Endophthalmitis

Classification

• Acute postoperative (after cataract surgery, most common)
• Delayed/subacute postoperative
• Bleb-related (post-trabeculectomy)
• Post-traumatic (including retained IOFB)

Postoperative Endophthalmitis (Most Common Form)

Incidence & Pathogenesis

• Posterior capsule rupture
• Prolonged procedure time / combined surgery (e.g. with vitrectomy)
• Clear corneal sutureless incision, temporal incision
• Wound leak on the first postoperative day
• Adnexal disease (blepharitis, dacryocystitis), diabetes
• Topical anaesthesia

Clinical Features

• Eyelid swelling, chemosis, conjunctival injection, discharge
• Relative afferent pupillary defect (common)
• Corneal haze
• Fibrinous exudate and hypopyon (hallmark sign)
• Vitritis with impaired fundal view
• Loss of red reflex
• Severe vitreous debris (see below)

Causative Organisms

Acute Postcataract

• Bleb-associated: Streptococcus or Gram-negatives (more virulent than post-cataract)
• Post-intravitreal injection: S. epidermidis and oral flora (notably Streptococcus)
• Post-traumatic: Staphylococcus spp. and Bacillus spp. (~90% of culture-positive cases)
• Subacute/delayed: Cutibacterium acnes (formerly Propionibacterium acnes), fungi

Differential Diagnosis

• TASS (Toxic Anterior Segment Syndrome): Occurs 6-24 hours post-cataract; diffuse corneal edema with KP; sterile, due to endotoxin on instruments. Responds to steroids.
• Acute noninfectious uveitis flare (HLA-B27 associated)
• Sterile endophthalmitis (e.g. after intravitreal triamcinolone or anti-VEGF)
• Retained lens particle uveitis
• Vitreous hemorrhage (especially depigmented blood)

Management

Step 1: Sample First

• Aqueous tap: 0.1-0.2 mL via limbal paracentesis (25G needle on tuberculin syringe)
• Vitreous tap: More likely to yield positive culture; 0.2-0.4 mL from mid-vitreous at 3.5 mm from limbus in a pseudophakic eye; use a disposable vitrector if available
• B-scan ultrasound before sampling if no clinical view (to exclude retinal detachment)

Note: C. acnes requires anaerobic culture held for 14 days - it will be missed otherwise.

Step 2: Intravitreal Antibiotics (Cornerstone of Treatment)

Intravitreal vancomycin used routinely as prophylaxis has been associated with haemorrhagic occlusive retinal vasculitis and should be avoided in prophylaxis.

Step 3: Adjuncts

• Oral fluoroquinolone: Moxifloxacin 400 mg/day x 10 days (excellent ocular penetration)
• Topical antibiotics: Vancomycin 5% or ceftazidime 5%, 4-6x daily (limited benefit, mainly to protect wounds)
• Subconjunctival antibiotics: Vancomycin 50 mg + ceftazidime 125 mg (doubtful additional benefit when intravitreal given)
• Topical steroids: Dexamethasone 0.1% 2-hourly; start after 48 hours (once fungal infection excluded)
• Topical mydriatic: Atropine 1% twice daily
• Oral steroids: Prednisolone 1 mg/kg/day in severe cases after 12-24 hours (fungal infection excluded); The EVS protocol used prednisone 60 mg/day x 5 days

Step 4: Pars Plana Vitrectomy (PPV)

• Immediate PPV is indicated when VA = light perception only -- 50% reduction in severe visual loss
• Eyes with VA of hand movements or better do NOT benefit from immediate PPV over tap-and-inject alone
• EVS conclusions apply to post-cataract surgery; cannot be extrapolated to all forms

Step 5: Follow-up at 48 hours

• Relief of pain is a useful early sign of response
• Look for contraction of fibrinous exudate and reduction of hypopyon
• If worsening: review sensitivities, modify antibiotics, consider PPV if not yet done, repeat intravitreal antibiotics
• Avoid repeated amikacin (retinal toxicity risk)

Delayed-Onset (Subacute) Postoperative Endophthalmitis

• Onset: Weeks to months after surgery
• Classic organism: Cutibacterium acnes -- presents as recurrent anterior uveitis, granulomatous KP, white lens capsular plaque, minimal injection/pain, only transient response to steroids
• Other organisms: Fungi (Aspergillus, Candida, Cephalosporium), S. epidermidis
• Treatment: Similar initial approach; if C. acnes, may require removal of IOL and capsular remnants; if fungal, intravitreal amphotericin B (5-10 μg/0.1 mL) or voriconazole (100 μg/0.1 mL)

Bleb-Related Endophthalmitis (Post-Trabeculectomy)

• Organisms are significantly more virulent than post-cataract (streptococcal, Gram-negatives)
• Symptoms far more severe than blebitis
• Signs: White milky bleb, severe injection, large hypopyon, vitreous involvement, loss of red reflex
• Treatment: Vitreous + aqueous samples immediately; ceftazidime 2 mg + vancomycin 2 mg intravitreal; repeat at 48h; consider posterior vitrectomy; oral fluoroquinolones x 10-14 days; topical steroids after 48h

Post-Traumatic Endophthalmitis

• Risk in ~1/10 penetrating trauma cases with retained IOFB
• Prophylactic antibiotics (ciprofloxacin 750 mg twice daily or moxifloxacin 400 mg once daily) for open globe injuries
• Prompt IOFB removal is paramount
• Prophylactic intravitreal antibiotics for high-risk cases (agricultural injuries)

Endogenous Endophthalmitis

• Hematogenous seeding in patients with sepsis, IV drug use, immunosuppression, or indwelling catheters
• Klebsiella pneumoniae associated with liver abscess is the leading cause of endogenous bacterial endophthalmitis (especially in Asia)
• Fungal endogenous: almost exclusively Candida spp. (yeasts); Aspergillus also occurs
• Treatment: systemic antibiotics targeting the primary source + intravitreal antibiotics

Prognosis

Prophylaxis (Cataract Surgery)

• 5% povidone-iodine in conjunctival fornices for ≥3 minutes before surgery (strongest evidence)
• Intracameral cefuroxime 1 mg/0.1 mL at end of surgery (first choice)
• Intracameral moxifloxacin 0.5 mg/0.1 mL if cefuroxime unavailable
• Treatment of pre-existing blepharitis, dacryocystitis, conjunctivitis
• Early resuturing of leaking wounds
• Avoid intracameral vancomycin as routine prophylaxis (risk of HORV)

• Kanski's Clinical Ophthalmology: A Systematic Approach, 10th ed., Ch. 10-11 (Acute & Delayed Postoperative Endophthalmitis; Bleb-Related & Post-Traumatic Endophthalmitis)
• The Wills Eye Manual, 8th ed., §12.13 (Postoperative Endophthalmitis)
• Tietz Textbook of Laboratory Medicine, 7th ed. (Eye Infections; Endophthalmitis)
• Robbins, Cotran & Kumar Pathologic Basis of Disease (Endophthalmitis)
• Recent meta-analysis (PMID: 39167582): Visual outcomes by organism in post-intravitreal injection and post-cataract endophthalmitis (2024, Retina)