (early).
  • Aching pain, photophobia, and decreased vision (late).
  • History of prior trabeculectomy or filtering surgery (months to years ago).

Clinical Findings

"White-on-red" appearance (pathognomonic)

  • Milky white, opaque filtering bleb (inflammatory material) contrasted against intensely hyperemic conjunctiva.
  • High diagnostic value: Distinguishes blebitis from simple conjunctivitis in a glaucoma patient.

Bleb characteristics

  • Microhypopyon may be visible within bleb loculations under high magnification.
  • Purulent material may collect inside the bleb or leak through a Seidel-positive microperforation.
  • Seidel test: Mandatory check to identify the portal of bacterial entry.
  • Intraocular pressure (IOP): Usually low or normal due to active aqueous outflow through the infected bleb.

Wills bleb-infection grading

  • Grade 1 (Blebitis proper): Infected bleb and conjunctival injection only; quiet anterior chamber (AC), no vitritis.
  • Grade 2: Grade 1 findings plus AC cells/flare ± hypopyon; no vitritis.
  • Grade 3 (Bleb-associated endophthalmitis): Grade 1 findings plus vitreous involvement (vitritis).

Substrate and risk

  • Most common substrate: Avascular, thin, or cystic blebs (frequently associated with mitomycin-C use).

Etiology

Pathophysiology

  • Localized infection of a filtering bleb following glaucoma surgery.
  • Primary organisms: Streptococci (S. pneumoniae), Staphylococci, and H. influenzae.

Predisposing factors

  • Late bleb leaks, contact lens wear, and chronic topical antibiotic use.
  • Thin, avascular bleb morphology (mitomycin-C augmentation).

Red Flags

  • White milky bleb + AC reaction + vision loss → bleb-associated endophthalmitis.
  • Late-onset infections (months/years post-op) are often fulminant Streptococcus.
  • Any trabeculectomy patient with a red eye requires urgent assessment.
  • Delaying treatment (even by hours) significantly worsens visual prognosis.

Investigations

Slit-lamp biomicroscopy

  • High-magnification check for microhypopyon within bleb loculations.
  • Seidel test: To identify bleb leaks/portals of entry.
  • Vitreous assessment: To rule out Grade 3 endophthalmitis.

Microbiology

  • Culture the bleb surface and any leaking discharge.
  • Anterior chamber tap for culture in Grade 2 or higher disease.

Imaging

  • B-scan ultrasound: If posterior view is obscured and vitritis is suspected.

Treatment

Grade 1 (blebitis)

  • Fortified Vancomycin (25–50 mg/mL) alternating with fortified Ceftazidime (50 mg/mL) every 30 minutes for 24 hours.
  • Loading dose: One drop of each every 5 minutes for 4 doses.
  • Alternative: Fluoroquinolone (moxifloxacin or besifloxacin) every 1 hour.

Grade 2 (AC involvement)

  • Same topical regimen as Grade 1 plus cycloplegics.
  • Add oral fluoroquinolone (moxifloxacin 400 mg daily or ciprofloxacin 500 mg BID).
  • Maintain a very low threshold for escalation to tap-and-inject.

Grade 3 (endophthalmitis)

  • Immediate vitreous tap and intravitreal injection (vancomycin 1 mg + ceftazidime 2.25 mg).
  • Early pars plana vitrectomy is strongly preferred; bleb-associated cases are often fulminant.

Clinical Pearl

A "white milky" bleb set against an angry red conjunctiva is blebitis—intensive topicals can save the eye, but if untreated, the infection enters the eye within hours.

Differential Diagnosis

  • Conjunctivitis (bilateral, no milky bleb)
  • Episcleritis (localized redness, minimal pain)
  • Endophthalmitis (vitreous involvement)

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