What is the recommended evaluation and management for acute endophthalmitis, including intravitreal antibiotics, systemic therapy, and indications for vitrectomy?

Management of Acute Endophthalmitis

Immediate Diagnostic Approach

Perform an urgent diagnostic vitreous tap (or aqueous tap if vitreous unavailable) before initiating any antimicrobial therapy to obtain culture specimens and identify the causative organism. 1, 2 This is non-negotiable—culture results will guide definitive therapy and distinguish bacterial from fungal etiologies. 3

• Direct ophthalmoscopic examination is mandatory to assess the extent of vitritis, macular involvement, and anterior chamber inflammation 1, 2
• Look specifically for hypopyon, vitritis, or retinal periphlebitis as early clinical signs 4
• Obtain blood cultures if endogenous endophthalmitis is suspected (immunocompromised patients, injection drug users, patients with endocarditis or liver abscess) 5

Empiric Intravitreal Antibiotic Therapy

Immediately after obtaining cultures, inject intravitreal vancomycin (1 mg/0.1 mL) plus either ceftazidime (2.25 mg/0.1 mL) or an aminoglycoside into the vitreous. 2, 6 This is the cornerstone of treatment for bacterial endophthalmitis and must not be delayed. 3, 5

• Intravitreal antibiotics achieve therapeutic concentrations directly at the site of infection, which systemic antibiotics cannot reliably accomplish 7
• Multiple injections may be required (average 5.8 injections in severe cases) if there is inadequate response 6
• Critical pitfall to avoid: Subconjunctival injections alone are ineffective and should never replace intravitreal administration 1, 6

Indications for Immediate Vitrectomy

Perform urgent pars plana vitrectomy in the following situations: 1, 6

• Severe vitritis with poor view of the fundus
• Macular involvement or threat to the macula
• No improvement or worsening after initial intravitreal antibiotics within 24-48 hours
• Post-traumatic endophthalmitis with retained intraocular foreign body 4

Vitrectomy is sight-saving because it removes the bulk of inflammatory debris and infectious organisms, improving antibiotic penetration and reducing toxic inflammatory mediators. 7, 1

Systemic Antibiotic Therapy

Systemic antibiotics are MANDATORY for endogenous endophthalmitis to treat the underlying bacteremia and primary infection source. 2, 5 Use broad-spectrum IV antibiotics (vancomycin plus a third-generation cephalosporin or fluoroquinolone) until culture results return. 5

For exogenous bacterial endophthalmitis (post-surgical or post-traumatic), the role of systemic antibiotics is controversial and not clearly beneficial. 5, 8 The infection is confined to the eye, and intravitreal antibiotics are the definitive treatment. 8 However, many clinicians still add systemic antibiotics for severe cases or when there is concern for orbital extension. 3

Fungal Endophthalmitis Management

For Candida Endophthalmitis:

If the isolate is fluconazole/voriconazole-susceptible, use fluconazole 800 mg loading dose, then 400-800 mg daily OR voriconazole 400 mg IV twice daily for 2 doses, then 300 mg IV/oral twice daily. 7, 2, 6

• For fluconazole/voriconazole-resistant isolates, use liposomal amphotericin B 3-5 mg/kg IV daily with or without oral flucytosine 25 mg/kg four times daily 7
• With macular involvement or vitritis, add intravitreal injection of either amphotericin B deoxycholate 5-10 μg/0.1 mL sterile water OR voriconazole 100 μg/0.1 mL sterile water/normal saline 7, 1
• Systemic antifungals are essential because they treat concurrent candidemia and achieve adequate concentrations in the highly vascular chorioretinal layer 7

For Aspergillus Endophthalmitis:

Administer IV amphotericin B plus intravitreal amphotericin B (5-10 μg/0.1 mL sterile water) following diagnostic vitreal tap, combined with pars plana vitrectomy. 7, 2, 6

• Voriconazole (administered intravitreally or systemically) is an alternative and may be preferred based on case reports 7
• Systemic amphotericin B and itraconazole penetrate poorly into the vitreous and aqueous humor, making intravitreal administration critical 7

Treatment Duration and Monitoring

• Continue systemic antifungal therapy for at least 4-6 weeks, with final duration depending on complete resolution of lesions 1
• For bacterial endophthalmitis, continue intravitreal antibiotics until clinical improvement is evident (typically 1-3 injections) 6, 5
• Serial ophthalmologic examinations are essential to monitor response and determine need for additional interventions 1

Prognostic Indicators

Direct macular involvement is the strongest predictor of poor visual recovery. 1, 2, 6 Even with optimal treatment, these patients often have permanent vision loss.

• More virulent organisms (Bacillus species, Staphylococcus aureus, streptococci) have worse outcomes than coagulase-negative staphylococci 4, 5
• Delayed treatment significantly worsens prognosis—endophthalmitis is a true ophthalmologic emergency 2, 3

Critical Pitfalls to Avoid

• Never delay intravitreal antibiotics while waiting for culture results—empiric therapy must be started immediately after obtaining specimens 3, 5
• Do not rely on systemic antibiotics alone for exogenous bacterial endophthalmitis—they do not achieve adequate intraocular concentrations 7, 8
• Do not use subconjunctival injections as primary therapy—they are ineffective 1, 6
• Do not miss endogenous endophthalmitis in at-risk patients (injection drug users, immunocompromised, patients with candidemia or endocarditis)—these require systemic antimicrobial therapy in addition to intravitreal treatment 2, 5