Postoperative Endophthalmitis

Postoperative endophthalmitis is intraocular infection after intraocular surgery, most often cataract surgery, with an incidence of about 0.04 to 0.2 percent. It is a vision threatening emergency.

• Acute (within 6 weeks, most within the first week): coagulase negative staphylococci (about 70 percent), Staphylococcus aureus, streptococci, enterococci, and Gram negative organisms (Pseudomonas, Haemophilus), which have a worse outcome.
• Delayed or chronic (over 6 weeks): Propionibacterium acnes (Cutibacterium), coagulase negative staphylococci, fungi (Candida, Aspergillus), and mycobacteria.
• Bleb associated: streptococci and Haemophilus after glaucoma filtering surgery, can occur years later.
• Risk factors: posterior capsule rupture with vitreous loss, clear corneal incision, prolonged surgery, wound leak, blepharitis, nasolacrimal duct obstruction, diabetes, immunosuppression, absence of intracameral antibiotic, contaminated solutions.

• Acute: marked reduced vision, pain (absent in a minority), red eye, eyelid swelling, corneal oedema, severe anterior chamber reaction with hypopyon or fibrin, vitritis with poor fundus view, absent red reflex.
• Delayed fungal or P. acnes: smouldering inflammation, white plaque on the capsule or intraocular lens, granulomatous keratic precipitates, recurrent inflammation after steroid taper.
• Visual loss is usually severe; there may be corneal ring infiltrate and wound abscess.

• Clinical diagnosis; do not delay treatment for investigations.
• Aqueous tap (0.1 to 0.2 mL) and vitreous tap or biopsy (0.2 to 0.5 mL with a 23 or 25 gauge needle or vitrectomy cutter) for Gram stain, culture (blood and chocolate agar, anaerobic broth, Sabouraud agar) and multiplex PCR or 16S ribosomal DNA PCR.
• B-scan ultrasound if the view is poor (vitreous opacities, retinal or choroidal detachment).
• Blood cultures in suspected endogenous cases; check glucose.

• Same day treatment (within hours). Obtain samples then inject intravitreal antibiotics:
  • Vancomycin 1 mg in 0.1 mL (for Gram positives), plus ceftazidime 2.25 mg in 0.1 mL (for Gram negatives). In patients with severe penicillin or cephalosporin allergy, use amikacin 0.4 mg in 0.1 mL (caution, retinal toxicity) in place of ceftazidime. Use separate syringes and needles.
  • Optional intravitreal dexamethasone 0.4 mg in 0.1 mL to reduce inflammation, given with or after the antibiotics.
• Pars plana vitrectomy: urgent when vision is light perception only or worse (shown to improve outcomes); also useful for fungal, delayed and non-responding cases. Repeat intravitreal antibiotics at 48 to 72 hours if the eye worsens.
• Adjunctive: topical fortified antibiotics (vancomycin 50 mg/mL and ceftazidime 50 mg/mL hourly), topical prednisolone acetate 1 percent every 1 to 2 hours (after the antibiotic is administered), atropine 1 percent twice daily, oral moxifloxacin 400 mg daily (good vitreous penetration) or intravenous in severe cases, and pressure control.
• Delayed P. acnes: intravitreal vancomycin 1 mg, vitrectomy with total capsulectomy, and lens removal or exchange when plaque persists.
• Fungal: intravitreal voriconazole 100 micrograms in 0.1 mL or amphotericin B 5 to 10 micrograms in 0.1 mL, vitrectomy, plus oral voriconazole 400 mg twice daily on day 1 then 200 mg twice daily (or 6 mg/kg then 4 mg/kg) for 4 to 6 weeks.
• Bleb associated: intravitreal vancomycin and ceftazidime, vitrectomy, treat the bleb.
• Prophylaxis: povidone iodine 5 percent to the conjunctival sac (3 minutes), 10 percent to skin, intracameral cefuroxime 1 mg in 0.1 mL (or moxifloxacin 0.5 mg in 0.1 mL) at the end of surgery, treatment of blepharitis and lacrimal obstruction, and sterile technique with meticulous wound closure.
• Review daily and expect improvement within 24 to 48 hours; failure suggests resistant organism, requiring repeat taps.